Grateful Dead Music Forum

deadguise wrote:

I tried all combinations of all levels and the Mesa was still clipping badly early. Not even 5 watts of clean headroom and shitty tone.

I run my SMS through an early 90s mesa 50/50, it was working fine until nrecently it's getting more distorted sounded. I had the power amp serviced a year ago and the tech had to reseat a "pre-amp tube"....
so apparantly these Mesa's had 12AX7s or something...maybe that might be the problem?

I saw a pic of the guts on a 50/50 and they indeed had a few 12AX7s - I know in my Mark III and Mark IV there's some 12AX7s in play when I run through the effects loop return. Hmmm . . . Brad, are you out there? Any input?

deadguise wrote:

I tried all combinations of all levels and the Mesa was still clipping badly early. Not even 5 watts of clean headroom and shitty tone.

I run my SMS through an early 90s mesa 50/50, it was working fine until nrecently it's getting more distorted sounded. I had the power amp serviced a year ago and the tech had to reseat a "pre-amp tube"....
so apparantly these Mesa's had 12AX7s or something...maybe that might be the problem?

Thanks, DG. I bought this used and only gave it a quick test and it seemed to work fine. Now I gave it a real test and it's funky. I think the best thing for me to do with it is to take it in for a tune-up so I can also be sure it's road-worthy.

tcsned wrote:strummin, what about the Mesa/SMS pairing didn't you like? I've been using my Mark III and Mark IV's power section and it works pretty well. It's hard to get the Mark IV to sound really clean - I think it might be the 8ohm 1x12 speaker at stage volume. I've been thinking of getting a Mesa 50/50 so I'd be interested to hear what your issues were.

tcsned... I might be able to help here on two levels, regarding a compare of the Mesa 50/50 vs. Mark III, when either is paired with the SMS CTP:

- Got my SMS in Feb and gigged a couple times with my original setup for it... SMS --> 50/50 --> JBL E-120s. Sounded great. Sounded pretty much how I'd hoped it would, which is to say... like the nice clear SMS signal into a nice, clear (perhaps a bit of Mesa mids?), powerful 6L6 power amp.

- The 50/50, bough off ebay, busted a gasket very recently (with tech now, but I think it was a bad resistor somewhere).

- Enter Plan B... SMS--> effects return of a Mark III blue stripe simul-class short head. Have now gigged with this a couple times, and love it too.

My gut says it's really not all that different from the 50/50. BUT... I have not been able to A/B the two power sections yet. I'm working form memory of the 50/50 vs current playing of the Mark III.

As soon as I get the 50/50 back from the tech (about 10 days...?), I'm going to compare them back-to-back, to see which goes to my #1 spot. I will post comments here as soon as I do... or PM me, and I'll get back to you. My gut is kinda telling me the Mark III EL-34s are adding a certain sweetness to my overdrive that wasn't there in the 50/50, but that's probably a stupid thing to say until I can play them back-to-back, and rule out bad aural memory!

Regarding keeping things clean: I've had no problem with a very clean signal, at higher volumes than I'd need, with either the Mark III or the 50/50. As someone else noted above, be sure to keep the SMS output knob (on back of unit), pretty low. Brad suggested about 9:00 o'clock to me, but I've found even lower... more like 7:00 or 8:00 o'clock, work better for me. I'm also running the Mark III into 2 8 ohm JBLs, so 4 ohm load... not smart enough to know what diff that makes. When the 50/50 is in there, it runs one channel each, 8 ohm, to it's own JBL.

thanks, I've had no problems with the Mark III into the 2x12 - the Mark IV combo with 1x12 sounds good but not super clean - it might be the 4ohm-8ohm or 2x12 v 1x12 issue I dunno. I haven't really had time to set things up and test it properly . . . darn kids!

helio, you are likely very right about the EL84s. They add a ton of character even before being overdriven!

I learned a long time ago that when setting levels you use your ears and then play. Don't know if I got a good lesson or not. But in my experience any gain stage can cause clipping but to your point the pre to poweramp is usually the #1 culprit!