Hi guys
Going a little mad with this for now.
I am building an intergrated amp of a mashup of designs. Output stage is fine for 15watts PP el84 driven by a LTP. Yes overkill, but I am wanting to experiment with them.
The linestage is an Allen Wright hybrid SLCF with 12au7 and it is fairly quiet, but not perfect. The phono is Again Allen’s phono but with 5842.
I did not use super reg. I am using 2 of k&k shunt and ccs kit, based on the Salas design.
I have checked for ground loops, but will keep looking. I have removed 6.3 A.C. from nearby but the el84 are A.C.
I have 1k grid stoppers
The hum that I am getting is a very wavy modulated sine wave.
Any suggestions?
Going a little mad with this for now.
I am building an intergrated amp of a mashup of designs. Output stage is fine for 15watts PP el84 driven by a LTP. Yes overkill, but I am wanting to experiment with them.
The linestage is an Allen Wright hybrid SLCF with 12au7 and it is fairly quiet, but not perfect. The phono is Again Allen’s phono but with 5842.
I did not use super reg. I am using 2 of k&k shunt and ccs kit, based on the Salas design.
I have checked for ground loops, but will keep looking. I have removed 6.3 A.C. from nearby but the el84 are A.C.
I have 1k grid stoppers
The hum that I am getting is a very wavy modulated sine wave.
Any suggestions?
so I have isolated just the phono stage and I still get the hum
Schematic of phono stage is on Allen’s website. I have just put in 5842 instead of 6922.
Only component changes are R2 is 68 ohms and R1 is 100 ohms.
Also note his comments about resistor choice are confusing. I have built 3 of these pre amps now all a little different. But this is my first time intergrated and first time using 5842
Schematic of phono stage is on Allen’s website. I have just put in 5842 instead of 6922.
Only component changes are R2 is 68 ohms and R1 is 100 ohms.
Also note his comments about resistor choice are confusing. I have built 3 of these pre amps now all a little different. But this is my first time intergrated and first time using 5842
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Just moved the choke out of the chassis and the issue is still there. Plus one of the shunt refs just died. I think I overheated it running it all morning on its side.
I have been reading on the 5842 and the talk about how easily it oscillates, but George from tubelabs gear only uses 1 grid stopper. So I used 1, because the 4 grids are connected internally.
I have been reading on the 5842 and the talk about how easily it oscillates, but George from tubelabs gear only uses 1 grid stopper. So I used 1, because the 4 grids are connected internally.
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