I want to fabricate a Nexus 7 to be the head unit for my car. help? - Nexus 7 Q&A, Help & Troubleshooting

http://amazon.nuforce-icon.com/NuForce-Icon-uDAC2-Silver-Headphone-Amp/M/B003Y5LY1C.htm
Will this work with a Nexus 7 charging with a high output car charger?
Also, since it's only 2vrms line output, and only two RCA outs, and I'd need to split it into 6 channels, 4 for my Alpine 4 channel amp, and 2 more for my Alpine 400 watt class D monoblock amp, I'd only have about .6 volts going into my amps which is nowhere near enough. Correct me if I'm wrong, but I'd need at least 18v total for the pre out ideally for lossless audio (3v per channel) to ensure minimal crosstalk between cables and good response from volume?
http://www.amazon.com/Rockford-Fosg...F8&qid=1349079396&sr=1-1&keywords=line+driver
My car system is high fidelity by all means. I have some 5.25" Kevlar woofers in the door panels I ripped out of my professional studio monitors, some swivel mount silk dome tweeters mounted at ear level, and the crossover system from a good Alpine 6.5" set that the tweeters also came out of pushing 80 watts RMS and about 90db efficiency in the door panels and some Alpine 6x9"s coaxial silk domes in the back pushing 70 watts RMS. 89db efficiency. the component speakers all easily handle over 200 watts peak, and I have a nice 4 channel Alpine 100 watt per channel 0.5%THD amp powering my components, then a 400 watt Alpine monoblock class D amp powering my dual Alpine 12" Type E Kevlar reinforced pulp cone subs in a really nice box good enough to have only one driver running, and the other will act as a passive radiator, in a vented box. They are 200 watt RMS and 750ish peak each and about 90db efficiency. Also a .5 Farad Capacitor is hooked up to both amps, just to help with lights dimming and give my system all the peak power it needs. Lights don't dim at all with the new cap, and subs/door speakers slam way harder than without it.
Anyway, some assholes are going to say my system is garbage, but A: I paid about $350 for it and installed it myself and B: it would cost more than I could even sell my car for for a professional to install what I installed. I'm guessing they'd ask at LEAST $1500 for what I have done to my car.
Anyway.. I need to know the best possible way to hook up a Nexus 7 fabricated into my dashboard, and will GPS work on the wifi model or no? I plan on having GPS everywhere, using my Galaxy note as a wifi hotspot with my grandfather clause unlimited data, and having the Nexus 7 act as the head unit itself. I doubt this has ever even been done before, and I doubt they even have a coax 4.1 high fidelity audio decoder for car audio application. Any hifi preamp Iv'e ever seen was around 2v pre outs. I need 3v+ per channel for 6 channels. Someone help me figure this out please?

Why is it every time you ask a question you go into some juvenile diatribe about everything you own. Don't you realize that makes people want to punch you in the face?
Sent from my SAMSUNG-SGH-I717 using Tapatalk 2

gps will work without wifi. just download a navigation app like route 66 or something.
there are many creative ways to mount your n7 as a audio system head for your car. you'll need a dedicated power source. a nice structure to dock it while looking clean. there are kits for the n7 out there to hook up the amp.

it will work.
https://www.youtube.com/watch?v=EdLi9wCFZ7M&feature=youtube_gdata_player
Theres a video showing it works.
I was recently at a car show in Tyler Texas. The dude had a Tablet molded in his dash. With the USB and 3.5mm aux cable attached. Non removable tablet. The aux cable was wired to his MEECHLESS Head unit in his glove box. It looked and sounds amazing. Had a few subs and amps.
If you don't want to use a seperate hidden head unit. There are control boxes that splice standard wire to a a set of 2volt preouts for your subs. F/r/s.

Related

Joying SQ

I've been reading mixed reviews on the SQ of these units. I've read about the mod and it sounded like the sound just got louder. But is the sound fine and just flat sounding or is it something else? I was thinking a line driver would help or maybe it would just amplify the noise. I have some decent audio equipment and I don't want to feel I'm not getting the full potential out of them. I do use some WAV and FLAC files. I guess I can't tell if people are commenting on the on board audio or from their amps hooked up to the RCAs.
I have a 2016 Jeep Wrangler Unlimited. I had the factory 430N head unit, with the base 8 speaker system. I replaced 4 of the 8 speakers with Kickers and add a Kicker sub and amp (amp is just for the sub), and it sounded better but still not great.
THis weekend I added a Joying Jeep specific unit, and I feel like the sound of the overall system is vastly improved. I think it sounds pretty good, I primarily use Google Play Music and Pandora.
CadillacMike said:
I have a 2016 Jeep Wrangler Unlimited. I had the factory 430N head unit, with the base 8 speaker system. I replaced 4 of the 8 speakers with Kickers and add a Kicker sub and amp (amp is just for the sub), and it sounded better but still not great.
THis weekend I added a Joying Jeep specific unit, and I feel like the sound of the overall system is vastly improved. I think it sounds pretty good, I primarily use Google Play Music and Pandora.
Click to expand...
Click to collapse
Did you add a line driver at all to bump up the voltage on the pre-outs?
splxtreme said:
Did you add a line driver at all to bump up the voltage on the pre-outs?
Click to expand...
Click to collapse
I did not add anything. The sub and amp are built for Jeep, so it might be a little weird:
http://www.kicker.com/SWRA411
have any of you measure the pre-out voltage on the joying? On my tonghai create 2nd gen unit, pre-out voltage is only 1V. What this means is you will have a high noise floor going into your amplifier. Then your amp will amplify any noise your pre-outs have picked up. So if you use a line driver to raise the pre-out voltage prior to going into your amp, the higher voltage actually LOWERS the noise floor, hence eliminating noise that your RCAs may pick up.
My advice is you MUST have a line driver if you plan to use these units w/ a external amp. The difference will be night and day, particularly in the higher frequencies, where amplified noise is more pronounced.
They are dirt cheap too. I bought one on amazon for ~$30. It is actually a 3-way cross-over/line driver combo. It feels cheap but does it's job as a line driver very well.
edit: I say the above from personal experience, as I literally spent months trying to figure out why my tweeters always sounded so terrible. Line driver did the trick. Now I have clean highs and more clear, vibrant mids. I don't seem to notice much difference in my bass, so apparently noise interference isn't audible in the lower frequencies.
explain "line driver" to a stupid dumb dumb person, not me of course, just so other people understand
CadillacMike said:
explain "line driver" to a stupid dumb dumb person, not me of course, just so other people understand
Click to expand...
Click to collapse
line driver is just another word for a voltage step-up device. It's simply a way to increase the voltage of the RCA pre-outs coming out of your HU. Most amplifiers can read all the way down to about .5V pre-outs no problem. So a low pre-out voltage isn't much of a problem in theory.
But, an amplifier is also a voltage step-up device. It's going to take the pre-out voltage and multiply it by a pre-determined amount. You can adjust that amount by modifying gain. Your speakers are rated for a certain RMS power (80W for instance). So, if your speakers are 4 ohms rated for 80W RMS, the formula for the voltage it needs from your amp is sqrt(80 * 4) = 18V. So for your speaker to get the full rated power, it needs at least 18V from your amp. Higher pre-amp voltage = easier to reach the rated output to your speakers, since less gain is required.
Also, I mentioned noise floor. It's explained well here -
http://www.glasswolf.net/papers/preouts.html
It's not so easy to explain in laymans terms, but just know that higher voltage pre-outs = higher signal to noise ratio (SNR), meaning more signal & less noise = lower noise floor.
The article does mention however that having too high of a pre-out voltage is not good either, as it can lead to clipping. Best to buy an adjustable line driver (the $30 amazon model I bought had this feature... this one -
https://www.amazon.com/SX310-Pre-Am...70255121&sr=8-1&keywords=electronic+crossover). Most devices that accept pre-outs max out at around 6V, some as low as 4V. So don't crank up the line driver to max... I leave mine around 75-80%.
Hope that helps.

