Ok, I set my gains by turning off bass boosts, treble, any EQ or loud functions first. Then I turn the gain all the way counterclockwise(which I always perceive to be "down" but I know it's up concerning signal voltage level).
Then I turn up HU volume until I hear distortion, and then back it off until distortion is gone. Then with that volume level, I set the gain by turning it clockwise(up, but really down, again it's confusing if you don't know what it's doing) until I also hear distortion, and then back it off just a bit until it's gone.
Then I turn volume back down, and reset all EQ, loud, bass, treble functions.
That's the safe way to set it so it doesn't ever clip or distort.
But I never ever turn my HU volume anywhere near what it was to set the gain. So the HU preamp voltage is never what it was when the gain was being set. And therefore, I would not get the full output of my amp into my speakers......would I?
If I'm still on track here so far, then wouldn't it make sense to set the gain with the HU volume more to the level you would turn it to when using it? That way, the amp can output it's full wattage into the speakers at the signal level being sent by the HU with the volume only moderately up. Yes, I know this would increase the chance of clipping cause the gain would be set to receive a much lower voltage, but if you know what you are doing, and don't drive it into distortion when playing it with excessive volume, then that shouldn't be a problem.
Or do I have a completely whacked idea of how a gain works and I'm all wrong here and maybe I should stick with the "safe gain setting way"? What do you think?
Replies (3)
uochronos on 02/7/2005 19:13:12
no your right if you used say 90% volume to set gain then your amp well never push 100% power. if you listen to it at less then say 70% but thats good... your not stressing the amp and your getting a clean signal.. if you push the amp to getr 100% power from it you end up getting unclean singal.
your losing lets say 100watts off full power on a 600watt amp if your running it at say 50-60% volume... mind you this is all random numbers just to give you and idea. well 100watt loss is less then 1db of volume at 600watts.. so why worry about it over 110db or so 1db loss isnt noticable really at all..
Chronos
audeogod on 02/7/2005 22:32:37
Ok, so I'm on the right track. That's good to know.
So at higher wattages, a loss of 100 watts wouldn't do a whole lot. I can see that cause it wouldn't even mean a whole 1 dB.
I was mainly thinking about it in terms of smaller amps. Like I have a 200 watt max Pioneer amp, but let's be real about it, it pushes 35 x 2 RMS, and 70 x 2 Peak. If I use this amp to power a set of coaxials, or components, then set the gain with the method described above, then I'd not get the full power rating, and if I lost any power at these lower levels, then that could be significant. If the amp was only putting out say....18 watts RMS per channel cause of the way I set the gain with high volume, then that would be 3 dB difference almost.
Is 3 dB's a significant loss?
On the other hand, is adding an amp like this and getting the whole 35 watts RMS per channel even worth it cause the way I see it, I'd only gain about 3 dB's since just deck power alone is 22 watts RMS. I figure I'm getting about 15 - 17 watts RMS per channel(just guessing) from the deck, and this would only just be doubling the power to get 35 RMS per channel.
swez on 02/8/2005 00:05:56
We can detect a +3 dB increase at low levels below ~90 dB. As we get past +95dB of SPL, our hearing begins to block out certain frequencies to protect our hearing.
If you want to know the true output power of a given amp, a bench test with a non-inductive "dummy load" (4/2 ohms) and read the AC voltage off the load poles.
Since we will hear no music, we need to use a sine wave generator and an O-Scope to see if any distortion is present at the output of the amp on test. An AC voltage test will tell us the actual watts of output into the load.
Also, when we add EQ or bass boost, we can adding/subtract several dB to the input signal that reaches the amp. The proper way to use EQ, is to cut frequencies above "0" dB ref and boost frequencies that are below "0" dB ref points. This requires either a very well trained ear or an RTA.
Since most do not have such expensive tools on hand, we can use our ears to find the best settings to suit out taste (hearing abilities) and how the audio was mixed. Pretty subjective to be sure... but all that really matters, is that it sounds good to us and does not drive the amp(s) into clipping. After a few beers... it does not really matter anyway.
