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Coupling Capacitors

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Posted on November 12, 2014 at 18:26:18
sony6060
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Closed.

 

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RE: Coupling Capacitors, posted on November 12, 2014 at 19:16:00
Chip647
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If you like the 8B it is not because of caps and you will not get that sound from caps. You like it because of the output transformers and the pentode input tube and the bodacious feedback used. The 8B ain't magic, it is talent in the design and money in the construction of the output transformers.

 

RE: Coupling Capacitors (not a direct answer), posted on November 12, 2014 at 19:24:07
Steve O
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IMO you're not going to best an 8B by simply rolling caps. As you already know, the 8B was a highly refined version of an existing design utilizing very special OPTs. You also probably know that the stock 8B was built with quality components but nothing really exotic. ex Most of the coupling caps were relatively generic polyester types.

Just my opinion but if you want 8B sound you'll probably get it best with a properly refurbished 8B.

 

RE: Coupling Capacitors (not a direct answer), posted on November 12, 2014 at 19:41:56
sony6060
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I know an 8B is an 8B. I understand the audio transformers with cathode feedback windings excel among other attributes. But, one can try to improve....... thus my original question.

 

Absolutely you can try to improve..., posted on November 12, 2014 at 20:10:51
Steve O
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...but your current "target" was the result of much more than just coupling caps. So while you might be able to improve what you now have by cap rolling, it's really doubtful you'll end up with an 8B equal much less a beater.

Now let's hear from the cap rollers for an alternate POV.

 

RE: Coupling Capacitors, posted on November 12, 2014 at 20:55:18
Michael Samra
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Jim
You found the same scenario a lot of is found..The K40Y-9 and the Vit Q are two of the finest sounding coupling caps ever made..Obviously they were both built to high standards because both were used in military applications.
The FT2s which are the 200v rated teflon caps that are capable of much higher voltages to over 750vdc in several tests..You have to mix coupling capacitor types to get a good balance..I typically use paper in oil or teflon on the output and driver stages and I use film and foil on the low voltage sections.
The thing I don't like about the Mundorf silver foil is the fact that after month,they can take on a harshness. I use them but in very selective areas.
I would try a mix of caps in your 8B..Did you try the 6L6gcs or KT66s yet in your 8B? It may be the alternate sound you are looking for.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

He's working on some amp other than an 8B..., posted on November 12, 2014 at 21:12:04
Steve O
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...and want to duplicate 8B performance/sonics in that amp by rolling caps.

 

RE: He's working on some amp other than an 8B..., posted on November 12, 2014 at 21:26:47
Eli Duttman
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JMO, the "iron" is much more important than the caps. are.


Eli D.

 

RE: He's working on some amp other than an 8B..., posted on November 12, 2014 at 21:37:51
Any comment on the quality of the reissue OPT's relative to the originals?

Dave

 

My first harsh lesson, posted on November 13, 2014 at 04:32:22
1973shovel
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I bought a couple of Dynaco MK IIIs from a friend many years ago, when I was just learning to solder. Holco resistors and MIT Multicaps (I used RTX Polystyrene Film & Foil) were all the rage in magazine reviews at the time. Any equipment which came with them installed just had to be a winner. Money was tight back then, but I was going to transform these (otherwise stock) Dynaco amps by using some magic parts.

When I was done there were some improvements, but nothing like the transformation I was expecting. The money spent on parts was worth it, if only for the lesson learned.

 

RE: Coupling Capacitors, posted on November 13, 2014 at 05:56:30
petercapo
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$64,000 question: "Which amp are you trying to improve by using different coupling capacitors?"

How about the power supply? Have you done any work there? I figure that's pretty important, too.

 

RE: He's working on some amp other than an 8B..., posted on November 13, 2014 at 13:42:09
Michael Samra
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If that's the case,that may be difficult to do..Amps like the 8B,the Macs,and the Citations have an inherent sound unto themselves due to the iron mostly.
"For every complex problem there is an answer that is clear, simple, and wrong" H. L. Mencken

 

RE: My first harsh lesson, posted on November 13, 2014 at 14:39:24
Jim McShane
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However, it isn't wise to generalize. In the right places and in the right gear Holco all copper resistors and RTX Multicaps can be really good. I'm a big fan of the RTX caps in particular...they do well used with K40s BTW.

 

The intent wasn't to generalize, or badmouth RTX caps Jim, posted on November 13, 2014 at 17:20:09
1973shovel
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The point was, I was under the naive impression 20 some years ago that upgrading resistors and caps to those of better quality would turn a pair of Dynaco MK-IIIs into a pair of Marantz 9s. That's a bit of an exaggeration, of course, but I knew nothing about the importance of power supplies, output transformers, and input stages back then. My expectations from a parts upgrade were unrealistic.

I posted my experience with RTX caps and Holco resistors based on the original poster seeking to close the gap between his amp, and the sound of a Marantz 8b via coupling caps, not to trash my choices.





 

$64,000 question? $0.64 answer!..., posted on November 13, 2014 at 17:58:40
Steve O
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...I wonder if the mystery amp is revealed in a recent post by the OP???

 

Understood...(nt), posted on November 13, 2014 at 18:11:52
Jim McShane
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RE: Absolutely you can try to improve..., posted on November 14, 2014 at 16:45:34
Caucasian Blackplate
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With global feedback, the amp will actually work to nullify any contributions from the coupling caps.

 

RE: My first harsh lesson, posted on November 18, 2014 at 10:32:11
DAK
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I did a similar thing with an EICO HF89 with all high quality caps, resistors, wire, an upgraded power supply to CLC, and was totally underwhelmed by the result. It has good points but it did not reveal the emotion in the music which really separates a good amp from the others. I think a push pull amp should probably be rebuilt with parts that is as close to stock as you can find rather than using "precision" or boutique parts. It doesn't seem that using premium parts will necessarily lead to a better sounding amp.
On the other hand single ended amps are a different story. cheers, Dak

 

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