Impact of phase inversion by preamp

ieales

Nothing is completely passive. The more revealing the circuitry, the more it exposes component ’flaws’.

Semantics. There is passive circuitry, and there is active circuitry. There’s no value in confusing the two.

Experience with phase flip switches in active and passive balanced hardware often left something to be desired in terms of routing and hence inaudibility.

Whose experience? With what hardware?

Decades back it was demonstrated there were distinct sounds in a system on the same source ...

When was that, and by whom? Where was the demonstration, what were the source and other components used?

@cleeds 
Nothing is completely passive. We may think of C in terms of uF, but there are L&R factors which pertain. Pull apart a switch and examine the contacts. One set may have a contaminants/wear/geometry that the other does not.

A great recording & electronic design engineer built an incredible sounding recording console that used mercury wetted relays as close to the active circuitry as possible to eliminate passive colorations from running traces [audible] to surface switches [audible] and back.

Mic pre's, EQ, recording consoles in the studio.

In the early 80's. Then state of the art LA recording studio. Participants were well regarded engineers and IIRC, some industry sales reps. Source was hot-rodded ATR-102 ½" master tape feeding Bryston amp stack and time aligned studio monitors. Test was change or no change. Blind. Most got most of the changes.

ieales

Nothing is completely passive ... Pull apart a switch and examine the contacts. One set may have a contaminants/wear/geometry that the other does not.

A mechanical switch is a passive component.

I’m sorry that you don’t have any details on the listening test:

... state of the art LA recording studio. Participants were well regarded engineers and IIRC, some industry sales reps. Source was hot-rodded ATR-102 ½" master tape feeding Bryston amp stack and time aligned studio monitors. Test was change or no change. Blind.

Without details, your claim really doesn’t mean much, except perhaps to you.

@ieales I believe the passive concept you are defending so vehemently has nothing to do with the passive comment from atmasphere. Different application. 

I'm sure you want to say something relevant I just couldn't understand your last posting if you could please elaborate more? 

Nothing is completely passive. The more revealing the circuitry, the more it exposes component 'flaws'.

Experience with phase flip switches in active and passive balanced hardware often left something to be desired in terms of routing and hence inaudibility.

Making both halves of a balanced circuit identical is EXPENSIVE. Add in tube vagaries and the probability of a sonic delta is fairly certain.

These statements are by no means universal truths :)


'Passive' refers to a component that does not involve a semiconductor or vacuum tube. Switches, sockets, capacitors, resistors, volume controls, transformers, wire and the like are considered *completely* passive.


Our MP-1 preamp was the world's first balanced line preamp for home use. The phase switch has been on it since its inception 30 years ago. Quite simply, operating the phase inversion switch is subtle- on multi-channel recordings you can't hear any effect at all. IMO whatever your experience was, it would seem to have been done with equipment that wasn't thought out all that well.

We use differential circuits for our balanced operation. This is not particularly expensive to do- our preamps are pretty affordable compared to the competition in the same class! It is true that each half of the differential amp is slightly different, but you might be amazed at how well they work- the key is a good constant current source, with which we get Common Mode Rejection Ratios (CMRR) in the neighborhood of 100dB, which is pretty good. In a nutshell, no 'sonic delta' when the inversion switch is used (unless playing a true stereo recording); but even if the differential amp is poorly balanced, its a simple fact that there is no 'sonic delta' anyway; you might want to think about why; hint: it has something to do with differential amplifiers :)