Recent content by AdmiralB

Yeah, it's tough to keep track of this stuff. On the Mark IVs, they just tape off the 5V windings.

I guess so. EDIT - I should be more specific. A Mark III PT is, by itself, incapable of powering 5U4 rectifier tubes. So there are two possibilities - either you don't have a Mark III PT, or, your amp has a secondary filament transformer for the 5V supply. I can imagine that Mesa probably...

The answer is, it can't. No Mesa amp used rectifier tubes prior to the DRs, at least no 100W amp. Therefore, you don't have a Mark III power transformer.

Yes, they claim that. That doesn't make it true. Generally speaking, one shouldn't mismatch. If you have to, going numerically lower is safer. So your second example is generally safe (it's how all those BF and SF Fender extension speaker jacks worked). Going the other way, not so much...

That's very interesting. How does a Mark III power transformer provide 5V for the rectifier tubes?

I assume we're talking about output transformers, since the power transformers were never from earlier amps. The early DRs did use non-Simulclass 100W Mark III outputs....easy way to tell, if you have a 16-ohm tap, it's not a Mark III OT. The Mark III-equipped amps have jacks marked '4 ohms'...

Aside from the transformers, the dual and triple are identical. So it's certainly possible that a triple could have been made with an earlier-than-RF-1E main board. But it certainly would not have had the 562100 OT. I guess it's conceivable that one could be built with the OT from the...

I started out driving regular cabs with a QSC PLX1802. I had a pair of traditional 412s (sounded great), a pair of vertical 212s (almost as good and a lot easier to move), and a pair of EVM Thieles (sounded terrible). I was going to 'standardize' on the 212s when I bought a pair of the QSC...

EVs haven't used AlNiCo magnets since the '60s. All EVMs are ceramic. The ones on eBay will either be OEM or have the Mesa Black Shadow label - depends mostly upon whether the cab they went in was closed or open. Yes, they're only about $50 cheaper than the new ones, but $50 is $50, is it...

Reverb comes before the loop, so reverb is either on or off on both 'sides' of the loop send.

It'd be a lot cheaper to buy used originals...

No to both, at least not easily. The Quad has a long tank and a short tank. The short tank is the one that goes away and is replaced by the PCB for the MIDI. There's simply not room for both, same for the Studio; the only way I can think of to do it would be to mount the second pan...

5Y3 is pin-compatible with 5AR4/5U4, but it's not really capable of suppling current to an amp larger than about 25W. Sell it/make a paperweight out of it, and get a 5U4 or 5AR4.

The MIDI Quads also lose one of the reverb pans to make room for the MIDI electronics. To me, the dual-pan Quad reverb is about the best spring verb I've heard. I wouldn't want to trade that.

Yeah, if you pull a pair from a Triple, you can leave the cab where it is, from an impedance perspective. I doubt it'll change the tone significantly, though. If you mean trying just a pair of EL34s in your amp, that'll be fine but do remember the impedance issues I mentioned above. And of...