PreAmp Gain and Impact on Amp


Question; if you increase the gain output of your preamp does this ease the workload on your amp(s)? If your preamp gain goes from 10db to 15 db then you should be able to adjust your volume control down to reach the same volume level at the listening seat. Does more gain in your preamp lessen the 'load' on your amps?
stickman451
I am not sure about the "load on amp". But it will impact the sound from your speakers - BIG TIME. I recently experienced this in my system. I used XLR to get a substantial gain from preamp to amp and the difference in the bass/mid-bass notes is nothing short of staggering. Like going from a thin cord to a thick rope.
It has nothing to do with load. If you feel that it's not enough gain(usualy you'd have to use the most of your volume control dial), you can either adjust it if possible or purchase different preamp.

Sufficient gain is as important as fuel delivery from fuel tank to the engine: poor fuel delivery will lack pressure and acceleration while rich fuel delivery will increase fuel consumtion but increase high-speed and high-rpm performance.

You need to 'fill up' the input of your amp with preamp making sure that output voltage with gain set to zero will deliver sufficient voltage for the full power output of your amp.

It's all usually written in specs tested at 1kHz: Output Voltage, Input Sensitivity, etc...
If you have the volume max'd, you don't have enough gain. If the volume control sits near the bottom, you have too much gain. The idea is to have just enough gain for adequate listening levels and a bit extra for that party and your son to blow the speakers. For less than adequate speakers, volume control and distortion control are fairly synonomous.

Some sources have an internal switch to raise output voltage, which is the same as more gain.
You should have full power on average at about 1 o'clock position to leave reserves of gain for soft sources or soft recorded CDs.
Full power is around 4pm on my volume control. The control has 2db increments so maybe I should remove the 6db gain reduction resistor?
4PM seems far but it is OK if you don't have much softer recorded CDs. I have level control jumpers on my Benchmark DAC1 in -10dB increments (0dB, -10dB, -20dB, -30dB). I found that 0dB (loudest) position gives me the best sound (vivid). I normally listen in 10-11 o'clock. Full power is at about 1-2 o'clock. If removing gain reduction resistors gives you better sound and you still have enough resolution when you listen at low volume then why not.
Question; if you increase the gain output of your preamp does this ease the workload on your amp(s)? If your preamp gain goes from 10db to 15 db then you should be able to adjust your volume control down to reach the same volume level at the listening seat. Does more gain in your preamp lessen the 'load' on your amps?
there's no "load" on your power amp if you have less or more preamp gain.
Each power amp has an input sensitivity that lets the user know what voltage level of input signal will give the max output power. The main idea here is to not feed the power amp with a very low voltage input signal that is trending towards the bottom end of the sensitivity of the power amp because below a certain voltage level the power amp cannot "see" the signal the preamp is feeding it. The power amp circuits are quite non-linear in that region & your power amp output can have high distortion. OTOH, you do not want to feed in a preamp signal with a very large voltage value such that the power amp output is trending towards is maximum power output level because, once again, the power amp circuits are non-linear in that region due to excessive signal amplitude thereby saturating (or trioding) the transistors. You want your preamp signal to be such that you are in the middle region of your power amp input sensitivity. Most of the time this happens to be in the 12 o'clock to 2 o'clock region of your preamp volume control. This also happens to be the sweet-spot for your preamp volume control circuit/potentiometer/resistor-ladder, etc. If you can, adjust your preamp gain accordingly.
Better yet is to adjust the gain of your CD player/computer HDD system (if you can) to get your desired level of SPL between the 12 o'clock to 2 o'clock region of your preamp volume control. It's always best to have gain as further up the chain as possible as you can set as high a SNR upfront. Then, as music signal proceeds to the preamp & power amp, the SNR only degrades as the other electronic components add their resp. noise floors & distortion components to the music signal. If you start off with a (very) high SNR, your overall SNR degradation at the power amp output will be minimized. FWIW.
Bombaywalla, I am Impressed.
If full up on your preamp is loud enough for you, it will not sound any better with more gain on the same preamp and only half up for the same volume as full up with less gain.

Cheers George
I also wanted to add but forgot, there is the same amount of dynamic headroom at half level as at full level on what I've said in the above post.

Cheers George