No, it doesn't degrade the signal because it's all passive switching (except for the buffer). It's a control convenience and understanding issue. If I'm using a PEQ for room correction, I want it on all the time, no matter what the source. If I put it in a tape loop, I'll have to leave that tape loop in "monitor" mode all the time, which means I'm listening to what's being piped to the record bus. That's the Record Selector, or the dubbing controls to route the source to the record bus. The return from the tape loop is activated by the "listening" button being set to Tape 1 or whatever (or by use of the tape monitor switch if there is one). On my Onkyo preamp, it means that the nice lighted controls to show the source basically always said "Tape" and I had to use other controls to select what was being fed to the tape loop (and therefore the EQ). Each preamp handles this a bit differently, and it can get confusing.au
What do you mean "in the playback chain" and what difference does it make in term of signal routing? You feel the tape monitor button degrade the signal?
And if I want to listen to a tape in the second tape loop, now I have to dub the second tape loop to the first tape loop, and still listen to the first tape loop's monitor input.
But if it has a processor loop, everything--tape monitors and sources alike and their buffering--get switched before going to the processor. So, the tape handling works as we expect it to, without having to run everything through a tape loop and then "dub" that tape return signal to the line amp. And it means the tape loop can be used for what it's supposed to be used for--recording stuff, including the ability to listen to a tape monitor for those recording systems able to monitor what's being recorded (both my tape decks do that, and so does any typical computer USB sound card that I might be using, say, for needledrops).
It's especially complicated for me, because I have a multi-tape/multi-processor signal router in the tape loop of my preamp, and believe me, the buttons on that thing are confusing enough. I need that to support computer recording and two tape machines, plus a switchable processor output at unamplified line level for going to my external headphone amp. But if I'm just listening to a CD, I unswitch the tape monitor and all that stuff is bypassed including any effect of the tape loop buffering, but the PEQ is still happily making room corrections in the processor loop.
In terms of connectivity, they are similar. The output from the preamp to tape loops and to the processor is just switched line-level audio from the input source. The difference is that the signal goes through all the tape loop switching before it gets to the processor loop switching. The return from the processor loop goes to the line amp, which is what feeds the external power amp.
Edit: pics...
The Record Selector is on the left--it determines what is fed to the record bus to go into the tape loop. The Source Selector next to it determines what goes into the line amp (through the processor loop, which is called the "eq loop"--see the button just left of the volume knob).
(borrowed from a for-sale listing that sold a long time ago)
"Tape" as an input on this is a separate line-level source, for a tape playback system only. For playing tapes from something in the tape loop, you have to press the "tape monitor" button just to the right of the source selector.
Rick "who has lived for years at a time with EQ in a tape loop, until preamps that had separate processor loops got cheaper" Denney
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