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Discussion Starter · #1 ·
Quick system break down. Car is a 2018 Audi A3

factory Mimi source unit used,
JL Audi box 700I5
Jl C5-650 in the factory locations up front
JL 10W3 in a power wedge box from JL.
rear doors and centre Chanel left powered off the head unit. The C5’s are running active off the amp. The amp was connected with line level inputs off the factory radio.

Long story short, had this all done by a shop and my car sounds like crap. So I brought it to another shop and I’m being told I need a “most interface” for another grand , and to re install everything. Looking for some direction on how to proceed. Originally thinking maybe something like a FIx would work to solve this. Now just not sure.
 

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I dont know what a most interface is.. maybe a pac amp pro? But yeah do you have a JL VXI dsp amp or whats going on with that?

what is "JL Audi box 700I5 "?
 

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Quick google turned this up. I know nothing about this so do your own research.
 

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Quick system break down. Car is a 2018 Audi A3

....

Long story short, had this all done by a shop and my car sounds like crap. So I brought it to another shop and I’m being told I need a “most interface” for another grand , and to re install everything. Looking for some direction on how to proceed. Originally thinking maybe something like a FIx would work to solve this. Now just not sure.
Essentially, these cars use a fiber output to the factory amp/processor. Ideally you're supposed to use a MOST adapter to get a proper clean flat output from the radio, rather than tapping in on stuff after the amp and factory processing. Unfortunately they do tend to be pricey.


I am guessing as a result of the shop cutting corners, you have sound that's already EQd for the stock tune and drivers on your new drivers... I/probably others cannot comment on the "re-install" everything unless the previous shop did a piss-poor job with mounting and fabrication of everything else, although it makes some sense as installers do not want to work on other's work when the quality is unknown- see Five Star's 911 videos where they tear everything out to ensure there are no hidden surprises.
 
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Adding a Most interface would make things work easy, but it not necessary needed. It all depends are the type of Stereo system you're looking for.

Nav-TV makes for a nice 'MOST interface' to make hooking up your Head Unit to multiple Amps ... here is a link >> NAV-TV - Interfacing the Future

I did a quick lookup of your amp from the info you posted... It looks like its a 5-channel marine amplifier, is this your amp? >> JL Audio M700/5

That's strange they would install a marine amp, You should get a firm answer from the original installer on exactly what amp you have.

Jl C5-650 = These are your Coaxial/Componet 6.5 Mid-base with tweeters and passive crossovers.

JL 10W3 in a power wedge box = is your sub box.

You don't need the MOST interface, because that amp you have can handle 'high level' or also known as 'Speaker level' input.

This means you use the speakers wires that were plugged into your speakers, and plug them into the Amp "high Level" input. (or splice into them at the HeadUnit).

Once you have the 'input' going into the Amp, then apply the correct setting on amp to send music signal to the Amps output channels. Then speaker wire from Amp to Subs, speaker wire from Amp to speaker 'passive crossovers', then from passive crossovers to the 6.5 Mid-Base & Tweeters.



 

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Adding a Most interface would make things work easy, but it not necessary needed. It all depends are the type of Stereo system you're looking for.

Nav-TV makes for a nice 'MOST interface' to make hooking up your Head Unit to multiple Amps ... here is a link >> NAV-TV - Interfacing the Future

I did a quick lookup of your amp from the info you posted... It looks like its a 5-channel marine amplifier, is this your amp? >> JL Audio M700/5

That's strange they would install a marine amp, You should get a firm answer from the original installer on exactly what amp you have.

Jl C5-650 = These are your Coaxial/Componet 6.5 Mid-base with tweeters and passive crossovers.

JL 10W3 in a power wedge box = is your sub box.

You don't need the MOST interface, because that amp you have can handle 'high level' or also known as 'Speaker level' input.

This means you use the speakers wires that were plugged into your speakers, and plug them into the Amp "high Level" input. (or splice into them at the HeadUnit).

Once you have the 'input' going into the Amp, then apply the correct setting on amp to send music signal to the Amps output channels. Then speaker wire from Amp to Subs, speaker wire from Amp to speaker 'passive crossovers', then from passive crossovers to the 6.5 Mid-Base & Tweeters.
Do you know if the high level signal is flat and without any phase corrections? I assume its not so he would need the adapter.
 

