Dos Hombres, a 14 Watt 2 channel 6CM6 combo amp build

T-Rex

T-Rex

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Hello all. I decided to show photos of a build that I am working on for myself. It is a two channel 6CM6 14 watt P-P amp. I have previously built the prototype of this same amp to get out the kinks in the design, and now it's time to build the grab and go for myself.

I borrowed concepts from a few amp manufacturers to come up with a small watt grab and go combo for my use. The cabinet is sized from a Tweed Super, but covered in ostrich tolex, built for me by Mojotone. The chassis was a custom built size, made blank, with a blank cover. I wanted as much room as I could get while still able to fit in the Super style cabinet. Speaker will be a Scumback that Jim built for me in 2012, a H75 / 30watt (thanks again Jim, great speaker).

This amp is a two channel, clean or overdriven, with a single input jack, but relay selectable Hi or Low option. Low is a single 12AX7 triode, high is another 12AX7 triode cascaded into the first. This option is available in either channel.

In the Clean channel Low or High goes through a Volume pot only, then straight to the PI (concept borrowed from a Friedman BE). There is no EQ /Tonestack in Clean mode, just the Volume pot, and no other stages.

In Overdrive channel Low or High goes to a sperate Gain pot, then though a Cathode Follower , through a Treble/Mid/Bass EQ stack on to the PI (same Friedman BE concept again). Presence for either channel is fixed with values the same as from a Marshall 4210, fixed Presence. Fixed bias on the 6CM6 power tubes. Photos below.




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Quick reference data from Sylvania:

The 6CM6 is a miniature beam power pentode designed for service as general purpose audio power amplifiers or vertical deflection amplifiers in television receiver sweep circuits. Except for bulb size and/or heater characteristics they are identical to the 6V6GT.

Note that these are 9 pin tubes that are roughly the same diameter as the EL84, but just a tad shorter, and operate on the 6.3V heaters. Heater current is 450mA. 8K plate load, so same OT as a 6V6GT, but at a lower wattage rating. Max plate is 315v. 14 Watt dissipation.

Pin out is :
1=Screen
2= not used
3+6=Grid
4=Htr
5=Htr
7=Cathode
8=not used
9=Plate
 
T-Rex said:
Hello all. I decided to show photos of a build that I am working on for myself. It is a two channel 6CM6 14 watt P-P amp. I have previously built the prototype of this same amp to get out the kinks in the design, and now it's time to build the grab and go for myself.
Click to expand...
Hey T-Rex... I didn't know for sure that you are a pro at this. This is a very highly professional build I'm witnessing. Very interesting features you have going on this amp. Please keep the details and pics coming in. I think I got a tubey growing... :sneaky:.

I'm a fan of Scumbacks. Did you know that Jim Seavall is getting the F out of California and relocating to Prescott, Arizona?

Do you know Mr John McDonald of V2 Amps? I recently found an old post of his from another forum while I was searching for any info on GR Amps. In that post, John complimented you highly on your builds. I recently and successfully build a V2 Caldera amp kit with lots of personal help and support from John... (y)
 
A note for those viewing. With the close of ClassicTone, which I still mourn over, I found this Hammond PT and Choke which on the prototype all the iron was ClassicTone. Also the OT is from MusicalPowerSupplies whom I have used extensively in the past for the OT's on my low watt builds. The availability of the OT needed for this build, that Matt had in stock, were only the newly sourced iron that he has contracted with a vendor in Mexico to build in an effort to keep pricing down. Matt claims there is no drop in tone quality.
 
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