webdzynes

I have a Kenwood HU putting out about 4.5 volts to the amp and the gain on the amp set at about 70% and it all sounds pretty good. But I got thinking about lower power NOT being good for the sub but high gain not (necessarily) being good for the amp.. What's better for the sub - higher gain/lower volume, higher volume/lower gain or leave everything alone and be happy? (It's a JL Audio 12w7 sub and a JL Audio 500/1 amp....)

JoeyG

Ideally you would look for high output signal, low gain and clean high output from your amp. If your setup works well now, why bother changing it?

Advice I learned a long time ago, turn the radio upto about 90% volume, or until some distortion is noticable through radio powered speakers. Then slightly turn the radio volume down. Finally adjust the amplifier gain control until the speakers being driven are at the loudest possible output with the least amount of audible distortion.

Again this is only an opinion. :cheers:

92TripleBlack

Run the gains at about 90% on all your amps and then balance them with the amp gains with the fader controls etc. set to neutral. Amp gains are better because low gains high volume adds more white noise.

AP

I set mine to 70% ... and then increase until you like it at the normal volume level ... I really like HU's with individual built in sub controls ... so I can adjust that from the HU and the rest can stay fixed ...

webdzynes

Here's a reply from caraudioforum.com: http://www.caraudioforum.com/vbb2/sh...threadid=95803

"It will sound louder as you increase the gains while leaving the HU volume at a fixed level. However, this is only because the amplifier will put out its maximum power with lower input. So if you turn your HU volume to 50%, it will be theoretically be sending 2.25 volts, and if your amplifier is set a 2.25 volts, it will put maximum power at this setting. The problem with this is that if you turn up the HU past this threshold, the amplifier will start clipping, which could damage your speakers and/or amplifier. Also, the higher voltage that travels through the RCA's, the less chance of interference. Bottom line then is, you want your amplifier putting out maximum power at approximately 85-90% of your HU volume range."

Who's right?

AP

The guys at the caraudioforum are right ... mostly likely ...
I would set the amp gains so that the max volume on the HU does not cause my ears to hurt ... so that there can never be a cases where the volume is too high or starts to clip...

92TripleBlack

Here's what I'm trying to explain in easy terms. I think we may be on the same page. If you play your amps at max with no radio signal, you here some distortion in the form of white noise. If you have very little signal from the radio, you will have a little music and this noise. What you want to do is not have the amps at max, by turning them down some, you get more from the radio. However, if you turn them down to much, you waste amp. We always turned the gains to full, then turned back 1/8 turn or so. This lowered the amount of white noise but left the amp at close to full power. It also left a little for balancing. If you go back to half however for example, then the radio can max out and you will not hit full output from the amp. I hope this clears it up, no pun intended.

AP

Sorry ... I just read this part ... I ask my local shop this same question this morning about my system ... and he said, for JL Audio Amps ...

The Input Sensativity setting is supposed to match the preout voltage. So for 4.5V ... you should set it to High Input Voltage and since the dial has a range of 7.2V ... I would go a little past vertical to match it 62.5(degrees) to be exact... but no higher ... he said that if the input is set higher... it will not hurt ... but at max volume it will start to clip ... matching the 4.5 to the amp is the best choice...

Not all amps use the voltage to set the input ... but JL does ... most good amps do ...

the source on this info is a very good audio shop, they designed Pioneers show cars for 1997 and 1998 ... so I trust his tips ...

gcrouse

The real question: does that "input level control" on your particular amp merely attenuate the input at the preamp stage? Or does it actually adjust the voltage gain of the power amp? I really doubt it does that as most all amplifiers have fixed gain in the power amp stage (except those Bob Carver designs).

Now it's entirely possible the preamp in your amp could do a better job than the one in your head unit, but we're trying to maximize S/N out of the deck and reduce the effects of inductive or RF noise picked up on those long RCA cable runs. So run the highest possible pre-out voltage you can get without distortion- hopefully it's good all the way up. Then turn down your amps accordingly so they are just below max (clipping) at this point. Making sure the amp can never clip will prevent speaker damage; and operating just below this point gives you every bit of *clean* power available.

But f for some reason your deck clips when approaching max volume, you'll just need to remember where that point is; i.e. 7 or 9, and not exceed it. Because the amp will faithfully amplify that clipped signal and deliver it to your speakers.