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Having owned (and done systems in) a number of Audi's and BMW's; I am very familiar with the MOST fiber optic network...

The MOST interface unit that the other shop is recommending, is the NAV-TV unit (it's MSRP is $800). I'll post a weblink to it at the bottom.

I can guarantee that if you installed this, then your sound quality would improve dramatically, as the NAV-TV unit draws the audio source directly from the fiber optic (MOST) network in your vehicle. It pulls a clean flat digital (optical) signal from the head unit (not EQ'd, not time aligned, just perfectly flat).

However, you are opening another can of worms when you go this route... as you will need to add more amplifiers. The NAV-TV MOST interface has a built-in DSP, which allows you to run your JL C5 components active. And your JL amp only has 5 channels (one of them for the sub). This means that this amp will be used exclusively for the front tweeters and the front 6.5" driver (and the sub).

The MOST Interface replaces the factory amp and is basically a pre-amp, so you no longer have use of your factory amp to run rear doors and center channel. If those are imporatant to you, then you will need to buy another amplifier and add it to the system. You'll probably also need to replace the rear speakers and the center channel, as these are cheap paper cones that most aftermarket amps will chew-up within a few hours of playing.

So, in summary...
I'm not surprised that your current system doesn't sound good. The install shop clearly didn't know what they were doing. But I'm also concerned that the new shop is recommending a MOST interface, without telling you about all the extra stuff that's going to be required to make it work... the thousand bucks they quoted you is just the tip of the iceburg. You'll need more amp channels as well as more replacement speakers. Plus the system will require tuning after the MOST interface and other equipment has been reinstalled. Typically a very basic tune will take an absolute minimum of 1 hour, but a decent tune will take 3 to 5 hours. I have to assume the shop knows how to do a proper tune (and will charge you for it).

Sorry if I sound like 'Debbie Downer'... but I want to be realistic with you, so that you don't get set-up for more disappointment by a second shop that might not be giving you the full story. Or even worse... maybe the second shop also doesn't know what they're getting themselves into.


 

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Discussion Starter · #8 ·
Sorry there was a typo in my first post. The amp is a JL Vx700I5. Thanks for all this input. It’s giving me a lot to think about. I’ll have to do some more research. Also thinking of talking to another shop just to get more input. Quickly thinking I should do this myself then just bring it in to get tuned. That way I’ll know what’s done.
 

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Discussion Starter · #9 ·
Having owned (and done systems in) a number of Audi's and BMW's; I am very familiar with the MOST fiber optic network...

The MOST interface unit that the other shop is recommending, is the NAV-TV unit (it's MSRP is $800). I'll post a weblink to it at the bottom.

I can guarantee that if you installed this, then your sound quality would improve dramatically, as the NAV-TV unit draws the audio source directly from the fiber optic (MOST) network in your vehicle. It pulls a clean flat digital (optical) signal from the head unit (not EQ'd, not time aligned, just perfectly flat).

However, you are opening another can of worms when you go this route... as you will need to add more amplifiers. The NAV-TV MOST interface has a built-in DSP, which allows you to run your JL C5 components active. And your JL amp only has 5 channels (one of them for the sub). This means that this amp will be used exclusively for the front tweeters and the front 6.5" driver (and the sub).

The MOST Interface replaces the factory amp and is basically a pre-amp, so you no longer have use of your factory amp to run rear doors and center channel. If those are imporatant to you, then you will need to buy another amplifier and add it to the system. You'll probably also need to replace the rear speakers and the center channel, as these are cheap paper cones that most aftermarket amps will chew-up within a few hours of playing.

So, in summary...
I'm not surprised that your current system doesn't sound good. The install shop clearly didn't know what they were doing. But I'm also concerned that the new shop is recommending a MOST interface, without telling you about all the extra stuff that's going to be required to make it work... the thousand bucks they quoted you is just the tip of the iceburg. You'll need more amp channels as well as more replacement speakers. Plus the system will require tuning after the MOST interface and other equipment has been reinstalled. Typically a very basic tune will take an absolute minimum of 1 hour, but a decent tune will take 3 to 5 hours. I have to assume the shop knows how to do a proper tune (and will charge you for it).

Sorry if I sound like 'Debbie Downer'... but I want to be realistic with you, so that you don't get set-up for more disappointment by a second shop that might not be giving you the full story. Or even worse... maybe the second shop also doesn't know what they're getting themselves into.


