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Discussion Starter · #1 ·
I have the following planned for use in one of my ongoing builds (the '01 325i) -

Audison AP4.9 (9 channel DSP + 4 channel amp)
Audison 5.600 (5 channel amplifier)
and (controversial choice I know) - an Android head unit for cosmetic reasons.

So I have 9 channels of DSP, 9 channels of amplification, and 9 individual drivers in my system. All good so far.

Presently, I have 4 channels of audio from the head unit to the factory amplifier via the original high-level wiring. From there, it is split into (an unknown number of channels - don't remember - but I had 10 OEM speakers to start with so let's say 10). I also have 3 pairs of RCAs that I pulled from the head unit to the amp rack in anticipation of needing them. Factory amplifier will be removed when the amps and DSP are installed.

Conventional wisdom and experience tells me I should use the RCA cables, but the AP4.9 has high-level inputs only. But conventional wisdom and experience also tells me to reduce the total number of components and interconnections in the signal path where possible. So my question is, which of the following would yield better results with the above listed equipment, or what are the merits and demerits of each option:

1) HU --> preamp RCA cable --> RCA to line level converter of some sort --> Audison AP4.9 --> Audison 5.600
2) HU --> line level outputs --> Audison AP4.9 --> Audison 5.600
3) Some other arrangement I'm not thinking of?

By ear, the amplified output of the Android HU seems adequate, and I've been blaming dips in the response on factory amplifier XO points not matching my drivers, and the fact that I've had to try to adjust for mismatched impedances and efficiencies of a-la-carte components - all stuff I would sort out via the DSP. My question is basically with a consumer grade radio, how much benefit is there (if any) to using the preamp outputs and then boosting the signal later, vs. letting it run through the HU's amplifier section only to be processed and filtered and reamplified down the line?

I don't have an opinion on this - interested in relevant experience or suggestions, under the assumption the HU and selected amplifier / DSP are to be retained.
 

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Discussion Starter · #3 · (Edited)
What's the point of using Audison Amps and whatever drivers if you are going to use a Android HU. Get rid of it
Thanks for the constructive and well reasoned response. I'm glad you straightened me out because this is DEFINITELY my first time around the block.

To answer your question, it's because I got the right number of amp channels and DSP that I need into just two components that will fit in the concealed space I have available. And for that utility, the cost was perfectly reasonable. The brand choice was not really a consideration, just the space constraint and an effort to simplify.

Despite all the snobbery, a head unit is a head unit is a head unit ... especially if you are using the preamp outputs and a DSP. And if it doesn't sound great? I can swap it. But until proven otherwise, my experience tells me it will be fine, and for now I'm happy with my OEM-looking navigation radio that isn't a theft magnet.

I found Audison does make an RCA to line input harness, so I'll probably just use that. Either that or get a signal box that converts the RCAs to an optical signal and use that input for the whole signal if I find the voltage is too low on the RCAs. Or put a line driver at the head unit end. Trying to pick the best approach of those options.

Don't mind trial and error (this is DIY after all), but I thought I'd check if anyone had useful input within the constraints of the question. I'll take your input into consideration, but it ain't what I asked.


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Discussion Starter · #5 ·
Looking at the manual, Audison sell this to connect RCAs to the AP4.9. You could just solder female RCAs to the standard input cables though.
Thanks Rich, that's what I concluded as well. If the voltage is for some reason less than 2 V RMS then I'll look to a distribution amplifier or line driver at the head unit end. But then that defeats the purpose of reducing the number of components in the signal path.


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