4.) Die Schaltung invertiert das Signal, wie alle Anodenfolger. Nicht tragisch, aber bei Hörvergleichen mit anderen Schaltungen/Geräten sollte das ggf. berücksichtigt werden (z.B. LS-Verbindungen umpolen).
Heute habe ich vom Entwickler eine eMail bekommen diesbezüglich...
Christoph;
I’m glad you liked the preamp. I’m assuming we’re talking about the 4S Universal preamp, correct?
This absolute phase issue comes up a lot on audio forums and the like. First let me say that there is no phase coherency in recorded audio. There are instances where if you have a differing number of phase reversal between two channels (as in the left and right stereo channels), that some signals can get poorly reproduced by the speakers. However, I can assure you that the absolute number of phase reversals has zero effect on music reproduction. So long as your left and right channels are the same, then there is no issue. The signals are reproduced exactly the same.
Now for a caveat. The human brain is highly suggestible. There are those who have convinced themselves that when they switch the phase of their speakers (or signal cables, etc.) they really can hear a difference. But any difference that is heard is a product of the brain and not the reproduction equipment. In reality, the swapping of the speaker polarity (so long as all channels get the same reversal) doesn’t hurt anything. So overall the issue is rather mute. If someone wants to do this I say go for it, because I know that there is really no difference in the equipment's functionality. To which I will add that what makes us enjoy a sound system is a highly complex interaction of many factors. These factors include not only the actual sound, but our opinion of the equipment, our mood, how much personal investment we have in the system, our thoughts about the style of music being played, and a myriad of other factors too numerous to mention. So I will withhold my personal opinion if someone wants to change something in their system. If they think it sounds better, then who am I to judge?
I will however add one additional caveat. And this has to do with phase coherency across drivers in a single speaker cabinet. The nature of speaker crossovers is that at the crossover frequency, the signal is reproduced by both drivers (i.e. the crossover has frequency overlap). It is imperative that individual drivers within a cabinet be wired in phase with each other. In phase, the signal mixes between the two drives and produces a single wavefront the magnitude of which rolls off with angle off of normal. However, if out of phase, the signals form what is called a difference pattern that has odd lobes and nulls that change with angle. This can literally destroy the sound of otherwise good speakers.
So now you have my thoughts on the subject. Glad you are enjoying the project. Do you have a picture? I really like to see other builders' projects.
Matt