I recently acquired a Classe 70 power amplifier. It's 20 years old so I think it's time to replace the filter caps. There are two 10,000uF caps per channel. These are the exact caps:
CGR103U050V4C Cornell Dubilier - CDE | Mouser
So it'd be a 10 minute job since CDE is still producing the exact same caps 20 years later.
However, I'd like to replace the caps with these intstead:
Mundorf Capacitor 10000uF 80Vdc MLytic® HC
Same diameter, same screw lug diameter, even shorter height, which is good. They're also rated to higher voltage (80V vs. 50V) and temperature (105C versus 85C).
But, ripple current may be much lower on the Mundorfs versus the CDE's. Does ripple current drop off dramatically as temperature increases? Mundorf is 8.1A at 100Hz and 105C, versus 18.5A at 120Hz and 85C for CDE. ESR is roughly the same between them. Given the application, are the Mundorfs a safe choice? I suspect they sound better ...
CGR103U050V4C Cornell Dubilier - CDE | Mouser
So it'd be a 10 minute job since CDE is still producing the exact same caps 20 years later.
However, I'd like to replace the caps with these intstead:
Mundorf Capacitor 10000uF 80Vdc MLytic® HC
Same diameter, same screw lug diameter, even shorter height, which is good. They're also rated to higher voltage (80V vs. 50V) and temperature (105C versus 85C).
But, ripple current may be much lower on the Mundorfs versus the CDE's. Does ripple current drop off dramatically as temperature increases? Mundorf is 8.1A at 100Hz and 105C, versus 18.5A at 120Hz and 85C for CDE. ESR is roughly the same between them. Given the application, are the Mundorfs a safe choice? I suspect they sound better ...
Last edited:
I see no benefit in replacing them at all. FYI - if they are red, they are original. If they are blue like the ones you linked, then they've already been replaced.
If you still want to change them, either will be fine.
The ones I would replace are the blue axial caps on the main board. These are still made as well (under Vishay or BC) and will be the ones to fail.
If you still want to change them, either will be fine.
The ones I would replace are the blue axial caps on the main board. These are still made as well (under Vishay or BC) and will be the ones to fail.
This "recapping" issue, which has taken worried/paranoid people by storm, is honestly silly.
Unless there's an obvious problem related to the capacitors in equipment, why not just leave things alone?
From my point of view, with 40+ years of professional servicing of consumer electronics, I really don't understand the benefit of such ideas.
Unless there's an obvious problem related to the capacitors in equipment, why not just leave things alone?
From my point of view, with 40+ years of professional servicing of consumer electronics, I really don't understand the benefit of such ideas.
Some (+1) find an improvement in SQ after recapping gear 35+ years old. That improvement probably tied to the quality (eg, budget NAD?) of the original caps. recapped "plenty" of 1970's gear with no significant SQ improvement, others where it's night and day. Doubtful that a 20 year old amp would need main caps replaced. Play a sustained bass track, eg a cello draw, if the bass is "tight" then all ok, enjoy for another 10 years +
I regret recapping my Luxman R-115. In my experience it sounded less warm and more clinical after the recap. So I agree, there is no need to recap unless the capacitor is faulty. I also managed to wreck PCB pads desoldering stubborn capacitors.
Last edited:
I bet the internet blogs were to blame....
Pushing people to mess with perfectly good equipment all the time.
I always say - don't believe everything you read on the internet.
And that's not being cynical or cranky, it's being smart, and using common sense.
Measure your wattage out just before clipping with a scope or analog voltmeter. No power loss, no rail cap problem. (V^2)/Z=P
I use 8 ohm log resistors and a simpson 266XLPM analog meter.
OTOH, new quality line caps means no cleanup of slime. I won't install anything <3000 hours service life. Now that newark/mouser/digikey will sell to individuals with a debit card, no need to put up with low life garbage like sprague atomlytics I got at Sterling Electronics TV parts store.
