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In Reply to: My PAS-3: Pictures and further commentary... posted by crooner on September 17, 2004 at 22:50:45:
If the soft/vauge sound isn't to your liking I'd suggest a few things. Number one, replace those old black coupling caps. Number two, replace those old poor tolerance resistors. 1/2 watt carbon films from radio shack are a good choice and sound a lot like carbon comps but have much better tolerances and I have found poor tolerance resistors to be a big factor in vauge soft sound. Number three, and this requires a fair bit of work, replace the stock selector switch and RCA jacks and rewire so the phono stage is only used for phone and not for tape head and special. If you do this twist hot and ground at the RCA jacks but connect the ground only at the RCA jacks and leave it floating at the selector switch. Do this for each and every wire going to the selector switch and keep all wiring for the phono section separate and well away from all other wiring. Lorlin sells a decent cheap selector switch and you can get it from major supply houses like newark, digikey, mouser, or allied....just can't remember who carries it. Two pole six posistion shorting type I think off hand. The best solution for the RCA jacks is to buy Curico's kit as it comes with a nice PCB board.
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They do not suffer from moisture problems and seldom leak. Black Cats are similar to the Good Alls, one of the very first Mylar caps used in audio.My philosophy on this is that "If It Ain't Broke, don't fix it". The Black Cats on my units are still working fine, so why replace them?
So, I guess Dave Hafler wasn't that cheap after all. He could have used plastic molded paper types such as Black Beauties. He instead used a mylar cap for greater reliability.
is ceramic. If you are happy with the sound of the unit as is that's cool. I was only trying to help based on my experiences with the PAS. If you feel the sound is somewhat soft and vauge replacing those caps with even a cheap polypropylene like orange drops will make a big difference. The tolerance rating on most of the stock resistors is 20%. Plus they usually drift quite high in value over the years. A new carbon film will have a 5% tolerance and won't drift much over time. But the only way to find out is to try it. I sincerely doubt you will want to go back to the old parts if you do bother to replace them but you always can and it really isn't more than 50 bucks and one afternoon of your time.
Caps go through a dielectric contamination process over time, especially under extreme stresses (high voltage, temperature). It may not be easily apparent from listening. My acid test is to measure the grid voltage. If you observe any DC - beware!
If you think those are cool, try the beautiful silver cover of paper in oil... NOS "Vitamin Q" look great!!!
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