Small guitar amp with 6JC5/6JB5 tube.

[davorin]

Just finished 2 small amp (Fender-Champ variation) with 6N2P-EV (good, cheep Russian military tube; similar with ECC83/12AX7), and 6JC5/6JB5 (Compactron beam pentode for vertical-deflection; "6V6 on steroids!"). Output power is >6W with clear, balance, harmonic and rich sound, much better than amps with 6V6GT in output.
Ua-k is cca.270-280V with Ia~50-55mA, and output transformer primary impedance is Ra=5200 Ohms.

 

[davorin]

More pictures!

 

[davorin]

One more!

 

[Cassiel]

much better than amps with 6V6GT in output.

I really doubt that, a little better would have passed unnoticed but 6v6 are just too good to be beaten badly.

 

[davorin]

Chassis are prepared to build in 1x12" box (like "Fender-Narrow panel-Champ").
6V6 is good tube, but 6JC5 (Pa=19W) and 6JB5 (Pa=15W) have much more clean power with the same tonal characteristics.

 

[Pckid212]

Looking good. How does it sound?

 

[davorin]

Very good clean sound, crunch after position volume at 8, and little fuzzy at all controls at maximum. Little more power with RCA (also ZENITH) tube, but little better sound with SYLVANIA output tube. At this moment I have only boxes with CELESTION speakers (4x12":VINTAGE-30, 4x10":VINTAGE-10, 1x12:G12H), but I have 2 speakers OXFORD-12K5-6 for the final version (boxes for combos are not finished yet).

 

[davorin]

Finally look of "Champ"-s (box is 20"x16"9,5"):

 

[davorin]

Box at beginning, and back side of finished amp (variation with black tolex and old "Oxford"-12" speaker-from 1972.year!).

 

[Glowbug]

Pretty cool

 

[davorin]

Third amp with CLETRON-12" finished.

 

[ISOTone]

cool amp!

i built a P-P similar to 18w marshall w/ 6AY11 and 6JB5. edcor wound the PT for this project. nice thing about the 6JC5/6JB5 is that lower 5932/6L6WGA characteristics seem to fit nice. the sylvania brand tubes seem to have a larger plate structure than the GEs, however, i like the tone of the GEs marginally better.

http://tubedata.milbert.com/sheets/137/5/5932.pdf

http://i2.photobucket.com/albums/y11/pmitchel/Compactronator-Preliminary-NFB.gif

http://i2.photobucket.com/albums/y11/pmitchel/DSC01371.jpg

http://i2.photobucket.com/albums/y11/pmitchel/DSC01377.jpg

http://i2.photobucket.com/albums/y11/pmitchel/DSC01376.jpg

 

[davorin]

Very nice job!
Yes, 6JC5 is like 6L6WA(WB?) with its electrical characteristics, but tone is more like "big and strong" 6V6.
"Zenith", "RCA" and "GE" tubes are all with 15W(6JB5) anode, only "Sylvania" is really with 19W(6JC5) anode. Try Your amp with 180ohms as common cathode resistor (with or without 50-220uF/50V parallel connected) at output tubes (only 6JC5!).
Which brand is Your speaker? Is it open, or close box?

 

[ISOTone]

thanks!

i thought all 6JC5 marked tubes were 19W plate - even the GE, RCA, etc.. the ratings are for sweep use, not surprising that we can up Pdiss 10-15% for audio.

i like the tone of the amp right where it's at right now. i may experiment with the higher Pdiss on my breadboard in the future; thanks for the tips.

--ISO