High Gain Amplifiers?

[mcstatz5829]

I'm curious what everyone's opinions are of important of gain on amplifiers. For example, I've seen some recommendations for PS Audio Amps, but the 30.5 gain scares me away a little. It seems counter-intuitive to me to have an amplifier gain so high that for many sources the preamp is going to be set at like -40. Am I crazy?

 

[Mr Peabody]

Maybe I've just gotten lucky I don't pay attention to the gain.

 

[Michaels HiFi]

That's an interesting question.

My Aries Cerat gear is super hot signal. In fact the DAC and Preamp have -6db toggle switches so they can be used with other gear that can't handle that hot a signal.

With all the gear coming and going, I use the switch more than I though I would.

Sometimes if too hot it will either induce a clipping sound or the volume dial stays so low as to not get into the "sweet range" of where the dial should be.

Interesting I've learned over the last several years different mfg.'s have different sweet spots for the dial with their gear.

So yes - you may have potential issues, especially if you have super efficient speakers as I do. Some gear has a channel imbalance when the volume is at very low settings.

 

[a.wayne]

A gain switch is good as it helps you gain match for best operating range for sonics and drive ..

 

[mcstatz5829]

Sometimes if too hot it will either induce a clipping sound or the volume dial stays so low as to not get into the "sweet range" of where the dial should be.

Yes, trying to get in the sweet range is what I am trying to do! But when I look at lines like PS Audio with preamps +12 and amps +30, and typical modern speakers with higher efficiency, plus louder sources, what are these people setting the volume to like -50 or something? Admittedly I have fairly limited experience and don’t have the budget to test a whole bunch of combinations, which is why I am overthinking it now…

 

[W9TR]

Not crazy. High amplifier gain often results in preamp volume controls being at 9:00 for normal listening levels. That’s just stupid.
Historic power amp input levels were 0.7 Vrms for full power. That’s lots of gain. Problem is, that gain also amplifies any noise coming out of the preamp, significantly reducing dynamic range.

Modern preamps have higher output levels, like 2 Vrms or 4 Vrms requiring much less power amplifier gain to get full output.

 

[Michaels HiFi]

Yes, trying to get in the sweet range is what I am trying to do! But when I look at lines like PS Audio with preamps +12 and amps +30, and typical modern speakers with higher efficiency, plus louder sources, what are these people setting the volume to like -50 or something? Admittedly I have fairly limited experience and don’t have the budget to test a whole bunch of combinations, which is why I am overthinking it now…

You need to know the stats on your amp to know which of the ones you need, Some pre amps have a high low switch right on them - Schiit does for instance.

 

[Bamalam]

mcstatz5829, I have PS Audio BHK600s in one of my listening rooms and have played with amp gain settings, either 26dB or 30.5dB. Given the output voltage of the pre amp in that system and the efficiency of the speakers, along with my listening style at a very moderate to lower level, I landed on 30.5dB through experimentation and long listening sessions across different music genres. Here are some additional thoughts on benefits and downsides of using the higher gain setting:​

Pros:

1. Increased Signal Strength: Higher gain boosts the input signal more, making it easier to drive the speakers or subsequent audio equipment.
2. Better Signal-to-Noise Ratio: In some cases, increasing gain can improve the overall clarity if the input source has a weak signal, as it amplifies both the signal and the noise, but the net effect can be positive if the original input is very low.
3. Greater Flexibility: Higher gain settings can be useful in situations with very weak input signals, such as microphones in noisy environments.

Cons:

1. Increased Noise and Distortion: Higher gain also amplifies any background noise or hum, potentially leading to a noisier output.
2. Reduced Headroom: High gain can cause the amplifier to clip more easily if the input signal exceeds its linear range, leading to distortion.
3. Less Control and Stability: Excessive gain can make the system more sensitive to fluctuations or interference, potentially causing instability or feedback issues.
4. Potential for Overload: With higher gain, even small input signals can overload the amplifier or speakers, risking damage or degraded sound quality.

 

[atmasphere]

I'm curious what everyone's opinions are of important of gain on amplifiers. For example, I've seen some recommendations for PS Audio Amps, but the 30.5 gain scares me away a little. It seems counter-intuitive to me to have an amplifier gain so high that for many sources the preamp is going to be set at like -40. Am I crazy?

The more powerful the amp, the likelihood is it will also have more gain.

This is simply because a more powerful amp is likely driving a speaker that is less sensitive/efficient.

