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   Home » Analog Playback» The last phonocorrector: “End of Life" Phonostage (311 posts, 15 pages)
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  »  New  Where are our good phonostages?..  Omnigon Tubes...  Analog Playback Forum     61  531281  05-31-2004
  »  New  The Expressive Technologies SU-1..  “too bright” or “resolution” or “details” with SUT prim...  Analog Playback Forum     33  310985  12-30-2004
  »  New  EAR 834P Modification Guide..  The cap will not change volume in the pass band...  Analog Playback Forum     45  517197  02-09-2006
  »  New  My Analog Playback: the fat lady has sung..  My analog setup update....  Analog Playback Forum     9  98814  04-04-2006
  »  New  Phono stages with SU-1..  SU-1...  Analog Playback Forum     4  54382  11-23-2007
  »  New  Chasing utopian better phono interconnect...  Did I miss something?...  Analog Playback Forum     6  92296  06-05-2008
  »  New  Buying a last cartridge...  Lucky you...  Analog Playback Forum     80  670905  09-05-2008
  »  New  EAR 834P mods..  The cap will not change volume in the pass band...  Analog Playback Forum     45  517197  11-04-2008
  »  New  AMR PH-77: just another phonostage or more?..  Oh, yeah... the sound of the Thing Itself......  Analog Playback Forum     11  105403  07-05-2009
  »  New  An interesting Russian pnonocorrector...  Uber-tweeky phono topologies deconstructed...  Analog Playback Forum     9  71076  03-01-2010
  »  New  Expressive Technologies SU-1 and cartridge output and i..  MV and Ohms...  Analog Playback Forum     2  25391  07-07-2011
  »  New  How to run MM-type cartridge into MC phonostage?..  Quite interesting....  Analog Playback Forum     6  50824  11-13-2011
  »  New  The tales of two phonostages: Allnic and 834PT...  The tales of two phonostages: Allnic and 834PT....  Analog Playback Forum     0  17949  12-21-2011
03-28-2020 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,264
Joined on 10-12-2006

Post #: 301
Post ID: 25811
Reply to: 25802
Tube Selection
Just tossing in as possibilities the old JAN GE 5751s. I had a pair of these that were very interesting, including excellent, very even sound density and truly great LF. The only tubes in my system now are the old, "New York" 6922s in my phono stage, and they must be fading. I HATE shopping for tubes, knowing no matter what sellers claim about them, they are what they are when I use them! Fortunately for me, Mark has an Amplitrex, and he knows how to use it!


Paul S
07-09-2020 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 498
Joined on 01-07-2006

Post #: 302
Post ID: 25877
Reply to: 25792
Valvo mesh 0A2
 N-set wrote:


Other changes to come:

- looking for Amperex 0A2 with mesh plates
- will rewire MM input in silver with silver WBT RCA's - it now welcomes my top cart, Decca London Reference with silver AQ Leopard phonocable (will post on that in a separate thread)
- considering another red tip 12AX7 for the output but given the change was not big at the input it's more of an itch...a costly one at $275

I've finally got some mesh plate 0A2 made by Valvo. Well, I didn't notice any difference compared to my previous Sylvania's so far. Perhaps...PERHAPS..a tiny bit more dynamical contrast but my aural memory too short to eventually spot such tiny changes. Also while A/B listening the Valvos were not warmed up. 



Cheers,
Jarek
STACORE
03-05-2021 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 303
Post ID: 26077
Reply to: 25877
Big output capacitor question.
Hi Guys,
The output impedance of ECC83 in cathode follower is around 625 Oms. But 1uF capacitor makes output impedance very big on low frequencies (around 8K Ohm at 20Hz). And in this schematics the global feedback doesn't work at low frequencies. So it looks reasonable to try to increase output capacitor value not to make lower cutoff frequency but decrees low frequencies output impedance.    Have anybody tried using a big output capacitor instead of regular 1uF?If yes, does it make any difference?
Regards,Alex.
03-06-2021 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,264
Joined on 10-12-2006

Post #: 304
Post ID: 26078
Reply to: 26077
Context/Application/Circuit
Hl, Alex. You might get more responses at the DIY Audio site. Sure, the general "rule" is more/lower LF with a bigger output cap -  to a point. But what is the make/model/function of the component in question, and what does the circuit look like?

