Dyna Saur
New member
Another little something I built up (actually I ended up building three of these, in slightly different variations). The power tubes are 6B4Gs (actually Russian 6C4C/6S4S), driven by a 6SL7 and fed with a 6AX5GT rectifier. OPTs are custom MQ RH-60s with belll ends and no UL tap, power trannie is a modern version of the Dynaco PA-774 as used in the ST-35 and SCA-35. The pretty red PC board is a design by Shannon Parks over at www.diytube.com. The 6B4G filaments have indicidual 6.3VDC supplies, the 6SL7 and 6AX5 have AC on the filaments. Chassis is another 12X10X2 Hammond Steel, with black powdercoating. These are very nice, indeed...
The full circuit details can be seen here: http://www.diytube.com/getsetgo/getsetgo_manual.pdf
The 6B4Gs' cathode resistors are 913 ohms, created by paralleling three 2740 ohm, 3W 1% power resistors.
The other two units use different OPTs, one with James JS-6113-HS, and the third with more modest Edcor GXSE15-8-5Ks.
In all three units I used 5K OPTs rather than the usual 2.5 to 3.5K, as the THD was much lower, at only a slight sacrifice in output power. I also modded the PSU from CLCRC to CLCLC, hence the second choke under the chassis.
In this unit, the Russian 6B4G/6C4Cs are1958 vintage twin plate, manufactured by Sventlana. These are nearly identical to the vintage USA 6B4Gs. The newer single plate Sovtek 6B4Gs are a bit more rugged, and can take more "abuse" than these more delicate vintage tubes. BTW, I also have run a pair of vintage, well-used Ken-Rad 6B4Gs in this unit, and they sound every bit as good, and perhaps a tad better, as the 1958 vintage Russki clones. The 6SL7 is NOS USA Tung-Sol, the 6AX5GT is GE. Note a couple of the green "Kommie Kaps" serving interstage coupling duty.
Top / Frontal view:
Under the chassis peek:
Yah, don't razz me about having the fuse in the neutral line, that has been corrected long ago... 8^0
I'll be groovin' along with this one untiol a Stereomour possibly comes my way ;-)
/ed B in NC
The full circuit details can be seen here: http://www.diytube.com/getsetgo/getsetgo_manual.pdf
The 6B4Gs' cathode resistors are 913 ohms, created by paralleling three 2740 ohm, 3W 1% power resistors.
The other two units use different OPTs, one with James JS-6113-HS, and the third with more modest Edcor GXSE15-8-5Ks.
In all three units I used 5K OPTs rather than the usual 2.5 to 3.5K, as the THD was much lower, at only a slight sacrifice in output power. I also modded the PSU from CLCRC to CLCLC, hence the second choke under the chassis.
In this unit, the Russian 6B4G/6C4Cs are1958 vintage twin plate, manufactured by Sventlana. These are nearly identical to the vintage USA 6B4Gs. The newer single plate Sovtek 6B4Gs are a bit more rugged, and can take more "abuse" than these more delicate vintage tubes. BTW, I also have run a pair of vintage, well-used Ken-Rad 6B4Gs in this unit, and they sound every bit as good, and perhaps a tad better, as the 1958 vintage Russki clones. The 6SL7 is NOS USA Tung-Sol, the 6AX5GT is GE. Note a couple of the green "Kommie Kaps" serving interstage coupling duty.
Top / Frontal view:
Under the chassis peek:
Yah, don't razz me about having the fuse in the neutral line, that has been corrected long ago... 8^0
I'll be groovin' along with this one untiol a Stereomour possibly comes my way ;-)
/ed B in NC
