# Aux direct to amp - No HU



## hispanic panic (Jun 20, 2013)

So i'm piecing together a system and i almost have all the pieces picked out. I'm removing a head unit entirely in favor of a tablet that will be mounted indash. It was recommended to me to have an EQ like a 1/2 din audiocontrol three.2 between the tablet and amp.

What say you guys? Any other brands or models or types of equiptment you reccomend to have between the tablet & amp??

Also, if i do use an eq, will i see much of a benefit from using the EQ or is it really only good for volume control? If that's the case, a JL audio RLC might be better.

Also, i don't know what preprocessors are or line drivers are (new to car audio), but would they have a place at all in this type of setup??


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## t3sn4f2 (Jan 3, 2007)

If you can afford it, run a JBL MS-8 and run the tablet's outputs into its AUX input.

http://www.diymobileaudio.com/forum/technical-advanced-car-audio-discussion/8257-jbls-ms-8-processor.html


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## hispanic panic (Jun 20, 2013)

Forgive my ignorance, but i think that may take overkill to a new level. An amp already has crossovers on top of the ones that come with the speakers, so i'm confused as to what benefit an ms-8 would provide over an eq outside of line volt amplification. I mean, i may be really ignorant here, which is probably the case, but i just don't see it.


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## sirbOOm (Jan 24, 2013)

Look at SoundMan Car Audio videos on YouTube to understand how to install a tablet into a car. The AUX cable connection outputs poor sound quality as the audio will have had to go through the internal audio processor of the tablet which is not as capable as a JBL MS-8, Rockford 3SIXTY.3, or Audison BIT. You'r goal should be to find a way to output the audio of the tablet through it's data connection port (USB or iPod cable), translate that to RCAs (or optical, if you can), and then go into one of the aforementioned processors. Or you can connect the tablet via USB to a hidden head unit - it doesn't have to be an expensive head unit, but that makes things easy. The AudioControl EQ you mention is certainly an option but it is not really a signal processor.


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## crackinhedz (May 5, 2013)

It would really help to know what tablet you ntend to buy, and what amp you have? Not very common for amps to have crossovers, more like high and low pass filters...not really the same thing if Im understanding your intended purpose.

Depending on which tablet you get, the best route is most likely a usb to optical converter , and getting yourself a signal processor that acceps optical, the MS8 being mentioned as one of them, Rockford 3sixty.3, Audison Bit 10D etc.


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## hispanic panic (Jun 20, 2013)

Thanks for dumbing it down for me, but it raises a few questions. If the tablet already processes the sound to a relatively low quality, how is the quality able to be increased afterwards? After a signal is degraded, it can't go back up, right?? So i guess that's the purpose of outputting the audio via USB cause it outputs a clean unadultered signal?

I still haven't decided which amp i want yet, but i've decided on speakers. FOCAL ACCESS 165 A3 for the front stage, and focal ca1 165 for the rear, and dayton hf 10 sub. I need an amp that supports 85w RMS in each channel and 350w rms for the sub. 

I mention my setup because i want to take full advantage of the potential sq but at the same time i realize some things may just be overkill. Is the usb vs aux output one of those items??

Also, i havn't decided which tablet. Still shopping around for that. Probably going to end up with a windows 8 tablet or an android based tablet. Likely 7-10 inch tab.


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## hispanic panic (Jun 20, 2013)

I stumbled upon a jvckd-x80bt. It seems that it could work with a tablet, but how would it compare to using a signal processor in the end?


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## sirbOOm (Jan 24, 2013)

I can sell you my Kenwood XR-5s in a month or so that meets your exact power requirements. A processor will be able to "save" some of the sound quality and improve upon it but it's always better to skip the tablet's internal processing via the USB output and if you can go optical, that means you're staying digital all the way to the DSP and that should generally be your primary goal (of course considering budget and environment).


