peavey 5150/6505/6505+ HT

[razorrick1293]

Hello there,

I dont suppose anyone knows the HT voltages a=in a peavey the stated peavey amps? it would be helpful and much appreciated if you could give a HT for each stage (preamp 1, 2, 3, 6l6g2, 6l6a). ive checked schematics and they dont say alot. and i dont know anyone with one that would let me check.

Thanks

[Nigel Goodwin]

Do you have a faulty one?, if so what's the problem? - the most common problem with valve amps are the anode loads of the triodes going high.

[indianajo]

You can look at the tube datasheets on triodeelectronics.com for max plate voltage (anode). Then make sure yours are less. Usually amps with tube input and drivers have uniformly increasing plate voltage from the input tubes to the output. The usual scenario is for the HV cap to get leaky somewhere about 20 years, and the big resistors drop too much. More rarely, a tube gets gassy or the bias voltage gets off, and the high voltage supply is okay, but the plate resistor drops too much.

[Enzo]

It is a commercial amp of which they have made thousands and thousands. The voltages won;t be too high for the tubes.

Typical Peavey 6L6 100 watt amp voltages will be like most similar amps. SOmething in the 480-500v range would be common on the plate node. Screens would be a few volts less, and the preamp nodes somewhere in the 300-350 range I'd expect.

A rule of thumb is about a milliamp or so for each 12AX7 triode. Calculate the3 total current through a B+ node and you will have an idea of the voltage dropped across the node resistor.

My shop has been an authorized repair shop for Peavey and fender and many others for 25 years or so, and I don't recall really needing a voltage chart. If a preamp triode is not conducting, the plate voltage will swing up to the supply voltage - Ohm's Law. Otherwise, the plate ought to be somewhere in the middle compared to the B+ there. SO if the plate voltage is really high, it usually just means the tube is not working or the cathode leg is open.

[razorrick1293]

i dont have one for it to be faulty! i wanted to build a preamp similar, but i wanted a rough idea of what the HT voltages would be. i know the main bulk of the preamp is the same as an SLO, but its the extra stages on the end of it that interest me, (also completely unrelated to the problem, i felt like haveing a go at building it point to point on tagstrip in a small of a space as possible )

[Nigel Goodwin]

Originally Posted by razorrick1293

i dont have one for it to be faulty! i wanted to build a preamp similar, but i wanted a rough idea of what the HT voltages would be. i know the main bulk of the preamp is the same as an SLO, but its the extra stages on the end of it that interest me, (also completely unrelated to the problem, i felt like haveing a go at building it point to point on tagstrip in a small of a space as possible )

Look for 200-250V feeding the preamp, the actual anode voltages will be much less due to the voltage drop across the load resistors.

[razorrick1293]

Originally Posted by Nigel Goodwin

Look for 200-250V feeding the preamp, the actual anode voltages will be much less due to the voltage drop across the load resistors.

really? isnt that a bit low? i expected more, but if thats the case thats perfect!

[Nigel Goodwin]

Originally Posted by razorrick1293

really? isnt that a bit low? i expected more, but if thats the case thats perfect!

That's all you need for the preamps and many amps probably run lower than that, anode voltages tend to by 60V - 150V or so.

Have alook at this Marshall example:

http://www.drtube.com/schematics/marshall/2204u.gif

It's really VERY, VERY non-critical.