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I have an old CAT preamp with two 47uF 250V electrolytic capacitors in the signal path. The caps are radial and are 5/8" in diameter. I would like to hear your thoughts on replacement caps.
I also have some caps that could use replacement in the power supply. They are 100uF 450V and 4700uF 25V. I would your thoughts on that, too.
Follow Ups:
http://www.partsconnexion.com/capacitor_film_mundorf_mtube.html
When I was looking at doing this, I contacted the guy who built my preamp (Stan Warren) and he prefered Panasonic FM caps to Blackgates.
the Panasonics are I believe still available
Blackgates are out due to lack of stock, unfortunately.
It is going to be difficult to get a film cap that high in value to fit. See if you can get a quality electrolytic and bypass it with a small value quality film cap. Blackgate has been my favorite for years, but are now out of production. AA sponsors like the Parts Connexion, and Michael Percy Audio carry the better quality parts.
The problem is that I can't find any Blackgate or audio grade Nichicon caps with that value.
I took a quick look and see a Blackgate at 160 volt rating at Percy. I wonder what voltage that cap sees? The Mundorf is huge. My initial response is to keep looking for a decent cap closer to the original size. Check the Panasonic and Sanyo caps and then get a good small value film and foil bypass
awsjr mentions Mundorf. How do they compare with other electrolytics and film caps like Solen? Also, I have a space problem on the board, I suppose I could add a board above the main circuit board to "house" the new capacitors. Any suggestions on how to do that?
Be careful what you do here. Are you sure these e-caps are in the signal path? That's a huge value to have in a preamp.
In any event, your best bet for caps are Panasonic FC or FM series. Blows Blackgates away. On top of that they are reliable and inexpensive. BG's are not. I used to use them quite a bit but the failure rate and the cost was way too high.
If you like the Mundorf, best place to buy is from Audiyo (www.audiyo.com)
"Panasonic FC or FM series. Blows Blackgates away."
Man do we have different tastes. I have used both and wouldn't put the Panasonic in the same zip code as the Blackgate. To my ears, the Blackgate has a much more natural presentation. Wood instruments sound like wood, etc. I have never heard that for a Panasonic electrolytic. Bon appetite
Yes we do have different tastes. I've always found BG's to be dull and lifeless. At least when they are directly in the signal path. When used for bypassing and filtering, they are no better than the Panasonic. In that use I've had a number of them go bad in a very short time. And that's using them at less than 75% of rating
JoKat,
If you look at the link below, you'll see that there are electrolytics near
the tubes. Now, as I'm just learning about upgrading component parts, I must confess that I can't say with certainty that the e-caps are in the signal path but it looks like it to me. Is it possible they aren't given their location?
http://www.gcaudio.com/products/reviews/infocat.html
Chances are they are either cathode bypass or local powersupply filtering. That doesn't mean a good quality cap won't make a differnce though.
What should I look for to confirm that the e-caps are being used as a cathode bypass or for local powersupply filtering?
There is no chance that the CAT uses large electrolytics in the signal path.
First of all, it's just common sense. That is a high dollar cost no object preamp. It makes absolutely no sense that they would severely compromise the design and sound by putting a electrolytic capacitor in the signal path. It makes as much sense as putting a one barrel carburetor with a 1" throat on a Corvette LT1. Second if you take the time to look at the picture of the unit you will see a couple of dozen plastic caps that are obviously the signal caps. Third, it even says in the blurb: CAT coupling capacitors are made to our specifications and are better than any other audiophile grade capacitor. Fourth, 47uF is not a value that makes any sense as a coupling cap.
There is no chance there is a electrolytic cap in the signal path on that unit.
Help me out here. If I'm looking at the circuit board traces, what would these caps be next to if they are being used for cathode bypass or local powersupply filtering?
Follow the trace to all the components that the cap lead connects to. Generally the neg end of a cap in the PS goes to ground. Look at the connecting part to determine its function i.e., if it goes to a rectifier tube it is a power supply cap. If it goes to a cathode resistor, then its a cathode cap. You will need to check your tube manual for tube socket connections and you may need to remove the PC board from the chassis to see both sides in order to follow a trace.
How do you know this?
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