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In Reply to: RE: Hello Alan posted by Cousin Billy on December 23, 2015 at 23:13:45
I admit this can be a difficult concept to grasp, but please re-read what I wrote. It is not the case that "half the wave form" is lost in SE connections. This is not to say that I completely agree with Alan that there is nothing to be gained in home audio systems by using balanced connections. Perhaps Ralph can chime in with a more erudite discussion that will edify you.
Anyway, in your re-statement of a specific question regarding an MA1, it is possible to give a better answer than I did the first time. In Atma-sphere amplifiers that provide an RCA jack input as well as an XLR input, the user performs an act that connects the grid of one side of the dual-differential cascode input topology to ground,when he or she elects to use the RCA jack. The other grid of the input stage is driven by the input coming via the RCA jack. (I cannot recall whether connecting the unused grid to ground is done with an external switch or with a modified XLR plug, because it's been so long since I've even thought about driving the amp with an SE input.) However, the amplified signal still appears at the plates on both sides of the dual-differential cascode, which via cathode-followers drives the output stage still in balanced mode. So, I think it's correct to say that in an MA1, SE input is converted to balanced output. But it's the balanced output of what was originally an SE signal, so there was no noise cancellation (Common Mode Rejection) operating on the signal that reached the RCA jack. Some of that will be cancelled in the balanced circuit, I think.
Note. This response is very specific to Atma amplifiers. I daresay most other commercial amplifiers that offer both XLR and RCA inputs will handle the signal differently. That is to say that many products are "feaux balanced". For this reason also it is misleading to think that you can look for XLR input jacks and assume that the product contains a balanced circuit design inside.
I admit this can be a difficult concept to grasp, but please re-read what I wrote. It is not the case that "half the wave form" is lost in SE connections. This is not to say that I completely agree with Alan that there is nothing to be gained in home audio systems by using balanced connections. Perhaps Ralph can chime in with a more erudite discussion that will edify you
Its best if you think of an non-inverted signal and an inverted signal, rather than 'half the waveform' which only introduces confusion. IOW, both phases are being dealt with at the same time.
When you drive the MA-1 through the RCA input, the input is single-ended even if the source is balanced. Single-ended and balanced are inherently incompatible so you usually have to jump through some hoops to make the components work together- special adaptors, transformers and the like. But the thing you want to remember is that the signal is either balanced, or it isn't, no in-betweens.
Suffice it to say, Atma-Sphere for life.
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