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## focused313 (Apr 19, 2012)

depending on what your quality needs are, you can definitely go the EQ route. I have an acer a100 and a Clarion EQ in my tablet set up. It's basically a bluetooth connection, from the bluetooth 3.5mm jack out to my EQ via RCA, then into my amp. There's no doubt that the audio quality is not as good as it could be, but given the quality of my mp3s to begin with, it's not that big of a deal.

I'm 100% sure though, with a some expensive signal processors, you could get better sound, I just don't know audible that quality would be to me. To other folks, it might be night and day.


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## hispanic panic (Jun 20, 2013)

Currently looking into USB sound processors available for pc's (should work for win8 tablets too). They seem to be a much cheaper alternative to using 800 dollar car audio sound processors.

Anyone have experience in that area? USB to 24 bit DAC with an optical/rca out. Some are even offered with a 3.5mm aux out. Not sure if there is a difference between optical/rca/3.5mm jack after the sound is properly processed & converted to analog.


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## hispanic panic (Jun 20, 2013)

Also, after further research, there are a select few tablets that output audio at a 24bit/192khz level, so technically i wouldn't need a sound processor in this case, correct???????? I would just need an EQ and perhaps something to raise the aux output to 5+ volts so my gain isn't maxed out on the amp. If my research is correct, this setup would be 100% identical to the sound quality of a car audio sound processor (brand quality & internal DAC potential for noise pollution aside). Additionally, there are apps or music players with very robust EQ's built in, so an external EQ may not be required.

Can someone please tell me if my research is leading to sound reasoning??? Is there something more to car audio quality other than 24 bit / 192 khz sound??? 

If all this is true, then i can have a tablet driven system that is literally half the price of the best HU's that is more capable with equivalent sound quality without expensive DAC's and processors (disregarding speaker channel timing).


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## hispanic panic (Jun 20, 2013)

Enable USB audio on any Android 4.0 smartphone/tablet - Page 3

that link has a bunch of people driving high quality audio to headphones from an android device. The application should be literally the same, except instead of headphone amps i'd be putting the signal into a car amp. 

What say you guys??


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## crackinhedz (May 5, 2013)

192/24bit is the quality of audio...keep in mind that high is very rare, as CD's are 44.1/16 and DvDs 48/24. Some high quality 96/24 but again this audio is less common. 

The problem with your application is yes, you could use a built in EQ app from the tablet but chances are they are very poor functionality wise...if you're truly concerned with audio quality you will want capabilities with numerous bandwidth adjustments, time alignment, phase etc. 

Your basic android/windows/apple app's wont suffice, not to mention the DAC of the tablet is most likely cheap quality.

This is where the DSP comes into play. It is designed solely for this purpose. And if you can keep it in the digital domain using optical cable, you will keep the best possible audio quality before it reaches the amps.


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## hispanic panic (Jun 20, 2013)

crackinhedz said:


> 192/24bit is the quality of audio...keep in mind that high is very rare, as CD's are 44.1/16 and DvDs 48/24. Some high quality 96/24 but again this audio is less common.
> 
> The problem with your application is yes, you could use a built in EQ app from the tablet but chances are they are very poor functionality wise...if you're truly concerned with audio quality you will want capabilities with numerous bandwidth adjustments, time alignment, phase etc.
> 
> ...




All great points, and after some research you're 100% right on the apps. Here's my rebuttals on use of a dsp as my research is proving.... let me know if i'm wrong on any of these.

1) Car audio DSP's can do many things. Unfortunately the output sampling rate does not surpass ~46khz. This is an obvious disadvantage to even a midgrade PC soundcard.

2) a handfull of tablets are coming out with 24bit/96khz - 192khz output quality on their AUX jack. You have to dig for this info, but even if the tablet doesn't do this, you can get a USB DAC for less than 200 that achieves this state of the art quality.

3) Discovered a Pioneer headunit that is capable of a 32bit/192 khz signal output. Unfortunately its $1,000 dollars. Audio quality between 32 & 24 bit is subjective at best (from what i read). A 1k head unit makes zero sense when i can get a reputable DAC for 200 that comes highly recommended by all the audiophile head-fi guys. 

