Early Mk III

[jcp61]

 

[jcp61]

also I have a tech question,
if I pull the power tubes out, can I run the preamp section without harm to rest of the amp?

run it into another amp from the direct out?

 

[Buster Leggs]

also I have a tech question,
if I pull the power tubes out, can I run the preamp section without harm to rest of the amp?

run it into another amp from the direct out?

I'll let a tech answer that but is your amp simulclass or 60/100 watt? In one photo you have all 6l6 power tubes and that would be ok for a 60/100 watt or a simulclass, but in the other photo you have I'm guessing 6l6's in the center sockets, I'm no tube expert they look like 6L6's to me but what are those in the outer sockets. They look like EL84's. If that's the case to my knowledge you can't run those in either a 60/100 or a simulclass. Unless those are some EL34's that I've never seen, don't play that amp until you hear from someone more knowledgeable than me. Running the wrong tubes can damage your amp.

 

[jcp61]

also I have a tech question,
if I pull the power tubes out, can I run the preamp section without harm to rest of the amp?

run it into another amp from the direct out?

I'll let a tech answer that but is your amp simulclass or 60/100 watt? In one photo you have all 6l6 power tubes and that would be ok for a 60/100 watt or a simulclass, but in the other photo you have I'm guessing 6l6's in the center sockets, I'm no tube expert they look like 6L6's to me but what are those in the outer sockets. They look like EL84's. If that's the case to my knowledge you can't run those in either a 60/100 or a simulclass. Unless those are some EL34's that I've never seen, don't play that amp until you hear from someone more knowledgeable than me. Running the wrong tubes can damage your amp.

those are yellow jackets,
http://www.yellowjacketstc.com/

pretty cool class A/B to class A converter
there safe. I run them in all my amps from time to time, depending on what sounds I want and what power levels I want.

 

[Markedman]

Not good!!!!! If it were simul-class you could use "Yeller Jackets" but not 60/100, no good!!!! You'll mess your amp up bud.

 

[jcp61]

there fine,
work fine in the 66 twin reverb, just fine in the jtm45 and have been working fine in the MKIII for better than a year,
it's what their made for

 

[Markedman]

Mesa's are tough, I'll give you that.

 

[jcp61]

Mesa's are tough, I'll give you that.

:wink:

 

[McBarry]

Agreed it' early MkIII
couple observations - the older blue relay without the clear top, (and not one of the newer red/orange relays), the earth strap hasn't been twisted and bent as happens when the PCB is removed or even when worked on..
One of the bias caps looks very old - not sure if other 2 are newer..

Re pull p/tubes and run as a preamp.. I'd suggest not but interesting question..

Needs some thought for a considered response..

DB

 

[jcp61]

Agreed it' early MkIII
couple observations - the older blue relay without the clear top, (and not one of the newer red/orange relays), the earth strap hasn't been twisted and bent as happens when the PCB is removed or even when worked on..
One of the bias caps looks very old - not sure if other 2 are newer..

Re pull p/tubes and run as a preamp.. I'd suggest not but interesting question..

Needs some thought for a considered response..

DB

Well when I built the jtm45 you do a complete voltage check without speaker load, provided that you did not have power tubes installed
they cited that if you have the tubes in without speaker load that the OT will cook, without the tubes the power section is essentially disconnected
but mesa's always seem to have unusual appurtenances', so I thought I would ask here 1st

 

[fretout]

So, wait, you wanted to know whether the Trans was a "105", and now you want to Slave the amp into another power section? Maybe I'm completely missing something.

All the Boogie manuals I have read mention that speaker load has to be used when slaving the Mark III into a power amp or mixing board, so I would assume the power tubes have to be plugged in, but no materials that I can locate mention removing the power tubes would be permissible if the Mark III is slaved, so the safe/short answer is "no, leave power tubes plugged in and speakers/power soak/attenuator hooked up". Otherwise, the best route is to call Mesa directly and see what they advise, and PLEASE respond in this thread with their response.

Those Yellow Jackets are pretty cool. They're made right down the road from where I live, and they are pretty cool for getting more "vintage" tones. I think most of the concern earlier in this thread was from the fact that it looks like you're trying to run your amp in "simul-class" when the amp may not be "simul-equipped".

 

[jcp61]

So, wait, you wanted to know whether the OT Trans was a "105", and now you want to Slave the amp into another power section? Maybe I'm completely missing something.

All the Boogie manuals I have read mention that speaker load has to be used when slaving the Mark III into a power amp or mixing board, so I would assume the power tubes have to be plugged in, but no materials that I can locate mention removing the power tubes would be permissible if the Mark III is slaved, so the safe/short answer is "no, leave power tubes plugged in and speakers/power soak/attenuator hooked up". Otherwise, the best route is to call Mesa directly and see what they advise, and PLEASE respond in this thread with their response.

Those Yellow Jackets are pretty cool. They're made right down the road from where I live, and they are pretty cool for getting more "vintage" tones. I think most of the concern earlier in this thread was from the fact that it looks like you're trying to run your amp in "simul-class" when the amp may not be "simul-equipped".

I called boogie,
pulling tubes will still risk the out put caps, and the direct out is not a low voltage output for power amps as I thought, it is a tap off the out put coil and the same voltage as the speaker out.
the correct method for slaving is as follows
split the signal from the FX send, and turn the master volume to 0
so I know I know.
also they yellow jackets tube converters should be fine although they have never tested them.

 

[fretout]

So, wait, you wanted to know whether the OT Trans was a "105", and now you want to Slave the amp into another power section? Maybe I'm completely missing something.

All the Boogie manuals I have read mention that speaker load has to be used when slaving the Mark III into a power amp or mixing board, so I would assume the power tubes have to be plugged in, but no materials that I can locate mention removing the power tubes would be permissible if the Mark III is slaved, so the safe/short answer is "no, leave power tubes plugged in and speakers/power soak/attenuator hooked up". Otherwise, the best route is to call Mesa directly and see what they advise, and PLEASE respond in this thread with their response.

Those Yellow Jackets are pretty cool. They're made right down the road from where I live, and they are pretty cool for getting more "vintage" tones. I think most of the concern earlier in this thread was from the fact that it looks like you're trying to run your amp in "simul-class" when the amp may not be "simul-equipped".

I called boogie,
pulling tubes will still risk the out put caps, and the direct out is not a low voltage output for power amps as I thought, it is a tap off the out put coil and the same voltage as the speaker out.
the correct method for slaving is as follows
split the signal from the FX send, and turn the master volume to 0
so I know I know.
also they yellow jackets tube converters should be fine although they have never tested them.

Very cool man. Thanks for reporting back! This will be helpful as it's not the first time I've heard this question.