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K250-4 filter caps [message #14961]

Mon, 27 December 2010 17:07

2dcapcom
Messages: 1
Registered: December 2010

Junior Member

Howdy!

I got this Kustom K250-4 a while back in a trade and I really haven't used it too much and now I'm thinking about using it so I assigned myself cleanup duty on it. The good news is that there really doesn't seem to be anything wrong with the head after going over it. After cleaning all the jacks and installing a 3 prong plug there doesn't seem to be any extra noise and everything seems to be working properly. I have a BS in Computer Science and have done some soldering and metering so getting into the basics of amp repair doesn't seem too daunting to me, just trying to pick it up a piece at a time.

The most common thing from what I have read is replacing the filter caps right off the bat. Examining them I saw that one of the indicators is raised so that one must be dried up, so I would like to just replace both of them. Now finally getting to my question I know that the stock ones are 50V 4500uF but I have read that most people replace them with higher values. This is where I am getting confused.

I am going to be playing this amp at high volumes so I want to maximize the volume I can get without amp distortion (I'll leave that to my Mesa v-twin rackmount if I want distortion), and I have read that putting in bigger caps helps keep it cleaner at higher volumes so that sounds like something I want to do.
Someone suggested 10,000uF but didn't say anything about voltage. I am hoping someone can explain what is an ideal Voltage/Farad rating for this head that maximizes volume without distortion. How high is too high? At what point do higher values not actually make a difference? Do any other components need to be upgraded if you go with higher values for your filter caps? Also when I search Mouser.com for 50V caps there are other ratings like Tolerance, ESR, Series, do I need to worry about any of these?
Post a link to an ideal cap for this head?

Also I know that new caps will be a different size so I'll wrap them or get new brackets. I will also discharge the old ones and check for voltage before touching them, but I've read that these caps don't hold a charge very long, why is that?

Sorry about the long post but I like to be thorough Smile

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Re: K250-4 filter caps [message #14963 is a reply to message #14961]

Tue, 28 December 2010 12:16

stevem
Messages: 4773
Registered: June 2004
Location: NY

Senior Member

Hello.
You need to use what is termed Computor grade caps like the big Mallory can types that are in the amp.

Up rating from the stock 4500 mfd to 10,000 is plenty.
Staying with the stock 50 volt spec is fine, but going up to a higher voltage will extend the caps life.
The only problem with going from the 50 volters to let say 75 volt is the big increase in cost with these can type caps, so in the end its up to your wallet.
The orignal 50 volt caps have been running at 40 volts for more than 30 years, so you be the judge.

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