Reply with quote #1
I've notice here of late some noise from one of the venerable T-16 monoblock amps. On the right side. The bias checked ok. But I wonder if the output cap is showing dielectric breakdown. Also, I wonder about polarity of film & foil caps. Rooting around the net has references to non polarized film caps actually having a "foil" side to ground that shows a higher peak on a oscilloscope with leads reversed to the non foil side. Does this have a noise optimization factor within circuits? In the old days most encapsulated orange, green, brown etc caps had a line indicating foil side, (which did not always match). Baring no oscilloscope to confirm this foil side polarity. How do you know? Is it, should it be a worthy factor?
Reply with quote #2
I've seen videos supposedly showing what you described, and perhaps it may make a difference in spots where there may be high EMI, but I haven't actually noticed any difference so far. But if I am not wrong, in order for this to actually work, one end (foil end?) is supposed to be connected to ground... Therefore if you're talking about a signal coupling (or DC blocking) cap, neither end is connected to ground and so I don't think this would help in any case.
It might be worthwhile swapping around the tubes to see if the problem "transfers" to the other monoblock; if it does then it is likely one of the tubes that need replacing and not one of the caps. Also, unless you're looking at one of the electrolytic caps, most polyester / polypropylene film and foil caps don't really suffer from dielectric breakdown purely due to age. It is mainly the oil type caps that are susceptible. Hope this helps.
Reply with quote #3
Have you not considered the tubes? Much more likely that this peculiarity of film-foil caps you describe. At about age 10 I had the driver tubes in T16 mono being to make noise. Replaced them.
Reply with quote #4
I moved the tubes over from the right mono to the left mono without the noise showing up on the left speaker. Upon replacing the tubes to the right mono, the noise resumed as before. Replacing the tubes back to the left mono I get a funky noise now from the left mono. So, yes Gary, I will put new tubes in all around. I only inquired about the caps in the T-16 because I had caps in my gg start to show crusty white residue around the ends of the cap. Which I replaced. I'm not particularly savvy to all the technical where with all that all you fella's here seem to be well versed in. That my initial inquiry seemed dubious only confirm's that. Guess I got my money's worth out of the original set of tubes eh? Thanks for the advice Mel. Hopefully fresh tubes will restore the great sound I've known for so long. Now I have to find another source of cheap Ruskie tubes that I'd gotten back when. He's not listed anymore on ebay.
Reply with quote #5
Also, learned fellow's. The driver tubes, should they as well be replaced?
Reply with quote #6
I bought 160 of the military grade 6C 19PI( American designation), 6S 19P V manufactured at the Ulyanovsk factory, from Tubes-store.com, in 2014-15, at 1.90 per tube. If you get the version with a box it's twice as much. I chose the cheaper route, and they pack them really well.
Reply with quote #7
Muchas gracias Sawolf! Wow, what a deal! I see they're even cheaper now, on sale for a whopping $1.70 apiece. Compare that to what an individual tube can cost stateside. You can re tube one mono for what a couple tubes would run. Thank you very much.
Reply with quote #8
You're welcome, I stumbled upon the site, and knew I hit paydirt. Enjoy em.