Decent audio upgrade: Adding cost effective low profile amp

Just found this cool amp the other day. Sorry if it's been mentioned before.
For those who don't know, head units have an amp, per say, built in to them. However, most are junk and just large enough to get you by. Even the ones that have high claims. Like 50watts X 4, but your really only getting like 15 watts per channel. A lot of people don't want to mess with all the wiring and connections and cost/space issues with installing a traditional outboard amp in their trunk. I came across this little bugger that has great reviews and may be the ticket for some of you. It's an amp, but with a slim profile and able to hide in your dash behind your headunit. Idk, just thought I'd share.
https://www.amazon.com/Alpine-KTP-445U-4-channel-Power-Amplifier/dp/B003VVYL46
well i clicked on this thinking i would not be interested, but now I'm thinking I might get this
hurtgen said:
Just found this cool amp the other day. Sorry if it's been mentioned before.
For those who don't know, head units have an amp, per say, built in to them. However, most are junk and just large enough to get you by. Even the ones that have high claims. Like 50watts X 4, but your really only getting like 15 watts per channel. A lot of people don't want to mess with all the wiring and connections and cost/space issues with installing a traditional outboard amp in their trunk. I came across this little bugger that has great reviews and may be the ticket for some of you. It's an amp, but with a slim profile and able to hide in your dash behind your headunit. Idk, just thought I'd share.
https://www.amazon.com/Alpine-KTP-445U-4-channel-Power-Amplifier/dp/B003VVYL46
Click to expand...
Click to collapse
45RMS, not terribly small there.
FYI: Those head units that say 40 or 50 watts x4 aren't lying -- they're quoting MAX, not RMS.
Generally speaking, you don't need more than about 40-50 max. If you send too much power, you will damage your speakers. The speakers that cars come with are a reasonable match with the FACTORY radio, which will give you around 40 max. Sustained use at even factory radio's highest output will dramatically shorten the life of the speakers, AND, is enough to cause permanent hearing loss.
Some aftermarket speakers can take a higher amount of input power, but they aren't necessarily LOUDER. They actually require more power to generate the same volume. Now of course, I'm not going into the discussion about which *sounds better*, rather just about raw power. My only point, is that if you have factory speakers, then even this amp is overkill. If you want to improve the sound QUALITY, then of course, by all means, knock yourself out. But don't forget to upgrade your speakers as well, or you're just throwing the money down the toilet.
The number one cause for blown speakers is driving them with an underpowered amplifier resulting in clipping. It's much more advisable to over power a speaker than to under power, which is the case in most cars in Stock form. This amp would be a great addition to a vehicle with either stock speakers or entry level coaxial or even some components. In my situation I'm running a pair of Infinity Kappa 60.11cs rated at 90 watts rms each @ 2ohm and powering them with a Rockford Fosgate p300x2 putting out 150 watts rms @ 2ohms per channel.
Reading the reviews, it sounds like many people are installing this with stock speakers in place and are having great results.

Joying finally made a head unit with DIGITAL OUTPUT SPDIF!!!

So i was browsing through joyings new intel head units on their site with DSP. I found that all intel based joying headunits with their DSP now have a SPDIF coaxial output. This is a huge step for them since many of us been trying to use a USB DAC for toslink or SPDIF output.
A regular name brand HIGh res deck with SPDIF output runs over 1200$ . And their not even touch screen.
Joying finally woke up and did it, now us guys with fancy name brand DSP’s can finally send true digital coax output to them. I will be ordering one of theses units and not utilizing the dsp that is built in. Simply because i find that they are not there yet with their built in dsp’s for individual speaker functions. I have a nice audio control dsp that has a coax input.
Enjoy!
if u order it pls make some pics of android board and som
Subscribed... I'm thinking buying one. I found two version. 2/16 and 4/32 GB. What do you suggest? Enough the 2/16, or better the 4/32 version?
Depending on what your looking at doing with the unit. Im going all out with the 4gb of ram. I caught myself multitasking on the 2gb ram units (not joying) and the audio would studder sometimes.
Theses new joyings will change the revolution of car audio with this coaxial output!
Ill be able to listen to “tidal” app do get high lossless sound tracks right to my Audiocontrol 608 DSP via coaxial.
The only other way to do digital sound is an ipad or the highly priced sony unit at 1500$ for a single dine with no display?.
mahtew said:
if u order it pls make some pics of android board and som
Click to expand...
Click to collapse
I will try and do so
Just ordered mine, but with 2.5inch curved IPS display. I will try to make a frame to fit my car.
I won't be using the digital out for now, I will try the RCA out first and see. I like the build in eq.
My last joying unit had hissing noise when not playing music, hope this one will be quieter.
Yeah. For the average user, their dsp seems to have eq front and rear independently. Which is nice.
You can also order a longer ribbon for their screens to locate the unit in a different area from their screens. This would probably help with the mold you want to make for your display.
If you have a high fidelity sound stage like me. : tweeter on an amp, mid ranges on a separate amp, woofers on another amp . Then rear stage on another amp, then all amps hooked up to a 10 ch output dsp to control each speaker independently.
The built in dsp is no good for me. But the digital output will be king to supply my external dsp with digital audio??
guimond47 said:
Yeah. For the average user, their dsp seems to have eq front and rear independently. Which is nice.
You can also order a longer ribbon for their screens to locate the unit in a different area from their screens. This would probably help with the mold you want to make for your display.
If you have a high fidelity sound stage like me. : tweeter on an amp, mid ranges on a separate amp, woofers on another amp . Then rear stage on another amp, then all amps hooked up to a 10 ch output dsp to control each speaker independently.
The built in dsp is no good for me. But the digital output will be king to supply my external dsp with digital audio??
Click to expand...
Click to collapse
I did research some DSP (Thanks for the tip on youtube). I came up with the Rockford Fosgate DSR1 for $283, which was the cheapest of them all. I will wait and try out the build in DSP first before jumping onto this one.
I currently have an 5 channel infinity amp coupled with a pioneer monoamp for the sub.
I am also using component in front and coaxial in rear. I am using the crossover that came with infinity speakers for the front.
Not sure if I should connect the sub directly to the unit or leave it connected to the infinity amp. I will have to play around and see which gives better sound.
The rockford is a nice unit, i tried it out myself. I am not sure if it has a coaxial digital input. I forget.
Another thing i did not like was it does not have presets and their app is not too android friendly...(to be run on a head unit apk)
And i also forget if it has volume control knob...
This is why i went with audio control.
My head unit should be arriving by next weekend i hope . Then ill be gearing up to make a huge review video , based on audio quality and features and obviously the new spdif digital output!
Can you test the rcas as well and not just spdif? I'm planning on getting one myself but I will only go digital if the normal rca output is bad. Also can you test spdif to see if you can control the volume through headunit or steering wheel controls instead of using dsp volume knob? I guess if you could be as thorough with some of thr main feature(wifi, Bluetooth, 4g, sound quality from both outputs, camera input etc) that would be very helpful. I've never pulled the trigger on an android headunit because the lack of some features and poor sound quality but I'm almost ready to get this one. Which size did you buy?
I will for sure be doing exactly as you mentionnned above. I will also be using my oscilloscope to measure distortion in the rca’s. I had a eonon headunit and there was terrible noise in the rca’s and even more noise when a Hard drive was plugged into the usb ports. And more noise with my 360view camera hooked up.
I will be doing bench testing first then i will be moving to vehicle testing.
I bought the double din 10.1” headunit intel with 4gb ram and 32gb ssd.
Its going in my 1997 chev c/k1500 pick up. I have hifi audio in there . Ill be doing more upgrades down the road as well.
Sweet. I'm excited to see the results. I just hope it isn't a let down. I really want to go ahead and order one but if you're doing a review I'd rather wait. I've wanted an android head unit since they came out. I've even looked at building a raspberry pi or like rock pi and adding a screen but I just don't think I'd be happy with the results. These Android head units really have a lot of features but the sound quality has been the deal breaker for me. I asked JOYING what their rca voltage is and they always tell me they don't have voltage... Not sure what they mean but whatever. For all of our sakes I hope this one gets the job done.
Mine will be delivered tomorrow, but I wont be to test it out until next weekend since i will be out of town.
For sound, i will be using the rca going to my amp, not planning g on using a DAC right now.
Just make sure you tell us about it as soon as possible lol.
Just got mine yesterday, but what a disappointment, no digital audio out. Although I did order the one with the digital audio out.
I emailed them back, but they told me they are on vacation and will not return until Feb14 or something, but the lady said she will replaced it for me.
I just powered it on on my bench, so I have not been able to play with the audio in the car or the equalizer, will do so this weekend.
The 10.1 2.5D curved screen is nice though
checksum123 said:
Just got mine yesterday, but what a disappointment, no digital audio out. Although I did order the one with the digital audio out.
I emailed them back, but they told me they are on vacation and will not return until Feb14 or something, but the lady said she will replaced it for me.
I just powered it on on my bench, so I have not been able to play with the audio in the car or the equalizer, will do so this weekend.
The 10.1 2.5D curved screen is nice though
Click to expand...
Click to collapse
Dang that sucks. It looks like it has the 4g dongle built in. Are you able to test that out?
Usually its under the yellow cap... instead of the yellow video 2 out, it will be a green rca. Take off your yellow caps.
My video should be on YouTube by tomorrow.
Everything you can ever possibly want in an android headunit is finally here. Crisp sound through the digital source and no noise or hiss on the rca’s .
Be patient i will post a youtube link shortly. Better grab popcorn, my vid is 1.5 hour long lol
guimond47 said:
Usually its under the yellow cap... instead of the yellow video 2 out, it will be a green rca. Take off your yellow caps.
My video should be on YouTube by tomorrow.
Everything you can ever possibly want in an android headunit is finally here. Crisp sound through the digital source and no noise or hiss on the rca’s .
Be patient i will post a youtube link shortly. Better grab popcorn, my vid is 1.5 hour long lol
Click to expand...
Click to collapse
That's great news. Can't wait to see the review. Did you order model(JY-UO134N4G)? I want to make sure I get the right one when I go to order.

