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Old 28th April 2006, 08:30 AM   #1141
Colin is offline Colin  United Kingdom
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Hi Peter

You don't have the Plitron transformers on your website at present - what are the prices and shipping to UK?

I notice the Plitron site has some specialised audio toroids, albeit starting at 500VA, designed with low noise in mind. Any experience with these?

All the best

Colin
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Old 30th April 2006, 06:17 PM   #1142
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Default DAC Coupling Caps

Hi Peter,

I've been researching the availability of audio grade capacitors in the 2.0 to 4.7uf range to do some experimenting. As I'm sure you are aware the selection is not great.

The Auricaps, Mundorfs, V-Caps, etc., are quite large (as well as expensive).

Do you have a preference between polarized and non-polarized?

And lastly, are tantalum capacitors an acceptable choice for coupling caps on the DAC.....I never see them being used in such an application and was wondering why? Is there an ESR or inductance problem with them? They seem to have pretty good availability in this capacitance range, and they are compact.

Robert
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Old 1st May 2006, 07:17 PM   #1143
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Default Re: DAC Coupling Caps

Quote:
Originally posted by Colin
You don't have the Plitron transformers on your website at present - what are the prices and shipping to UK?

I notice the Plitron site has some specialised audio toroids, albeit starting at 500VA, designed with low noise in mind. Any experience with these?
300 VA Standard toroid is USD$80 (current Plitron pricing). Shipping to UK is either CAD$50 by surface or $92 air (4kg). I never tried those LoNoise units, I'm having amorphous core toroids cutom built in Europe instead.


Quote:
Originally posted by rjkdivin
Hi Peter,

I've been researching the availability of audio grade capacitors in the 2.0 to 4.7uf range to do some experimenting. As I'm sure you are aware the selection is not great.

The Auricaps, Mundorfs, V-Caps, etc., are quite large (as well as expensive).

Do you have a preference between polarized and non-polarized?

And lastly, are tantalum capacitors an acceptable choice for coupling caps on the DAC.....I never see them being used in such an application and was wondering why? Is there an ESR or inductance problem with them? They seem to have pretty good availability in this capacitance range, and they are compact.
I never tried current production tantalums, I don't expect those would be any good. However, when I was modifying Accuphase 101 tuner, those old type blue tantalums appeared better for coupling than BG N.

It's alsways better to use nonpolarized caps in coupling. Here's a link to interesting comparison between capacitors: http://www.humblehomemadehifi.com/Cap.html
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Old 1st May 2006, 07:38 PM   #1144
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Default Re: Re: DAC Coupling Caps

Quote:
Originally posted by Peter Daniel


It's alsways better to use nonpolarized caps in coupling. Here's a link to interesting comparison between capacitors: http://www.humblehomemadehifi.com/Cap.html
I recently replaced a pair of those blue tantalums in a 2A3 amp with Ven-Haus OIMP V-Caps with great results.

Though not updated in a while, this is another interesting page on audio capacitors. Interesting how he describes how film caps break-in and self-heal, or not...:

http://ldsg.snippets.org/appdx-ec.php3

-Rob
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Old 1st May 2006, 08:55 PM   #1145
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Default Re: DAC Coupling Caps

Quote:
Originally posted by rjkdivin

I've been researching the availability of audio grade capacitors in the 2.0 to 4.7uf range to do some experimenting. As I'm sure you are aware the selection is not great.

The Auricaps, Mundorfs, V-Caps, etc., are quite large (as well as expensive).
How about 50 cents each? Of course you have to buy 30 of 'em and they cost $24 to ship from the Ukraine...

There's still a bunch of Russian military NOS caps on the market, available on eBay. As evidenced by this search:

http://tinyurl.com/mrxpx

I've got a slew of the K40 PIOs in .22uf/1000V value en route from the Ukraine. They say they ship airmail, I'm thinking they must be using a Zeppelin.

None the less, legend has it these things equal or exceed the pricey REL TFT Exoticas and V-CAPS. Folks jest that Richard Marsh of RELCap and Chris VenHaus of V-Cap can't wait for th supply to dry up.

They are still big, esp. the glass-encapsulated designs. But with caps, there's no free lunch on size.

Here's a listing for thirty 2.2uF/400V PIOs for $15.00.

http://tinyurl.com/qc2zg

If anyone gets some, I'll trade you some of my .22s for another value.

-Rob
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Old 1st May 2006, 09:44 PM   #1146
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Default Another PDGC is born...

I finally got around to putting together a PDGC yesterday. I used the premium kit with the BG caps per the Patek, one rectifier board and a massive dual 22V/400VA Antec toroid (c. $44).

No chassis yet. Clamped the chips to a 1/2" block of aluminum and fired it up. Right off the bat it sounds terrific into my 97dB ORCA designed custom line arrays. (Funny to see a little pile of parts bowl you over through 800lbs of speakers.)

Have been burning in the amp since last night with a FryKleaner on high with a pair of 8 Ohm Mills 50W power resistors on the outputs. Next listen should be interesting...

While burning in I could fry a little quails egg on the aluminum plate until I recently placed a big heat sink under it.

I've been listening to modded Wright 2A3 monos, a modded Music Reference RM-9 100 WPC KT-88 PP amp and a Spectron Musician II as references. This little PD GC is a contender, the detail of the 2A3, the dynamics of the PP tubes and the slam of the 600 WPC Spectron?!!!

More to come...
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Old 1st May 2006, 09:51 PM   #1147
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Default Re: Another PDGC is born...

I must say, for anyone who hasn't delved into DIY and is looking for a place to start, this project is so easy, the price so low and the results so worthwhile, that this is the way to get your feet wet.

I started DIY building kits in the early 70s with SWTP Tiger .01 amps, and have always enjoyed it. The renegade, true DIY nature of the PD project is even more appealing to me that a traditional "kit". The only challenge in this kit would be doing the NFB Caddock on the chip legs, which you don't have to do, but for me was the most fun...

Here's a pic of one channel with NFB resistor on the amp chip:
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Old 1st May 2006, 09:54 PM   #1148
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Default Re: Re: Another PDGC is born...

Quote:
Originally posted by Rob Thomas


Here's a pic of one channel with NFB resistor on the amp chip:
Peter,

I think I reversed the orientation of the BG N caps at the chips from what you do on the Patek.

Does it indeed make a difference and can you describe it sonically?

And Bravo on your execution.

-Rob
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Old 2nd May 2006, 12:47 AM   #1149
karma is offline karma  Canada
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ahh it has been sent thanks peter, now to save for the next offering


cheers
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Old 2nd May 2006, 01:00 AM   #1150
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Default Re: Re: Re: Another PDGC is born...

Quote:
Originally posted by Rob Thomas
Does it indeed make a difference and can you describe it sonically?
Yes, it makes a difference. With one way, it's more focused, and it seems more accurate, sort of like playing with signal polarity. Even if you cut the pins, you can still identify the sides, as NONPOLAR print is always on the side of shorter pin (+ by my preference).

There is an easy way to install feedback resistor on my boards: http://www.diyaudio.com/forums/showt...427#post584427

Later, you can also try shorting 220R series input resistor, it usually sounds better without it (and I'm not using that resistor in Patek amp).
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