C1 and C2 should be 1000uF caps as per 6L6's schematic posted earlier in this thread,the 220uF in the sim was me playing around with different values.Source resistance is as per 6L6 schematic if using irfp240's.I don't want to comment on what to use if you are using SemiSouth fets as I don't know.As for sonic differences with different C connections,sims show with connection as per schematic H3(3rd harmonic) is dominant which I find more in your face and bland.The other connection you mention(same as the sim) allows degeneration (AC wise I think) and sims show H2(2nd harmonic) dominant which I find more airy and wider sound .It is a matter of personal preference as our ears are all different although I've heard H2 dominance is preferred by a lot of people(that is what a lot of tube amps produce).
Many reasons:
1) Some holes of my diyaudiostore boards destroyed dye expiriments with capacitors, resistors, recently i discovered that for my ears and my setup Nichicon FG sounds more pleasant than KZ, i don't care maybe they need burn-in time.
2) I do not want to apply any modfications to the chasis (enclosure).
3) I want that my build, looks completed.
Really i'am not need any big modfications to these PCBS, just need to remove 2 mount holes and move transistors plus decrease pcb size by using unused space. That's all.
So if someone want to earn some money, please PM
P.S Build not a commercial, i build amplifer for myself.
I got idea how to combine non-standart chasis and UMS, and want to share it with others
Idea is quite simply, get a part of aluminium list around 4mm thick, drill original case mount holes, then drill UMS holes over. Paint with black heat-resistant paint or anodize it. Then use thermal paste to make contact between chasis and aluminium list and screw pcb over
Same idea can be used for other PCB's that you need to mount to your non-UMS chasis without applying any modfications to it
Of course for not heat emitting PCB's like PSU, protection boards e.t.c, you can use thinner aluminium list around 1-2mm thicker.
Also i make picture explaination, so hope everyone understands it
So where's my cookies now?!
Idea is quite simply, get a part of aluminium list around 4mm thick, drill original case mount holes, then drill UMS holes over. Paint with black heat-resistant paint or anodize it. Then use thermal paste to make contact between chasis and aluminium list and screw pcb over
Same idea can be used for other PCB's that you need to mount to your non-UMS chasis without applying any modfications to it
Of course for not heat emitting PCB's like PSU, protection boards e.t.c, you can use thinner aluminium list around 1-2mm thicker.
Also i make picture explaination, so hope everyone understands it
So where's my cookies now?!
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Finally Finished!
After starting a F6 one and a half years ago, I finally finished today. Power-up was uneventful and after a hour of warm-up I have it biased at 1.2 A per channel with less than a mV of DC offset.
Upon hooking up to my speakers, which have a sensitivity around 94 dB/W, all was silent. But, when I hooked up BOTH RCA inputs I got hum from both channels. If I remove one input the hum goes away. Changing sources from my CD player to tuner does not change the hum. The hum is present in both channels. The hum is not noticeable during playback, only during silence between tracks.
The input wiring is coax from the inputs to the board.
Any ideas where I should look?
After starting a F6 one and a half years ago, I finally finished today. Power-up was uneventful and after a hour of warm-up I have it biased at 1.2 A per channel with less than a mV of DC offset.
Upon hooking up to my speakers, which have a sensitivity around 94 dB/W, all was silent. But, when I hooked up BOTH RCA inputs I got hum from both channels. If I remove one input the hum goes away. Changing sources from my CD player to tuner does not change the hum. The hum is present in both channels. The hum is not noticeable during playback, only during silence between tracks.
The input wiring is coax from the inputs to the board.
Any ideas where I should look?
Attachments
PSU Picture
Here's the PSU. I wired the transformer with industrial terminal blocks. The green/yellow block is bonded to the case. The PSU 0V is tied to it via a thermistor. The static shield from the transformer (purple) is landed directly to ground. I have a ferrite on each of the primary windings.
The PSU measures +/- 24.3 VDC.
I'll work on getting a closeup pic of the input wiring, once I'm done listening to this track. Despite the hum during silence, this thing is amazing!
Here's the PSU. I wired the transformer with industrial terminal blocks. The green/yellow block is bonded to the case. The PSU 0V is tied to it via a thermistor. The static shield from the transformer (purple) is landed directly to ground. I have a ferrite on each of the primary windings.
The PSU measures +/- 24.3 VDC.
I'll work on getting a closeup pic of the input wiring, once I'm done listening to this track. Despite the hum during silence, this thing is amazing!
Attachments
You have a ground loop. That's why it's silent except when both RCA's are attached.
Looking at your photos the first thing I see is you have just one wire link between the 2 sides of the power supply PCB. There's holes for 6, use them all.
That, by itself, won't fix it, but it will help.
Next thing to try is attaching all the PSU grounds (Both PSU zero volt lines, both speaker negatives, and the CL-60 ground lift) into the same set of pads on the PSU. This should help the problem a lot. You have very nice looking wiring and it's a shame to cut into it, but you need to.
Do that and report back.
Looking at your photos the first thing I see is you have just one wire link between the 2 sides of the power supply PCB. There's holes for 6, use them all.
That, by itself, won't fix it, but it will help.
Next thing to try is attaching all the PSU grounds (Both PSU zero volt lines, both speaker negatives, and the CL-60 ground lift) into the same set of pads on the PSU. This should help the problem a lot. You have very nice looking wiring and it's a shame to cut into it, but you need to.
Do that and report back.
alvinlim: I lifted the static shield and found no change. I then landed it onto the thermistor lifted ground and found no change. The static shield is now back on the chassis ground.
6L6 : I was worried about that. I've attached some more pictures of my PSU. Do you think it will be necessary to move the 0V lines (green) in by one pad, or do you think they will they be okay where they are. If I have to move them in, I'll save a spot for them, otherwise I'll just use the spot for another 0V jumper.
6L6 : I was worried about that. I've attached some more pictures of my PSU. Do you think it will be necessary to move the 0V lines (green) in by one pad, or do you think they will they be okay where they are. If I have to move them in, I'll save a spot for them, otherwise I'll just use the spot for another 0V jumper.
