Balanced vs Unbalanced?

Ralph, you are such a tease.

Ralph, I agree with all of that. I wasn't very clear when I said

for everything to work as designed you have to have a circuit capable of producing 2 signals that are exactly the same except for their polarity.

I never meant to make any correlation between signal and CMRR. I should have said

to maximize CMRR the circuit must amplify any common mode signal to produce 2 noise signals that are exactly the same except for their polarity.

If one side amplifies the common mode signal i.e. noise more than the other then they don't completely cancel. That can't be corrected in the next stage. Sorry for the confusion.

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All things being equal, truly balanced is no better than single ended. Without regard to any budget considerations I only use single ended.

My sources run through 3 stages of gain before reaching the speakers. Three triode tubes. I have no noise unless I put my ear up to my speakers. I see no reason to complicate things by adding a bunch of extra stuff.

As somebody said earlier this has been debated to death. I haven't read anything so far that hasn't been said in numerous threads, including what I said.

Sidssp, There are many forms of distortion. SETs are the most linear devices on the planet. How does that equate to distortion generator? I lived through the distortion wars of the 80's where we ended up with vanishingly low distortion on amplifiers that would make your ears bleed.

The problem with SET amps, low power. The solution, highly efficient speakers.

Good source + triodes + good horn speakers = bliss

Sitting with a smile on your face and your toes tapping or dancing around the room are the defining factors. Audiophile nerds who sit frozen in one spot, never moving, never physically reacting to the music, discussing how black the background is and how much air there is around the instruments have so completely missed the point that they are hopeless. I hope you aren't one of these nerds.

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Audiogalore, I've never heard there was less chance of phase shift in a balanced circuit, Could you please explain?

I would like to point out that it's not all lollipops and roses. One unmentioned difficulty is that for everything to work as designed you have to have a circuit capable of producing 2 signals that are exactly the same except for their polarity. I agree that using a differential circuit makes it easier but there are still a lot of things that can cause an imbalance. If there were not the CMRRs achieved would be much higher than they are.

The other problem I see with Atmasphere amps is the OTL output. Ralph has done an admirable job of overcoming the stability problems experienced by earlier designs but I don't think you can overcome the inherent problems caused by paralleling a bunch of tubes and using them in a push-pull circuit. I have no explanation but cathode follower amps have never sounded as good to me as common cathode.

I have 3 directly coupled triodes and an output transformer between my source and my speakers which I believe leads to much better sound than you can achieve with a more complex circuit. Of course, if anybody wants to send me an OTL amp to try I would be happy to entertain them.

While I do agree with Ralph's explanation of the technical side of things I disagree that this leads to circuits that sound better than an SET, but of course this is a debate that cannot be won on either side.

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even if their amplitudes are slightly different.

I thought one requirement for a high CMRR was that an equal input was amplified by an equal amount so they cancel? How does that get corrected in the next stage?

That is no different from using multiple tubes or transistors in other amplifiers

I completely agree, and all of those would be better if they could avoid doing so.

Unlike an SET, they don't make nearly as much distortion at higher power,

Totally agree, that's why I use 107dB efficient horns and usually listen at moderate levels. If I crank it up I'm not too worried about distortion as long as it isn't gross.

BTW I have heard your amps at the Analog Room in San Jose hooked up to a pair of Avalons and it sounded very, very good. Too bad the proprietor is so condescending and the place reeks of cigar smoke. I readily admit it looks like you have turned the OTL from a fireworks display into a fine sounding piece of equipment.

Bob, I was talking about the output voltages having different amplitudes because they get amplified by different amounts. Isn't Whitlock saying that it will still reject noise even if the signals aren't balanced? I don't think that is the same as saying it will reject noise if the two inputs aren't amplified by the same amount.

Ralph, I get what you are saying, and I may try it sometime, but I don't use a bypass cap. I have the filament current of my input tube going through the cathode resistor to establish bias. That R is only a few ohms so too low to do what you say.

Thanks for the idea though.