bottom line on Android head units and connecting amps and subs

I've actually purchased a few of these over the years, mostly because they were very vague on this specific feature. Given many of these units are identical just rebranded copies it's hard to sort things out.
The following is based on countless hours searching the web and 4 or 5 personal purchases of these Android head units. If any of this is incorrect please tell me because I have been desperately searching for one due to BMWs incessant need to one off everything.
In my experience the bottom line is no. Android head units do not offer genuine sub support. Yes you can use the rear output and a line converter or run the signal into the high level inputs on your amp (if it has it) but there is still a very simple a basic problem. You still won't have the needed components and or firmware to properly run it. Specifically frequency control, crossover or even a 7 band eq on the unit. I only found one that offered that last and it was janky to say the least (more probably offer the eq now but still very subpar) assuming you can run v4a on the unit that may clear some up but that was written for head phones not a 4 or more speaker system.
Another point is most mainstream headunits, pioneer, Kenwood, alpine heck even boss have 4v rca preout and signal conditioners not to mention both high and low-pass crossovers.
Unfortunately to my knowledge these Chinese Android suppliers have really missed the ball. Yes they offer some cool features but car audio guy's spend many thousands of dollars on these systems and to be honest I have a avh-4500NEX in my 325xi and since it mirrors wirelessly as well as Android auto and car play wireless it provides excellent sound.
Major difference my NEX $1800.00 us brand new these Android's I've seen get spendy but mostly right around 150-400. But you get what you pay for.
The biggest bonus I found though was you can put them anywhere since they are mostly just and inch or two deep.
If I missed the mark please let me know and if you could send a link to where I can pick up a decent one. The I-Drive in my 535i is making a stereo upgrade next to impossible
this is the honest **** i been scouring for... as a AV guy everyone keeps telling me go daisaita blah blah blah but everyone here seems to not have ears or know what they are talking about when it comes to sound... my original gut was to pick up a NEX but i got side tracked with Atoto and the rest because everyone talks out their ass about how amazing they are... with no clue about their soul purpose
they do have
b1n4ry said:
this is the honest **** i been scouring for... as a AV guy everyone keeps telling me go daisaita blah blah blah but everyone here seems to not have ears or know what they are talking about when it comes to sound... my original gut was to pick up a NEX but i got side tracked with Atoto and the rest because everyone talks out their ass about how amazing they are... with no clue about their soul purpose
Click to expand...
Click to collapse
They have amazing abilities for instance the iDrive in my 525i is old and outdated and these Android HU are the only option and they are fully functional and compatible which no mainstream HU can claim that I'm aware of. But I'll deal with old and crappy and tap the harness for a signal for my amp before I'll downgrade on sound quality.
You can use an Android successfully IF you install an EQ and probably noise filter but there goes the saving you would have seen.
Spdif out to dsp-amp is possible with Joying for example. SQ shouldn't be problem with it.
Kelynaw said:
If I missed the mark please let me know and if you could send a link to where I can pick up a decent one. The I-Drive in my 535i is making a stereo upgrade next to impossible
Click to expand...
Click to collapse
I've had pioneer, Kenwood, Alpine, Blaupunkt and a few others and you haven't missed the mark at all. The audio quality on these Chinese head units is just not comparable and the RCA output voltages (1.4 volts) are standards from 15 or 20 years ago. And yes... they are NOT true sub outputs.
Now having said that, it doesn't mean that you can't bring the audio quality up to par. It does however require some extra money and extra components. I don't run Dasaita's sub outputs but rather have an active electronic crossover which can generate a sub output and I run that plus the Dasaita's front/rear outputs through an AXXESS dsp sound processor before the signals go into the amps.
It's certainly a bit of extra money spent on top of it all, but IMO, worth it because these Android head units beat out the traditional Kenwood's and pioneer's in just about every other respect.
It WOULD be nice however if these Chinese manufacturers started paying a bit more attention to audio quality at the end of the day.
Bob_Sanders said:
I've had pioneer, Kenwood, Alpine, Blaupunkt and a few others and you haven't missed the mark at all. The audio quality on these Chinese head units is just not comparable and the RCA output voltages (1.4 volts) are standards from 15 or 20 years ago. And yes... they are NOT true sub outputs.
Now having said that, it doesn't mean that you can't bring the audio quality up to par. It does however require some extra money and extra components. I don't run Dasaita's sub outputs but rather have an active electronic crossover which can generate a sub output and I run that plus the Dasaita's front/rear outputs through an AXXESS dsp sound processor before the signals go into the amps.
It's certainly a bit of extra money spent on top of it all, but IMO, worth it because these Android head units beat out the traditional Kenwood's and pioneer's in just about every other respect.
It WOULD be nice however if these Chinese manufacturers started paying a bit more attention to audio quality at the end of the day.
Click to expand...
Click to collapse
except that axxess unit costs more than the 4/64gb headunit itself... USA MSRP: $422.00 USD
b1n4ry said:
except that axxess unit costs more than the 4/64gb headunit itself... USA MSRP: $422.00 USD
Click to expand...
Click to collapse
HUH??
$279 on ebay
https://www.ebay.com/itm/Axxess-AX-...241633?hash=item445ecc93e1:g:194AAOSwUKRfRo-R
My new Dasaita cost $586
https://www.aliexpress.com/item/4001197637149.html?spm=a2g0s.9042311.0.0.554d4c4duJ2EgH
Bob_Sanders said:
HUH??
$279 on ebay
https://www.ebay.com/itm/Axxess-AX-...241633?hash=item445ecc93e1:g:194AAOSwUKRfRo-R
My new Dasaita cost $586
https://www.aliexpress.com/item/4001197637149.html?spm=a2g0s.9042311.0.0.554d4c4duJ2EgH
Click to expand...
Click to collapse
DSP
https://axxessinterfaces.com/product/AXDSP-X
unit i was looking at
https://www.aliexpress.com/item/4001244806859.html?spm=2114.12010612.8148356.2.51e67ea7IZbacK
Dash Kit
https://www.scosche.com/2003-to-2007-honda-accord-integrated-touchscreen-control-colution-dash-kit
Apparently you haven't played with any of the recent Joyings....You also obviously don't have much experience with different cell phones out there either.
Ok, fine....show me a Pioneer, Alpine, Kenwood, etc that can run Google Maps, Waze, Firefox, Gaia Navigation, Torque Pro, APRS Droid, etc natively, right on the unit....just ONE unit, from ANY of the "big name" manufacturers...they just plain don't exist. Not a single one that runs Android natively, or anything else other than their own, completely closed souce, proprietary OSes that we can't do anything with beyond what comes installed on them from the factory. Don't like their nav app, launcher, or general interface? Tough schmitt...
I've said the same thing for many years...I'd be HAPPY to drop a $1,000USD or more on a solid unit from a major manufacturer that runs Android natively. Or even a Linux based OS, that I can add additional apps to. Hell, I was dropping a thousand plus on putting a touch screen in my dash connected to a PC tower in the back YEARS before these factory double din units hit the market. Some company like Pioneer drops one of them, and I'd be one of the first in line screaming "take my money!!".
