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Old 4th February 2008, 05:11 PM   #321
Bobken is offline Bobken  United Kingdom
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Quote:
Originally posted by KP11520
Dave,

Bob, I would still like to chat about what you did with that Rotel CD Player.

Keith
Hi Keith,

I'm sorry to say that I had completely forgotten about that matter, so put it down to a 'senior moment' on my part!
Sometimes my short-term memory fails me nowadays, although I can recall incidents from over 60 yrs ago with complete clarity.

Anyway, I have been a bit tied up with other things for a few days, but I will make the effort to look out the schematic and my notes, as soon as I get some time to spare. I have quite a large 'archive' of such items, after all these years!

I'll contact you separately to avoid too much 'off topic' here, though.

Regards,
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Old 4th February 2008, 05:18 PM   #322
KP11520 is offline KP11520  United States
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Hi Bob,

I have senior moments in my 40s! What do I have to look forward to in my 60s? YIKES!

That sounds great! I have a few threads I started about the Rotel with schematics and other things here on DIY if you cant find your notes!

Thanks.

Regards//Keith
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Old 4th February 2008, 05:34 PM   #323
Davet is offline Davet  United States
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Quote:
Originally posted by KP11520

Also send or post a pic of the area in the amp where the input cap goes please. I get better ideas with a visual of what you have to work with.

Keith
I will take a photo and identify where the caps are go into the PCB.

I have been giving some more thought to having the various bypass caps as close as possible to the electrolytic. It seems to me, if I keep all the leads the same length that whatever additional LCR that is added to the circuit would be the same for all caps under test.

So, I will probably go back to the test bed that has served me so well. With these caps being so small connecting and disconnecting is a real hassle.
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Old 4th February 2008, 05:58 PM   #324
KP11520 is offline KP11520  United States
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Dave,

I was thinking that some of the "smaller" bypass caps have short leads and the larger input caps make it difficult to parallel. Rather than extending the bypass caps leads extend the larger input caps and find a way to install as close to the PCB (where the one cap should go) as possible.

Hopefully this wouldgive the best results!

Regards//Keith
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Old 11th February 2008, 07:12 AM   #325
dweekie is offline dweekie  United States
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I managed to get hold of some Siemens/Epcos B25834 caps in 3.3uf. They're machine caps just slightly smaller than the big Obbligato PIO caps.

There has been some hype of these kinds of caps in the past from a couple users and a failed group buy. The main source was from Dice45 in various forums around the web. Another well known figure of these forums Peter Daniels posted that this cap outperformed his Jenson Copper + rtx + silver foil bypass in his tweeter (http://www.diyaudio.com/forums/showt...895#post172895)

If you like Obbligato caps, these B25834 caps improve upon many of its weaknesses. Firstly, the the overall tone is nearly the same. Everything is very smooth and warm. The vocals and instrumental tone is essential the same between the two.

The difference lies in the overall balance. The B25834 is balanced from top to bottom, wheras the Obbligato seems to exhibit much less top end and, to a lesser extent, less bottom end. The soundstage/depth is much better in the B25834. I think this is the result of the improved high frequency performance of the amp.

I tried bypassing the Obbligatos with some 0.01 caps. First was the MKT1822 0.01uf, then MKT1837 0.01uf, naked Russian teflon 0.1uf caps + MKT1837 0.01uf, and finally some Mojo Dijon 0.01uf caps. They all improved high frequency performance, but things never sounded quite like the bare Obbligato. The bypass caps seemed to take away the original sound that made the Obbligatoes so attractive in the first place. That was my failed attempt at trying to up improve the Obbligato performance.

I think the B25834 caps are for the people that love Obbligato caps, or for those that love the tone of the Obbligatos but could not live with the soundstage/depth/high frequency tradeoffs. If you found the Obbligatos lacking in edge or apparent detail, then these caps are not for you.
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Old 11th February 2008, 03:47 PM   #326
KP11520 is offline KP11520  United States
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Hi Dweekie,

Have you played with bypassing these yet? I would be interested to know how that goes.

When you say "I think the B25834 caps are for the people that love Obbligato caps, or for those that love the tone of the Obbligatos but could not live with the soundstage/depth/high frequency tradeoffs. If you found the Obbligatos lacking in edge or apparent detail, then these caps are not for you."

I'm sorry, but what you are saying about comparisons is not that clear to me. Would you mind framing out this statement for me to see a bigger picture?

Also do they come in 4.7uf and at what voltages and are they Radial or Axial?

BTW, if you are a "One Cap Man" (don't like bypass caps) these sound like a great choice!

Thanks as always!

Regards//Keith
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Old 11th February 2008, 05:20 PM   #327
dweekie is offline dweekie  United States
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Here's the datasheet to answer some of your questions (http://www.epcos.com/inf/20/50/db/power_99/01280167.pdf). In short, they are radial, come in 4.7, and are available in 600v and higher.

I found them surplus and had bought out a group-buy sized lot. I may offer them for sale in the trading post soon after I decide how many I want to keep, but I really don't want it to be a self promotion. Send me an email if you want me to send you a pair. I offered some caps to Dave to test since he can do a much better job with a wider range of better caps.

I have not tried bypassing these caps yet and don't feel motivated to do so. They seem to pass all the information that the 0.01uf caps add to the Obbligato PIO caps in my opinion without some of the disjointed sound I sometimes notice between the caps.

Quote:
Originally posted by KP11520
When you say "I think the B25834 caps are for the people that love Obbligato caps, or for those that love the tone of the Obbligatos but could not live with the soundstage/depth/high frequency tradeoffs. If you found the Obbligatos lacking in edge or apparent detail, then these caps are not for you."
What I meant to say is that these B25834 caps are very similar to the Obbligato caps. They are very smooth and warm, but the B25834 caps seem to address some of the "mono" soundstage that some people describe. They still sound very similar to the Obbligatos overall, and people that do not like the PIO properties will still not be satisfied with the B25834 caps.
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Old 11th February 2008, 06:18 PM   #328
KP11520 is offline KP11520  United States
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When you refer to the Obbligato Caps you write PIO. The ones I bought from DIYHIFI supply were actually black, Film/Oil (Polypropylene) 630 volt Radial caps. Are these the ones you tested too?

They are supposed to be warm with great soundstage and detailed and decently balanced from bottom to top. based on Dave's experience and what I read other places. From what I understand, your experience is somewhat close to this explanation but the bottom and top are just a little lacking.

Or are the Obbligatos you tried different, hence PIO?

BTW, I am interested to buy a pair of 4.7uf caps!

Thanks again!

Regards//Keith
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Old 11th February 2008, 06:50 PM   #329
dweekie is offline dweekie  United States
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Sorry, I just have a habit of calling all oil caps PIO caps. The Obbligato cap is the one you referred to listed at $5.50 for 2.2uf, and $6.75 at 4.7uf.

The B25834 and Obbligatos both make the splashing noise when you shake them.
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Old 12th February 2008, 08:09 PM   #330
dweekie is offline dweekie  United States
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DaveT will be getting a pair of B25834 caps to play with very soon
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