# Can I turn the gain of amplifier to the maximum ?



## presscot (Aug 7, 2015)

My system 
Head unit : Nakamichi Mobile Tuner Deck-1
Amp : Soundstream References 405 
front : 4" boston acoustics 704
rear : 5" a/d/s/ 320is
subwoofer : 10" a/d/s/ s10 x2

I couldn't find the sweet-spot on my system anymore. The sound is very thin and annoying. No warmth and thick which I do prefer at all. Last week I was angry with my system so I just turn the gain switch of all channel on my SS405 amp to about 15 o'clock (my ss405 can be fully turned at 17 o'clock). Previously, they're set at 11 o'clock. After that I can feel the sound is present and warmer! It played nice but as I opened up the owner manual of the ss405 amp, it said that "The best Signal to Noise ratio is achieved when the amplifier input gains are set between 2.5 V and 0.5 V" which is about 7 o'clock to 12 o'clock.

So I'd like to ask, Are there any disadvantages or harm to my speakers (or my whole system) if I would turn the gain of the amp to more than 12 o'clock or maybe to its maximum (0.1 V) ?


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## Victor_inox (Apr 27, 2012)

if you set gain to 0.1V and send 0.2V from head unit you will overload your amp.


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## MacLeod (Aug 16, 2009)

The gain is not a volume control. It matches the input of the amp with the output of your head unit. So when you turn your head unit to 75%, your amp will be at 75%. Setting the gain too high can cause clipping. If your gain is too high when you've got your head unit at say 50%, the amp is at 85% so if you turn the volume up a little more you're trying to get 101% which the amp can't do and you get clipping which sends out a distorted signal at a power level limited pretty much only by input voltage. It can be well over double the normal rated power of your amp. That can blow your speakers. 

Find a well mixed CD that best represents the music you most listen to. Turn the gain all the way down and the volume up to 75%. Now slowly turn the gain up on the amp until you hear distortion in your speakers. Back it down to the point where the distortion just disappears. You're done. 

That's a fast and sloppy way of setting gains. Not quite as accurate as using an O-scope or multimeter but it'll get you pretty close and keep you from frying your speakers.


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## Victor_inox (Apr 27, 2012)

yes but he wants it louder!


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## presscot (Aug 7, 2015)

In fact, I used to do the procedure of your saying which is same as told by the manual. But as I did a little try I found it hard to do because the sound was too loud and I was afraid that it would blow my speakers before they went to the distortion. 

So, Are there another way to set the gain without doing that loud procedure ?

What if I know how much my output gain of my head unit and then followed setting to the gain of my amp ? This is the reason for setting 11 o'clock gain on my amp in the previous time when my head unit said it has 1 V output and so I observed 1 V gain equals to 11 o'clock on my amp.


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## Weigel21 (Sep 8, 2014)

Setting gains with the aid of test tones lets you much more easily hear the onset of distortion as the tone will change from a hum to more of a buzz. You'll want to wear hearing protection IMHO, as it gets loud and once it's so loud, it's more difficult to concentrate on the sound, listening for the point that it changes. "I" was able to confirm that at least "I" can detect 1%THD while wearing ear plugs while playing test tones. 

I also recommend being in a quiet place and doing this earlier in the day before your ears have become desensitized or fatigued.


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