Can you show a picture please? I don't understand what you mean. How separate is diode ground from ground of filter capacitors? What connect them together? And what means "after" if the IC has a single ground leg?
My contribution: I hope that it answers a few questions. It is not the complete CTC Blowtorch power supply, but it is close enough for discussion.
I would keep the +and - supplies completely separate and then only combine them after regulation. Then your audio ground cannot get mixed up with the PSU ground.
I mentioned in an earlier post a few other tricks to keep the supply rails conducting only DC (or as near as dammit to DC). On the amplifier ground side, split it into decoupling ground and signal ground. You will have AC in the ground, but at least it's split into two parts then: signal AC and decoupling AC.
Do you mean Schaffner makes filters usable as input filters for sensitive analog devices? What's the part number?
Schaffner Mains Filter Fn2060 10 06
Looks nifty :
http://www.schaffner.com/components/en/_pdf/Datasheet FN2060 e 54.pdf
Looks nifty :
http://www.schaffner.com/components/en/_pdf/Datasheet FN2060 e 54.pdf
Last edited:
Bonsai, you mean well, so I will explain. The split bobbin low coupling capacitance transformers that we use, do NOT have or need a screen, because of the large physical spacing between primary and secondary.
The Harris hi speed-soft recovery diodes don't appear to need any snubbers, but I would not question someone adding them.
The Harris hi speed-soft recovery diodes don't appear to need any snubbers, but I would not question someone adding them.
I would keep the +and - supplies completely separate and then only combine them after regulation. Then your audio ground cannot get mixed up with the PSU ground.
I mentioned in an earlier post a few other tricks to keep the supply rails conducting only DC (or as near as dammit to DC). On the amplifier ground side, split it into decoupling ground and signal ground. You will have AC in the ground, but at least it's split into two parts then: signal AC and decoupling AC.
You are absolutely right Bonsai - it appears not everyone including some
'heads of state' here understand this.
T
I would use the Medical version to eliminate the Line/Neutral to ground caps. The current to ground, especially if that ground connects to audio, is not helpful. Worse is the misguided effort removing the ground connection with those filters, pulling the chassis to 1/2 of the line potential.
I just checked a power supply design I'm working on with one of those types of transformers for capacitance from primary to DC output: 38 pF. While a double shielded transformer can be lower (.001 pF for a Topaz) it only is if you can really manage the shield connections optimally. 38 pF is low enough that the cord orientation may be a bigger problem.
Which Medical version do you mean? I have not seen filters without that Y-caps, so I never used them.
John, the Signal Splitrans are nice transformers. I used them on an intrumentation product when I worked in the USA 25 years ago, although on recent audio projects have gone with Amveco. I would concede that the Amveco's have higher pri-sec C, but they are mechanically very good and low profile. Agree with the snubber comment.
Wavebourn, Schaffner - AC mains filters. There are some who believe any ferrite material - even on the AC side of a piece of audio equipment - alters it for the worse. I do not believe ferrite can do that so thats why I said I have no qualms using these devices.
Wavebourn, Schaffner - AC mains filters. There are some who believe any ferrite material - even on the AC side of a piece of audio equipment - alters it for the worse. I do not believe ferrite can do that so thats why I said I have no qualms using these devices.
Last edited:
It is not a problem, since currents from shields are under control, and isolated in own closed loops. However, parasitic capacitance between primary and shield is kind of a problem for ground loop between interconnected equipment through the outlet, but filter without Y - caps would help.
I would say, for power amps with transformer balanced inputs it is not a problem at all; I never heard "sounding power cords" on my amps. Nor on mic pres and consoles, since inputs and outputs are transformer balanced.
The majority of problems are results of "rules of dumbs" instead of careful thinking.
I don't mind ferrites, but some filters are hard to disassemble to cut that Y-caps.
- Status
- Not open for further replies.