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Phase Inversion in Preamplifer?

I just bought a used Audible Illusions 2D here on a'gon. This will be my first venture into separates. I've learned that AI preamps have inverted phase, so it's recommended that I switch +/- polarities at the speaker-amp hook-up. OK. But according to AI literature the phono stage of the preamp is NOT inverted, only the output stage is. So, since I listen to both vinyl and CDs, what do I do? Should I reverse speaker wire polarity or not?

Incidentally, the amp I'll be using is an ATI 1502 -- still haven't been able to find out if it inverts polarity or not. But based on my (limited) research thus far it appears that phase inversion is a design of preamplifiers more than power amplifiers. Is that right?

Thanks,
Rich
winegasman
david_berry
211 posts
 
It does appear that the phase inversion issue happens more in preamps than in amps.
I do not believe that it make a great difference at all. My Joule Electra LA 150 preamp inverts phase as well and in my research it really does not matter and is not something to keep you up at night.
Also keep in mind that even within the same CD, the songs can/do flip/flop the phase.
winegasman OP
100 posts
 
Yes, thanks for the reply, but what about the fact that the phono stage is not inverted while the rest is? Is this anything I need to do anything about?
larryi
3,969 posts
 
I have a preamp that allows for inversion of phase by remote control. Yes, one can hear a difference quite readily. But, with most recordings, the difference is subtle, and it is not entirely clear which is the preferred setting (e.g., with one setting the vocals may be more realistic, while the piano becomes unnaturally phasey).

Because recordings seem to be all over the place, there is no reason to really worry about phase if you don't have the means (and will) to switch on a recording-by-recording basis. That kind of switching is only practicable with a phase switch, preferrably, one switch by remote.
jmcgrogan2's avatar
jmcgrogan2
6,346 posts
 
The fact that the phono stage does not invert is meaningless. The signal still passes through the line stage after leaving the phono stage, so even when using phono your output will be inverted when leaving the AI, period. You have what is called an integrated preamp, which is similar to an integrated amp. Instead of a preamp and amp in one box, you have a phono stage and line stage in one box. As you become more familiar with seperates, you will realize that the phono stage runs through the line stage and then on to the amp.

Bottom line, everything coming out of your AI will be inverted. The only concern you would have is if the phono stage also inverted, which would then cancel out the line stage's inversion. However, it does not, so you have no worries.

So change the polarity of your speaker cables only once, either at the amp output OR at the speaker input. Note that if you change polarity at both ends you will defeat the purpose.

Hopefully this helps.

Regards,
John
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