Question for those running preamp>amp setups

RHafley

RHafley

Member
To achieve your desired level of overall volume do you (a) turn the gain all the way up on your amp and run your volume on the preamp lower or do you (b) back off the amp gain and run the preamp volume higher?

I'm just curious what would be the "proper" operation, if there is one. What are the pros/cons of either method?:scratch2:
 
My current power amps don't have the ability to adjust the output, but when I did I usually set the amp's control at the 1-2:00 position and adjusted from there with the pre. This left the power amp plenty of headroom, LOL, as if the speakers could take even half what that amp had on tap.
 
I have been running my amps (either and M60 or MX460) at about 3/4 of the way up which lets me run my pre (a C-80) up to around the half way mark. Any higher than that and I would only be using the first bit of volume knob travel.
I am picking up an Adcom amp soon which doesn't have any knobs at all and am curious to see where it falls on the volume scale of the C-80.
 
Generally speaking, running a power amp with no attenuation will give the best performance -- but there's no reason not to use the attenuators on a power amp (if it has one) to allow for a particularly "hot" preamp. That's what they're provided for.
 
Generally, running the preamp higher and the power amp lower gives better s/n ratio. It also provides more resolution/more fine adjustment of the volume. Rather than going "0-60" in the span of two clicks you can spread that over a wider range.

As well, the gain controls are not power controls so they really don't change headroom or limit output. All they do is change how much input signal is required for a given output.
 
Not sure if it's clear in the other posts, but most amps or pre-amps don't really have "gain" controls, they are attenuators for 0db to -whatever/infinity.

FWIW, except for a sub amp I tend to adjust from the front panel (have to turn it down for HT) I leave all the amps attenuators set to 0db (max volume/input level) If you have to attenuate input to mask noise, you're just masking some other problem.

Then again, the other posts do have merit if you want more granular control of the volume...

In the end, it's what works best for your setup.
 
brutal said:
Not sure if it's clear in the other posts, but most amps or pre-amps don't really have "gain" controls, they are attenuators for 0db to -whatever/infinity.
Click to expand...

I was wondering how long it would be before someone threw that out. :)

For all practical purposes they are gain controls. It's perfectly acceptable to call them as such.

By changing their position you change the overall ratio of output to input where it actually matters, from the input jacks to the speaker terminals. The ratio of output to input is the basic definition of gain.
 
My power amp has no gain controls

RHafley said:
To achieve your desired level of overall volume do you (a) turn the gain all the way up on your amp and run your volume on the preamp lower or do you (b) back off the amp gain and run the preamp volume higher?

I'm just curious what would be the "proper" operation, if there is one. What are the pros/cons of either method?:scratch2:
Click to expand...
just input for preamp and output terminals to speaker. Preamp controls level of gain
 
I turn mine down (on the ones that have them) only when I need a more linear control of the preamp's volume control. If that isn't needed (late night listening levels) the power amp controls are set to the max.
 
brutal said:
....If you have to attenuate input to mask noise, you're just masking some other problem.

....
Click to expand...


Missed that on the first pass.

All gear, in this case let's consider just the preamp for sake of discussion, has an inherent noise floor (I believe Yamaha, for example, refers to this as "residual noise").

An amplifier amplifies everything that comes in; the preamp's residual noise and the signal. Residual noise is essentially a fixed value, the signal level can be varied using the volume control. Both get amplified equally when they hit the power amp.

So, by running the amp lower and the preamp higher, what goes into the amp is a higher percentage of signal to residual noise. Thus, what come out of the amp follows the same with a higher percentage of signal to noise.

I will grant you that on very quiet gear, which Yamaha tends to be, you'd be hard press to tell much difference in most situations. However, all gear and all situations are not the same in this regard. And, even though you may not hear the difference in your system the effect is still the same. Amp lower, preamp higher = better S/N ratio.
 
