10uf, 1uf, .47uf/ 50v Capacitors

[jckid649]

I'm trying to modify a tweed kit that I have and wanted to play with the values of the cathode bypass capacitors but the ones in those areas are rated at 50v. The problem is that the pickings are very slim for these particular values in that volt range. Is it possible to use higher volt caps in these areas without negative outcome or am I just stuck to the crappy brand of parts that actually still offer these values at that voltage?

[rock_mumbles]

For the 6V6 cathode you can use up to 100V

for the preamp bypass cap(s) you can use 16 volt

[jckid649]

What really sucks is that F&T doesn't offer anything rated less than 500v and Sprague Atom only offers 10uf and 8uf at 150v. What is a good cap that that I can get 10uf or under rated in the 50v-100v range?

[Firestorm]

What really sucks is that F&T doesn't offer anything rated less than 500v and Sprague Atom only offers 10uf and 8uf at 150v. What is a good cap that that I can get 10uf or under rated in the 50v-100v range?

Plenty of values in Sprague ATOMs or Type TE.http://www.mouser.com/catalog/catalogusd/645/925.pdf

[collinsamps]

For the 6V6 cathode you can use up to 100V

for the preamp bypass cap(s) you can use 16 volt

The time constant or Xc for ANY dc voltage you can get your hand on is fine for a cathode bypass cap. You are not limited to 100V for a 6v6 or any tube, nor are you voltage limited on preamp tubes unless you get down to 2 - 5vdc. Hogwash.

[jckid649]

For the 6V6 cathode you can use up to 100V

for the preamp bypass cap(s) you can use 16 volt

The time constant or Xc for ANY dc voltage you can get your hand on is fine for a cathode bypass cap. You are not limited to 100V for a 6v6 or any tube, nor are you voltage limited on preamp tubes unless you get down to 2 - 5vdc. Hogwash.

You know somehow I thought that was the case. I thought I had read somewhere that higher voltage ratings actually might even give you a little more insurance against surges. Don't know if that is true but I do remember reading that going higher is not a negative.

[Gaz]

What do you mean by "crappy brands?" Are they just more modern caps? If so, the specs are probably better than any vintage-styled electrolytic. Merlin (Valve Wizard) suggests the lowest value voltage suitable in the circuit and using bi-polars when using electrolytics as bypass caps. Just a though.

-Alex

[jckid649]

What do you mean by "crappy brands?" Are they just more modern caps? If so, the specs are probably better than any vintage-styled electrolytic. Merlin (Valve Wizard) suggests the lowest value voltage suitable in the circuit and using bi-polars when using electrolytics as bypass caps. Just a though.

-Alex

I mean like dime store grade Radio Shack parts or something like that just to find a certain spec. I want good grade, high quality parts and some of the values that they used to make are getting hard to find anymore.

[lzzrdgrrl]

I dunno.......

I just pulled a 1998 era Pioneer home theatre amp out of the bin and there's any number of 50v bypass electrolytics in that. Probably like Nichicons and I don't know builders having problems with that.......

[Paul Fawcett]

I dunno.......

I just pulled a 1998 era Pioneer home theatre amp out of the bin and there's any number of 50v bypass electrolytics in that. Probably like Nichicons and I don't know builders having problems with that.......

Reusing *any* 14 year-old electrolytic cap is a false economy, It's just asking for trouble, don't do it. This is particularly true since this dates to exactly the era of the "capacitor plague". There's nothing really magical either about the voltage rating -- there's no particular issue with using a higher voltage cap in a lower voltage application, except that the form factor of the higher voltage caps can be potentially difficult to accommodate in a space originally intended for something smaller.

Merlin, I think, is also mistaken about bipolar caps being superior in this application. I can't think of any good reason why this should be the case, and I'd be surprised if he is still willing to defend that point of view. By nature of their construction they will always have higher ESR than polar caps with otherwise similar chemistry.

In high-fi and pro-audio applications, the rule of thumb is never to use an electrolytic to set a time constant if it can be helped, and, if you must use e-caps for something like a coupling application, use a cap with a capacitance rating sufficiently large to minimize distortion, -- typically much larger than what you think you might need just on the basis of the bandwidth involved

[Reeltarded]

Uhoh.. cause I have 10-50uF Erie bias pulls that are no younger than 40 years old. They work great as bypass. Out of more amps than you can count on three hands, not one problem.

Yet?

[Paul Fawcett]

Uhoh.. cause I have 10-50uF Erie bias pulls that are no younger than 40 years old. They work great as bypass. Out of more amps than you can count on three hands, not one problem.

Yet?

You may be lucky. On the other hand, the bypass cap application is not one where you would so readily notice as the ESR begins to creep up.

Either way, I maintain my original assertion that it's absolutely a false economy to use 14 or 40 or even 2 year old pulls... Why?

Here's one example... Mouser sells Panasonic 105 Deg low ESR 50V 22uF caps with specs that blow the doors off any old-timey cap for .... drum roll please .... $0.09. At nine cents each for a new part, it's not even worth the time to unsolder the old ones.

[Structo]

Reusing *any* 14 year-old electrolytic cap is a false economy, It's just asking for trouble, don't do it. This is particularly true since this dates to exactly the era of the "capacitor plague".

Yep, I made some money replacing motherboard caps during that time, that is unless they had already exploded.

Some guy got the electrolyte formula wrong and they made a boat load of defective caps that were used in a lot of devices.