The idea is that one preamp can drive them all.

The converse of this is lower powered amps often have less gain, since the speakers they are intended to drive tend to be more efficient. So you simply don't need the gain in the amp.

 

[mcstatz5829]

The more powerful the amp, the likelihood is it will also have more gain.

This is simply because a more powerful amp is likely driving a speaker that is less sensitive/efficient.

The idea is that one preamp can drive them all.

The converse of this is lower powered amps often have less gain, since the speakers they are intended to drive tend to be more efficient. So you simply don't need the gain in the amp.

the other option though, is for the amplifier to have a higher input sensitivity, right? As in, if two amps are identical except one has higher power, then it must have higher gain and/or input sensitivity?

I think practically speaking you are correct but theoretically speaking there are more than one way to skin a cat.

I find it interesting that the output of a typical line source like a streamer is around the same as the input sensitivity of a power amp. Which means the source so hot if it were sent unattentuated into a power amp something would break including ear drums. Which means somewhere in the chain we need to attenuate the signal significantly. Add that most systems will have a preamp stage of +8 or more db, we’re talking of minimum attenuation of -20db which is a whopping 90% attenuation, not for comfortable listening levels, just so you can try to hear past the ringing in your ears as the cops cite you for a noise violation.

 

[atmasphere]

the other option though, is for the amplifier to have a higher input sensitivity, right?

This is exactly what I was trying to convey. Input sensitivity and how much gain is present are pretty well the same thing.

I find it interesting that the output of a typical line source like a streamer is around the same as the input sensitivity of a power amp. Which means the source so hot if it were sent unattentuated into a power amp something would break including ear drums. Which means somewhere in the chain we need to attenuate the signal significantly. Add that most systems will have a preamp stage of +8 or more db, we’re talking of minimum attenuation of -20db which is a whopping 90% attenuation

<rant>This is the classic problem introduced by the Red Book, which is the original 16 bit standard to which nearly all digital products are built.

You are exactly right! Apparently someone at Phillips didn't really understand the problem of how to drive a power amp as best I can make out. You might think 'how could Phillips and Sony make such a mistake?' but they are companies composed of humans and humans make mistakes.

IOW if you're going to put out 2V, that really should be how much the CDP or DAC makes after you crank its internal volume control up most of the way. If no internal control, the output really should have been at 1V, which was more or less the standard to which tuners, cassette machines, reel to reel tape machines and phono preamps were designed to do back when the Red Book was created. Put simply they just blew it.

I think the idea was a bit of hubris, that the digital device was going to be so much better than the prior art that 'why would anyone listen to anything else' became the mantra. But they simply misunderstood that 2V might drive some amps to clipping, but didn't think you'd need to control the signal level as well. 'Dumb' is being polite...

</rant>

 

[Mr Peabody]

This is exactly what I was trying to convey. Input sensitivity and how much gain is present are pretty well the same thing.

<rant>This is the classic problem introduced by the Red Book, which is the original 16 bit standard to which nearly all digital products are built.

You are exactly right! Apparently someone at Phillips didn't really understand the problem of how to drive a power amp as best I can make out. You might think 'how could Phillips and Sony make such a mistake?' but they are companies composed of humans and humans make mistakes.

IOW if you're going to put out 2V, that really should be how much the CDP or DAC makes after you crank its internal volume control up most of the way. If no internal control, the output really should have been at 1V, which was more or less the standard to which tuners, cassette machines, reel to reel tape machines and phono preamps were designed to do back when the Red Book was created. Put simply they just blew it.

I think the idea was a bit of hubris, that the digital device was going to be so much better than the prior art that 'why would anyone listen to anything else' became the mantra. But they simply misunderstood that 2V might drive some amps to clipping, but didn't think you'd need to control the signal level as well. 'Dumb' is being polite...

</rant>

I also wonder if they were thinking how people perceive louder is better.

My preamp and I've seen others offer a variable input level. I can go in and balance all my inputs to the same loudness if I wish. I used mine on the phono input to further give my TT a boost.

 

[MikeCh]

One solution for gain matching between preamplifier and power amplifiers was provided with the ARC SP-11. Having separate Gain and Level adjustment (knobs) allowed a user to drive power amps however they wanted. With the variable Gain adjustment you could dial in the "power-band" so to speak of virtually any power amp...then adjust the Level for volume of your liking. I don't know of any other similar designs from other manufacturers since the SP-11 and also wonder why ARC didn't employ it in latter designs.