Screen mirroring isn't an option for everyone either, as screen mirroring is largely based on Miracast. Especially so for anyone with a Google phone, such as my Pixel. Google has gone out of their way to limit or even eliminate that ability to push more sales of their lousy Chromecast devices, and they have stripped Miracast support out of the core Android as of version 6 (Marshmallow). If your phone supports screen mirroring, that's because whoever made it added Miracast support back in themselves. Android Auto is also a rather lousy compromise for many of us, such as myself, that want to run alternative apps. If it wasn't coded to run within Android Auto, it generally ain't happening which is the case for the navigation app that I use for off road purposes.
I've tried several different Pioneer double din touch screens with several different Android phones. Never once was I able to get screen mirroring/mirrorlink to work correctly to truly screen mirror the phone. Only the crippled Android Auto worked...which is what ultimately pushed me into completely going with these Chinese Android head units.
That said, the Joying JY-UO135N4GS - https://www.joyingauto.com/joying-l...avigation-system-with-built-in-4g-module.html that I have in the truck right now does have a 16 band EQ built in, F&R RCAs as well as a dedicated Sub RCA output, though it's a single. I haven't put a meter on it to verify voltage, but I'm guessing it's around 2V based on gain settings on the amp compared to other head units that I've known to have 2V outputs. A LOT of "brand name" head units today still come with 2V outputs. Also has both LPF and Subsonic filters on the sub output, as well as independent HPF crossovers on F&R channels. I currently have my subs set to 30Hz-100hz, fronts set to 80Hz high pass, and rears at 135Hz high pass (yeah..blame Chevy and their piss poor design on their trucks). Subs are a pair of JBL GTO 12s fed by a Kenwood monoblock amp. Door speakers are Infinity Kappa 6.5s, rears are factory 4x10s.
Is the sound quality on par with the Pioneer head unit that it replaced? No. Can I hear the difference at 75mph over the wind and diesel engine noise? Nope. Maybe I'd hear the difference if I put one of these Joyings in my Cadillac...Do I plan to replace this Joying with a Pioneer/Alpine/Kenwood/etc? Wait for it....has not ever once crossed my mind. I also have a Joying in my Suzuki Samurai, and am shopping for another Android unit for my Suzuki Grand Vitara.
urbex said:
Apparently you haven't played with any of the recent Joyings....You also obviously don't have much experience with different cell phones out there either.
Ok, fine....show me a Pioneer, Alpine, Kenwood, etc that can run Google Maps, Waze, Firefox, Gaia Navigation, Torque Pro, APRS Droid, etc natively, right on the unit....just ONE unit, from ANY of the "big name" manufacturers...they just plain don't exist. Not a single one that runs Android natively, or anything else other than their own, completely closed souce, proprietary OSes that we can't do anything with beyond what comes installed on them from the factory. Don't like their nav app, launcher, or general interface? Tough schmitt...
I've said the same thing for many years...I'd be HAPPY to drop a $1,000USD or more on a solid unit from a major manufacturer that runs Android natively. Or even a Linux based OS, that I can add additional apps to. Hell, I was dropping a thousand plus on putting a touch screen in my dash connected to a PC tower in the back YEARS before these factory double din units hit the market. Some company like Pioneer drops one of them, and I'd be one of the first in line screaming "take my money!!".
Screen mirroring isn't an option for everyone either, as screen mirroring is largely based on Miracast. Especially so for anyone with a Google phone, such as my Pixel. Google has gone out of their way to limit or even eliminate that ability to push more sales of their lousy Chromecast devices, and they have stripped Miracast support out of the core Android as of version 6 (Marshmallow). If your phone supports screen mirroring, that's because whoever made it added Miracast support back in themselves. Android Auto is also a rather lousy compromise for many of us, such as myself, that want to run alternative apps. If it wasn't coded to run within Android Auto, it generally ain't happening which is the case for the navigation app that I use for off road purposes.
I've tried several different Pioneer double din touch screens with several different Android phones. Never once was I able to get screen mirroring/mirrorlink to work correctly to truly screen mirror the phone. Only the crippled Android Auto worked...which is what ultimately pushed me into completely going with these Chinese Android head units.
That said, the Joying JY-UO135N4GS - https://www.joyingauto.com/joying-l...avigation-system-with-built-in-4g-module.html that I have in the truck right now does have a 16 band EQ built in, F&R RCAs as well as a dedicated Sub RCA output, though it's a single. I haven't put a meter on it to verify voltage, but I'm guessing it's around 2V based on gain settings on the amp compared to other head units that I've known to have 2V outputs. A LOT of "brand name" head units today still come with 2V outputs. Also has both LPF and Subsonic filters on the sub output, as well as independent HPF crossovers on F&R channels. I currently have my subs set to 30Hz-100hz, fronts set to 80Hz high pass, and rears at 135Hz high pass (yeah..blame Chevy and their piss poor design on their trucks). Subs are a pair of JBL GTO 12s fed by a Kenwood monoblock amp. Door speakers are Infinity Kappa 6.5s, rears are factory 4x10s.
Is the sound quality on par with the Pioneer head unit that it replaced? No. Can I hear the difference at 75mph over the wind and diesel engine noise? Nope. Maybe I'd hear the difference if I put one of these Joyings in my Cadillac...Do I plan to replace this Joying with a Pioneer/Alpine/Kenwood/etc? Wait for it....has not ever once crossed my mind. I also have a Joying in my Suzuki Samurai, and am shopping for another Android unit for my Suzuki Grand Vitara.
Click to expand...
Click to collapse
If you are fine with sub par audio Then your opinion doesn't matter
The #1 purpose above all the bull**** you rambled on about is SOUND that's the purpose of an aftermarket head unit... Regardless of additional features
b1n4ry said:
If you are fine with sub par audio Then your opinion doesn't matter
The #1 purpose above all the bull**** you rambled on about is SOUND that's the purpose of an aftermarket head unit... Regardless of additional features
Click to expand...
Click to collapse
It's already been stated that audio quality is not the best. It's also been made clear that for some extra bucks and a few more components you CAN have your cake and eat it too. Now if you wish not to go that far then why are you here? Go to the pioneer forums.
As for the purpose of an aftermarket head unit.... yesteryear it WAS all about sound. Now it's more about central information centers. All kinds of information at your fingertips... and these Chinese units just beat the crap out of ANY of the traditional units as general information centers. Try hard as you can to make a traditional head unit do something to this level of detail and customization:
{
"lightbox_close": "Close",
"lightbox_next": "Next",
"lightbox_previous": "Previous",
"lightbox_error": "The requested content cannot be loaded. Please try again later.",
"lightbox_start_slideshow": "Start slideshow",
"lightbox_stop_slideshow": "Stop slideshow",
