What is recommended volume level for Source, Preamp and Power amp?

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I have very less idea about these stuff but Im pretty certain that a power amp should not have any volume control. The source also should not have any volume control. Volume should only be controlled from preamp , also the gain.
 

Kannan

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It is a wonderful device to match your source with your power amplifier. It has a volume control and has a unity gain.
Buffer is not always necessary unless your components are a bit vintage or you have some tube gear.
Most modern amps have pretty high input impedance of 100K and above (150k is quite common now). Most modern DACs n pres have output impedance at less than 500ohms.
If you are above 20/30 times of input impedance on the power stage, that is good enough.

It is quite a hard bargain between the dynamics of active pre and the transparency of the passive pre.
With good gain on modern sources, high gain active preamps are now redundant.
 

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This is not a simple question and the answer to your question is not simple too. Gain and volume are different animals. Simplistically, gain is a load at the input while volume affects the output. What is the output impedance of your pre? Your manufacturer should be able to tell you that. Based on that, your amp manufacturer should be able to tell you what the ideal gain setting should be kept at the amp.
The volume pot is a resistive element so the more it is opened up the better the sound. So once the gain on the amp is determined and fixed, you don't play around with that any more. You play around with the pre volume and the source volume to determine what is best sounding for YOU!

Edit: I see Joshua beat me to it. :D
Precisely.
 

keith_correa

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@Kannan you're right, I have checked with the power amp designer as well and he suggested the same.
The volume attenuator provided is useful while directly connecting source without pre amp.
Though I will try both settings.
You should also try connecting the source directly to the power amp which I understand has a volume pot in addition to a gain switch. Who knows, you may like a passive preamp better than an active.
 

adas

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@vbutani from the specs, I see that the amp has input sensitivity settings of 0.5 V and 1.5V.
The volume control on this power amp it is only an attenuator, to be used only if you do not have a dedicated preamp.
Since you have a dedicated preamp, set it to full (no brainer here).

Of course put the digital output full on your LG source aswell.
Try both 0.5 and 1.5 volt sensitivity on the power amp.

Go with the sensitivity that offers a wider bandwidth on the volume pot of the preamp. I guess with modern DACs pushing out 2 volts, 0.5 should be good enough on the power amp, but try both settings
What kannan is saying is absolutely correct , the amp volume is to be kept at 100% and the adjustments are to be made on the preamp side and as the preamp can push out 2V it's best to keep the gain at low setting.

Regards
Aniket Das
 

bornfi

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Power amp and dac at 100% and control the volume using preamp. This is one of the reasons why one buys a preamp. Sorry, I couldn’t read the entire post but this is what I have on my system.
 

Yelamanchili manohar

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One could take a KT88 valve, which is a power amplyfing valve, bias the voltage to make it output 8 watts at 0.1% THD. And one could bias the same valve to output 12 watts at a lot more percentage of THD. As we increase the gain, we increase the distortion.

Usually solid state power amps don't have adjustable gain. They are set at factory to output a particular gain. And makers qoute thd vs watts figures for the same, at that particular gain. Which to be honesr is at the upper limits of a power amps ability.

Whereas many tube amps come with adjustable gain. So that one can choose to run their tube amps easy at a lower gain setting, with the preamp running at full pelt. But the preamp, though working at lower 2V voltages is also struggling with a 2V load. So an ideal balance has to be found between preamp volume and poweramp gain.

In my own system, I use a passive preamp at 2 o'clock volume position, with my power amp gain at 80% gain. And not to mention, that in the best interest of prolonging tube life, I run the tubes at below their recommended bias voltages.

So there is no one hard and fast rule governing this in my humble opinion. So one has to experiment and find balance. And if the poweramp comes with a gain knob, then there are sonic benefits to be had, by not running it at 100% gain.
 

Kannan

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@vbutani Please check the possibility with @adas Aniket and see if the attenutor on the power amp can be bypassed. In my opinion you will benefot from it if you are using a dedicated preamp.
It is just a matter of couple wires that you need to desolder and rewire to take the potentiometer from the circuit.
 

adas

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@vbutani Please check the possibility with @adas Aniket and see if the attenutor on the power amp can be bypassed. In my opinion you will benefot from it if you are using a dedicated preamp.
It is just a matter of couple wires that you need to desolder and rewire to take the potentiometer from the circuit.
Keeping the volume at 100% is essentially Bypassing the attenuator , because the center leg of the potentiometer touches the other end when it's at 100% there by essentially Bypassing it.

Regards
Aniket Das
 

vbutani

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You should also try connecting the source directly to the power amp which I understand has a volume pot in addition to a gain switch. Who knows, you may like a passive preamp better than an active.
I was using power amp directly connected to source and it sounds good.
I wanted to try tube based sound as never heard it before.
After introducing tube pre amp in my setup, I really liked the sound! Vocal became more natural!
I tried very old Gujarati folk song and it sounded very natural to me! The vocal details mesmerized me!
It also improved overall sound and pre amp disappeared in the setup.

Thanks to all dear forum members, it was really a good learning experience!

I tried multiple combinations and found following volume levels sound good to my ears:-
Source (mobile) volume 15 out of 75 >> Pre amp 40-50% volume >> power amp in low gain mode (volume 100%)

I think my source amp is powerful so I may try to get line output by using digital usb c not sure much in this but fingers crossed!
 

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SanVJ

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