Peavey Classic 400 schematic ?

[nsubulysses]

This amp does,

4 ohm setting on amp, 4 ohm load -- 34V RMS, 289W


4 ohm setting on amp, 8 ohm load -- 49V RMS, 300W at 8 ohms or hmmmm 4 ohms on the amp means 6 ohms? just so happens to add up to 49^2 / 6 = 400.1666666666666667W hmmmmm


8 ohm setting on amp, 8 ohm load -- 47V RMS, 276W


8 ohm setting on amp, 16 ohm load -- 70V RMS, 70 x 70 / 12 = 408W



Perhaps I am doing the math wrong but based on looks alone it certainly does better at an impedance mismatch. RMS is listed in yellow in the bottom left corner

[vintagekiki]

Are you measuring how much is transfer ratio (Uaa~/ Usec~) OT for 4 ohm load and for 8 ohm load to know how much is Primary load (Raa) ??

Question.
Is OT for 8x6550 (KT88) in original condition or is it rewind?

[g1]

You're not doing the math wrong but you're using the wrong numbers.
Use the actual load value.
If you want to see what it does with a 6 or 12 ohm load, you will have to "make" those value loads and test.

[nsubulysses]

Vintagekiki I don't mean to disregard your questions but I dont' understand how to measure/answer them unfortunately. They are beyond my knowledge sorry.

BUT, and I don't mean to be rude when I say this, but some of the things you and Juan are saying and asking in this thread makes me think you have never seen a PV classic 400 in person or tested one or worked on one. I have only seen this ONE here at my workspace ever. So I know they are rare. I doubt there are many of these outside the US??? And it seems like you two are both in different countries? know Juan is, and that's why I asked if he's ever seen one. If he had it in person I don't think he would be so doubtful as he was throughout the thread that this thing can do 400W. Do you have personal experience with working on a bunch of these amps that makes you think something is still wrong? OT is the original and I dont know how it would be possible to get it rewound in this country unless you pay Mercury Magnetics more to rewind it than what it would probably cost to just have Heyboer make a new custom one.


This thing works exactly as the PV engineer said, so it seems like it works 100% correct, although slightly weird, but the insanely weird aspect of it has been figured out by gaining special insight into what happened during the design process, by asking PV themself -- the OT is spec'd for 90s made in China 6550s that are not real 6550s and have a different plate impedance and are not made anymore. So the amp will never work "normal" unless at an impedance mismatch or by using the 6L6-ish 6550s it was designed with.

By going over this amp 10X and also getting info from PV it seems like the story checks out 100% and this thing works as it should

[Jazz P Bass]

Thank you Peavey.

Can you imagine trying to get that kind of info from any other manufacturer??

[timv]

Sorry for a late addition to this thread but I have played with these quite a bit.
The tube type was brought up on the super thread on talkbass.
I saw the power output in action a few times.
The worst match I found for power output was a great matching set of 8 GE 6550's! I only got about 200 watts clean out.
With peavey's chinese tubes I always get very close to 400 watts clean on my bench.
The best recent tube tested are JJ KT88's, they put out close to 350 clean.
I swapped output transformers with one I have from a Marshall 2001 bass amp and got similar results. I assume they had the OT's made to match similar tubes.