"lightbox_full_screen": "Full screen",
"lightbox_thumbnails": "Thumbnails",
"lightbox_download": "Download",
"lightbox_share": "Share",
"lightbox_zoom": "Zoom",
"lightbox_new_window": "New window",
"lightbox_toggle_sidebar": "Toggle sidebar"
}
Now.. do I have to put some extra money in making the sound better? Yup, sure do, but to my eyes it's worth it.
I´m running my Joying still from speaker out to Match M5DSP. SQ is even now better than with stock HU (PSA MyWay) that I used to feed M5DSP. I don´t hear any problems and I´ve been hifi-guy nearly 30 years.
Why is it not a true subwoofer output? I have a 1500w rms amp connected to the green subwoofer output and a dayon max mx12 and its clear as day. My only problem is my hengcheng which is like a teyes c3 clone only has front rca output and I want to leave my front speakers on the tda7851 built in amplifier and connect my rear speakers to a 200w amp in the back. But if I use the front rca out I will loose fader control cuz the system will think my rears are front speakers. What about the output voltage? I don't have a line out converter and everything sounds fine.
Kelynaw said:
I've actually purchased a few of these over the years, mostly because they were very vague on this specific feature. Given many of these units are identical just rebranded copies it's hard to sort things out.
The following is based on countless hours searching the web and 4 or 5 personal purchases of these Android head units. If any of this is incorrect please tell me because I have been desperately searching for one due to BMWs incessant need to one off everything.
In my experience the bottom line is no. Android head units do not offer genuine sub support. Yes you can use the rear output and a line converter or run the signal into the high level inputs on your amp (if it has it) but there is still a very simple a basic problem. You still won't have the needed components and or firmware to properly run it. Specifically frequency control, crossover or even a 7 band eq on the unit. I only found one that offered that last and it was janky to say the least (more probably offer the eq now but still very subpar) assuming you can run v4a on the unit that may clear some up but that was written for head phones not a 4 or more speaker system.
Another point is most mainstream headunits, pioneer, Kenwood, alpine heck even boss have 4v rca preout and signal conditioners not to mention both high and low-pass crossovers.
Unfortunately to my knowledge these Chinese Android suppliers have really missed the ball. Yes they offer some cool features but car audio guy's spend many thousands of dollars on these systems and to be honest I have a avh-4500NEX in my 325xi and since it mirrors wirelessly as well as Android auto and car play wireless it provides excellent sound.
Major difference my NEX $1800.00 us brand new these Android's I've seen get spendy but mostly right around 150-400. But you get what you pay for.
The biggest bonus I found though was you can put them anywhere since they are mostly just and inch or two deep.
If I missed the mark please let me know and if you could send a link to where I can pick up a decent one. The I-Drive in my 535i is making a stereo upgrade next to impossible
Click to expand...
Click to collapse
They are mostly the same but not all the same, I.e. MTCD with MCU mod sub out.
Yes, line level is 1.5-2v RMS not 4v as car audio mostly is.
Your post doesn't list "Android units" so cant tell what your test units were.
Why is it not a true subwoofer output? I have a 1500w rms amp connected to the green subwoofer output and a dayon max mx12 and its clear as day. My only problem is my hengcheng which is like a teyes c3 clone
marchnz said:
They are mostly the same but not all the same, I.e. MTCD with MCU mod sub out.
Yes, line level is 1.5-2v RMS not 4v as car audio mostly is.
Your post doesn't list "Android units" so cant tell what your test units were.
Click to expand...
Click to collapse
Which one is
Excuse my ignorance, I don't do high end stereo builds for cars(home theater yes).
Just curious, if you're trying to put out that kind of wattage and care that much about crystal sound, why aren't you using spdif(optical or coax) to output digital from your stereo regardless of brand. Then your Head unit is for the features/apps and screen and your high end equip is for signal processing?
Because the optical is 5.1 so a DAC would be mono output to each speaker, and there isn't a digital rca spdif or optical that is stereo. I thought about doing that and just using y cables but not with it really the signal wouldn't be any better just less chance of interference and I have none. An amp with optical starts around 1k unless you go aliexpress or something. My amp topsolidgear 1600w 1 ohm stable as tested by wiliston audio on YouTube is $150. My Dayton MX12-22 12" subwoofer was $140. I have it running 600w @ 4 ohm and its already crazy. After I break it in I may switch to 1 ohm and get even louder. My speakers are coaxial ds18 3 way black diamonds ($39) and my rear speakers are component ds18 6.5 with 3.5" bullet tweeters with built in crossover ($70) so it's a budget system. But it sounds great. All my audio is high resolution lossless flac files and the dsp does a great job. The 32 band equalizer let's me adjust subwoofer frequency and speaker frequency so I can turn my speakers off between 30_whatever hertz and set my sub anywhere from 30_70 hz range. It also has time delay and surround function and turns my amp on and off with a trigger wire amongst some other settings I haven't figured out yet.
Can't figure out what bass enhancement does. Bass filter is to filter bass from speakers and surround is to adjust timing.
Here is a pic.
CaliBurr said:
Because the optical is 5.1 so a DAC would be mono output to each speaker, and there isn't a digital rca spdif or optical that is stereo. I thought about doing that and just using y cables but not with it really the signal wouldn't be any better just less chance of interference and I have none. An amp with optical starts around 1k unless you go aliexpress or something. My amp topsolidgear 1600w 1 ohm stable as tested by wiliston audio on YouTube is $150. My Dayton MX12-22 12" subwoofer was $140. I have it running 600w @ 4 ohm and its already crazy. After I break it in I may switch to 1 ohm and get even louder. My speakers are coaxial ds18 3 way black diamonds ($39) and my rear speakers are component ds18 6.5 with 3.5" bullet tweeters with built in crossover ($70) so it's a budget system. But it sounds great. All my audio is high resolution lossless flac files and the dsp does a great job. The 32 band equalizer let's me adjust subwoofer frequency and speaker frequency so I can turn my speakers off between 30_whatever hertz and set my sub anywhere from 30_70 hz range. It also has time delay and surround function and turns my amp on and off with a trigger wire amongst some other settings I haven't figured out yet.
Click to expand...
Click to collapse
"there isn't a digital rca spdif or optical that is stereo"
not sure I understand this statement? Digital is stream is whatever is on it the stream. I send stereo over optical all the time in home theater(well I used too, it's OLD now ;-) Yes technically each speaker would be mono(it's channel) maybe I'm missing something.
I understand your point on cost, but if you already have the amp you want with solid RCA then just use a 50 dollar 4.1 or 5.1 DAC to RCA
It will skip the "crappy" DAC in the the HU and avoid interference(sorry but from what I read they ALL have it). I know both mine do.
The only reason I can think it will still be bad is if they are still doing DAC then reversing it for the optical. Again I have not tested the optical on the one I have with it as my stock system doesn't do spdif or even RCA.

