Iskra or Beyschlag 470k?

glpg80

glpg80

Well-known member
Anyone have an iskra, phier, or beyschlag 470k resistor with long or short leads they wouldn’t mind letting go of? I’ve found a bad Phier resistor in my 74 and it’s in a location that metal film sounds too sterile and the composites I have on hand are too noisy. Newer carbon films just sound like ass to me so that’s a no go either.

I really don’t want to go on eBay to buy from Italy for a single resistor so I’m hoping some of my amp modding gurus on here have one they’re willing to let go of?

I don’t mind paying S&H.
 
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I found a source and ordered 470k, 330k, and 220k Beyschlags. Excited to replace what’s in that part of the amp and I’ll report back how they sound :rock:
 
scottosan said:
I know too lates but these are regarded for their warmth.

http://www.soniccraft.com/index.php/takman-carbon-film-c-29_55_302
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My Ed-spec Superlead has some excess hiss but the plate resistors for V1 and V2 are metal film (some largish blue ones I got from @FourT6and2 a few years ago). Many others in the amp are NOS Allen Bradley. My Super Reverb clone also is a similar situation.

I’d like to get something for replacements. Watching this thread to see what @glpg80 says about the Beyschlag.

Hey @glpg80 , are you getting the new Vishay/Beyschlag from Mouser et al or something NOS?
 
SpiderWars said:
My Ed-spec Superlead has some excess hiss but the plate resistors for V1 and V2 are metal film (some largish blue ones I got from @FourT6and2 a few years ago). Many others in the amp are NOS Allen Bradley. My Super Reverb clone also is a similar situation.

I’d like to get something for replacements. Watching this thread to see what @glpg80 says about the Beyschlag.

Hey @glpg80 , are you getting the new Vishay/Beyschlag from Mouser et al or something NOS?
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If my memory is correct, the ones you got from me are Beyschlag MBE0414. You can get 'em from Mouser now :)
 
FourT6and2 said:
If my memory is correct, the ones you got from me are Beyschlag MBE0414. You can get 'em from Mouser now :)
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Sweet, thanks. What locations would be causing the hiss? The PI plates? The SLP is so gainy I kind of expect it but in a BF Super Reverb? Actually that one doesn’t have Beyschlags because I was out. But still not cc in the early stages.
 
SpiderWars said:
Sweet, thanks. What locations would be causing the hiss? The PI plates? The SLP is so gainy I kind of expect it but in a BF Super Reverb? Actually that one doesn’t have Beyschlags because I was out. But still not cc in the early stages.
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It's hard to say where the hiss is coming from. I would need some photos of the amp and a more detailed explanation of the issue.

But generally, the 1M input ground reference resistor, the input grid stopper, and the plates should be 1W metal film to reduce thermal noise/hiss. And make sure lead dress is good. Also amp bias plays a role in how much hiss there is.
 
Technically any component touching small signal ground can act as a noise generator since cascaded noise in the frequency spectrum adds following the noise factor equation.
 
I have some new relays coming in that I just ordered. I am in the process of fixing my layout to be less noisy and to add back in stability as I found the cause of instability to be how I did my relay board layout (not circuit level, think locations of signals related to their phase).

Once I get the amp back together I’ll bump this thread with a comparison. So far I like them though. Not as good as NOS Phier carbon films but still really good. A bit colder sounding but not as much as general metal films.
 
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