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In the Forum: Analog Playback
In the Thread: About EAR 834P Modifications
Post Subject: Already donePosted by rowuk on: 3/28/2020
Thorsten Loesch who came up with the mods, details what caps and why on the first page of this thread. Lacking interest for multiple years of auditioning caps, I just built it that way (2012 or so) and have had no urge to change anything. Romy has pictures and details of his mods.
"Change over C8 and C9 to larger value, "known good" sounding electrolytics, I'd be tempted to specify at least 100uF/385V Nippon Chemi Con (radial leads) VX series, these will be a VERY "tight fit". Also find a way to bypass them with at least 0.47uF Wima MKP04 or better (tight fit again). You could use Black Gates again, or Elna Cerafine if you can find them, the Cerafines I quite like, the Black Gates I don't like that much.If I'd build another unit from scratch I would use a pair of Ansar
Supersound 32uF + 32uF 400V, but these are 4" long and 2.5" in diameter, no way you get them inside the original EAR case. And they cost around 50 Bucks each too.... ;-)
They are available from Cricklewood Electronics in London, you'll have to e-mail them for details.
http://www.cricklewoodelectronics.com/
If you modify an existing unit retaining the on-board supply change D1 & D2 to soft switching, superfast types and place a 100 Ohm 2W Resistor between the transformer HT secondary and the Diodes.
In a scratch build unit I actually would/do use a 240-0-240V Mains transformer and a Valve Rectifier (6X4/EZ90 or 6CA4/EZ80/EZ81), and make two electrically independent supplies, with the HT Rail in the EAR split up between the channels, so that C8 and C9 doubled up, R13 doubled up but changed to 200/220K per channal and R14 doubled up and changed to 20/22k per Channel."
Anything else that you do that is different will be "different". I do not believe most of what is written online. "People" are too willing to prove how knowledgable that they are and you find out the hard way that their level of "hearing" is not good enough to back up their claims (if they even did what they post).
I would suggest not reinventing the wheel. Either duplicate the efforts of someone else or return your device to the original state. If you are using one of those DIY kits, all bets are off on how long the traces hold up when unsoldering/resoldering.
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