Best regards,Paul S
03-06-2021 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 305
Post ID: 26079
Reply to: 26078
EAR
Hi Paul,
My question was of cause about my phonostage based on EAR834p and "End Of Live" modification with air capacitors and LCLC + 0A2 power supply.
A couple weeks before I increase the second stage ECC83 cathode capacitor value to 43400uF (Kaisei non-polar 100uf + Elna Simlinc 3300uf + 4x Nichicon KA 10000uf). This change is like "fix bias" emulation in cathode bias mode,improved bass definition and texture and made better separation of instruments on complex music with big amount of bass. 
So the second thing I want to try increasing output capacitor C7.
Regards,Alex.
03-06-2021 Post does not mapped to Knowledge Tree
Paul S
San Diego, California, USA
Posts 2,264
Joined on 10-12-2006

Post #: 306
Post ID: 26080
Reply to: 26079
Of Course...
Sorry, Alex, I guess I was not paying attention. If Romy or Thorsten see your post, they can help, for sure, and a few others here also use that model. I know little about this phono stage.

Best regards,
Paul S
03-07-2021 Post does not mapped to Knowledge Tree
rowuk


Germany
Posts 364
Joined on 07-05-2012

Post #: 307
Post ID: 26081
Reply to: 26079
834pT
Hi Alex,I am sorry, what you claim can not be. No cap is going to separate bass instruments better.
The brilliance of the 834p circuit is that the EQ also uses the miller capacitance of the tubes in a very brilliant way. The power supply caps are very well dimensioned. There is no issue with bass definition or texture with the original or the Thorsten Loesch mod. There is no big current drain on those caps that would need "bigger". Separation of instruments on complex music with a lot of bass sounds bogus to me. I generally only want the big caps early in the power supply and smaller ones for "isolation" between stages. I do not use tube rectification or regulation on the phono corrector. The EAR834p is "soft"enough with MM or MC HO cartridges, but with a proper SUT is wonderful with MC. I am using an Ortofon T30 and an Ortofon Rohmann cartridge.

The output cap is another issue. It is only to prevent DC from getting out. I tried the 12AX7, 12AT7, 12AU7 and 12BH7 for the output tube. The 12BH7 stayed. It had the most grunt with longer interconnects. No change to the cap was necessary - even with 10 meters of interconnect. Using my Shure ERA4 test record, there is plenty of output to 10 Hz. Sure, maybe 1 Hz is theoretically cool, finding a great sounding cap for that will be a challenge.
I have often thought about putting the series output cap (or transformer) at the input of the amplifier so that the interconnects are biased with whatever DC happens to be left over. I believe that this bias is the reason that studios can have miles of microphone cables and still get "reference sound". The phantom power keeps the cables biased.


Whenever I feel blue, I start breathing again.
03-07-2021 Post does not mapped to Knowledge Tree
Romy the Cat


Boston, MA
Posts 9,740
Joined on 05-27-2004

Post #: 308
Post ID: 26082
Reply to: 26077
Who knows....
Alex,
 
I cannot answer your questions objectively. It was over 15 years ago when I was working with this phonostage and since I built the last version, I did not make any experiments with it. I do feel the design is spectacular, and I am lucky enough to use possibly the best imaginable step-up transformer, which in my view highlights the advantages of this phonostage. However, I would not deny that any further modification might even improve what it does - I just did not do it. The output capacitors is a big subject, and certainly "better" capacitors might produce better results. The conversation as to which output capacitor is better is a big subject, and people have their own opinions. A long time ago I found peace with electrocube 950 and I did not revise my view on it, but it was over 25 years ago. I very much presume that over the last 25 years there are better capacitors. I do warn you that it is not just about quality of capacitors but also application of capacitors. For example, the same capacitor which acts as a coupling capacitor between two stages and driving directly heated single ended triode might not be such a wonderful thing. As it is famous, when we drive powerful single ended triode with a powerful current source we take advantage to the preceding stage current to drive the triode into class 1B operation. We are taking advantage that direct heated triodes can work with grid current and it gives an additional oomph to drive complicated loads (base reflects design).   The classic example would be Lamm ML3, where 4 parallel powerful drivers are driving GM70. Everybody praises how wonderful it is as it can drive something like Wilsons and indeed GM70 is wonderful to work on the negative side. There is a problem however with this thinking. If the amplifier like ML3 has a coupling capacitors between the stages, and Lamm does use electrocube 950s, then in the time when driver stage pushing amplifier in plate currents the polarity of the capacitor changes. It means each time when driving voltage higher than bias volutage, the tubes can handle it but the capacitors repolarize in real time. From my perspective, I would rather prefer to have crappy capacitor which would be positively or negatively biased than to have capacitors which repolarize in real time, particularly during loud passages. 
 
