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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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Tweakers' Asylum Tweaks for systems, rooms and Do It Yourself (DIY) help. FAQ. |
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In Reply to: Re: Experimenting with Power Supply Filter Caps. posted by Clayton Oxendine on July 9, 1999 at 16:18:27:
>>Where have you been? Have not seen you post anywhere in a while.<<Not much to say lately. Besides, I've been trying to actually complete a speaker project. I have four pairs of Strathearn Ribbons I've been hoarding for years and I've been working on a design for them, among other things.
>>Why didn't you tell me about power supplies sooner?<<
You weren't ready to know, my son. Now you are and can become one with your audio chain. ( A little Zen action there. =;-o) )
I think a lot of designers don't consider the PS to be of much importance.(Re PS upgrades, one EE type told me that "it's a waste of parts".) The unit will still meet its specs with a skimpy supply and if they don't care about realistic sound or can't hear it - then cheaper and simpler is better. But that's good news for us. We can buy one of these inexpensive players, do some mods, get audio nirvana and have fun in the bargain. The power supply in a CDP has to do a lot of things - power the motor, the servo, the display, the DAC, the output filter and on and on. No wonder PS mods make a big difference in sound.
It has been my experience that exotic caps in the PS don't make an audible difference (waste of parts?) - but I use Panasonic caps wherever I can in the PS and try to get the PS output cap just right because that affects the transient response of the supply.
>> I really wish I had some schematics so I could find where my output cap is on the CDP.<<This is one of the reasons I have only Philips CD players. Philips will sell anyone a repair manual for any of their products. They don't give you that "are you a dealer or repair center?" crap. Same deal with their parts. I noticed Sony is getting better about that too. Maybe you can contact Onkyo America and see if they'll sell you a repair manual - but sometimes they can be a bit pricey .
Your unit may or may not have caps at the output. I'm looking at a schematic for an Onkyo DX-200 (whatever that is). I can't make head or tail of it, but there aren't any series caps at the output. But if your unit is like the Philips and some Sonys that I've seen, the output caps should be one of the last two or three things in the circuit before the RCA jacks. So trace the circuit back from the output and there should be a cap for each channel. The "minus" side of the cap will be going toward the output. There may be things like a series resistor and a mute circuit or relay between the cap and the output. The players I have have had values ranging from 10uF to 330uF, but I don't know about 800uF . I replace these with 10 or 20 uF film caps. A conservative approach could be to substitute Panasonic "Z" or "HFS - HFQ" electrolytics of similar values - they're almost as good as polypros.
I recently got a Philips CDC-751 that sounded good right out of the box. I upgraded the op amp to an NE5535 (biased for class A ala Walt Jung) and gave it its own PS. Then I changed two 100 ohm SMT resistors at the output for real resistors and took out the output caps and ran leads from there to the outside of the player. I kept swapping caps and listening until I found a combination I liked (oil and polypropylene). A few hours of tinkering and listening - I had all the parts in my junk box - and Shazamm! high end sound. The result is quite musical but still not quite as good as my super POOGED Magnavox 650.
Let us know how you're progressing but, by all means, try to avoid the dreaded disease "Tweakitis".
AWP
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- Re: Experimenting with Power Supply Filter Caps. - AWP 14:34:29 07/11/99 (0)
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