Yeah, no change. What a pain. Are your temporary shields grounded? They won't have any effect if they aren't... Can you shift the power trannies to the side of the amp and attach them there, so that they're oriented vertically? You should still try the single input/output with simple twisted pairs, but flipping the trannies on their sides might help...
I agree, even the handheld scope would reveal more. But in the meantime...
perkri, have you swapped tubes from right to left channel and vice-versa? Some tubes, even brand new ones, can have a lot of heater-to-cathode leakage. I had to pitch some brand-new EH 6SN7s because they simply would not work in my Williamson amps, amazing amount of hum, really threw me off!
perkri, have you swapped tubes from right to left channel and vice-versa? Some tubes, even brand new ones, can have a lot of heater-to-cathode leakage. I had to pitch some brand-new EH 6SN7s because they simply would not work in my Williamson amps, amazing amount of hum, really threw me off!
Duh…
I’m an idiot
When I put shields in my Hiraga build, I grounded them. Had “temporary” on the brain with these, and of course I DIDN’T ground them….
Thank you. Will do so now.
Sadly, the way I built the box, the transformers had to sit on top of a wooded block, so the mounting bolts had something to mount to. The wooded block is glued/screwed to the top of the box, so there isn’t any room for them to sit sideways. And removing that block, well…
I’ve started making the wires/RCA’s to try bypassing the rear panel/RCA/wires there.
Going to just run the new in/outs to the outside of the chassis so I don’t have to disassemble the rear panel completely.
Yeah, guess I gotta figure out this scope…
Suspect I could build a new amp by the time I figure out how to use it
I’ve tried swapping them L/R and front/back. No difference.
Two of the tubes (Electro Harmonics Gold) I bought new, and have been working as drivers in my Cary. The RCA tubes I know nothing about. They came w some speakers I bought years ago and have not been in use for any meaningful amount of time.
Both sets of 6SN7’s are dead quiet as drivers in the Cary. I know, different usage, but thought I should mention.
The 6X5 in current use, is noisy. At least it’s noisier than the Sylvania NOS tubes I was using that went poof.
The Hiraga is a 30w Class A SS amp
And I would need to open it to confirm the exact details of the grounding protocol.
Will try to open and take a photo of the inside.
There is a Soft Start and two power supply boards - one for each channel.
Everything goes to a star ground.
The amp boards have three wires going to them from the power supply rails.
I have a feeling, and my memory could be wrong as it’s been a while since I’ve peered inside the VFet, but I believe there is a cap on the incoming signal as it’s a single ended SS amp?
Also, it has an SMPS power supply. Im using a power cord with a lifted ground - it’s been cut off the plug I keep it around as a test to see how the ground reacts.
When I use a regular power cord, the hum goes up in volume.
Also, as it has much lower gain than the Hiraga, I suspect that’s why the noise floor is lower???
And I would need to open it to confirm the exact details of the grounding protocol.
Will try to open and take a photo of the inside.
There is a Soft Start and two power supply boards - one for each channel.
Everything goes to a star ground.
The amp boards have three wires going to them from the power supply rails.
I have a feeling, and my memory could be wrong as it’s been a while since I’ve peered inside the VFet, but I believe there is a cap on the incoming signal as it’s a single ended SS amp?
Also, it has an SMPS power supply. Im using a power cord with a lifted ground - it’s been cut off the plug
I keep it around as a test to see how the ground reacts. When I use a regular power cord, the hum goes up in volume.
Also, as it has much lower gain than the Hiraga, I suspect that’s why the noise floor is lower???
it looks like you have dual power supplies, check that each has no leaky capacitor and both B+ quiet
Sometimes the volume pot can cause a ground loop...
My aikido was just a prototype and I was just so lazy I kept it that way, I originally had a filter choke of 40H or so and removed it and put just resistors in series, it has massive power supply and EZ81 rectifier tube,
I run all my heaters in AC, I have 0 hum just slightly increase as input noise if I turn the volume up, still very minimum.
I use 6sn7 tubes all the way, I had super expensive Copper paper in oil output caps and alluminum foil decoupling caps, I removed all this too, sound is very good
The only part I could upgrade is the volume control I use MONO controls, maybe you should try to use mono?
Sometimes the volume pot can cause a ground loop...
My aikido was just a prototype and I was just so lazy I kept it that way, I originally had a filter choke of 40H or so and removed it and put just resistors in series, it has massive power supply and EZ81 rectifier tube,
I run all my heaters in AC, I have 0 hum just slightly increase as input noise if I turn the volume up, still very minimum.
I use 6sn7 tubes all the way, I had super expensive Copper paper in oil output caps and alluminum foil decoupling caps, I removed all this too, sound is very good
The only part I could upgrade is the volume control I use MONO controls, maybe you should try to use mono?
I’m starting to feel like I’ve thrown everything except the kitchen sink at thus to try to fix this hum…
I’ve moved the power supply caps L/R - noise remained in right channel.
Gone through this again and again. Trying different things w the ground.
As the unit sits now, it is grounded exactly as the instructions say to ground it.
Through this process, the two things that have helped are grounding the top metal plate, and moving the input/output wires outside of the box.
Aside from that, using the DIY Audio VFet, with the supplied SMPS and a non grounded power cord has provided the sound w the least noise, only barely audible with ear pressed up against speaker (102db sensitive…)
I’ve moved the power supply caps L/R - noise remained in right channel.
Gone through this again and again. Trying different things w the ground.
As the unit sits now, it is grounded exactly as the instructions say to ground it.
Through this process, the two things that have helped are grounding the top metal plate, and moving the input/output wires outside of the box.
Aside from that, using the DIY Audio VFet, with the supplied SMPS and a non grounded power cord has provided the sound w the least noise, only barely audible with ear pressed up against speaker (102db sensitive…)