Unity gain devices and processor loops...

MarkWComer

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#1
Fiddling around between PL4000/II and a Carver C-1 preamps, I just recalled something from the 4000 user manual (page 7):

AUXILIARY EQUIPMENT HOOK-UP
Equalizers such as the Bose Equalizer should not be inserted into the Tape Monitor path of the 4000. It must be installed between the preamp and the power amp. This rule applies to any accessory equipment that normally would conect in the Tape Monitor path if the unit: (1) Does not have unity gain, and (2) Does not have flat frequency response. A tape recorder, a Dolby processor, or a DBX expander may be used through the Tape Monitor path if desired.


So, an equalizer does not have flat frequency response, but is a "near" unity gain device, but not fully due to any boosting or cutting of frequencies. No go, right? Why doesn't PL want me to do this- it's common practice for people to use their tape loops for processing ports! The Carver does have a processor loop...

This reminds me of I guy I knew who said "it's louder when I run it through tape monitor!" Well, yeah, bozo- you crank the output of your tape deck up and probably your input as well! Of course it will be louder if you pump more into your amp!
 

Gepetto

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#2
One would have to look at the circuit to understand the roots of this warning.

It could be because it upsets stability, that is what the unity gain warnings and frequency shaping warnings imply. But again would have to examine the circuit.
 

Lazarus Short

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#3
I remember plugging a tape deck directly into a power amp. It sounded very clean, but of course it was too loud.
 

MarkWComer

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#4
One would have to look at the circuit to understand the roots of this warning.

It could be because it upsets stability, that is what the unity gain warnings and frequency shaping warnings imply. But again would have to examine the circuit.
Too much trouble to bother…
I’ll just follow their recommendations.
 

BlueCrab

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#5
I suspect it has to with with the Peak Unlimiter and/or the Correlator. That altered signal could pass through those circuits, if switched in, and the effects of the external processing could impact what they do, particularly the Peak Unlimiter. Just my guess.
 
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