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Clearly I do, as I have a pair of 2A3 parafeed monoblocks.
And they do sound very good as is, with a Solen teflon coupling the 396A/2C51/5670 to the EML Meshplate 2A3.
But the stock parafeed cap is a pretty generic Solen so...
What to do?
As I have Edgar Horns plus a pair of separately amped horn subs, I really don't need (or want) much lower frequencies than 80Hz (if even that) from these amps and the stock part is 12uF 650V optimized for ridiculous low (lower than the OT will go) frequencies.
What's a poor boy to do.
4uF to 6uF at about 650V would do nicely.
Any recommendations?
$100 each +/- range.
"Reality cannot exist because it cannot keep up with the lies on the Internet."
Follow Ups:
Parafeed should be viewed as a low-cost item only, but here's
what one can do-- Easy to solve. Start with a 4uf Dynamicap.
Parallel it with Dynamicap .68uf, .33uf, .22uf, .068uf, .033uf
and .01 uf.You might still need a large-value cap to start with-- how about
a Genteq paper-in-oil refrigeration (motor-run) Cap? Genteq,
NOT other brands!Watch max. voltage swings in your parallel caps--- don't
override a capacitor.Values in between these may also be experimented with, the
object being to attain a wideband, linear overall response.Trash nearly all Solen products if you like music.
Don't forget Mundorf silver/oils or silver/gold oils,
which are both excellent. Certain WIMA flat-pack caps
are also very good. The Wimas that work are the smallest
physically for the same uf value, and voltage rating.Why? Wima uses more expensive THINNER dielectrics where
a high voltage rating must be attained, but also, the cap
has to be physically small. Motto? HIGH voltage rating,
SMALL cap-- for the same value. Wima makes anything you
can dream-up. SOME of these are GREAT! Others? NOPE!There you are. Arm yourself with an assortment of these
4 outstanding cap brands, and proceed. Your reward is
more better music!-Dennis-
Edits: 06/14/23
I used Obbligato Film and Oil Caps in my Parafeed, direct coupled 45 amp . 10uF 630V just $11.60 from Parts Connexion.
Novus Ordo Seclorum
The way I understand it, you need a large parafeed cap to damp the resonance peak caused by the LC tank circuit. If you try to use the parafeed cap size as a high pass filter you will end up with a resonance peak that will cause audible problems. Do the filtering elsewhere, like at the grid of the input stage.
Tre'
Have Fun and Enjoy the Music
"Still Working the Problem"
When I had a couple EE/Biomedical PhD's at my beck and call, we were doing some research on Jack Eliano's 'Ultrapath' and, at least if Terman is to be believed, large humps or frequency spikes were predicted (cap size dependent?) who can remember?OK, ultrapath is a different animal than parafeed, but still...
Recall the DRD amp Jack designed of 'Randal Museum' had a HUGE (80uF) ultrapath cap.
"Reality cannot exist because it cannot keep up with the lies on the Internet."
Edits: 06/10/23
as Parafeed caps for 2A3. Wonderful caps. Quick search on the bay turned out a matched pair 6uF/550V ones for $45 plus shipping..
They are quite nice. Scored two boxes of 1.5 uF/660VAC rated ones a long time ago. For two-stage amp coupling caps, they work quite nicely. Kind of large though... :)
Douglas
Friend, I would not hurt thee for the world...but thou art standing where I am about to shoot.
!
The Mind has No Firewall~ U.S. Army War College.
So many times I have spent a lot on expensive components because I felt I should rather that being able to really hear, past the placebo effect.
Bypass your Solens with 1uf film/foil or paper/foil to fill your soul with audiophilac peace. Solens get a bad rap but I would be lying if I could pick them out in a blind swap in something like a parafeed cap.
I can remember a day when a parafeed cap might well be an electrolytic.I have a slew of VERY nice REL caps just for that purpose so...
Maybe?
That said, "everything in in the signal path", even the cat. :-)
"Reality cannot exist because it cannot keep up with the lies on the Internet."
Edits: 06/09/23
I remember the electrolytic parafeed days...
REL is usually my go-to in more important applications (but I've never done parafeed). REL might not be as trendy as they were 15-20 years ago, but I've always liked them.
As they say, smoke 'em if you got'em.
Back for a bit again. Ignore me if you like.
Being as this is the DIY forum...
How about a large bank of Leyden jars?
Actually, I've become more interested in parafeed lately. What type choke do you use with the 2A3s?
Choke on the 2A3 is rated at 60H (50ma?) but the kit builder (Doc Bottlehead) isn't revealing their current 'winder' or many other specs.
Lots of active loading and shunt regulation around the 396A/2C51/5670 driver tube, so these are clean/detailed/uncolored sounding amps. EML 2A3 mesh plate tube adds a bit of 'mellow' to the party.
Also have a full set of custom wound Tribute 'double 'C' core iron for a 45> 845 parafeed> parafeed amp with 200H/50ma and 100H/100ma chokes which are MASSIVE.
Have heard a few tube amps in my day and some of the best sounding were parafeed. With 106 dB horns I don't require much in the way of wattage so SE 2A3 is more than enough.
"Reality cannot exist because it cannot keep up with the lies on the Internet."
What I find attractive about parafeed is the elimination of the shortcomings of large gapped transformers. I'm interested in the concept of a parafeed design that would combine a relatively inexpensive choke with an ungapped iron or ferrite output transformer. The downside to parafeed for me has always been my dislike of large series caps carrying the signal. However, I've come to realize that low frequency response and other characteristics of gapped transformers commonly available for higher power levels are probably worse, sonically speaking. It all depends on whether a cap can be found that is truly transparent in the midrange.
Edits: 06/09/23
Lots of H with not some much R being good and not THAT expensive as chokes go.
OTOH, film caps of the size and voltage required for blocking DC are getting better and better and decent can be had cheap (Solen) with better but a few $$$ more.
And for that you get some PS isolation and quiet, or so I am told.
I can recall many moons ago when a 5uF 600V-800V parafeed cap would by default be electrolytic.
Same for cross-over caps in your favorite speaker. But we lived through it.
With horns and a horn sub, I have no need for a low frequency capable power amp.
"Reality cannot exist because it cannot keep up with the lies on the Internet."
How about these? https://www.digikey.com/en/products/detail/cornell-dubilier-electronics-cde/UNL10W10K-F/1531169
Also 4.7 @ 1500V and 7.5 @ 1200V in that can size.
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