Hi Steen,
my source resistors are 0,33 ohms so the matching seems to be ok......
Patrick,
the transformers do seem to be very sensitive as there are moment when they are almost quiet......
I´ve ordered my transformers from Tauscher in Germany and they produce large amounts of mechanical hum. The problem is that I don´t know where to buy new ones because when I ask the salesperson directly if I can sent them back when they hum I always get a no for an answer. I´ll contact you for some details on your transformers.
thnks,
William
my source resistors are 0,33 ohms so the matching seems to be ok......
Patrick,
the transformers do seem to be very sensitive as there are moment when they are almost quiet......
I´ve ordered my transformers from Tauscher in Germany and they produce large amounts of mechanical hum. The problem is that I don´t know where to buy new ones because when I ask the salesperson directly if I can sent them back when they hum I always get a no for an answer. I´ll contact you for some details on your transformers.
thnks,
William
William,
I also had quotes from Tauscher before.
I found them expensive, large (physically), and not very helpful for technical details.
I tried Sedlbauer then. They will start thinking for 300 pcs minimum. Then I contacted Airlink in England. And as you might know by now, not everyone was satisfied in the UK toroid group buy the end.
I used Multi PCB in Munich in the end (just Google). (Onvinyl sent me a mail asking the same thing but I cannot reply as he has not allowed email to him.) The only problem with them is that they ONLY deal with companies and not private individuals. And they do indutrial product (relatively inexpensive), so they don't want to know special requirements for Audio. But I got what I wanted, including electrostatic and magnetic shields.
It is always a gamble, there is no guarantee. I think it is best to order oversize to be sure. I use 1500VA for +/-24VDC 7.7A total bias.
Contact me by private email. Maybe I can even lend you one to try first. We (a group of DIYers near Stuttgart) have a few sitting around at the moment.
Groeten,
Patrick
I also had quotes from Tauscher before.
I found them expensive, large (physically), and not very helpful for technical details.
I tried Sedlbauer then. They will start thinking for 300 pcs minimum. Then I contacted Airlink in England. And as you might know by now, not everyone was satisfied in the UK toroid group buy the end.
I used Multi PCB in Munich in the end (just Google). (Onvinyl sent me a mail asking the same thing but I cannot reply as he has not allowed email to him.) The only problem with them is that they ONLY deal with companies and not private individuals. And they do indutrial product (relatively inexpensive), so they don't want to know special requirements for Audio. But I got what I wanted, including electrostatic and magnetic shields.
It is always a gamble, there is no guarantee. I think it is best to order oversize to be sure. I use 1500VA for +/-24VDC 7.7A total bias.
Contact me by private email. Maybe I can even lend you one to try first. We (a group of DIYers near Stuttgart) have a few sitting around at the moment.
Groeten,
Patrick
wuffwaff said:
This is a line of questioning that interests me greatly. Intermittant transformer hum, mostly in one channel, is the only thing I can find fault with sonically with my aleph-x project. At times the transformers are nearly silent and at other times they hum loudly enough, with a hint of buzz, to be heard at my listening position. I haven't yet been able to find any correlation with external events or changes in voltages around the circuit.
Plitron 1000VA toroids
Bias ~7.3A, +/-24VDC
If a solution could be found, such as reducing the current imbalance between the + and - supplies due to absolute DC offset, that would be great. It would save me from buying two more transformers and using one 1000VA transformer for each rail.
Jeremy
(my apologies if this is too far off topic)
kropf said:
Do you have dual bridges in PSU ?
http://www.diyaudio.com/forums/showthread.php?s=&threadid=93712
I think you might want to try one of those DC blocking circuits for your 230V AC main supply before trying new transofrmers. There are plenty published here, including one from Peter Daniel for his Aleph-X.
And if you do want to try new transformers eventually, try a 1500VA or 2000VA. They are further away from saturation than a 1000VA.
Patrick
And if you do want to try new transformers eventually, try a 1500VA or 2000VA. They are further away from saturation than a 1000VA.
Patrick
EUVL said:
Thanks for the suggestions. Unfortunately, I have already tried DC blocking circuits to no apparent effect.
I am certainly on the edge of overloading the transformers. The power draw according to PSU Designer is somewhere close to 750VA, despite the much more modest +/-24V, 7.3A draw of the amplifier. My brute force fix is to add a 1000VA transformer to each supply, so as to have one transformer for the positive and one for the negative rail. I would then have the equivalent of 2000VA for each monoblock. The reason I hold on to hope another fix can be found is that the power supply of one of the monoblocks is consistently reasonably quiet, while the other goes from quiet to loud, but is mostly loud.
Khaho,
Yes, I am running dual secondaries and bridges for separate +/- supplies.
