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Discussion Starter #1
I have this question more for "academic" reasons than practical/application ones... I have one of the amps in question, but I'm not using it to take advantage of this "feature."

I'm currently using a late model, A/D/S/ "Power Plate" (P640) amp in my ride and when I was scanning through the manual I noticed that you can indeed use a high-level signal source but there is no connections specifically for high-level inputs. The manual says that you can take the high-level wires from the head unit and connect them to RCA plugs and plug them into the amp, no strings attached. The manual states that this can be done due to the "wide input level adjustment range." The manual states that the input adjustment range is 100mv to 10V, this does seem pretty large but my Zed PA1002 has a 100mv to 8V range, and quite a few others can accept up to a 7V signal (many companies that looked to sell their line drivers with amps). Do you think a 100mv-7V input adjustment range would suffice to perform while doing the technique A/D/S/ outlines? Would this depend on the input impedance of the amp? Would a extremely large input impedance be beneficial to doing this (the A/D/S/ are 47k, my JBL GTQ240 is 100k, many others are 10k)?

The manual claims that this technique (attaching speaker level wires to RCA's) will give a cleaner signal than a line-output converter, do you believe this would be true?

I appreciate if anyone can shed some light on this. I'd like to know just for the sake of knowing. Travis
 

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Discussion Starter #3
Bump... There are some excellent 12v theorists here, I don't see why this question is unanswerable.
 

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It will work just like they say, I even did it with Linear power amps and 5v HU (5v speaker outs). The problem is finding a HU that has unclipped speaker outs, you know 'garbage in/garbage out.' So you can't turn it up that high, but it works. Sometimes you can run into ground loop issues too, it depends on how the amp and HU handle grounding. I hardly ever had a SQ issue with 2v preout HUs, so rarely did that stuff, only for other people. IMO there is no point to being different just for the sake of being different, unless you have a special application where something like this actually gives you an advantage. You can run a 10v line driver and likely get better results because it will not clip, though you then have an extra amplifier inline to add its noise....hard to say what would work better. There is a reason why home audio still uses the same old preout voltage with no problems. Sure it is a nicer environment for the equipment, but it gets the job done fine so why screw with it, screw with something that actually will give you more SQ like your speakers/etc. But who knows, the situation may come up where it would work better that way. Try it and see is my favorite thing to do, or was back when I had time to screw with things way more than I can now.

A preamp can be made to handle about any input, so it depends on what the amp designer did far as what it will take. If the manual says so it should work. In the case of LP amps, I found that a PA2 line driver worked the best to get the most out of them. Given that was back in the days of HU 2v preouts max, and the PA2 was 5v just like LP said would work best. You set it not to clip and it was golden. Today my 880PRS HU has it built in.
 

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Discussion Starter #5
I had considered it for a friend that wants to run the factory head unit but is looking at a amp with no high-level inputs. I would never consider it for myself, my setups have aftermarket HU's with low-level outs. I just wondered why A/D/S/ would say that this method would be superior to a LOC.
 
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