6KN6-PP-guitar slave

[davorin]

Halo! Have anybody experience with 6KN& or 42KN6 tubes? I just finished PP guitar "slave" amplifier, with fantastic sound and plenty of power (~28V/8 ohms at start of clipping=~100W RMS; ~23V/8 oms=70W RMS with ~2%THD).

 

[davorin]

Here is schematic (hand draw).

 

[davorin]

More picture

 

[Geek]

Not bad at all! Great to see some sweeps make music 😀

How is the cooling done? Straight convection?

Cheers!

 

[davorin]

Yes, but finally plan is mount amp in 19´rack/box with fans (also with pre-amp, noise-gate, hall-effect and main voltage conditioner).

 

[Geek]

Very good sir! 🙂

I would suggest though a computer PS fan in there maybe, just incase it's operated outside the rack (portability for gigs/remote recording) or main fan failure.

Cheers!

 

[davorin]

Yes, good idea, but I must find very slim model of fun (max 15mm).

 

[Wavebourn]

Good usage of RCA sockets. 😉

Thanks for sharing!

 

[davorin]

OT, "home made" have 1760 t/primary for 2Kohms(4x440t/0,40mmCuEW), and 78t/secondary(1,50mmCuEW)for 4ohms plus 34t for 8ohm(1,25mmCuEW), all in same direction.
P1_P2_S1+S2_P3_P4
Start P1 to anode1; end P1 to start P3; end P3 to +340V
Start P2 to +340V; end P2 to start P4; end of P4 to anode2
Start S1 to ground; end S1 to start S2 and to 4ohms output; end S2 to 8ohms output
Iron: EI-type(40mm) and 50mm tall (S=20cmcm/br; S~18cmcm/nt)

 

[davorin]

Details...

 

[kenpeter]

RCA trick for the anodes, awesome!
Will get used again, I can promise.
Sometimes its the little details.

 

[davorin]

Test results:
Uin:1V (sinus, RMS); Rout: 8ohm (resistant 400W/noninductiv);
THD:2%
F Uout Pout
40Hz 14V 26W
100Hz 23V 70W
1kHz 23V 70W
5kHz 21V 58W
10kHz 18V 43W
THD:10%
40Hz 25V 82W
100Hz 28V 103W
1kHz 28V 103W
5kHz 28V 103W
10kHz 21V 58W
Output tubes operating point at Pmax (Po):
Ua=340V(346V);Ug2=150V(152V);Ug1=-38,5V(-38,3V); Uf=6,33V(6,28V)
Ia=2x60mA(2x205mA);Ig2=2x0,5mA(2x16mA);Raa=2kOhm;Rg2=2x100ohm

 

[loopsva]

Any idea on the screen current of your 6KN6 amp?

 

[davorin]

IG2=2x0,5mA (NO signal)
IG2=2x16mA (MAX. power)

 

[loopsva]

So, the total iG2 range is 1mA - 32mA for a pair? That would be tough to regulate with an 0A2/0D3.

 

[davorin]

Yes, total Ig2 grow from ~1mA (NO signal) to ~32mA (maximum power at output).
Regulated area: 0A2: 5-30mA; 0D3: 5-40mA

 

[loopsva]

When you made your own transformer (1760t : 78t +34t), was the primary 880t + 880t? Meaning, that each 6KN6 is driving a 500 ohm load?

 

[davorin]

Correct.