With the amp already having a dsp in it. Do I need that nag-tv unit? Or would something like the JL audio Fix 82 or 86 do the same thing?
 

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@Audi-A3 I feel for ya having to go through this, first off, I owned an Audi S3 and I know these cars are nice and expensive vehicles, I do many DIY things but have always paid a professional when it came to messing with my cars electrical system.

Money aside, if it were me, I would be searching out the most reputable shop in your area or even state, you could go on JL Audios website and look for their authorized dealers in your area (does not guarantee their a great shop) but it gives you a starting point. I would only look for a shop that does custom installs/fabrication because to me, that means they are more knowledgeable and vested in the trade. Look for an install gallery on their website that highlights their work.

Todays cars are complicated and I would guess that an Audi/German Engineering ranks up there.

Maybe you can convince the original shop to take the equipment back. If it were me, I would have the new shop install all their equipment so the whole thing is warrantied through them... equipment and install.

You're asking the question but there are many people out there in the same situation that will benefit from this post.

Good luck and keep us updated!
 

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With the amp already having a dsp in it. Do I need that nag-tv unit? Or would something like the JL audio Fix 82 or 86 do the same thing?
Yes. The NAV-TV is the interface to your vehicle. It has a DSP in it... but it's crap, so you're better-off just using it as the interface to the vehicle's MOST system. Then from the NAV-TV you would run an optical Toslink cable into your JL VX700l5, and do the system tuning it with the DSP in the JL. This bypasses the crappy DSP in the NAV-TV (which is what I've always done).

In theory, you could use a JL Fix... but it's like putting lipstick on a pig. It just tries to mask the original problem, which is a crappy source signal coming from your factory amp. If you're going to spend the money on a JL Fix, and then try to tune-out the crappy source signal and re-tune it so it sounds good... then you might as well spend that same money on a NAV-TV unit, and start out with a perfect source signal.

I know this is starting to sound like dollar signs adding-up... but I am confident that you'd be way happier with the end result, if you got a NAV-TV unit and went that route. Do the system properly... otherwise you're never going to be happy with it. Trust me.
 

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Yes. The NAV-TV is the interface to your vehicle. It has a DSP in it... but it's crap, so you're better-off just using it as the interface to the vehicle's MOST system. Then from the NAV-TV you would run an optical Toslink cable into your JL VX700l5, and do the system tuning it with the DSP in the JL. This bypasses the crappy DSP in the NAV-TV (which is what I've always done).
NOT TRUE.... the Nav-TV DOES NOT have a DSP. It will remove any EQ & Delay settigs that has been applied to the factory Amp, because the NAV-TV bypasses the factory Amp. So, by bypassing the Factor Amp, it is just bypassing where the EQ and Time Delay is introduced into the system..The Nav-TV just sends a plain 'ol flat signal from HU to Amp. So, A real DSP will need to be added to stereo system.

Below is copy/past from the Nat-tv webside for the Navt-TV unit for his audi A3.

"Utilizing the same processing power as NAV-TV's competition proven M650-GM, the ZEN-V produces a completely flat audio output without any factory time delay or equalization, eliminating the need for summing devices, an audio correction DSP or the removal of the factory audio compensation microphones."

In theory, you could use a JL Fix... but it's like putting lipstick on a pig. It just tries to mask the original problem, which is a crappy source signal coming from your factory amp. If you're going to spend the money on a JL Fix, and then try to tune-out the crappy source signal and re-tune it so it sounds good... then you might as well spend that same money on a NAV-TV unit, and start out with a perfect source signal.
The JL Fix, yes DOES have an EQ, not a good one, but it does have one.The JL Fix is a audio correction DSP. It works by cleaning up the signal after the Factory Amp,(Nav-TV does not clean up the signal from factory amp because it bypasses the factory amp) and the JL Fix EQ is used mostly to make adjustments to send flat signal out to Amps. A real DSP will need to be added to stereo system.

I know this is starting to sound like dollar signs adding-up... but I am confident that you'd be way happier with the end result, if you got a NAV-TV unit and went that route. Do the system properly... otherwise you're never going to be happy with it. Trust me.
To boil it all down, the units provide 2 different ways to get a plain flat signal to the Amps and/or DSP. I've used both units in the same vehicle, and since both units still requires a real DSP, and for other reasons, I ended up going with the NAV-TV.....

