Capacitors in tone control circuit

62vauxhall

62vauxhall

Veteran and General Yakker
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No such things as bad days, just bad moments
In the hopes it will fix a dead and or weak channel as it did before, I spent the afternoon re-capping a second APT Holman preamp that came into my possession. With only a few left to go (there are 41 of them), I pulled one in the tone control circuit and thought to ask before replacing it with one I have on hand.

I've been routinely using capacitors with voltage ratings one level higher than what I removed. What was in the tone control circuit is 16v 22mf but I have no 25v of same but I do have 50v.

My hesitation to use those is due to something I read recently whereby using a capacitor of higher voltage provided the capacitance rating is the same makes no difference in most cases but it can have an effect in some circuits with a particular design intent.

My understanding is that the guy who designed this pre-amp was a bit of a tweaky fellow so I was looking for opinions whether installing a higher voltage capacitor in a tone control circuit is safe to do or should I wait until Tuesday and get some 25V or even 16V.

I can't remember what I used in the first pre-amp, probably the 50v and I didn't notice anything amiss. As a matter of fact I think I recall that being so because the local shop didn't have any 25v or 35v 22mF when I re-capped the first pre-amp so that may be why I came to have these 50v in the first place.

EDIT: I was told once that in these pre-amps, there are only two electrolytics that the signal passes through but damned if I know which they are.
 
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The factory used higher voltage ratings when they ran out of the correct ones. I see it in Carver stuff and a few others. I also do it. No harm, no foul, just stick with the farad rating (iffn you aint an engineer and know what can be tolerated).
 
Use shouldn't run into problems using higher voltage caps. It's just a max rating that the cap can handle. You can however run into problems if you change the type of cap in some applications. Say using an electrolytic to replace a tantalum or ceramic. This can be related to polarity, thermal or reliability issues. Worse that can happen is the cap may pop. Mind the polarity for the electrolytic, don't change types and you should be ok.
 
Thanks and 'twas as I thought so I'll use what I have.

I dug around a bit and found what I'd read about signal going through electrolytics and it wasn't those 22mf. They were 100mf's and I've already replaced those.
 
62vauxhall said:
Thanks and 'twas as I thought so I'll use what I have.

I dug around a bit and found what I'd read about signal going through electrolytics and it wasn't those 22mf. They were 100mf's and I've already replaced those.
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uf (micro farad?)
 
You'll sometimes see mfd too. As you probably know it's actually µf, not uf. Mu being the greek letter generally associated with micro.
 
Gepetto said:
My first Lafayette short wave receiver kit used the mF and mmF nomenclature as did my first Eico amp kit so I guess that makes me old school :-)
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In the 60's -70's Lafayette use to be the go to place for electronic parts and products. I still have one of their tube receivers and several of their quad 8 track car players. They made nice stuff in their day.
 
Netfly said:
In the 60's -70's Lafayette use to be the go to place for electronic parts and products. I still have one of their tube receivers and several of their quad 8 track car players. They made nice stuff in their day.
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I can see my catalogs from where I'm sitting! Right next to Allied & Radio Shack.They make me happy.
Remember 'Condensers'?
 
Yes! I have one Allied catalog from 68 and Lafayette from 67-79.
 
Gepetto said:
My first Lafayette short wave receiver kit used the mF and mmF nomenclature as did my first Eico amp kit so I guess that makes me old school :-)
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You're older than dirt anyway....... so......
 
62vauxhall said:
Thanks and 'twas as I thought so I'll use what I have.

I dug around a bit and found what I'd read about signal going through electrolytics and it wasn't those 22mf. They were 100mf's and I've already replaced those.
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Ok; The voltage thing was pretty easy. Now, how do you fine tune your choices? Take just the one brand of Nichicon & look at the audiophile sales pitch mumbo jumbo:

http://www.mouser.com/new/nichicon/Nichicon-Audio-Caps/
 
laatsch55 said:
You're older than dirt anyway....... so......
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I was God's original spokes model for dirt but then the guy on the trouble campaign broke probation so I was reassigned.
 
orange said:
I was God's original spokes model for dirt but then the guy on the trouble campaign broke probation so I was reassigned.
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I could be a spokes model for Joe Dirt. We have a lot in common....................
 
WOPL Sniffer said:
Musta been WAYY old school. Even the old navy manuals for our ancient radios used uf......
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Hamilton Jr. Secondary School Grade 9 electronics class - passing grade - class of '68.

After shotgunning all the electrolytic capacitors, this second APT Holman pre-amp that was dead or nearly dead in one channel is working again....for now.

Will be waiting for APT Holman pre-amp #1's subsequent problem to manifest itself in this one. Should know in a couple of weeks.
 
Gepetto said:
My first Lafayette short wave receiver kit used the mF and mmF nomenclature as did my first Eico amp kit so I guess that makes me old school :-)
Click to expand...


Mouser would have a fit if i ordered mf or mmf, the modern world is using uf so you old farts need to join the rest of us so we are all on the same page.
 
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