Line out question on Tube 5150 II

[RCAGuy05]

I want to run the preamp out of my 5150 II into a processor that does stereo panning and then run the L and R outs into seperate solid state combos. For a stereo sound. Now if I'm just running the preamp out on the 5150 head without any cabinet or anything, just the head itself on soley used for its preamp out, could this short something or fry the tubes. I gotta know soon for project.

[timthetortoise]

Never, EVER, run a tube head without a cabinet plugged in. EVER. Your transformer(s) need a load and if they don't see one they will fry. If you can't have sound coming out of your cab, get a dummy load. NEVERNEVERNEVER use without a load.

[ggunn]

Originally Posted by timthetortoise

Never, EVER, run a tube head without a cabinet plugged in. EVER. Your transformer(s) need a load and if they don't see one they will fry. If you can't have sound coming out of your cab, get a dummy load. NEVERNEVERNEVER use without a load.

Couldn't he do it if he pulled the power tubes?

[xtjdx]

NO! You need a load, plain and simple. The tubes have nothing to do with it. The output tranny needs a load.

[boingoman]

Originally Posted by xtjdx

NO! You need a load, plain and simple. The tubes have nothing to do with it. The output tranny needs a load.

The tubes have everything to do with it. They provide the voltage. With the tubes unplugged, the trannie is just sitting there, basically.

I can't comment about ggun's idea, I've done it on a bench for testing and diagnosing preamps, but not in real life. I can't think why it wouldn't work, though.

You could also just wire a 25W resistor across a piece of speaker cable and plug it into the speaker jack, since you aren't going to use the output section.

Some 5150s have the standby switch on the output tubes only, leaving the preamp active. In that case, you could put the amp in standby. The resistor would be for safety in case the amp got switched on accidentally.

[timthetortoise]

So you're saying that if the tubes are taken out the output transformer isn't trying to feed voltage into a load? I'm not buying it. But, oh well. I'm not an amp tech or an electriconics guy so you're probably right. Whatevs.

[ggunn]

Originally Posted by timthetortoise

So you're saying that if the tubes are taken out the output transformer isn't trying to feed voltage into a load? I'm not buying it. But, oh well. I'm not an amp tech or an electriconics guy so you're probably right. Whatevs.

That's exactly it. Take a look at the way the 6L6GC power tubes connect to the output transformer in this example: http://www.ampwares.com/ffg/schem/su...b568_schem.gif

The power tubes are the source of the AC voltage that feeds the primaries of the output transformer. There is a small DC voltage across the primaries, but that's there in any case and doesn't get passed to the load. I don't see why this wouldn't work.

[RCAGuy05]

I get such great distortion into other amps with this thing, particularly stereo split.
Hey boingoman, or anyone, it has a standby switch, would it be ok to use the head without a cab if I just leave it in standby??

[boingoman]

Originally Posted by RCAGuy05

Hey boingoman, or anyone, it has a standby switch, would it be ok to use the head without a cab if I just leave it in standby??

I'm not sure. The schematic I have is for a 5150, not 5150 II.

I sent an email to Peavey about it, though. When I hear, I'll post.

[ggunn]

Originally Posted by RCAGuy05

I get such great distortion into other amps with this thing, particularly stereo split.
Hey boingoman, or anyone, it has a standby switch, would it be ok to use the head without a cab if I just leave it in standby??

I'm not familiar with your amp, but the standby switch on Fender amps cuts off the high voltage supply from the preamp tubes as well as the power tubes.

[RCAGuy05]

I talked to Peavey tech support and he said it does need a load and the standby thing won't work.
He was suggesting that if I wanna do the stereo thing and still use the 5150 preamp what I'd do is run the effects loop send on the 5150 to the input of the processor and then run one of the stereo outputs on the processor into the effects loop return. Then take the other stereo output on the processor and run it into a power amp, in this case he suggested the Peavey 50/50 cause its got the same or similar powersupply as the 5150 and also has resonance control(to retain the bass response that the 5150 poweramp has). So then I'd be running 5150 with a cab, and the poweramp into another cab.
I'd keep the amazing 5150 sound all the while. Only thing is I don't know what Ohm the Peavey 50/50 provides, so I'm not so sure what ohm of a cabinet to get just yet.
Anybody know the ohm of Peavey 50/50 classic power amp??????!!!! Is it switchable from 4,8,16 like the 5150 is?(a feature I love about it)
I love this head.

[timthetortoise]

Looks like it has 4/8/16 ohm stereo switching, and 2/4/8 mono. Good luck.

Oh, and here's one. I've been reading up on these and I'm gonna try to get one soon. Sounds like a killer power amp.