#A-47

[Dlacx]

Picked up a piece of Mesa history. This is a 1971 100 Watt #A-47. It has been rode hard (to use a metaphor!). Guts and transformer look good, but the power toggle was probably damaged during shipping. It's on the way to Mesa today for a check-up. I'll share some details as it comes along.

 

[user 41014]

Nice amp!
Are there PWR and preamp board #'s? I'm just about to post a 1976 version that I've been working on with a PS3 preamp and a PWR3 board that looks a lot like the one in your amp.

Also, what is the pot on the back of the chassis? Slave? Seems like enough pre tubes for reverb.

 

[Dlacx]

I honestly didn't have it in my hands long enough to know anything about it. I'm not skilled to work on this myself and certainly don't want to botch it up. The power toggle was broken on arrival so I was not able to fire it up. I only looked at it and took some photos before sending it on to Mesa. It arrived there this morning.

It does have reverb and it does slave. I'll put together some photos I got before I mailed it and post them.

Should I move this thread to the Mark series area? I'll post as I get information. I have a 2/77 Boogie also. I might have some gut shots of that one also. I absolutely LOVE how it sounds! Just a massive amp.

 

[mark1406]

Picked up a piece of Mesa history. This is a 1971 100 Watt #A-47. It has been rode hard (to use a metaphor!). Guts and transformer look good, but the power toggle was probably damaged during shipping. It's on the way to Mesa today for a check-up. I'll share some details as it comes along. View attachment 719View attachment 718

I don’t know anything about the early Mesa amps and how they evolved into the Mark 1 series. I’m aware there are different variations of Mark 1 amps. There are two different P.I. stages, there are differences in the triode gain stage on the front of the amp.

Regards

Mark

 

[user 41014]

The gut shots of the '77 might really help with the '76 I'm working on.

Plus I've been interested in the evolution of the pre boards. There is a big gap between my SP-3 and SP-8B,

Your A-47 should give an idea of where it all started.

 

[mark1406]

The gut shots of the '77 might really help with the '76 I'm working on.

Plus I've been interested in the evolution of the pre boards. There is a big gap between my SP-3 and SP-8B,

Your A-47 should give an idea of where it all started.

Ha, I only have more questions, what is a SP-3 and a SP-8B?

I would appreciate the explanation if you have time.

Regards

Mark

 

[Spinaltap11]

and another one I would love to get my hands on

 

[user 41014]

Hey Mark, I see from the other post you already got that these are the pre amp boards.

I've got IIB's with SP-8B, a few SP-9A's, RP-8C and I think a RP-9A, some which go back to the earliest IIB's but I would like to see the 8A board and its date/serial.

I saw a pic of the SP-3 on one of the Mark I threads and I think it might have been a '77. So maybe they didn't move past '3' until Mark II.

If anyone has pcb's of SP/RP-4 thru 8A I'd like to know and it looks like most of that span may be the IIA.

 

[bluebug]

Mine is an SP-3 and it is a 03/78. Maybe the use of the different boards depends on the options and not only the dates? I don’t have a reverb, and I saw some of the mark 1 preamp boards had an additional preamp tube compared to mine, I guess it was the reberb tube.

Fred

 

[user 41014]

The SP-3 must have been a venerable board. I really don't know and am just going by the standard I've seen in the IIB and later ones to think there is both SP/RP. In that case it would be RP for reverb or as was pointed out to me, if they were out of RP boards the R could be hand wired to a socket.

There's a good chance that if your 3/78 is still a SP-3 it rode out the 1st Mark. Can't wait to see what Dlacx's board is.