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In Reply to: Re: Ideally a cap and a resistor in parallel posted by grhughes on April 4, 2007 at 14:56:23:
And with a bridge there would be four of these bundles. Yes I got it, Thanks.
Follow Ups:
Treat the disease first by using Ultrafast Soft recovery diodes.
Then treat the remaining (reduced) symptoms with the R and CEVERY amp Tube or SS in which I have replaced the power supply diodes with Ultra Fast Soft Recovery has sounded better immediately - sometimes dramatically so.
Yes, I have had the same experience.In some of the first amps I built, I used standard diodes, diodes
are diodes right, or so I thought. After discovering UF diodes I
upgraded and the results were remarkable.
I agree with Ian. Perhaps an International Convention could be negotiated that outlaws 1N400n diodes in audio equipment. ;~) UF400n diodes are quite inexpensive and do a BETTER job.The late John (Buddha) Camille did the "leg" work on the RRSF. He was able to reduce the already low switching noise of UF4007s to the point of invisibility on his BROADBAND o'scope.
If you don't want to bother with "snubbers", use high PIV Schottky diodes. They are "noiseless" without the use of RC networks.
Eli D.
> Perhaps an International Convention could be negotiated that outlaws 1N400n diodes in audio equipment.Most of the problems arise as a result of failure to use proper techniques. The HV supplies in many of my amplifiers include 1N400x rectifiers, and there are no spikes or any other unwanted HF noise of any significance whatsoever on the chassis, B+ lines or signal paths. I have tested this with both digital scopes and spectrum analyzers.
To keep supplies clean, I use the following techniques:
1. Locate the supply a suitable physical distance from the front end
2. Install a cap (w/ or w/o parallel resistor) across every rectifier diode
3. Use a good quality 5-20H choke (not necessarily at the input)Follow these common-sense steps and the diode issue goes away.
TK,That your B+ is clean is beyond question. The filter choke sees to that. However, that's not the whole story. SS diode switching noise can get into the amp via the power trafo and filament winding. Buddha's RRSF kills the "hash in both directions. Even CRC filters have proved adequate.
Eli D.
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