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   Home » Analog Playback» About EAR 834P Modifications (46 posts, 3 pages)
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  »  New  Denon 103: myths and the reality..  A young but mature horowitz...  Analog Playback Forum     29  324005  06-08-2004
  »  New  About EAR 834P Modifications..  The cap will not change volume in the pass band...  Analog Playback Forum     45  494388  12-29-2004
  »  New  EAR 834P Modification..  The cap will not change volume in the pass band...  Analog Playback Forum     45  494388  01-27-2005
  »  New  The last phonocorrector: “End of Life" Phonostage..  Valvo mesh 0A2...  Analog Playback Forum     301  1465296  11-13-2007
  »  New  EAR 834P mods..  The cap will not change volume in the pass band...  Analog Playback Forum     45  494388  11-04-2008
  »  New  AMR PH-77: just another phonostage or more?..  Oh, yeah... the sound of the Thing Itself......  Analog Playback Forum     11  100186  07-05-2009
  »  New  Denon 103: myths and the reality..  A young but mature horowitz...  Analog Playback Forum     29  324005  06-08-2004
  »  New  The tales of two phonostages: Allnic and 834PT...  The tales of two phonostages: Allnic and 834PT....  Analog Playback Forum     0  17062  12-21-2011
03-28-2020 Post does not mapped to Knowledge Tree
Taso
Posts 1
Joined on 03-28-2020

Post #: 41
Post ID: 25809
Reply to: 22573
Caps infos
hello guys, greetings from Italy !! ..I would have a question being that they are still being optimized.

I have to buy the 6 caps that are on the PCB valves .. those at 400-450v.

On my ear..which I bought on ebay..they were self-built by a fan..the 100uf 400v caps were mounted..Sanwa brand, SD..85 ° series .. and I would say very normal.

Since I have a doubt about their state of health ... I avoid explaining why ... I was about to buy another 6 ... to assemble.

I would have found some Kendeil .. K05 series..a great price..I can choose between 100uF 450v or 220uF 400v..all 105 °.

I'm also finishing to solve hummm problems .. which are not however given by any mass loops .. those I have already fixed for good ... having excellent results.

I was wondering ... I was asking you..so .. if you buy back 100uF .. Kendeil..o if you switch to 220uF.

I would not, however, with such a higher capacity ... create noise problems .. overload diodes .. in short .. what I am looking for is exactly the opposite ... or improve something!

On some forums .. also on this ... I see in some photos that, for a fee, one cap, 4 caps are the same .. I don't know the value however .. but the other two are bigger .. I think the ones near the valve V1 or V3.

anyway give me some advice? while I buy them .. if I can benefit from them ... I would go to 6 x 220uF ... or maybe .. if I had to follow the photos I see on some forums .. put 4 of 100uF and 2 of 220uF ... even if not I know where the big two go !!

The fact is also that it seems to me that the original ear mounts 6x22uF ... and that the Chinese kits provide 6x47uF.

I point out that I have also redone the power supplies .. both anodic and filaments .. if you want to place the pattern and give me an opinion. maybe it can be useful to someone.

Thanks !!! and sorry for my english
03-28-2020 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 350
Joined on 07-05-2012

Post #: 42
Post ID: 25810
Reply to: 25809
Already done
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.



Whenever I feel blue, I start breathing again.
09-02-2020 Post does not mapped to Knowledge Tree
Terry Maddocks
United Kingdom
Posts 4
Joined on 04-04-2017

Post #: 43
Post ID: 25931
Reply to: 9091
Deletion of V2 cathode capacitor and gain
Hi Romy,
I am currently in the process of rebuilding my 834 PT. I see you don't use the capacitor bypass on V2, does this have any effect on overall gain of the corrector? I've recently acquired audio Technica ART7 cartridge which is low (0.12 mv) output and for that, and other reasons, I do not want to lose gain in the rebuild. I'm assuming that there is also some benefit for sound in omitting it?
Cheers
Terry


"Music is enough for a lifetime, but a lifetime is not enough for music" Sergei Rachmaninoff
09-03-2020 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 350
Joined on 07-05-2012

Post #: 44
Post ID: 25932
Reply to: 25931
834pt is MM level
I also built one. It does not have enough gain for a low output MC cartridge. You need a step up transformer. I use an Ortofon T30.


Whenever I feel blue, I start breathing again.
09-03-2020 Post does not mapped to Knowledge Tree
Terry Maddocks
United Kingdom
Posts 4
Joined on 04-04-2017

Post #: 45
Post ID: 25933
Reply to: 25932
834PT and MC cartridges
Hi Rowuk,


Thanks for reply, I use step up transformers, old Partridge 1:12 I think they are model 973B if memory serves me correctly. I haven't installed the ART7 yet. I currently use another AT cartridge - 33ptg ii which is a more "normal" output of circa .3mv... The gain from the combination of Partridge + 834 at present is just right for me, when I switch to the ART 7 I may have to go for a higher ratio.. Maybe 1:20 such as S&B or the Silk models from Sac Thailand.. And of course there are others.. But back to my original question as to whether the removal of V2 cathode bypass capacitor will reduce overall gain of the stage? 


Cheers


Terry


"Music is enough for a lifetime, but a lifetime is not enough for music" Sergei Rachmaninoff
09-04-2020 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 350
Joined on 07-05-2012

Post #: 46
Post ID: 25934
Reply to: 25933
The cap will not change volume in the pass band
The cap was only to block DC and is not required at this position. I think that Tim (the developer) removed it on later versions himself.


Whenever I feel blue, I start breathing again.
Page 3 of 3 (46 items) Select Pages:  « 1 2 3
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Denon 103: myths and the reality..  A young but mature horowitz...  Analog Playback Forum     29  324005  06-08-2004
  »  New  About EAR 834P Modifications..  The cap will not change volume in the pass band...  Analog Playback Forum     45  494388  12-29-2004
  »  New  EAR 834P Modification..  The cap will not change volume in the pass band...  Analog Playback Forum     45  494388  01-27-2005
  »  New  The last phonocorrector: “End of Life" Phonostage..  Valvo mesh 0A2...  Analog Playback Forum     301  1465296  11-13-2007
  »  New  EAR 834P mods..  The cap will not change volume in the pass band...  Analog Playback Forum     45  494388  11-04-2008
  »  New  AMR PH-77: just another phonostage or more?..  Oh, yeah... the sound of the Thing Itself......  Analog Playback Forum     11  100186  07-05-2009
  »  New  Denon 103: myths and the reality..  A young but mature horowitz...  Analog Playback Forum     29  324005  06-08-2004
  »  New  The tales of two phonostages: Allnic and 834PT...  The tales of two phonostages: Allnic and 834PT....  Analog Playback Forum     0  17062  12-21-2011
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