Perhaps the circuitry introduced too much noise or something? If it did/does, I still don't notice any but find the function convenient as all heck.

 

[W9TR]

I for one am happy the device output level standard is increasing to 2 V or even 4 V. As thermal noise limits the ultimate noise floor of all audio gear you can get better system noise and dynamic range with higher output voltages.

The broadcast standard level has increased over the years from 0 dBu, 0.775 V, to +4 dBu, 1.224 Vrms or sometimes +8 dBu, 4 Vrms, depending on the facility.

I’ve found most audio gear chains have too much gain, so volume controls are below 12 o’clock at normal listening levels.

 

[mcstatz5829]

I for one am happy the device output level standard is increasing to 2 V or even 4 V. As thermal noise limits the ultimate noise floor of all audio gear you can get better system noise and dynamic range with higher output voltages.

The broadcast standard level has increased over the years from 0 dBu, 0.775 V, to +4 dBu, 1.224 Vrms or sometimes +8 dBu, 4 Vrms, depending on the facility.

I’ve found most audio gear chains have too much gain, so volume controls are below 12 o’clock at normal listening levels.

I think you might be on to something. perhaps the ideal situation is to eliminate the preamp gain stage all together. I think there are systems out there like that.

 

[atmasphere]

I think you might be on to something. perhaps the ideal situation is to eliminate the preamp gain stage all together. I think there are systems out there like that.

There's no way to do that on a general basis.

Some amps are monoblocks so its inconvenient to put a volume control inside them. You might also have multiple sources and some of those will need some gain so the amp can be driven properly.

In an individual system, particularly if you only have a digital source, then this can work.

 

[mcstatz5829]

There's no way to do that on a general basis.

Some amps are monoblocks so its inconvenient to put a volume control inside them. You might also have multiple sources and some of those will need some gain so the amp can be driven properly.

In an individual system, particularly if you only have a digital source, then this can work.

there are passive preamps that are basically just source and volume control. why wouldn't those work as long as the source is well buffered? I think three inputs would cover the vast majority of use cases: streamer/dac; phono amp; ht passthrough.

Edit: would need to be a hot phono amp that is compatible, not just any phono amp. but that's the tradeoff here. pros: minimalist, eliminate unnecessary components, good matching of gain stages, source levels, and volume control; cons: compatibility with other gear.

 

[atmasphere]

there are passive preamps that are basically just source and volume control. why wouldn't those work as long as the source is well buffered? I think three inputs would cover the vast majority of use cases: streamer/dac; phono amp; ht passthrough.

Edit: would need to be a hot phono amp that is compatible, not just any phono amp. but that's the tradeoff here. pros: minimalist, eliminate unnecessary components, good matching of gain stages, source levels, and volume control; cons: compatibility with other gear.

Preamps have 4 functions:
control volume,
select input
add any needed gain and
control artifacts of the interconnect cable between the preamp and amp

The last function is poorly understood in home audio (although it is significant as an entire cable industry around this issue demonstrates) although it is well-known in recording and broadcast.

Passive controls seem to only do two of these functions.

 

[W9TR]

I think you might be on to something. perhaps the ideal situation is to eliminate the preamp gain stage all together. I think there are systems out there like that.

I really like the way McIntosh builds their volume controls. They use a reed relay-based stepped attenuator to select a specific set of discrete resistors providing 1 dab volume steps o(or less) up to 0 dB gain. Above 0 dB gain they employ a variable gain amplifier up to the max volume.

This minimizes sound degradation compared to a traditional potentiometer or silicon based volume controls or arguably digital-based volume controls that throw bit perfect out the window.

 

[atmasphere]

I really like the way McIntosh builds their volume controls. They use a reed relay-based stepped attenuator to select a specific set of discrete resistors providing 1 dab volume steps o(or less) up to 0 dB gain. Above 0 dB gain they employ a variable gain amplifier up to the max volume.

This minimizes sound degradation compared to a traditional potentiometer or silicon based volume controls or arguably digital-based volume controls that throw bit perfect out the window.

The 'variable gain amplifier'... is that a Voltage controlled amplifier chip?

We designed a pretty sophisticated reed relay based control that did the same thing. I think that was about 22 years ago. We could never get it to sound as good as the volume controls we were building from custom built switches. I'm guessing the relay contacts were not as good as the mechanical switch contacts but we really didn't pursue it.