Discussion in 'Tube Audio' started by WhiteSE, Apr 15, 2018 at 3:16 PM.
The 2 red WIMA caps soldered to the output, how important are they? why are they there?
Looks to be the output coupling caps which are very important.
Exactly what are we looking at? Mono tube pre of some sort?
Its 6SN7 stereo preamp...
I have some Mundorf's to replace the WIMA with...I was wondering if it was worth it...
Perhaps. I know that VTL uses Mundorfs in the later version of my MB-450 amps. Audio Research gear uses WIMAs in a number of places, but uses custom teflon caps for output coupling.
I believe they are there to keep DC voltage from the output jacks, allowing the AC signal to pass.
In my Cary AE3 preamp. which is also 2 x 6sn7 with just a VC and selector switch. I used Vitamin Q PIO output caps. This helped to smooth out the sound some and seems to have better detail.
I have no idea what type of Mundorf caps you have to use of course, and I'm not trying to bash Mundorf caps in any way. But, I wanted to upgrade the coupling caps in a 6AQ5 SEPP amplifier. I wanted to try Mundorf, but couldn't afford the higher range supreme oil caps. I figured I would try the standard EVO non-oil metalized polypropylenes, they are rather cheap...maybe too much...
When I was forming and fitting the leads for installation of one the Mundorfs, one of leads seemed like it broke or came unglued from inside the cap...which it did.
I never had this happen, and I've swapped more than few coupling caps in amplifiers. Maybe I was too aggressive? Really? It didn't take very much stress to do it.
The leads are glued to the electrodes. That might be okay in a speaker crossover, but I dunno about for coupling... I'm glad I didn't use them...
"Don't be Vague, Ask for Sprague."
Not impressed with the Mundorf, but there's a lot of good stuff happening construction-wise in that amp shot- nice job!
Actually, I used the same as you...I used the higher Mundorfs in my amps, but I did not want to spend too much...maybe I will rethink that.
That's a very nice build, Mike. Love the Tek standoffs. Very clean wiring. Would like to see more of your work!
I believe they all do it that way for these type of caps, which are mettalized plastic conductor. The "glue is also a conductive type. I am guessing on that failed mundorf the either the glue got hard before the end cap was pressed on or the joint was dirty.
I also have Mundorf Supreme, oil blah blah cap that sounds ok in one of my SEP KT120 amp, and it sounds decent, maybe more towards neutral? But someone gave me those caps so i have nothing at stake in how they turned out in this amp.
I really need to source some 2.5K OPTs of high quality that can handle a good 90-100 milliamps of current, so I can free up my universal OPTs for bread-boarding again...
Wow, what an amp! Did you ever do a thread on it's construction?
I have several Tektronix scopes awaiting pillage. What solder did you use and how easy was it to flow?
This floats my boat. Back when I recalled which end of the soldering iron to hold I kept a 3"x5" module built by a ham. It has a single UTC A-19 on it and a tube as well as some other circuitry. I bought it to strip the UTC off but the construction detail was so superb I used it as a reference when I was tempted to rush. Your work is absolutely on par with that.
I try to use the little spool of solder that comes inside the Tek scope whenever I've done this. I have a Tek scope graveyard in my basement...
Now I need to dig one out and check for that.
It's a small white spool about the diameter of a nickel. IIRC it has a little nub on one side that pops in to a hole inside the chassis to hold it in place. Should be in an obvious location, usually right inside one of the removable side panels.
Not here. I do have a build thread on the Klipsch "talking tubes" sub-forum. There's a forum member "Tube Fanatic"...Maynard is a retired television/radio repair guy who has posted many single-ended tube amplifier designs of his own on the forum. All the designs are based on cheap easily obtained television and radio tubes. Most all designs (if not all) use SS rectification and Hammond iron.
The Tek stand-offs and solder they used was silver-bearing solder if I recall. I used the Rat Shack silver-bearing solder and it worked fine for me.
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