before I get it back to the bench, I would like to ask for expert opinion please!!last time I had an issue like this it was a faulty pot/volume control.
Other things to check would be value of the grid stopper resistors, and make sure your heater voltages are good not only at each tube but for the channel (bank of 2 tubes) especially if you are running the heaters in series, lastly check each cathode resistor value and voltage for correct bias operation.
Other things to check would be value of the grid stopper resistors, and make sure your heater voltages are good not only at each tube but for the channel (bank of 2 tubes) especially if you are running the heaters in series, lastly check each cathode resistor value and voltage for correct bias operation.
PP mono pair, 6n6p / kt120 with lundahl IT phase splitter and CCS cathode bias. Built them a few years ago.
I have been itching to build something but have no time, the aikido was purchase about three years back and was sitting in my garage collecting dust. So I figure its time to build it.
My main pre is a Monarchy nm24 tube DAC / pre. I have read that the nm24 weakest link was the line section so the aikido should give me some thing to compair it to. It's too soon to make conclusion, I need to play with the aikido more before I jugde.
Thanks!
Here's a shot of the set up
I have been itching to build something but have no time, the aikido was purchase about three years back and was sitting in my garage collecting dust. So I figure its time to build it.
My main pre is a Monarchy nm24 tube DAC / pre. I have read that the nm24 weakest link was the line section so the aikido should give me some thing to compair it to. It's too soon to make conclusion, I need to play with the aikido more before I jugde.
Thanks!
Here's a shot of the set up
Attachments
I'll try to dig it up and post it.
The original design was base on Push-Pull Amplifier.
The only difference is Ofcourse my b+ and the ccs bias for the kt120.
The original design was base on Push-Pull Amplifier.
The only difference is Ofcourse my b+ and the ccs bias for the kt120.
interesting...I am in the final stages of an EL34 PP amp that I have been noodling with for some time. Now I am basically using the Oddwatt circiut with 6SL7 in SRPP into the EL34 section in SIPP using LM317HV for a CCS bias to probably 100mA per channel.
If this works well then I may take on some type of monoblock design for my next power amp project using something in the KT88 family. So far I really like the KT90EH's.
Are you paralleling the sections of the input tube or just using one section?
If this works well then I may take on some type of monoblock design for my next power amp project using something in the KT88 family. So far I really like the KT90EH's.
Are you paralleling the sections of the input tube or just using one section?
Ok fellas!
I have gone through the board and check every possible detail and I don't see any mistake, I have done my best according to the manual, But I still get 7.5vdc on the filament.
The only thing I can think of is the filament transformer.
The transformer I use was the one recommended by Broskie VPT12-4170 Triad Magnetics | Mouser
12vct @ 4.17amps. I have it wired as full wave center tap.
Was I suppose to wired it as voltage doubler instead?
I have gone through the board and check every possible detail and I don't see any mistake, I have done my best according to the manual, But I still get 7.5vdc on the filament.
The only thing I can think of is the filament transformer.
The transformer I use was the one recommended by Broskie VPT12-4170 Triad Magnetics | Mouser
12vct @ 4.17amps. I have it wired as full wave center tap.
Was I suppose to wired it as voltage doubler instead?
So it looks like you can only deal with the tubes heaters wired in parallel. So you either need to feed it 6 VAC and use the voltage doubler or 12 VAC and either bridge or FWCT.
I would first take measurements at pins 4 and 5 with all the tubes in and remove them 1 by 1 and see if one of the tubes is the culprit.
The other thing that comes to mind is trying a 6VDC setup with the bridge setup. Wiring the xformer in series to get 12 VAC and 4 amps pre rectification might be pushing the limits for 4 5687s.
I would first take measurements at pins 4 and 5 with all the tubes in and remove them 1 by 1 and see if one of the tubes is the culprit.
The other thing that comes to mind is trying a 6VDC setup with the bridge setup. Wiring the xformer in series to get 12 VAC and 4 amps pre rectification might be pushing the limits for 4 5687s.
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