So, to answer more or less methodologically/objectively what kind of output capacitors should be used in this phonostage, we certainly cannot think abstractly but we need to conduct experiments and make empiric judgements about the results. I disagree with rowuk that capacitors might not lead to separation of musical instruments. Anything can lead to anything. The key is to find methadologically proper approach to evaluate it and reflect how this change in the sound can lead you to improve your personal listening objectives. Pretty much if I were to commission myself a task to question the quality of my output capacitor, it would probably take a couple of weeks of experiments to do it more or less convincingly against my own self-criticism. With all the craziness around me right now I cannot pull it off, so I probably will wait until kids go to college. Smile
 
Alex, please if you do some experiments and you come to some kind of conclusions, please post them.  


"I wish I could score everything for horns." - Richard Wagner. "Our writing equipment takes part in the forming of our thoughts." - Friedrich Nietzsche
03-08-2021 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 309
Post ID: 26083
Reply to: 26082
EAR834p how does RIAA feedback work?
Hi Romy,
I read about EAR834p modifications in number of forums. And I never found any explanation how does RIAA feedback work.Only from you I heard about Miller capacity that used in this RIAA.I tried to do my calculations and as I understand the Miller capacity is a function of gain and it should be different on different frequencies because the gain is not constant. So, it make it even more tricky for calculation. I don't understand which gain I need take in account open loop gain or closed loop gain.
I was wrong in my previous post. The feedback should work in this circuit on low frequencies. As result output impedance is much smaller then I calculated before.
But I was right about the trick with huge cathode capacity. It works! If you can do a fixed bias - it is the best. But if you can't (because schematic) or don't want (too lazy to adjust fix bias) huge capacitors make "fixed bias" sound. How does it technically works. Maybe it works, because, extra big capacitors move a cathode bias phase hump around 1-5Hz to lower frequencies. But the more obvious explanation is - huge capacitors makes cathode to ground impedance very small at hearable low frequencies.
Regards,Alex

03-08-2021 Post does not mapped to Knowledge Tree
N-set
Gdansk, Poland
Posts 498
Joined on 01-07-2006

Post #: 310
Post ID: 26084
Reply to: 26083
Where?
Alex, where exactly have you added your big cap bank? The second stage cathode is at the ground. Do you mean the exit of the filament supply which serves to bias the second stage?



Cheers,
Jarek
STACORE
03-08-2021 Post does not mapped to Knowledge Tree
AlexBerger
Israel, Beer Sheva
Posts 20
Joined on 04-19-2010

Post #: 311
Post ID: 26085
Reply to: 26084
Big cap banks
Hi N-set,
Yes I added big cap bank to the second stage cathode. Yes it is possible to use filament power supply for fixed bias like Romy did.But I have a stereo EAR834p with a single filament PS. So, I was afraid that one PS for both channels can cause some extra crosstalk. Probably I was wrong.
I also used big bank cap in cathodes of my SET in the first (6sn7 R load) and the second stage (6f6 in triode, R load) with similar good results.
Regards,Alex.
Page 16 of 16 (311 items) Select Pages:  « First ... « 12 13 14 15 16
   Target    Threads for related reading   Most recent post in related threads   Forum  Replies   Views   Started 
  »  New  Where are our good phonostages?..  Omnigon Tubes...  Analog Playback Forum     61  531281  05-31-2004
  »  New  The Expressive Technologies SU-1..  “too bright” or “resolution” or “details” with SUT prim...  Analog Playback Forum     33  310985  12-30-2004
  »  New  EAR 834P Modification Guide..  The cap will not change volume in the pass band...  Analog Playback Forum     45  517197  02-09-2006
  »  New  My Analog Playback: the fat lady has sung..  My analog setup update....  Analog Playback Forum     9  98814  04-04-2006
  »  New  Phono stages with SU-1..  SU-1...  Analog Playback Forum     4  54382  11-23-2007
  »  New  Chasing utopian better phono interconnect...  Did I miss something?...  Analog Playback Forum     6  92296  06-05-2008
  »  New  Buying a last cartridge...  Lucky you...  Analog Playback Forum     80  670905  09-05-2008
  »  New  EAR 834P mods..  The cap will not change volume in the pass band...  Analog Playback Forum     45  517197  11-04-2008
  »  New  AMR PH-77: just another phonostage or more?..  Oh, yeah... the sound of the Thing Itself......  Analog Playback Forum     11  105403  07-05-2009
  »  New  An interesting Russian pnonocorrector...  Uber-tweeky phono topologies deconstructed...  Analog Playback Forum     9  71076  03-01-2010
  »  New  Expressive Technologies SU-1 and cartridge output and i..  MV and Ohms...  Analog Playback Forum     2  25391  07-07-2011
  »  New  How to run MM-type cartridge into MC phonostage?..  Quite interesting....  Analog Playback Forum     6  50824  11-13-2011
  »  New  The tales of two phonostages: Allnic and 834PT...  The tales of two phonostages: Allnic and 834PT....  Analog Playback Forum     0  17949  12-21-2011
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