Instead of a 212 Marshall Cab at a Small Gig

[KRZ4TELE]

Rather than hauling a 212 Marshall cab into a small gig I got the idea of running a 30th Anniversary Marshall head through a Peavey SP 15 monitor for me and sending the guitar signal out through the mains. The monitor is 8 ohms like the speaker line on the amp. Will this work without damaging amp or monitor?
Thank-you for your thoughts

[Ben Harmless]

Work? Yes. Damage? Nope.

Sound good? Nooooooo....

If you stick a guitar speaker in the box, it'll be much better, but running a guitar head into a full-range speaker just kills the soul of the tone.

Even then, the box isn't a guitar cabinet, and probably doesn't have anywhere near the internal volume. Depending on its construction, it could sound great, or it could sound crappy.

And how were you planning on getting the signal into the house? You could absolutely mic up the monitor box, but if you're willing to compromise your overall tone because it's "just a monitor" then you'll just be mic'ing that compromised tone. Other solutions (DI) would probably be worse.

The right box on stage would probably work just fine though. Unfortunately, it's hard to predict.

[KRZ4TELE]

Thank-you Ben. I know from your posts you are an experienced sound tech.
The Marshall 30th has a balanced and an unbalanced out that can go straight to the board. The Peavey SP 2 15" (unpowered monitor) would be used for me. I can live with a less than steller tone for myself as long as I know the house is getting good tone direct from the amp. Could I run the monitor from one of the balanced/unbalanced outs and skip the speaker input all together?
I didn't know if the amp had to have a load coming out of the speaker input on the amp.
Johnny A does the amp/monitor approach with Marshall 30th Anniversary amps but I do not know the specifics of his rig.
Regards

[trag-o-caster]

There has to be a guitar speaker, or some kind of speaker simulation otherwise your tone is going to be REALLY lame. That includes that direct out as well. Taking a line out, direct out, etc. from a guitar amp into the board without some kind of speaker simulation is not a good thing tone-wise.

[Ben Harmless]

There are, of course, exceptions to every rule, but a basic direct out from a guitar amp has never sounded good to me - it's always shrill and tinny compared to what comes out of the speaker. The speaker is a big part of the sound of any amp - which is why a guitar-specific speaker will do a lot better in your monitor than the full-range driver it came with.

Yes, a tube amp absolutely needs a load on the speaker out, or you'll fry your output transformer in short order.

Without really knowing what's going one, Johnny A could be doing a number of things:
1. Running his amp into a stage monitor and into a speaker cabinet which is mic'd - the cab could be off stage or even isolated in a box.
2. Running his amp into a speaker simulating load box, and then pumping it back into the monitor and into the house system.
3. Mic'ing the monitor speaker - which could indeed sound just fine if it's a good box.
4. Actually using two separate amps, one powering the floor monitors and one mic'd up as usual - perhaps isolated.
5. He could just set his guitar amp up like you would a side-fill monitor - off to the side, pointing at him more than at the audience.

I tried looking it up, but came up empty. Do you have any links to somewhere where his rig is discussed?

Personally, I would have no problem running the amp into a floor wedge, and mic'ing that as long as it sounded decent. I think it was Mesa that actually made some wedge guitar enclosures for awhile, but I've never seen any.

EDIT: I found this article where he says he uses the "speaker direct out" of the amp. That could still mean a number of things, but I suspect there's a little more going on than just a direct signal out of the amp. I know someone with a 30th anniversary, and he's tried recording it every which way. He can't stand anything but a real speaker. Again though, exceptions to every rule. Try it out and see what happens!

[KRZ4TELE]

Thank-you for the advice and your time gathering information for the posts Ben. The info you provided is very helpful.
Regards