Dumb and Dumbler

[talbany]

Eric
Thanks for the play by play.. Looks good so far.. I have a Super Twin on my Music man.. You'll dig it..

Build on..

Tony

BTW.. A little rust helps shorten the Eddy current field

[ToneMerc]

Left: Beyschlag 1 and 2 watts, they are big boys, carbon film and they don't seem to have that much drift in them. Also sold as Piher. Vishay bought up Beyschlag years ago. Being from Germany you see them in Marshall, Hi watt etc. They were also used pretty much exclusively in old Fischer tube stereo equipment. I think they sound warmer than current stuff. HAD used them in early amps as they were plentiful back when there was a surplus market.

The 2W in the middle is a Piher, flanked by two Beyschlags. Marshalls commonly had Morganite CC, Piher CF, then 1 and 2W Iskra CF and then a combo of Piher and Iskra. Pihers were made in Spain, Beyschalg of course in Germany. A common mistake is that Beyschlags are called or passed off as Pihers. The Dumble called #40 is full of Piher 1/2W CF in the signal path along with a couple of 2 watters.

Here's some NOS Beyschlag, Iskra and Piher resistor porn along with the coveted Radiospares & Lemco silver mica caps.

TM

[dreric]

I am curious about the picture of the Dumbler.

The way you oriented the filter cap board, is that how you are going to run it?

Usually the row of eyelets are towards the back of the chassis.

That's cool to build two versions of this amp side by side.

No, I just tossed it in there for the picture, then I saw that it was in the wrong position.

Eric

[dreric]

Eric
Thanks for the play by play.. Looks good so far.. I have a Super Twin on my Music man.. You'll dig it..

Build on..

Tony

BTW.. A little rust helps shorten the Eddy current field

Thanks Tony,

Seeing that you've used a super twin perhaps you can share with me the OT wiring. The output section has the ultra linear taps (I think) that made these amps so popular. They would be the blue/white and brown/white taps? Am I correct in assuming that I tie these off and just run the brown and blue?

Thanks

Eric

[dreric]

Here's some NOS Beyschlg, Iskra and Piher resistor porn along with the coveted Radiospares & Lemco silver mica caps.

TM

TM

Thanks for the clarification. Nice collection!!!

Eric

[talbany]

Am I correct in assuming that I tie these off and just run the brown and blue?

Yep!!

T

[markusw]

Dumb is a 102 / Ford build:
CE Chassis
Magnetic Components PT and choke
NOS Fender "super twin" OT

Hey Eric,

wasn't the Super Twin a 6x6L6 amp?
Suppose the impedance mismatch doesn't really matter...

Peace,

Markus

[grtamp]

Hi Eric, what's the big radial blue cap in power supply board?
Cornell Dubilier?

[dreric]

Hi Eric, what's the big radial blue cap in power supply board?
Cornell Dubilier?

Those are Sprague 320 uf @ 350v. that I got from Steve (69plexi). I try and orient things so that I can see the values but with these it wasn't really possible. Steve and Tom (structo) have both made builds with these caps and been happy with the results.

[grtamp]

Wow.....I know they are out of production or I'm wrong?

[dreric]

Wow.....I know they are out of production or I'm wrong?

These are NOS from Steve ....... 67plexi. He's posted on this thread and as far as I know he still has some for sale. He's easy to do business with.

Eric

[markusw]

Dumb is a 102 / Ford build:
CE Chassis
Magnetic Components PT and choke
NOS Fender "super twin" OT

Hey Eric,

wasn't the Super Twin a 6x6L6 amp?
Suppose the impedance mismatch doesn't really matter...

Peace,

Markus

Hey Eric,

didn't mean to offend you
Just trying to learn...

Peace,

Markus

[dreric]

Dumb is a 102 / Ford build:
CE Chassis
Magnetic Components PT and choke
NOS Fender "super twin" OT

Hey Eric,

wasn't the Super Twin a 6x6L6 amp?
Suppose the impedance mismatch doesn't really matter...

Peace,

Markus

Hey Eric,

didn't mean to offend you
Just trying to learn...

Peace,

Markus

Dude, my lack of response wasn't due to offense just my own ignorance. My whole purpose in these builds is to learn more. OT and impedance / tube compliment is one of those areas where my knowledge is seriously lacking. Hence my silence.

You are right the super twin is a 6 6L6 amp and I'm building a 4 6L6, I don't know if the mismatch is important. Perhaps (tony) someone who's (tony) done this (tony) type of build (tony) could chime in with some clarification.

Thanks for your sincerity, no offense taken. (I'm kind of counting on the group to point out my mistakes)

Eric

[markusw]

You are right the super twin is a 6 6L6 amp and I'm building a 4 6L6, I don't know if the mismatch is important. Perhaps (tony) someone who's (tony) done this (tony) type of build (tony) could chime in with some clarification.

Hey Eric,

thanks a lot for your answer!

My guess was, that the 180W OPT should handle the mismatch when run at 100W.

Peace,

Markus

[talbany]

Eric/Markus
Should have mentioned earlier..
Running off the 8 ohm tap should help with the mismatch..
FWIW..If you feel adventurous ..try it with a reverse speaker cable.. You may like it better..
Hope this helps!!
Tony