4) Noise. How much noise does it take to make a damn difference? Onboard DAC's of electronics are discounted as being inherently 'noisy'. External DAC's seem to be commonly recommended. This may be a misunderstanding as most onboard DAC's on electronics are 8 bit, with high quality ones being 16bit/48khz at best. ALL aftermarket external DAC's are 24+bit/96+khz. This difference in quality obviously not related to 'noise'. Maintaining optical/spdif connections all the way to the amp are credited as being best, but i have currently found no _hard_ information that has yet to prove this. Amps that have optical inputs on sound are expensive and not that common from what i've found. So does noise in the situations above make a damn difference??? I honestly have no clue. But if your system has the proper ground loop isolator's and your RCA cables are properly shielded & routed, I'll bet you a dollar it doesn't make a damn difference at the SPL levels your average system puts out.

5) I'm not saying DSP's are useless, i'm just saying in a properly built system, they're not needed.


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## hispanic panic (Jun 20, 2013)

I've decided this is the setup i'm going with.

Tablet (with 24/192 onboard DAC) >> Clarion EQS746 >> Kenwood XR-5s >> Speakers

All on shielded RCA wires. 

Win8 Tablet - ~$400
Clarion EQs746 - $60
Kenwood XR-5 - $280
Focal Access 165 A3 (front) - $350
Focal Access 165 A1 (rear) - $120
Dayton HF 10 - $150

Total ~1400




As long as everything is properly Isolated, the 24/192 onboard DAC of the tablet should allow me to play lossless audio at superb quality. Now i've just got to find someone to help me out with the install.......


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## crackinhedz (May 5, 2013)

Think about this, even with the iPhone/iPad (considered at least pretty good quality) people look to bypass the internall DAC for use of external DAC which to me indicates the DAC is not very good...I dont have specific knowledge just from various readings. So to me a tablet DAC is not ideal especially when it comes to the rca jack output.

Regarding the optical connection you can run optical the entire length of you vehicle from your tablet to a DSP, keeping everything in the digital domain...then output from the DSP to the amps using very short RCA's. At such short length noise would be non issue. Sure you could find amps that accept optical, but not necessary. 

Not trying to dictate how you spend your money, but if I were going with a tablet only I would like to have same if not better capabilities of a decent headunit. An optical signal to a DSP is already digital, so no need for an unecessary ADC to DAC conversion. 

Sure your vision would probably satisfy your needs, and you could always go the DSP route later in the future if warranted. Just wanted to give you ideas.

Would love to see your end progress so keep this updated!


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## crackinhedz (May 5, 2013)

Also, depending on the DSP the output sample varies from 48/24 to 192/24 not sure where you read 46? (typo?)

Also the DAC is key to quality...


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## hispanic panic (Jun 20, 2013)

crackinhedz said:


> Also, depending on the DSP the output sample varies from 48/24 to 192/24 not sure where you read 46? (typo?)
> 
> Also the DAC is key to quality...


You're absolutely right on the optical vs rca routing thing. I have a feeling (albeit a naive one) that if the RCA's are properly shielded & routed, the difference should be minimal. 

I meant 24/48 on the DSP's i've found, and 24/192 quality can be achieved for a lot less with a handheld external dac (in case i can't find the right tablet or the onboard dac has a lot of noise). The best apple products output audio in 16 bit as i've discovered. None are 24/192. By skipping a DSP alltogether, that leaves 1 function on the table that i'm leaving out. Speaker timing. I remember coming a cross a handheld device that auto times the speakers for you but i can't remember the name of it. Can anyone shoot me in the right direction?

I'll do my best to keep the internet updated with my progress. I've searched this topic for literally 5 weeks to gather all of this information, and it would be a shame not to share it. I've discovered a lot of misinformation and rabbit trails in my search, and i'd like to provide the straight facts to those that attempt something like this in the future.


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