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Hi Folks,

I wonder if y'all might be willing to list the different coupling caps you may have tried in your GSG's and take the time to give me a discription of your opinion(s) of them.

Thanks,
Fran

The only caps I ever tried in my GSG are the Russian military surplus K40Y-9. I like them, but they are too big to fit easily on the board. I had to cross the channels to get them on.

I try and stick to:

1) Panasonic ECWF (sound like a WIMA MKP10)
2) Illinois Capacitor MPW (sound like an orange drop)
3) Cornell Dubilier 940C is BIG tube amps.

Cheers!

Ty_Bower wrote:The only caps I ever tried in my GSG are the Russian military surplus K40Y-9. I like them, but they are too big to fit easily on the board. I had to cross the channels to get them on.

Hi Ty,
If you don't mind me asking, where'd you get yours?
Thanks,
Fran

I've got the same K40Ys in my GSG. I haven't compared them to anything, but I haven't come up with a reason to bother. I got a large box full of them from ebay for a reasonable price. I can't remember that price off the top of my head, but it was comparable to the cost of orange drops, and I've only heard good things about them.

very strange the K40Y-9's I have in mine, don't look like the one's in Ty_Bowers...mine fit quite nice on the board...

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fran604g wrote:(???) very strange the K40Y-9's I have in mine, don't look like the one's in Ty_Bowers...mine fit quite nice on the board...

Mine are the 1000V rated, 0.22uF parts. Are yours 400V or 600V rated? They are quite a bit smaller.

Those caps appear to be the same 0.1 uF / 400V (400B in Russki) K40y-9s that I used in this and other GSG builds:



Note for those with eagle eyes: The two octal sockets ar wired for 6AV5GAs, and not 6B4G / 6C4C, as marked on the chassis.

The blue anodized chassis plate is a very early prototype version of the Front Panel Express plate shown in the previous builds.

The K40y-9 are one of my favorite coupling caps, and are probably just as good as the highly vaunted and treasured Sprague Vitamin Q PIO caps.

/ed B

Ed - I think the Russian caps in Fran's amp came from you,
via Shannon to me when I built a couple of the early g*s*g's.

... tom

That would indeed be the reason I'm so confused about the size.



I should replace these with the proper values, then, correct?

Hi Folks,
I ordered a pair of Angela/Jensen Copper Foil PIO's...
I'll be sure to post my results. Can you guys explain to me why the .22uF's instead of the .1uFs?
Thanks for all the help!
Fran

Ed - I think the Russian caps in Fran's amp came from you,
via Shannon to me when I built a couple of the early g*s*g's.

... tom

They may well have originated from me, I've done so much "hoss trading" here and over at NNETG, over the past years that I have lost track of who got what and when

The big K40y-9 caps are OK, there is no real reason to change them out, unless you want to try other brands and makes. I've used some significantly oversized caps in some of my builds, like the big 0.1 uF / 500V teflon caps, which are nearly the size and weight of D cell batteries The green "kommie kaps" are also somewhat oversized, about the same diameter, but half again as long as the 0.1 uF K40y-9s. These "green meanies" are polyprop in oil, not paper in oil. Still good sounding, and I still have LOTS of them, though I have used up all my K40y-9s. (the Russian letter y is really a u, so these would be called back in the motherland, K40u-9s.

The "outer foil" end is allegedly indicated by the little symbol in front of "400B". Which, in your board, would be the ends of the caps closest to the 270K resistors, R9 and R10.

0.22 uF instead of 0.1uF would theoretically extend the lower frequency response by an octave, but the ultimate limiting factor would be the OPTs.
THe operating voltage would have no effect as long as it is at least high enough to withstand the existing circuit voltages.

HTH

/ed B

Thanks Ed,

Helps a lot!

As I'm sure by now it's pretty obvious of my very limited knowledge, but, I do a lot of reading and ask a lot of questions and I am learning. I'm beginning to understand how the simplist circuits work. I've seen quite a few schems today using 2A3, 6A3 and 6B4 circuitry, mostly PP designs using 6SN7's for drivers/splitters(?)

Great stuff. I started out like most folks these days, not really caring WHY something does what it does, as long as it does it. Now, however, I find myself more and more interested in the WHY as much as how well.

I appreciate your time, thank you very much,
Fran

fran604g wrote:Can you guys explain to me why the .22uF's instead of the .1uFs?

As Ed says, in theory the .22 will go a little lower. I think the math is something like F = 1/(2*pi*R*C). In this case, R is R9 or R10 (475K). If I can remember how to convert uF to F, then the corner frequency for the 0.22uF part should be 1.5 Hz. The corner frequency for the 0.1uF part would be 3.3 Hz. The difference is irrelevant, as far as I would be concerned.

The 1000V rating is way overkill, but it's what I had on hand.

Thanks for the info, Ty. Being that I understand so little about building amps and such, I just got curious. What do you mean by "corner frequency?" I appreciate the time you guys are giving me answering my questions and concerns.
Fran

Edit: Nevermind the explanation for "corner frequency"