(All the details here: http://www.diyaudio.com/forums/showthread.php?s=&threadid=49828)
Jeremy
carpenter said:I may be wrong, but if you're attaching the transformers directly to a piece of plywood, it can act as a "sound-board"-- the way it does in a piano. Have you tried suspending the transformer above the plywood base with a rubber spacer?
John
Sadly, two years later my power supplies are still mounted to the plywood. I'll try isolating as soon as I find a suitable piece of rubber.
Jeremy
I removed the bolt holding the transformer and set the transformer on a piece of medium stiff foam. As you suggest, the plywood was acting as a "sound-board". The buzz/hum is now reduced noticably, particularly the buzz. It's still present, but the transformer noise has receded further into the background. One transformer is quiet and nearly still, while the other hums and vibrates. It may take a couple more ideas to completely solve the problem.
Thanks for the idea.
Jeremy
Thanks for the idea.
Jeremy
carpenter said:
John,
I was afraid you (or someone else) would suggest that. All of my measurements indicate that the current drawn by both amplifiers is the same and the same within each amp for the +/- rails once they warm up and the absolute DC offset does away. If there is extra current drawn in the noisy PS, it has to be between the transformer and R2 in the R1-C-R2-C filter bank.
Jeremy
Possibilities:
--Loose winding on transformer.
--DC on AC line. Over the past year I have gone from never to a dozen times or more per day hearing annoying buzzes from various devices around the house.
--High resistance short inside the transformer drawing current that you're not measuring from the outside.
Grey
--Loose winding on transformer.
--DC on AC line. Over the past year I have gone from never to a dozen times or more per day hearing annoying buzzes from various devices around the house.
--High resistance short inside the transformer drawing current that you're not measuring from the outside.
Grey
Funny, since I finished the Aleph-X's I havent thought one second about what to build next I always did that before. I dont know if these are the final amps for me, but I think they come pretty close. The only thing I want right now, is to listen to music. Well, thats nothing new, but not wanting to build something is
I am really exploring the Blues right now. Thanks Allan, for pointing me in that direction. Looking in the rearviewmirror, I knew that was comming. Diving in to the roots is a great experience. The old Blues masters are just great. Man I didnt realise their music was that great until now Listening to Son House, Bessie Smith and Robert Jonson is a great experience and lets you know where "modern" music comes from. They were great musicians, and created the music as we know it!
Regarding the buzzing trafo, here is a few things to make them do that: 1) Bad mounting! Bolt it tightly to a heavy chassis and the mechanical buzz will be as low as it can.
2) DC on the mains. This is real, but a X2 rated cap across the mains, will take care of it, if that is the problem.
Well, have a look at a small collection of classic Blues The Scorsese series comes highly recommended
Steen
I always did that before. I dont know if these are the final amps for me, but I think they come pretty close. The only thing I want right now, is to listen to music. Well, thats nothing new, but not wanting to build something is I am really exploring the Blues right now. Thanks Allan, for pointing me in that direction. Looking in the rearviewmirror, I knew that was comming. Diving in to the roots is a great experience. The old Blues masters are just great. Man I didnt realise their music was that great until now
Listening to Son House, Bessie Smith and Robert Jonson is a great experience and lets you know where "modern" music comes from. They were great musicians, and created the music as we know it!Regarding the buzzing trafo, here is a few things to make them do that: 1) Bad mounting! Bolt it tightly to a heavy chassis and the mechanical buzz will be as low as it can.
2) DC on the mains. This is real, but a X2 rated cap across the mains, will take care of it, if that is the problem.
Well, have a look at a small collection of classic Blues
The Scorsese series comes highly recommendedSteen
Attachments
steenoe said:Funny, since I finished the Aleph-X's I havent thought one second about what to build next
I am really exploring the Blues right now. Thanks Allan, for pointing me in that direction. Looking in the rearviewmirror, I knew that was comming. Diving in to the roots is a great experience. The old Blues masters are just great. Man I didnt realise their music was that great until now
Regarding the buzzing trafo, here is a few things to make them do that: 1) Bad mounting! Bolt it tightly to a heavy chassis and the mechanical buzz will be as low as it can.
2) DC on the mains. This is real, but a X2 rated cap across the mains, will take care of it, if that is the problem.
Well, have a look at a small collection of classic Blues
Steen
have you around ........4 pieces of ECC88 or PCC88 or 6DJ8?
besides Tannoys,mebbe is time for one nice susy toob preamp
lousy little jfets are soooooo hard to find,and toobz are better anyway
Nope
Yeah, maybe it is....
I have a healthy little supply of those
Let me know, if you want to have me handle the J-fet part of the Babbel-thing
I can put up the money in front for a minor GB (for the Babbelfish) I have to admit, that what I want the most is a GB of Babbelfish-X! I am feeling pretty certain that a Babbel-X would sweep the DIY scene Having heard an Aleph-X and the Babbel, makes me dream of combining them I cant!! You can!! I can only build the thing Steen
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