xlr vs rca

Herman, I guess I should have phrased my question differently. I am aware of the Atma-sphere dual differential topology and how it works; I am just not aware of any other way to do it with tubes. Perhaps I should have asked how can you do it differently with tubes, and who (what company) uses other than a differential topology to achieve true balanced operation with tubes? Also, in any "balanced" design, an early stage, have to split the signal into positive and negative halves? It seems to me that at least the phase-splitting step is easiest to achieve with a differential topology. Downstream from the phase splitting, I get that additional differential topologies may not be necessary. Sorry that this is somewhat OT, but it's interesting, at least to me.

It's amazing how audio myths and misinformation persist in the minds of audiophiles. I vote with Almarg. He is about the only person who got it all correct. Raul was not wrong, either. His response was just not complete. Others get part credit. Herman, please tell me how the balanced differential circuits of Atma-sphere products are not "completely separate". Atma-sphere should get all credit for pioneering the use of balanced circuits at a time (early 80s) when such topologies were practically unheard of in commercial audio gear.

Herman, I have never seen a tube preamp or amp that achieves balanced operation using completely discrete amplification for the plus and minus halves of the signal. I wondered if you had, and I guess not. BAT most certainly does balanced operation the same way Atma-sphere does. I think to do balanced operation without the differential topology would be a disaster because of the difficulty matching Rp, mu, and Gm for two completely disconnected sets of tubes. At least in differential topology the current can be held constant for the two halves of the circuit by using a CCS in the cathode of the dual-diff amplifier, and the current on one side will go down by the exact complement of the increase in current on the upgoing side. The only place I have seen balanced without differential is in the context of using an IC or a 2-section bipolar transistor, which can have incredibly closely matched sections.

Yes, I know an MC cartridge is an inherently balanced signal generator if hooked up to a balanced input. I guess I was thinking of a single-ended signal from a cdp or other source.

Herman makes some excellent points. There are many folks who dabble in the "high end" who are convinced that single-ended circuits are inherently advantageous (in fact), because fewer parts are needed to construct them vs balanced circuits. I disagree with the idea that the parts count is relevant, for complex reasons, but I do agree that one should keep an open mind on the balanced vs single-ended debate, only one of many that rage among us crazies. I would only say that if the circuit is inherently single-ended (and you like it), go with that and don't try to create a pseudo-balanced interface.