Android head unit change parts

Hello,
I have bought a 2 DIN Android 10 head unit for my car.
I found the only product matching with my car (alfa romeo 147) to fit properly.
But I am very disappointed about what is inside.
First specifications do not match (4 gb RAM instead of 8, 800x480 instead of 1024x600...)
In addition sound is not very good.
I wonder if it is possible to change parts like
- Screen , to increase resolution
- Sound board , to have a better audio quality
- Increase RAM ...
Is there standard connection, like in a PC, allowing us to change some elements ?
Thank you for your responses
theog11 said:
Hello,
I wonder if it is possible to change parts like
- Screen , to increase resolution
- Sound board , to have a better audio quality
- Increase RAM ...
Is there standard connection, like in a PC, allowing us to change some elements ?
Thank you for your responses
Click to expand...
Click to collapse
Screen size has nothing to do with screen resolution: GIYF ...
Sound quality can get increased with an EQUALIZER app: GIYF ...
RAM may get increased physically, but will not be detected. You may try to install a SWAP memory ( virtual RAM ): GIYF ...
To manage Android OS from PC via USB cable you use ADB.
Thank you for your re
jwoegerbauer said:
Screen size has nothing to do with screen resolution: GIYF ...
Sound quality can get increased with an EQUALIZER app: GIYF ...
RAM may get increased physically, but will not be detected. You may try to install a SWAP memory ( virtual RAM ): GIYF ...
To manage Android OS from PC via USB cable you use ADB.
Click to expand...
Click to collapse
For screen resolution, with a higher resolution you are able display more information with a same size screen. If you don't believe me try to connect your PC to your TV and play with resolution.
Sound quality is not really increased by the equalizer APP. You can tune a little but if your device is poor, you will never have good sound
It sounds like there is enough wrong here so that it's not worth it. Just a new higher res screen will set you back a pretty penny.
Either live with it or return/sell it and start over with a better known brand.
Sorry but all incorrect answers. Every single aspect of the unit can be improved. Especially sound quality.
It will require hardware modding as well as software modding but it is more than doable.
We run a charity project where I bring these £100 units to a level of products costing many thousands, only spending £50-£100 in materials.
One of the mods we do is to replace the need of external amplifier and DSP altogether.
You can check out extrememod.co.uk for more ideas, particularly the FAQ section.
iceblue1980 said:
Sorry but all incorrect answers. Every single aspect of the unit can be improved. Especially sound quality.
It will require hardware modding as well as software modding but it is more than doable.
We run a charity project where I bring these £100 units to a level of products costing many thousands, only spending £50-£100 in materials.
One of the mods we do is to replace the need of external amplifier and DSP altogether.
You can check out extrememod.co.uk for more ideas, particularly the FAQ section.
Click to expand...
Click to collapse
Charity is lovely I respect that. But do you seriously believe that your mod can truly replace the need for a power amp? If so then please tell how you mod the headunits output to deliver 500+ watts of clean RMS power required to power a sub+woofers+midbass+tweeters with sufficient headroom in a noisy environment like a car?
And regarding the DSP. Sure any DSP with time alignment is better than no TA but a nice dedicated DSP offers so many features that no mods will bring these headunits.
So please stop spreading false claims about 100$ mod magically transforming these headunits into sql competition winning material.
Ok I checked Extrememod.co.uk and that page was just about as untruthful as Chinese sellers on AliExpress. Quote: "These units come equipped with a powerful built-in audio amplifier"
Very powerful indeed -and miraculously only require a tiny winy power cable AND runs fine with a 10A fuse. A truly Nobel prize worthy achievement!
Allan_Hun said:
Charity is lovely I respect that. But do you seriously believe that your mod can truly replace the need for a power amp? If so then please tell how you mod the headunits output to deliver 500+ watts of clean RMS power required to power a sub+woofers+midbass+tweeters with sufficient headroom in a noisy environment like a car?
And regarding the DSP. Sure any DSP with time alignment is better than no TA but a nice dedicated DSP offers so many features that no mods will bring these headunits.
So please stop spreading false claims about 100$ mod magically transforming these headunits into sql competition winning material.
Ok I checked Extrememod.co.uk and that page was just about as untruthful as Chinese sellers on AliExpress. Quote: "These units come equipped with a powerful built-in audio amplifier"
Very powerful indeed -and miraculously only require a tiny winy power cable AND runs fine with a 10A fuse. A truly Nobel prize worthy achievement!
Click to expand...
Click to collapse
All great points. Now let me respond to some of them.
1. I believe you missed the core point of it all - we build Android head units for audiophiles on budget. This essentially means all the people looking to have great sound at the smallest cost while keeping full functionality of an Android device.
2. Your comment on "500W RMS" and "tiny tiny cables" is irrelevant. Why? Because your sound will only be as good as the source. An Android Head unit will often output very poor sound from pre-outs. We therefore maximise the internal amp and surrounding electronics, advising folks not to use external amps and DSP's. Most of the cars we build for use 18 AWG speaker cables already, same as in the ISO harness. We do however use 16 AWG power cables with proper grounding.
3. I'm sorry but I'm yet to see a DSP processor that offers what Viper4Android does. Especially within feasible cost range.
4. The units we build have their TDA7850 amps running at 18v, not 12v - obviously with bespoke cooling to support the high temps. In most cars, true 200W output will be more than enough.
To summarize, we started this project to build all-in-one Android Head Units that offer everything an audiophile would want without spending thousands of dollars, while keeping all that an Android can offer. We had a good look around and found absolutely nothing in the Android Head unit space that did not require the user to sacrifice at least something, whether it's the sound, the handsfree quality, the UI, Android apps limitations etc.
The real reason for why no manufacturer is building units such as this - is the cost. In mass-production, it would simply be too expensive. Luckily we can work with what we've got and replace components with much better ones, hardware and software alike.
We are also looking into optimizing these units specifically for people that want to use external amps and DSP's. This too requires quite a lot of modding to ensure the pre-outs deliver as high quality output as possible. We'll be looking for audio pro's to test them and give us feedback. You can apply on our site if you're interested and located near London, UK.
iceblue1980 said:
Sorry but all incorrect answers. Every single aspect of the unit can be improved. Especially sound quality.
Click to expand...
Click to collapse
I didn't say it can't be done. I said it's not worth it. There is a difference.
If you want to mod and improve, then start with a good quality base. This head unit is not that.
iceblue1980 said:
4. The units we build have their TDA7850 amps running at 18v, not 12v - obviously with bespoke cooling to support the high temps. In most cars, true 200W output will be more than enough.
Click to expand...
Click to collapse
Replacing (and using) internal amps is a useless and fruitless endeavor. There are far more options available in external amps, quality and ease of installing when going with external amps. Indeed, if you are on a budget then external amps (and dsp's if need be) are the better way to go because you can upgrade a bit at a time.
