Why dual volume controls?

[Elephas]

Why do some amps have two volume controls?

My HeadAmp KGSS has two volume knobs. I always set them at the same setting. I would prefer one knob and not have to set the volume twice or use both hands at once. They are stepped attenuators so it isn't too difficult to do so, but one knob would still be more convenient.

Is there a reason for this?

[Salt Peanuts]

Probably because HeadRoom Blockhead (the first balanced headphone amp, AFAIK) had two volume controls - sort of like dual 3-pin XLR jacks on most balanced headphone amps.

[dc]

to cure channel imbalance may be one reason.

I'm glad my Stax SRM-1/MK2 has dual volume control. Since I did a driver transplant on my Lambda Pros there has been imbalance, so this has been an absolute life saver.

However that is 2 controls in a single pot, that can adjust the channels separately if desired, otherwise if when you turn it it will adjust both automatically.

I admit on stepped attenuators it's probably less useful for fine tuning and probably annoying as hell.

[luvdunhill]

better signal path separation?

[n_maher]

Potentially easier to find and less expensive. I'm not sure how available 4-gang steppers were as little as 5 years ago.

[postjack]

I always hear "channel imbalance" in response to this question, but to me thats a pretty weak answer. If my headphones are so out of balance that a step on a SA normalizes the channels, then I just need new headphones.

I think the real answer is what Nate said, that its cheaper. And maybe there is a bit of a cool factor going on as well.

[jinp6301]

its so people can use their magic rubber band mods across the two knobs. I've tried those ones you get with asparagus but it made the sound too stringy and hard. So instead of using 1 large rubber band, I used a bunch of thinner ones made of Jena wire to get a more euphoric sound.

Rubber bands FTW

[mulveling]

I always hear "channel imbalance" in response to this question, but to me thats a pretty weak answer. If my headphones are so out of balance that a step on a SA normalizes the channels, then I just need new headphones.

I think the real answer is what Nate said, that its cheaper. And maybe there is a bit of a cool factor going on as well.

If owners could somehow accurately measure their headphones, I think they'd be surprised at the occurrence of imbalances in the ballpark range of 1db (sometimes even more). At 2db it becomes pretty noticeable. I believe the numbers some manufacturers throw up on driver matching (0.1-0.05db, etc) are likely BS. Sennheiser headphones have been pretty consistently well balanced though, IME. Not basing this on hard numbers, just my subjective experience. 1db imbalance is actually pretty damn hard to detect at first, until you know it's there. Stereo cartridges (many of which are spec'd at 0.5db+ matching), and even the odd record, can be equally likely source of imbalance. Then add in the effect of some pots - and you might have quite the cumulative imbalance, if you're unlucky.

Let's not forget that many have a natural imbalance of the way they hear, in their own ears. Personally, I find that if there's a slight imbalance towards the left side, it can be very aggravating. Same imbalance on the right is not so bad - must be something about the right brain/left brain thing.

[laxx]

Or it could be for people who have natural hearing imbalance. I know a few people who hear better out of one ear, so dual mono would help for that.

[grawk]

My guess is it's simply pandering to the purists who feel like any connection between the two sides will result in cross talk, even if it's in the volume control.

[guzziguy]

My guess is it's simply pandering to the purists who feel like any connection between the two sides will result in cross talk, even if it's in the volume control.

This make sense to me. It would be easy to have separate volume and balance controls. I seem to remember it being done before. This is certainly easier for the user and assuming decent balance and volume controls, there should not be any issues with sound quality either.

[Elephas]

I'm glad my Stax SRM-1/MK2 has dual volume control. Since I did a driver transplant on my Lambda Pros there has been imbalance, so this has been an absolute life saver.

I forgot my Stax SRM-T1W also has independently adjustable left and right volume on one knob. I've never adjusted them separately.

I've experienced imbalanced hearing once, which was due to excessive earwax in my left ear. After it was cleared, I suddenly heard better and more clearly from the left ear; everything was louder on the left side. After two days, both sides became balanced again.

I can understand dual volume controls on balanced amps, which can adjust volume for two single-ended headphones independently. But I think it would be more convenient to have one knob on a KGSS or SinglePower ES-1.

[recstar24]

I could understand two seperate volume pots for the reason Mike stated above. A lot of people can hear louder/better in one ear, so if I had two pots I would just play a mono record or something and match the channels until it was dead on center to my ears. Also a lot of cans have a slight channel imbalance as well, and would agree the senns are one of the more consistent and balanced in that regard. I am not sure what the studies show but in America I think most americans have a slight more hearing loss in the left ear as a result of driving on that side of the car and wind noise in the left ear when you drive with your window down.

And yes postjack I agree with your assertion that if your cans/hearing is so imbalanced that you will need one whole step on a SA to balance it (if that is even possible) you have more pressing issues.

[ojnihs]

we all have a dominant ear, just like we have a dominant eye. i would go so far as to say that it's pretty normal to hear slightly different in both ears.

[Dusty Chalk]

My guess is it's simply pandering to the purists who feel like any connection between the two sides will result in cross talk, even if it's in the volume control.

better signal path separation?

This is the reason on at least my Manley Stingray. It's a dual monoblock design.

[darkless]

better signal path separation?

This is the reason on at least my Manley Stingray. It's a dual monoblock design.

The better signal path separation is also the main reason my amp has separate volume dials. However, since my amp will also function as an integrated speaker amp, the idea of having control over the balance lends itself well to less than ideal speaker placements.

[spritzer]

It also bothers me a lot and I'll go for a single RK50 4-tier pot in my next amp.

[justin]

Why do some amps have two volume controls?

My HeadAmp KGSS has two volume knobs. I always set them at the same setting. I would prefer one knob and not have to set the volume twice or use both hands at once. They are stepped attenuators so it isn't too difficult to do so, but one knob would still be more convenient.

Is there a reason for this?

Because I couldn't afford to buy balanced attenuators directly from DACT, and nobody stocked them for DIYers

[Pars]

Dual volume controls have been used on a few classic preamps, notably the Audible Illusions Modulus. And these aren't even balanced... two mono volume pots. As noted earlier, this also handles any balance concerns in a speaker rig.

[deepak]

It also bothers me a lot and I'll go for a single RK50 4-tier pot in my next amp.

Good god it really is all out assault

I was all about the $180 Joshua Tree I plan to use.

[swt61]

Don't be fooled by the JT's price, it's an impressive piece.

[thrice]

Don't be fooled by the JT's price, it's an impressive piece.

It is indeed. Although, I would love a 4-gang RK50 someday.

[postjack]

i personally wouldn't mind dual volume control, with SAs. it takes, what, an extra 2 seconds to change the volume with the dual controls? i also tend to keep my volume pretty stable...

I'm pretty sure my incoming beta22 has dual volume pots, and thats fine with me. I definitely set it and forget it, especially since I typically listen to whole albums at a time.

[spritzer]

Good god it really is all out assault

I was all about the $180 Joshua Tree I plan to use.

I'm not really good at compromises so if it is good enough for Kondo it is good enough for me. The irony is that it will probably be disconnected most of the time if my damn APL 3910 ever gets here as it has a brilliant volume control.

[thrice]

I'm pretty sure my incoming beta22 has dual volume pots, and thats fine with me. I definitely set it and forget it, especially since I typically listen to whole albums at a time.

Yes, it does. Well, stepped attenuators,not pots.