Nav-TV is used to remove EQ and Timing by bypassing the factory Amp.
JL Fix is a audio correction DSP, used to remove EQ and Timing after factory Amp.



EDIT: I just looked up his real Amp.... and it looks like a nice Amp that DOES HAVE a DSP.... Still everything I stated above is correct, except that you do not need to add a DSP to the stereo system..ya already got one in the Amp.
 

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With the amp already having a dsp in it. Do I need that nag-tv unit? Or would something like the JL audio Fix 82 or 86 do the same thing?

I didn't see this post.... my bad.
As I stated above, with the 2 choices, in the end, both do the same thing, just in different ways. I would recommend using the NAV-TV....Its more expensive, but a much better/cleaner & easier install, and is better than JL Fix.....
 

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Do you know if the high level signal is flat and without any phase corrections? I assume its not so he would need the adapter.
Thats why I mentioned in my post > "It all depends are the type of Stereo system you're looking for. "

If he does not use the MOST Interface or a JL Fix, the high level signal from the output side of factory amp would NOT be flat and would contain the factory EQ & Time settings... Which means his new Amp would receive all the junk information in the signal............ I was just trying to explain that it COULD work without the Nav-Tv or JL Fix...... Yes, he needs one of those adapters... either the Nav-tv or JL Fix...
 

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Best of luck on this journey. Working with shops can be super challenging especially if they don't know what they are doing.
 

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rear doors and centre Chanel left powered off the head unit. The C5’s are running active off the amp. The amp was connected with line level inputs off the factory radio.
Big yikes

Long story short, had this all done by a shop and my car sounds like crap. So I brought it to another shop and I’m being told I need a “most interface” for another grand , and to re install everything. Looking for some direction on how to proceed. Originally thinking maybe something like a FIx would work to solve this. Now just not sure.
This second shop is correct. I wouldn't touch any car with a MOST fiber system without using a preamp like the Helix SDMI25 (for MOST25) or the Nav-TV MOST150 offerings (for MOST150). Using a JL fix in this, as with almost any newer car with anything other than a very basic OEM system, will result in something worse than you already have.
 

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I didn't see this post.... my bad.
As I stated above, with the 2 choices, in the end, both do the same thing, just in different ways. I would recommend using the NAV-TV....Its more expensive, but a much better/cleaner & easier install, and is better than JL Fix.....
They absolutely do not do the same thing. One is an auto eq/signal summing device that corrects factory eq, timing, and polarity (will NOT correct or counteract all pass filters). The other is a MOST150 preamp that takes the digital signal on the MOST150 fiber loop and converts it to a format that is usable by us.
 

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If he does not use the MOST Interface or a JL Fix, the high level signal from the output side of factory amp would NOT be flat and would contain the factory EQ & Time settings... Which means his new Amp would receive all the junk information in the signal.....
Yep, this is why his system currently sounds like garbage.
Original installer just pulled the signal from the factory amp, then added a DSP/amp to the mix, and probably tried to EQ an already EQ'd signal.

@tjk_bail is correct. My apology for the incorrect statement about the NAV-TV having a DSP built-in. It does not.

Funny thing is... I've just bought a new Audi RS5, and am in the process of doing a NAV-TV system as we speak.

To the OP; I know I mentioned extra amps and speakers for rear doors / center channel, etc... but you wouldn't need to get these right away. They could be added later. It just makes it easier to tune the vehicle with everything in it at once. If you just got the NAV-TV installed now; you could run it to your JL Amp/DSP and have front speakers and a sub. They might not give you the full sound you're looking for... but as long as the shop tunes the system properly, there's no reason why just these shouldn't sound great!
 

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I am with the other guys in going with the NAVTV for the integration. I would focus on getting that put in and integrating it with the amplifier you have even if the channels are limited where you lose the rear and center channel. To me deal with the need for more channels beyond that amplifier after you get everything else right. That way your money would be put into getting the best interface you can for the best signal and using the amplifier you already have.

If you decide to get hands on with it then you are more than welcome to share some pictures of what you see or to provide some context to what you are trying to do. There are a great number of people on this board that have prevented people from beating themselves up over crappy installers who shouldn't be in business while providing critical guidance on resolving an issue from their own personal/professional experiences.

Good luck.
 
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