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Author Topic: peavey classic B coupling caps  (Read 14260 times)

Enzo

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Re: peavey classic B coupling caps
« Reply #45 on: July 21, 2014, 05:12:46 PM »
Look at the schematic.

On the V Classic, there are two jacks, marked MAIN and AUX.  See the tip contacts are connected together?   That is a parallel wiring.  The only difference between the jacks is that the MAIN jack has a shorting contact.   That protects your output transformer.   The bottom line of that is simple:  You have to plug into the MAIN jack first.  The AUX is only used for a cord to a second cab.

Matching is not so much about "maximum power transfer" as it is about sounding right.   Remember, these are just guitar amps, not precision laboratory systems.  It won;t hurt the amp if you are off by a step on impedance.   If you plug one 8 ohm load into the amp, it will still be happy.

If you have a pair of parallel 8 ohms in there now, that is a 4 ohm load.  If you then add another cab, it will parallel those, and your total will be lower than 4 ohms.  Wonb't hurt the amp, but you may or may not like the results.

Roly

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Re: peavey classic B coupling caps
« Reply #46 on: July 22, 2014, 01:05:21 PM »
Quote from: ilyaa
whats the right way to interpret the two speaker jacks on the output?

What's the right way to wire an XLR?  There are two ways you can do it (keeping ground on the same pin), and both are used, PLUS people like me use XLR's off broadway as speaker connectors &c.  How many ways can you stuff a three-pin standard?

So no, there isn't a standard for this either, and if there was, somebody would break it, so the only real way to know what you gear does for sure is go inside and have a look.  They may be just connected in parallel as in Fenders and hang the mismatch, or they may have switching contacts on the Aux to select a lower tapping - could be anything depending on how many the designer had for lunch.


Generally speaking valve amps are more tolerant of load variations than transistor amps and are not particularly bothered by a factor of 2:1 high or low on nominal (e.g. 16 or 4 on "8", but the maximum available power may be reduced).  Guitar amps tend to the low side plate-to-plate impedance of the Hi-Fi "optimum" for minimum distortion, trading distortion for power.
If you say theory and practice don't agree you haven't applied enough theory.

Enzo

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Re: peavey classic B coupling caps
« Reply #47 on: July 22, 2014, 01:25:02 PM »
Except in this case, there is a schematic telling us how it is wired, or was intended to be wired if someone has changed it.

Peavey Classic B series.