Clone of JTM45

[davorin]

Just finished clone of JTM45 (with some modification) with very good sound! OT and choke are diy-winding (on very old iron!) in my lab, head cab is home-made (very old-from early '70!) and PT is from unknown tube amp (Europe-no 110-120V tap!; 700VCT/200mA, 6,3V/4A, 58V/30mA).
Output tubes are at last 2x6L6GC-Shuguang (coke b.)(try also pairs NOS-KT66-GEC, KT66-Shuguang, NOS-6L6GC-Sylvania, NOS-6L6GC-GE, NOS-6L6GC-RCA, 6L6WGT-Groove/Russian, 6L6WGC-Shuguang, 5881WGC-Ruby/Russian, 6L6GC-Fender/Russian, 5881WB-Marshall/Russian, NOS-6P3S-EV-Reflector/Russian, NOS-6P3S-Saratov/Russian and NOS-6V6GT-Brimar, all work fine!) with best tone!? Small anode like 6L6G without any slot, and 420V on G2, but no glow area with Ia~60mA in idle!(Pa~25W idle!)
Input tubes are now 12AX7WA-EH (minor better are various NOS tubes), and rectifier is GZ34 (PHILIPS-MüLLARD/Blackburn, but GZ34-JJ work also fine).
Ua is 420-430V, and Ik is 2x35-36mA.
Shock-input capacitor is 0,1uF/1kV/PP.
First filter capacitor is 22uF/550V(F&T)+10uF/630V/PPiO, than 3 times 22uF/550V(F&T), and last is 2uF/600V/PP. Choke is 10H/50mA/400ohms, and all resistors in filter are 10Kohms/2W.

 

[TheGimp]

Nice looking build.

 

[Miniwatt]

Yeah, nice job

 

[danFrank]

Did you build the chassis and case or was it an old Marshall that you gutted and put in your electronics? Either was it looks great; just like it sounds!
Good Job!

 

[davorin]

Chassis, front and rear plate are new from eBay(260703102720).
Big surprise for me is that best sound come from cheep output tubes (6L6GC-Full Music/Shuguang), instead expensive NOS tubes!

 

[danFrank]

Chassis, front and rear plate are new from eBay(260703102720).
Big surprise for me is that best sound come from cheep output tubes (6L6GC-Full Music/Shuguang), instead expensive NOS tubes!

A lot of the chinese tubes sound great; they just don't last that long. Back in the 1990's I liked the EL34's they made (very inexpensive) but I had to change them out every couple of months.

 

[davorin]

Yes, it is true, but few years ago, Chinese, Russian and Slovak tubes comes better with longer life time and closer characteristics.
I can't find 6L6GC-Valve Art/Suguang-"coke-bottle" at eBay any more?!
Other variants of 6L6GC or 5881 haven't that good sound (not close!).

 

[kenpeter]

Valve Art 350B, same thing only different? Pinout like 6l6, not like WE350b. Coke Bottle...

 

[davorin]

Valve Art 350B, same thing only different? Pinout like 6l6, not like WE350b. Coke Bottle...

Interesting! Thanks very much!
Thinking: Maybe my "Valve Art" 6L6GC are renamed 350B...?
Other tubes from "Valve Art"(Shuguang), including KT66, not close good sounding!