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Has anyone had any success repairing open filaments? I've read about using a charged 50uf capacitor and zapping to re-weld the filament.
Follow Ups:
Cheap and tough for $60
That may work if you can see the break and then lie the tube in a position where the filament makes contact with the lead out rod. Many 45's, IIRC have that "W" shaped filament and if the spring loaded filament is broken, forget it.
Would you really want to base your entire audio system, and listening time, on such a tube ??
A decent used Type 45 is about $30.00.
Jeff Medwin
I was thinking sort of the same thing. A good used tube would at the very least give you better peace of mind and not have you wonder every time you turn on the amp whether the tube is going to light up.
By the way Jeff, how are you liking your most recent build that uses the 45? Is it what you expected thus far?
Cheers
I went through about three or four iterations of parts changes over the past two months, before I got it as I thought it should play and should be. Now, its much FUN to hear. Journeyed from multiple bypassing with Wima MKPs, to REL RTs, to DynamiCaps, and to Teflons, and then to mixtures of vintage and new bypass caps.What a huge undertaking. Fifty seven caps in a Direct Coupled 45 amp, film, no electrolytics, all selected by ear !! I am exhausted.
Though experimenting and attentive listening, I also LEARNED much about the total importance of, ( and how to better wire ) a S.E. amplifier, which we can not find in any book, nor on-line.
So, all in all, I am pleased to have worked on this new project!
I have had the Teflons breaking-in, on AM radio music, into power resistors, 7-24. Attached photo is closer, ( but not quite finally ), where I ended-up. Thanks for asking.
Jeff Medwin
Edits: 07/30/15
Don't take it the wrong way but that sounds contradictory to a direct coupled amp unless these are power supply bypass caps.
Where are you using them in the circuit?
Edits: 08/04/15
Look at the first photo a bit more closely. L1/C1/L2/C2 to Finals.EVERY power supply cap in the amp is multiple film bypassed, and the driver and finals Rks are multiple film cap bypassed. The audio circuit uses NO series coupling caps.
I hate caps.... the worst part in audio !!!
However, in a SE amp, ALL the caps are IN the audio circuit.
But since caps PLAY narrow band, I am forced to use multiple bypasses to get the audio circuit to PLAY linear - the way " I " wanna hear it.
"In the end, we are all listening to a modulated power supply," how good is yours ?? Mine's OK !!
The photo in this post ( above ) SHOWS my short direct coupling path, multiple silver RCA jack, to driver - double silver , to finals - triple silver. Those Rs are all long gone, using paralleled Caddocks 7-2015.
Jeff Medwin
Edits: 08/04/15 08/04/15
Yes, I'll agree it had to be quite an undertaking judging by the looks of it. Very nice and well thought-out layout as well as first rate workmanship - congrads on what must be a great amp and happy listening.
It would be hit and miss at best. You might get lucky.
I have a 2A3 with an intermittent filament in one plate only. Thump it, and the other half heats up. What you suggested might be worth a try.
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