Does an external amp increase audio quality ?
I think if source is not very good, external amp will just allow more power output, but what about quality ?
How to check if head unit has DSP ? Mine is supposed to have but I want to verify
theog11 said:
Does an external amp increase audio quality ?
I think if source is not very good, external amp will just allow more power output, but what about quality ?
How to check if head unit has DSP ? Mine is supposed to have but I want to verify
Click to expand...
Click to collapse
An internal amp does not increase audio quality any more or less than an external amp does, so it is a moot and irrelevant question. If you have bad audio quality going into an internal amp, then the outcome is exactly the same. Regardless of what amp you use (internal or external), if the audio quality is bad going into the amp, then it will be bad going out of the amp too.
What an external connection with external amps does is allow more flexibility in the quality of amps used, the number of amps used, and the power involved. You can also add external dsp's if you wish.
Bob_Sanders said:
I didn't say it can't be done. I said it's not worth it. There is a difference.
If you want to mod and improve, then start with a good quality base. This head unit is not that.
Click to expand...
Click to collapse
It is a charity project so Besides, we're focusing on 8227L units primarily. They are cheap and pretty much made for low-cost modding with more than respectable outcomes.
Bob_Sanders said:
Replacing (and using) internal amps is a useless and fruitless endeavor. There are far more options available in external amps, quality and ease of installing when going with external amps. Indeed, if you are on a budget then external amps (and dsp's if need be) are the better way to go because you can upgrade a bit at a time.
Click to expand...
Click to collapse
But then I would go back to the point 1 I made - the bottleneck is the Android Head unit itself. If it doesn't deliver good output at pre-outs, no point in investing in external gear. Today you pretty much forced to choose - either good sound or an Android Head Unit. This is what we're trying to remedy, while keeping the cost in the lower brackets.
iceblue1980 said:
But then I would go back to the point 1 I made - the bottleneck is the Android Head unit itself.
Click to expand...
Click to collapse
That has nothing to do with the choice of amp (internal or external) you use. The output of the RCA's is the same input for either amp. It is simply delivered internally to the internal amp and through RCA's for the external. If it is not clean audio from the RCA's then it also won't be for the internal amp. The only difference is that the internal amp is cheap and under powered so it can't emphasize the crappy audio as well as a cleaner and more powerful external amp can
Internal amps are crappy.... always have been... and with the cheap price of external amps these days and the large selection of them, it doesn't make sense to upgrade an internal
And with that, I go back to my original point.... modding and improving a cheap head unit is not worth it. You are better off starting with a good quality base model first.
This particular head unit is clearly a sub par unit with bad sound quality, low screen resolution, and insufficient memory, so all of that would have to be fixed first before anybody worries about an output amp to begin with.
The long and short of it is that the OP is going to be spending probably twice as much as the head unit is worth trying to make it into what he wants.
Bob_Sanders said:
That has nothing to do with the choice of amp (internal or external) you use. The output of the RCA's is the same input for either amp. It is simply delivered internally to the internal amp and through RCA's for the external. If it is not clean audio from the RCA's then it also won't be for the internal amp. The only difference is that the internal amp is cheap and under powered so it can't emphasize the crappy audio as well as a cleaner and more powerful external amp can
Internal amps are crappy.... always have been... and with the cheap price of external amps these days and the large selection of them, it doesn't make sense to upgrade an internal...
Click to expand...
Click to collapse
I have to respectfully disagree. In these units, there is little to no correlation of the sound output between the internal amp and RCA's. This is why there are 2 different directions that modders take - one focused on the internal amp and one focused on the RCA output. Both mods cannot exist in the same unit by the way.
The RCA's have poor electronics behind them as well as poor shielding, resulting in the equally poor audio output. What you will be amplifying is just that - poor sound.
Bob_Sanders said:
And with that, I go back to my original point.... modding and improving a cheap head unit is not worth it. You are better off starting with a good quality base model first.
Click to expand...
Click to collapse
I would agree to a point but many "hi-end" android head units are very difficult if not impossible to mod and it's also a matter of price. As this is a charity project, we're looking to keep the cost low while maximizing the value.
Bob_Sanders said:
This particular head unit is clearly a sub par unit with bad sound quality, low screen resolution, and insufficient memory, so all of that would have to be fixed first before anybody worries about an output amp to begin with.
Click to expand...
Click to collapse
Yes many of these units are honestly not worth touching. As for CPU and memory - the use of these can be considerably optimized with Android programming skills, making them very much usable in day-to-day scenarios. As an example, you can check out the video in my signature and fast forward to where we show the Google Maps loading times on a 1Gb RAM unit.
Bob_Sanders said:
The long and short of it is that the OP is going to be spending probably twice as much as the head unit is worth trying to make it into what he wants.
Click to expand...
Click to collapse
This is probably true. But then again, he as many others are always faced with a choice of what to prioritize: sound quality or a fully-fledged Android onboard computer.
Finally, I think anyone can improve their head units if they would really want to as there is so much information out there and guides. It would cost time but not much money. This is, I guess, why XDA also exists - for everyone to share knowledge
iceblue1980 said:
I have to respectfully disagree. In these units, there is little to no correlation of the sound output between the internal amp and RCA's. This is why there are 2 different directions that modders take - one focused on the internal amp and one focused on the RCA output. Both mods cannot exist in the same unit by the way.
Click to expand...
Click to collapse
Yes there are.
The output from the fm chip (just for example) does not have separate outputs for rca and internal. It has only one (L&R) output set which is fed to an input selector which is in turn fed to a preamp. That preamp output is fed to the internal amp with what basically amounts to a tap off to the rca's. Aside from a few decoupling caps and such, along with a filter and output set for the sub, the RCA signal is virtually the same as what is being fed to the internal amps.
"poor shielding" amounts to a crappy set of rca output cables which can be replaced for a couple of bucks if you have shielding issues.
BOTH the internal and external amps get their signal from the same preamp and filter stages. Not only that, but the internal amp also gets its power from the same internal power supply as the rest of the head unit does, so if that power supply is not clean then it affects the internal amp too. Drive any power supply too hard then you start getting dirty sound. An external amp has it's own dedicated power supply, which means you don't have to drive the head unit's power supply very hard at any time. That leads to a cooler running head unit with lots of power to run its other components.
Internal amps are IMO... a crappy way to go.
