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In Reply to: RE: 2A3 Options posted by maxhifi on December 21, 2016 at 10:23:30
Hi,
I think there is possibly only one "other" 2A3 to own, and that is the EML, but in your amp's implementation, I think the differences will really not be worth the expense.The JJ-2A3-40 is the best choice in new, available 2A3s. All the Chinese stuff is junk, and due to their markedly inferior metallurgy, all Chinese 2A3s will turn to junk in short order.
If you want to treat yourself to something good for Christmas, I will help you re-design your B+ filter to the Finals.
(1) Your choke is likely 10 HY and 100 Ohms, needs to be no more than 20 Ohms, and
(2) never a 'C" input filter as implemented, a second serious design error.
(3) Needs to have chokes under 11 Ohms and L1/C1/L2/C2 as the topology to the 2A3 Finals, so you can hear a 2A3 as it should be heard !!
I can refer you to discriminating music listeners, who I've helped to make such changes, for their testimony...and...what they heard afterwards, if you need re-assurance.
Contact me by Forum email, and I will design it for you - gratis, on an amateur basis. Easy to make big sonic gains this way, and the amp, afterwards, will likely play your Tannoys with gusto and verve!
Jeff Medwin
Kyle, no caps, thanks.
Edits: 12/21/16 12/21/16 12/21/16Follow Ups:
I agree with the Doc. He has more experience than most.
I use only choke input power supplies and not higher than about 20-25 ohm choke resistance. I only use paper/oil caps for filtering. New Obbligato capacitors are good & cheap.
As far as I can tell, there are no Obbligato paper/oil capacitors, only metallised film in oil. The only new (partial) PIO capacitors that I could see myself trying for filtering and cathode bypass are the new Rike S-Cap 2... but it will be co$tly.
Cheers,
91
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
There's the rectangular USSR made paper in oils all over eBay. I got a couple of them for another project, and they tested good on a Sprague tel-ohm-mike. Did not use them yet. Dead on value and no leakage. I suspect similar construction to the old US PIOs.
If nothing else I sure prefer the appearance of paper in oil caps over electrolytics.. they're always a sign of serious quality in vintage gear.
Russian pio
Yep, that's similar to what I use for screen bypass. Unfortunately, those 1000Vers are only 0.5uF... I'd need 100 for each driver PS node and 250 for the output stage. It could be expensive and difficult to fit into the chassis.
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Oh that's right. I got that one to use as part of a hum cancel network in old RCA amps,
Thre original capacitor leaked an actual puddle of oil under the amp. My quest to replace like with like ended with those caps, and I was nicely surprised with how they tested so well.
They do have more appropriate values for filter networks. I have seen 10uf and 20uf at reasonably high voltages. I don't think you could design a whole amp around them but they're high enough to be usefully incorporated as elements of a filter network.
.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
screen bypass... but have not seen any with sufficient capacitance and voltage for for my amps. Still, I should continue to look.
Thanks for the info!
Cheers,
91.
"Confusion of goals and perfection of means seems to characterise our age." Albert Einstein
Are those Obbligato filter capacitors motor run caps which have been painted, or is there something else special about them?
They look exactly like the capacitors usually connected to 4 pole single phase motors, but with a nice paint job and a higher price.
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