John Curl's Blowtorch preamplifier

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PHEONIX

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john curl said:
I might use Panasonic PS series today. [/B]
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Hello John.

The Panasonic PS series that you use today , is this a current series ( I cant seem to find a data sheet).

Out of curiosity why do you use these parts , and seemingly spend lots of time obsessing about resistors.
For what its worth dont you think these parts play a big role in the final sound, and yet I see no obsessing of which electrolytic cap to use.

Regards
Arthur
 
john curl

john curl

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I thought so, PMA, AND it is that 100-220pf cap on the input that I often worry about with the mid-fi designers represented here. This is where it is difficult to notice, at a glance whether the cap is NPO or something more compromised. IF not non-linear distortion, then DA can still be significant in many compromised caps, other than polystyrene, polypropylene or Teflon. Mica is also marginal, BUT easily identifiable as a device, so that I know where I stand, at a glance.
I tend NOT to use surface mount, so I may be avoiding certain tradeoffs that others must make. Still, the principles are the same.
 
john curl

john curl

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Please understand everyone, the best quality costs big money. I have a .3 uf Teflon cap in my new phono stage that costs me $40. Do you think that I would not replace it with something cheaper, IF I thought it would sound just as good?
IF you don't give a darn about what works and what does not, please just defer from taking cheap shots at the rest of us.
 
john curl

john curl

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OH baloney, Anatech. I got my first large value ceramic caps when I worked in the Ampex research department. They were MORE expensive than mylar, but they were small.
There was NOTHING on the cap spec sheet that warned us against using these parts for audio coupling. I know this, because I checked it out. The manufacturers are interested in SELLING us product, not warning us against it.
For example, anyone here have the AUDIO HANDBOOK's put forth by National Semi, years ago? You will find PLENTY of large value ceramic caps selected as input and output coupling caps. ARE THEY NOT ENGINEERS? I thought so, as I attended graduate engineering classes at UC Berkeley, with one of them, and he is now VP of RANE (or at least, the last time I looked).
 
andy_c

andy_c

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anatech said:
And I will also happily use NPO ceramics in some applications.
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Chris, here's an off-the-wall question. I'm in need of a Miller compensation cap for a high-power amp with boosted front end supplies (+/- 100V). So I need a cap with a voltage rating greater than 200V of course. I was originally going to use mica here. But the data from Bob Pease's 1982 article on DA (attached below) shows mica to be inferior to NP0 ceramic with respect to DA. Now I seem to remember syn08 has done some research showing DA to be a nonlinear phenomenon. This cap would of course see the full output voltage swing, so its nonlinearity could conceivably be a concern for a sub-ppm THD design. So I thought I might look to see if there were any NP0 ceramics available in, say, a 500V rating. The Mouser catalog shows that the cheapo Xicons meet this requirement. They make a 39 pF, 500V NP0, which is just what I'm looking for. Have you ever tried the Xicon NP0's?
 

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Peter Daniel

Peter Daniel

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I wouldn't agree that they are much less important in absolutes, of course it may be circuit dependant. The point is, that your typical signal path caps can make the circuit sound more or less good, but improperly chosen, PS filter caps can make the circuit unlistenable.

I don't spend much time thinking about "signal path" caps choices, I ususaly use V-caps or BG Ns. But I spend most of my time experimenting with PS caps (size and type), as I can never predict how they gonna sound in a particular circuit.
 
bear

bear

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bearlabs.com
janneman said:
OK, I'm not an expert here either. You may be right.

Tell you what, do me a favour. Download DiffMaker, and listen to the following tracks:

- The difference track between no cap and a film cap;
- The difference track between no cap and a ceramic cap;
- Test track # 1 (for convenience) difference track between track with sousa and without.

Now as you listen to the difference tracks, you in fact listen to the 'aberration' in isolation, which is present in one track of each pair, but not in the other. I would be interested in your view of which one you expect is easier to detect down in the track.

Jan Didden
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Jan,

I will listen, it won't be immediate, and it will not be played back intitially on pristine gear at all, probably a lowly laptop with half decent phones...

Having said that, my intitial reaction is that I have no idea which one ought to be more detectable. Or if either is, given this specific example.

The other thing that occurred to me, is this is a difference track, are we making an assumption that the no cap version is either "better" or that the version with the cap has "more artifacts"?

I can see a situation where the opposite would be true. Fwiw.

Which one is "accurate" is another matter... of course.
Which one is sonically more "natural" to the ear is also another matter.

_-_-bear
 
bear

bear

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bearlabs.com
Caps.

A case can be made for not repeating the same brand/type cap over an over in a circuit, as the "signature" will then be repeated over and over... whereas if one switches to different brand/type caps the signature is spread, and perhaps limited to inaudibility. Or not.

Let's assume that whatever we're using is of very limited "aberration" or "signature"... for the benefit of discussion, of course. :D

_-_-bear
 
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