I would agree to a point but many "hi-end" android head units are very difficult if not impossible to mod and it's also a matter of price. As this is a charity project, we're looking to keep the cost low while maximizing the value.
Click to expand...
Click to collapse
Well... you mention "charity" not the OP, but the point is that the cost is NOT low when you start talking about having to purchase higher res screens (complete with driver), new memory and dsp boards. Your pretty much replacing more than half of the head unit's essential electronics. Heck... if you're going to be replacing that much.... you may as well start from scratch and build one from the ground , up
Bob_Sanders said:
Yes there are.
The output from the fm chip (just for example) does not have separate outputs for rca and internal. It has only one (L&R) output set which is fed to an input selector which is in turn fed to a preamp. That preamp output is fed to the internal amp with what basically amounts to a tap off to the rca's. Aside from a few decoupling caps and such, along with a filter and output set for the sub, the RCA signal is virtually the same as what is being fed to the internal amps.
"poor shielding" amounts to a crappy set of rca output cables which can be replaced for a couple of bucks if you have shielding issues.
BOTH the internal and external amps get their signal from the same preamp and filter stages. Not only that, but the internal amp also gets its power from the same internal power supply as the rest of the head unit does, so if that power supply is not clean then it affects the internal amp too. Drive any power supply too hard then you start getting dirty sound. An external amp has it's own dedicated power supply, which means you don't have to drive the head unit's power supply very hard at any time. That leads to a cooler running head unit with lots of power to run its other components.
Internal amps are IMO... a crappy way to go.
Click to expand...
Click to collapse
Ah, I see now what you're trying to say. Okay so yes, you are correct on a number of points, however, as I mentioned before - we are driving the internal amp with a separate 18v 15A power supply (we only need 10A but there you go). A power supply that is custom-built using a step-up DC-DC converter with temperature-controlled cooling (at 8A+ it starts to get pretty warm).
The internal amp is completely disconnected from the internal 12V power, while still being connected to everything else. We improved the audio output quality by quite a staggering 40%.
Internal amps will never be able to compete with external equivalents, but when you put it in a perspective of an Android - it's a totally different comparison. Like comparing cars with trains. Sure, both are means of transportations but quite different in themselves.
By the way, the "RCA" mod actually removes the internal amp altogether from the circuit.
I will agree that 200 true Watts is probably enough for most people -If they also have a powered sub. Check the recommend amps for popular subs like alpine and JL. Deep bass require some muscle. And 200W feeding a sub, two (mid)woofers + two tweeters ain't much. Heck my woofers sounds notably better @2x150W compared with 2x75W.
Most modern car subs are mostly optimized for low frequency production in small boxes. This is achieved with a stiff suspension and big motors. -Not a very efficient in therms of db/W.
I also think your definition of true watts is quite different than mine...
In my book true watts means continuous 20-20khz 1% THD.
I just checked the 7850 specs, and it is actually quite impressive for it's size. With 18V input it delivers almost 90W. BUT at 30W the distortions increases and at 40W it skyrockets!
Regardless of budget I don't think many "audiophiles" would appreciate >10% distortion...
For a budget android car hifi experience I believe HU, USB DAC + external amp would be the way to go.
IMHO Viper is by far the best sound mod app but it can't replace a DAC. Does Viper have auto tune? Automatic input selection ? Autoand programable turn on/off?Hardware volume control? Ground isolation? Logic 7 centerchannel? Fully costume covers?
Viper and a standalone DSP is two rather different things.
My DSP also have high level inputs so maybe I should try if the 7850 output vs the preamp RCAs. You do seem to know the HU's internals quite well. Can you explain why internal amp sounds better compared to the preamp output?
Isn't the 7850 recurving same signal as the preamp plugs?
Allan_Hun said:
I will agree that 200 true Watts is probably enough for most people -If they also have a powered sub. Check the recommend amps for popular subs like alpine and JL. Deep bass require some muscle. And 200W feeding a sub, two (mid)woofers + two tweeters ain't much. Heck my woofers sounds notably better @2x150W compared with 2x75W.
Most modern car subs are mostly optimized for low frequency production in small boxes. This is achieved with a stiff suspension and big motors. -Not a very efficient in therms of db/W.
I also think your definition of true watts is quite different than mine...
In my book true watts means continuous 20-20khz 1% THD.
I just checked the 7850 specs, and it is actually quite impressive for it's size. With 18V input it delivers almost 90W. BUT at 30W the distortions increases and at 40W it skyrockets!
Regardless of budget I don't think many "audiophiles" would appreciate >10% distortion...
For a budget android car hifi experience I believe HU, USB DAC + external amp would be the way to go.
IMHO Viper is by far the best sound mod app but it can't replace a DAC. Does Viper have auto tune? Automatic input selection ? Autoand programable turn on/off?Hardware volume control? Ground isolation? Logic 7 centerchannel? Fully costume covers?
Viper and a standalone DSP is two rather different things.
My DSP also have high level inputs so maybe I should try if the 7850 output vs the preamp RCAs. You do seem to know the HU's internals quite well. Can you explain why internal amp sounds better compared to the preamp output?
Isn't the 7850 recurving same signal as the preamp plugs?
Click to expand...
Click to collapse
You're absolutely correct. While this unit will drive some of the passive subs (thanks to all the additional cooling), we do highly recommend using an active subwoofer for the best sound experience. Even an underseat sub like Kenwood KSC-SW11will make enough of an impact as many people don't want to use the extra space for a sub.
You're absolutely correct on the distortion part. I haven't experienced it driving 4 Ohm speakers in various cars but all of them had active subs.
On USB DACs - totally correct. However these head units have fairly unreliable internal electronics to effectively drive them (surprise surprise). Hardware modding is required and we haven't been able to get any good results. The internal hardware is too weak to drive DAC's. Drivers are unstable as well. External DAC's was one of the first things we tried.
As for internal vs RCA output - what you're mentioning is correct when it comes to most devices out there. This is how it should be. On these head units however, it's a bit of a mess. In fact, we tried to "rewire" it internally but it resulted in an even worse output from RCA's.
The internal electronics are many times completely removed and we install an internal preamp microchip with separate power supply (step down DC-DC converter) and redo the capacitance as well as internal shielding.
We haven't had any requests yet for RCA-only projects so it's still very much an area of testing and development for us.
My DSP is connected through usb and it works fine with USB audio player pro. For anything else I use the optical output. Do you think the speaker output would improve the soundquality compared to the optical output?
Also tried a I had a 8227L I also tried a E1DA 9038D DAC and it worked except I could not control the volume, so it would play at full volume. So I guess a DAC with a volume dial could work.
Your statement about only needing 10A at 18V don't match your claim about 200 true watts. The 7850 is class AB so efficiency is probably about 75% . 10x18x0.75=135W...

Categories

Resources