I haven't had any rail cap blow since the CDE B+ can in a ST70, but I've measured power as low as 2% rating (1980 Allen organ in 2017) and frequently find 50% or below in 25 year old amps. ST70 ate store shelf quality caps every 7 years or ~14000 hours. When it started sounding meek & polite, was putting out ~7 W/ch. The alarmist that told me to suspect mains or rail caps was the MacIntosh amp clinic salesman. Rectifier tubes too, he said about my ST70 (he was right). The 1967 H182 organ took 77 ecaps to get from 5 W/ch to nominal 13 on the trebles and 32 w/ch on the bass. Also when I got the H182 in 2005 the string bass didn't work and the percussion (attack) didn't work. That 1968 organ had replacement cathode bypass caps (tantalum) dated 1969, 70, and 72 and the motor run cap had exploded at some point and burned the wiring harness, which the dealer serviceman failed to replace the insulation of.
I use 8 ohm log resistors and a simpson 266XLPM analog meter.
OTOH, new quality line caps means no cleanup of slime. I won't install anything <3000 hours service life. Now that newark/mouser/digikey will sell to individuals with a debit card, no need to put up with low life garbage like sprague atomlytics I got at Sterling Electronics TV parts store.
I haven't had any rail cap blow since the CDE B+ can in a ST70, but I've measured power as low as 2% rating (1980 Allen organ in 2017) and frequently find 50% or below in 25 year old amps. ST70 ate store shelf quality caps every 7 years or ~14000 hours. When it started sounding meek & polite, was putting out ~7 W/ch. The alarmist that told me to suspect mains or rail caps was the MacIntosh amp clinic salesman. Rectifier tubes too, he said about my ST70 (he was right). The 1967 H182 organ took 77 ecaps to get from 5 W/ch to nominal 13 on the trebles and 32 w/ch on the bass. Also when I got the H182 in 2005 the string bass didn't work and the percussion (attack) didn't work. That 1968 organ had replacement cathode bypass caps (tantalum) dated 1969, 70, and 72 and the motor run cap had exploded at some point and burned the wiring harness, which the dealer serviceman failed to replace the insulation of.
Last edited:
When I do recap, I use components with 28,000 hour rated lifetimes, which is at the maximum stated ripple current at the maximum rated voltage. Even under those condtions this is 15 years of use at 8 hours a day five days a week less holidays.
I've never been offered an e-cap with longer than a 12000 hour service life. That is in 10-47 uf, usually can't get above 4000 hours in x000 caps. Have a $40 Peavey MMA-81502 that started buzzing instead of music in November, couldn't buy any 4700 u better than 2000 hr @ 105 C Friday. Probably a slimy mess in there.
I'm quite fond of classical music radio, racked up ~2000 hour a year on my dynaco tube equipment starting during college. Less in peak earning years, got down to only a clock radio working at the end. >400 caps installed since 2008. Maybe more hours/year now that I am retired. I have amps+speakers in 2 rooms. The music/living room & TV+internet room. Re-equipping after burglary of all electronics media tools collectables 9/14.
I'm quite fond of classical music radio, racked up ~2000 hour a year on my dynaco tube equipment starting during college. Less in peak earning years, got down to only a clock radio working at the end. >400 caps installed since 2008. Maybe more hours/year now that I am retired. I have amps+speakers in 2 rooms. The music/living room & TV+internet room. Re-equipping after burglary of all electronics media tools collectables 9/14.
Last edited:
Speaking of clock radios, the GE digital clock/radio that I purchased back in 1985 is still on my nightstand.
Consumer Reports touted it as a "best buy" for $45, a bit high-priced for the time.
Never needed "recapping" or anything, still works perfectly, asides from a "touchy" on/off button on the touchpad.
Attachments
So does one of my GE clock radios, bought about 1988. Its clone bought the same day is dead.
GE late 80's apparently bought e-caps sealed with the good stuff, not gum rubber. I have 2 pocket radios purchased same day, off the GE employee sale trailer, still working. One of them the 1/8" phone jack is dodgy.
But enough hours will kill even an Allen organ, that the factory rep tells organforum.com, "never need electrolytic caps".
GE late 80's apparently bought e-caps sealed with the good stuff, not gum rubber. I have 2 pocket radios purchased same day, off the GE employee sale trailer, still working. One of them the 1/8" phone jack is dodgy.
But enough hours will kill even an Allen organ, that the factory rep tells organforum.com, "never need electrolytic caps".