# Change input sensitivity (lower)



## MADXF (Jun 30, 2010)

Quick breakdown on my system.
JVC 926BT HU (5V line out)
Kenwood KAC-943 (Bridged for 2x subs) 
Kenwood KAC-923 (Fronts) 

I have the gains turned all the way down on both amps and have adjusted the sub volume down to match the rest of the system. (The amps are rated for 0.15-3.0V input)
General listening is around level 14 to 17 depending on the song (I think the max is 50).


I'm pretty much addicted to tinkering so I've recently thought perhaps I could lower the sensitivity on the amps so they're not being pushed so hard with such little output from the HU, surely that would help SQ even if I can't perceive it.


Is this possible? Would it be as simple as adding a couple of higher value resistors in the gain circuitry? and, Where would I find schematics for these amps?


Cheers,
Paul.


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## SPLEclipse (Aug 17, 2012)

I wouldn't go messing with the amps internals. It would be much easier to insert an audio taper potentiometer inline with the RCA(s) and use it as a voltage divider to reduce the signal.

BTW I'm jealous, lol. Wish I had that problem.


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## SPLEclipse (Aug 17, 2012)

Did a quick google search and found this; it explains it very well. You're basically doing the same thing you planned by increasing resistance eon the signal wire, just doing it in a way that you have control over and won't potentially screw the amp up.

Stereo Volume Controls


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## ATOMICTECH62 (Jan 24, 2009)

Just turn the Sub volume output down on the deck.


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## MADXF (Jun 30, 2010)

SPLEclipse said:


> I wouldn't go messing with the amps internals. It would be much easier to insert an audio taper potentiometer inline with the RCA(s) and use it as a voltage divider to reduce the signal.
> 
> BTW I'm jealous, lol. Wish I had that problem.


Thanks for the response, but I'd prefer to make the adjustment in the amp to reduce the potential for noise in the RCA's to be amplified. I don't like those pots, there always scratchy.
I'm not concerned about wrecking the amp. I can handle a soldering iron.





ATOMICTECH62 said:


> Just turn the Sub volume output down on the deck.


That's not my problem. As I stated in the first post, I've already adjusted the sub to match with the rest of the system. I want to turn the whole lot down so I will need to use higher volume level from the HU which should reduce noise being picked up in the RCA's and amplified.

I'm happy with the way it sounds as it is, but feel like tinkering simply because I can.


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## ATOMICTECH62 (Jan 24, 2009)

Are you saying you have noise being amplified now with the gains at minimum?
I am running older amps that have a range of 0.3-2volt.My deck will produce 5.25volts RMS unclipped at max volume with a -0db test disc.I have the gains set on the amps at about 30% where they reach clipping out at about 1.7volts input.

Some music will not even push the amps to the point of clipping with the volume maxed on the deck.Dire Straights"Brothers in arms"is one of them.Elton John is another.But things like Kid Rock,Godsmack and Skid Row will max them out at the volume on 21 out of 35.
With the system on and the volume at minimum I can no noise of any kind with or without the motor running.I hear the fans on the amps running though.If I put my ear up against the tweeter I can hear a faint his which is a byproduct of the signal to noise ratio of all the equipment in the signal chain.
I have the gain on the sub amp at about 90%to get some of the lower level music to max the amp out but I had to put a RCA line level bass knob on it to cut the bass on louder music and using the Epic160.


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## MADXF (Jun 30, 2010)

I haven't noticed any noise in normal listening, but I haven't put my ear up to any speakers yet to check for it.

The only track I can really turn up is Drum Improv from Sheffield 'Drive', but then I end up at 40 (of 50)
Billy Joel Greatest hits also need to be turned up a fair bit too.


I probably don't need to do anything, but since I like to play, I figure it can't hurt. 
I can always put it back.


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## MADXF (Jun 30, 2010)

Regardless of whether the HU can actually do it, is having an output of 5V going to an amp with lowest input sensitivity of 3V bad?
Does over-driving the input circuitry risk electrical failure, or just bad sound?


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