Aaargh - half wave!
It won't change the shape of the ripple for half wave, but the waveform will be shifted in time (you'd only notice this if you'd used an external trigger on your oscilloscope). Please, please, don't tell me that we're dealing with half-wave rectification (and all the nasties that it implies)...
It won't change the shape of the ripple for half wave, but the waveform will be shifted in time (you'd only notice this if you'd used an external trigger on your oscilloscope). Please, please, don't tell me that we're dealing with half-wave rectification (and all the nasties that it implies)...
Re: Aaargh - half wave!
It would certainly be bad practice to have the dual mono supplies out of phase, IF this was the case, IMO.
I'm not sure about the relative merits of half-wave rectification , bi-phase half-wave rectification or full-wave rectification when using valves myself......I *guess* Bas will just use whatever the designer specified.
EC8010 said:
It would certainly be bad practice to have the dual mono supplies out of phase, IF this was the case, IMO.
I'm not sure about the relative merits of half-wave rectification , bi-phase half-wave rectification or full-wave rectification when using valves myself......I *guess* Bas will just use whatever the designer specified.
Yes and no 😉
Yes, we used full wave tube rectification....but no...we used 6X5 however instead of AZ1 (cheaper and available)
Re: Re: Aaargh - half wave!
CORRECTION: IMO it's ALWAYS bad practice to have the mains transformers out of phase.
Bas: if you have full-wave rectification changing from dual mono to single stereo psu *shouldn't* have had the effect it did. Maybe use the other psu for stereo too, and see if it's still OK. You could also put a dummy load on the psu you are not using, to replicate the magnetic field produced when in dual mono mode. After that i think we're down to the 'scope to see what's really going on. Not sure i can come over this w/e now, the boss may have something planned😱
Mark25 said:
CORRECTION: IMO it's ALWAYS bad practice to have the mains transformers out of phase.
Bas: if you have full-wave rectification changing from dual mono to single stereo psu *shouldn't* have had the effect it did. Maybe use the other psu for stereo too, and see if it's still OK. You could also put a dummy load on the psu you are not using, to replicate the magnetic field produced when in dual mono mode. After that i think we're down to the 'scope to see what's really going on. Not sure i can come over this w/e now, the boss may have something planned😱
Oh, it's a preamp....
Bas,
From what I've gathered from the discussion and from Triode Dick's schematics, I don't think that choke orientation is the main issue. You could run just one channel with the chokes sitting on the top of the chassis and rotate them to see if there is a big change in hum. Disable the phono stage while you're at it. That's a very high gain part that will catch any hum going. You'll be left with a single low gain buffer stage to play with. It should be possible to make that completely silent.
Maybe you've tried this already in the last 24 hours...you've been very quiet...😉
Bas,
From what I've gathered from the discussion and from Triode Dick's schematics, I don't think that choke orientation is the main issue. You could run just one channel with the chokes sitting on the top of the chassis and rotate them to see if there is a big change in hum. Disable the phono stage while you're at it. That's a very high gain part that will catch any hum going. You'll be left with a single low gain buffer stage to play with. It should be possible to make that completely silent.
Maybe you've tried this already in the last 24 hours...you've been very quiet...😉
Hi John,
I've been quiet...but the preamp not!!
(I've kept the phono amp turned off all this time) First things first.
I basically isolated the whole preamp...and built a 6n1p version using only the input/output rca's, input selector/stepped attenuator and the psu...the noise that comes out of this preamp seems to be constant no matter what I do...I must have something wired up wrong!.
I've been quiet...but the preamp not!!
(I've kept the phono amp turned off all this time) First things first.
I basically isolated the whole preamp...and built a 6n1p version using only the input/output rca's, input selector/stepped attenuator and the psu...the noise that comes out of this preamp seems to be constant no matter what I do...I must have something wired up wrong!.
wiring
Hi Bas,
not that I'm an expert in tube amps, but after finishing my first tube amp ever ( a headphone amp with C3g) I sure have learned my bit about wiring! Your wiring caught my eye immediately........being somewhat....well....you know what I mean.
I was advised to keep signal wires as short as possible, use even shielded wire, keep them away from AC (OK we all know that...) and try to avoid ground loops.
Having those things in mind I completely rewired my amp (see pic) and got rid of the hum to a last tiny bit that doesen't bother me.
My next project just came to life a couple days ago and also has a bit of the hummers, so here we go again!
Good luck,
Oliver
Hi Bas,
not that I'm an expert in tube amps, but after finishing my first tube amp ever ( a headphone amp with C3g) I sure have learned my bit about wiring! Your wiring caught my eye immediately........being somewhat....well....you know what I mean.
I was advised to keep signal wires as short as possible, use even shielded wire, keep them away from AC (OK we all know that...) and try to avoid ground loops.
Having those things in mind I completely rewired my amp (see pic) and got rid of the hum to a last tiny bit that doesen't bother me.
An externally hosted image should be here but it was not working when we last tested it.
My next project just came to life a couple days ago and also has a bit of the hummers, so here we go again!
Good luck,
Oliver
I've never had problems like this with my wooden chassis!😀
With metal chassis...you have to learn a whole new set of rules.
By the way...good looking amp you've got there!
With metal chassis...you have to learn a whole new set of rules.
By the way...good looking amp you've got there!
- Status
- Not open for further replies.