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I have an Audiosource amp with individual gain controls for each channel on the back, and a volume knob on the front. The preamp/tuner unit it came with also has a volume control. So four volumes to set. You would think that would introduce some extra noise but it seems fine. Just really confusing.
 
My Pre Amp has Buffered Passive (bypasses gain tube), Normal Gain and High Gain while my amp has no adjustments.

For normal loud listening I use Normal, but for evening listening I switch to the Buffered Passive where I can get a nice volume without the in your face gain.

Best of both worlds!
 
I would set the gain controls for the power amp so when using one of your louder sources, Say CD, it delivers its full rated output between 2 O'clock and 3 O'clock. This would allow for fine adjustments to volume with that source, And still allow you to play quite sources, Like perhaps a TT at full volume.

That's based on my observation's that It seems most amps with fixed gain controls, Or integrated amps reach their full power at between 2 O'clock and 3 O'clock. I've found the less powerful receivers may get to full power at 1 O'clock with a loud source.

Since many power amps don't come with gain controls, Whether setting them the way most amps are set, Or adjusting them to another reasonable level won't much difference in terms of SQ if you listen at the same volume. So why have them? Gain controls are handy if you are bi-amping speakers and wish to back off either the low or HF do to room acoustic or speaker placement (corners may over boost bass), or to match the level with another amp. They are also useful for commercial applications.
 
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This of course is 100% correct and irrefutable.

Leaving power amps 'wide open' results in much lower volume pot range on the preamp, coarser overall control, greater localised pot track wear and subsequent wiper noise and a significantly poorer overall S/N ratio. Many pre-amplifiers actually get quieter in terms of residual noise at or near maximum volume.

The only issues that can occur sometimes are HF roll off in certain power amps due to interaction with the input stage LPF (R(pot)-C-R).

There is absolutely no sensible reason to not utilize the most of the 270 degrees of your volume control. Trouble is, people like to boast and say "Look how loud it is and it's only at 9 o'clock", which actually is meaningless.



whoaru99 said:
All gear, in this case let's consider just the preamp for sake of discussion, has an inherent noise floor (I believe Yamaha, for example, refers to this as "residual noise").

An amplifier amplifies everything that comes in; the preamp's residual noise and the signal. Residual noise is essentially a fixed value, the signal level can be varied using the volume control. Both get amplified equally when they hit the power amp.

So, by running the amp lower and the preamp higher, what goes into the amp is a higher percentage of signal to residual noise. Thus, what come out of the amp follows the same with a higher percentage of signal to noise.

I will grant you that on very quiet gear, which Yamaha tends to be, you'd be hard press to tell much difference in most situations. However, all gear and all situations are not the same in this regard. And, even though you may not hear the difference in your system the effect is still the same. Amp lower, preamp higher = better S/N ratio.
Click to expand...
 
Thanks for the replies. I've only ever had integrated amps so I didn't know if there was a "rule of thumb" to go by. The gain or attenuator controls on my amp go from 10 to 0 (with zero being no attenuation I suppose). Running about 2.5 seems to work well for me.
 
Whatever works best.

Part of what you're trying to do is balance the line level to feed each component to where it's happy. I run my amp off a tape loop on my Sansui quad via a Maverick TubeMagic D1+. Source is an HTPC. Through trial and error, I find I get the best results with the D1+ three clicks down from full on and the amp just north of 8. I control system volume using the software control in jRiver Media Center with the WindOhs! volume set at 100%.

Other sources are close enough to tweak volume with the D1+ ... couple clicks either way will do it. I went with dual volumes on my custom amp and use those for balance.

Your results may vary.
 
All my Yamaha amplifier gains are set to max.
They all run cool even when presented with tough loads(reputedly).
I have no idea if this beneficial to SQ or to the benefit of the amp.
 
tubed said:
All my Yamaha amplifier gains are set to max.
They all run cool even when presented with tough loads(reputedly).
I have no idea if this beneficial to SQ or to the benefit of the amp.
Click to expand...

See posts 12 and 16 as regards implications to sound quality/signal to noise ratio.
 
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