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In Reply to: RE: converting to critical L input filters or not ... posted by deathtube 667 on October 09, 2016 at 04:09:45
Hi Deathtube.So glad that worked for you.
As long as you measure 5 mVAC or less of ripple, with the inputs shorted, at the output jacks, you are "good to go" on our sensitive high efficiency speakers.
Just came back from RMAF where I listened for three full day's continuously to Serious Stereo's latest 2A3 DC amp, and it sounded to me like a superb amp, I am guessing, the world's best 2A3 amp effort, ever.
Unfortunately ( IMHO ) the RMAF show-goers listened to ONLY " redbook " digital, but in after-hours, we hooked up analogue, etc and it was "all there", in spades. Lovely. I was pleased, impressed.
The newest Serious Stereo amp is constructed with refinements : reduced wire lengths, and the two filter chokes have been reduced in DCR from about 10 Ohms ( Stancor NLA part ) to ( custom-made my Magnequest, to D.F.'s spec )..... 4 Ohm DCR chokes. Configured as Dennis' LSES filter.
There is a question, unanswered in my mind at THIS point in time, ( 10-2016 ) Deathtube, as to "WILL a three stage filter sound less-direct than a two stage". However, either filter is superior, music-playback-wise, IMHO, to conventional designs.
( We are talking about LSES : L1/C1/L2/C2 OR a Flywheel : L1/C1/L2/C2/L3/C3. In both, all Ls sub critical and under 20 Ohms DCR and all Cs under 50 uF. ) Messers John Swenson and John L. Hasquin , Forum Members and EEs, posted their theory and listening results about this, on this Forum, some years ago.
All one needs to do is build it, wire it well, and compare... BY EAR. Then the discussion ends !!
No need to study 100 year old EE text book theory. Use your 10,000 year old ears and decide, after all....listening is what matters.
Use PSUD to design it, check with a step-test and check for ripple. Typically, I would suggest, the output stage B+ needs to PSUD at up to 800 mVAC of B+ ripple, and the input stage B+ needs 2 mVAC or less, prefer 1 mVAC. See attached PSUD2 shot as just one example of a Flywheel-inspired filter doing two JJ 2A3-40 s in a DC stereo amp, 274BX PT.
Regards, have fun.
Jeff Medwin
Edits: 10/10/16 10/10/16 10/10/16Follow Ups:
"As long as you measure 5 mVAC or less of ripple, with the inputs shorted, at the output jacks, you are "good to go" on our sensitive high efficiency speakers."
I am surprised you can tolerate 5mV of output ripple. I tested that on 98dB speakers and it was beyond anything I would be willing to put up with.
Chris
Thanks to a shielding issue on my TX-output linestage, I get 3-4 on the outputs terminals. With shielding, I can easily get it much lower( or at least adequately lower ). But that is just me, doing non-critical listening...if I had to tell conclusively what the amp is up to, it has to be lower...:)
cheers,
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
The more sensitive our speakers, the lower the hum level needs to be.
Jeff,
I sent an email to your gmail account.
Take a look when you get time.
Glad to hear that RMAF went well for you and DF/SS.
DT 667
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