Just a thought,
Swez GRIN
Then I turn up HU volume until I hear distortion, and then back it off until distortion is gone. Then with that volume level, I set the gain by turning it clockwise(up, but really down, again it's confusing if you don't know what it's doing) until I also hear distortion, and then back it off just a bit until it's gone.
Then I turn volume back down, and reset all EQ, loud, bass, treble functions.
That's the safe way to set it so it doesn't ever clip or distort.
But I never ever turn my HU volume anywhere near what it was to set the gain. So the HU preamp voltage is never what it was when the gain was being set. And therefore, I would not get the full output of my amp into my speakers......would I?
If I'm still on track here so far, then wouldn't it make sense to set the gain with the HU volume more to the level you would turn it to when using it? That way, the amp can output it's full wattage into the speakers at the signal level being sent by the HU with the volume only moderately up. Yes, I know this would increase the chance of clipping cause the gain would be set to receive a much lower voltage, but if you know what you are doing, and don't drive it into distortion when playing it with excessive volume, then that shouldn't be a problem.
Or do I have a completely whacked idea of how a gain works and I'm all wrong here and maybe I should stick with the "safe gain setting way"? What do you think?
Replies (3)
uochronos on 02/7/2005 19:13:12
no your right if you used say 90% volume to set gain then your amp well never push 100% power. if you listen to it at less then say 70% but thats good... your not stressing the amp and your getting a clean signal.. if you push the amp to getr 100% power from it you end up getting unclean singal.
your losing lets say 100watts off full power on a 600watt amp if your running it at say 50-60% volume... mind you this is all random numbers just to give you and idea. well 100watt loss is less then 1db of volume at 600watts.. so why worry about it over 110db or so 1db loss isnt noticable really at all..
Chronos
audeogod on 02/7/2005 22:32:37
Ok, so I'm on the right track. That's good to know.
So at higher wattages, a loss of 100 watts wouldn't do a whole lot. I can see that cause it wouldn't even mean a whole 1 dB.
I was mainly thinking about it in terms of smaller amps. Like I have a 200 watt max Pioneer amp, but let's be real about it, it pushes 35 x 2 RMS, and 70 x 2 Peak. If I use this amp to power a set of coaxials, or components, then set the gain with the method described above, then I'd not get the full power rating, and if I lost any power at these lower levels, then that could be significant. If the amp was only putting out say....18 watts RMS per channel cause of the way I set the gain with high volume, then that would be 3 dB difference almost.
Is 3 dB's a significant loss?
On the other hand, is adding an amp like this and getting the whole 35 watts RMS per channel even worth it cause the way I see it, I'd only gain about 3 dB's since just deck power alone is 22 watts RMS. I figure I'm getting about 15 - 17 watts RMS per channel(just guessing) from the deck, and this would only just be doubling the power to get 35 RMS per channel.
swez on 02/8/2005 00:05:56
We can detect a +3 dB increase at low levels below ~90 dB. As we get past +95dB of SPL, our hearing begins to block out certain frequencies to protect our hearing.
If you want to know the true output power of a given amp, a bench test with a non-inductive "dummy load" (4/2 ohms) and read the AC voltage off the load poles.
Since we will hear no music, we need to use a sine wave generator and an O-Scope to see if any distortion is present at the output of the amp on test. An AC voltage test will tell us the actual watts of output into the load.
Also, when we add EQ or bass boost, we can adding/subtract several dB to the input signal that reaches the amp. The proper way to use EQ, is to cut frequencies above "0" dB ref and boost frequencies that are below "0" dB ref points. This requires either a very well trained ear or an RTA.
Since most do not have such expensive tools on hand, we can use our ears to find the best settings to suit out taste (hearing abilities) and how the audio was mixed. Pretty subjective to be sure... but all that really matters, is that it sounds good to us and does not drive the amp(s) into clipping. After a few beers... it does not really matter anyway.
Just a thought,
Swez GRIN
Copyright ClubKnowledge 2009 * All Rights Reserved
