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Old 15th May 2012, 12:20 AM   #21
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Originally Posted by djn View Post
I run 1386volts to the front of my amp to the 6D22S rec tubes, but then I have to run the B+ from there back to the tall set of caps. I am concerned that I will run a wire with more than 1000 volts along the chassis and the volts can "jump" or arc to a ground. So how do I run the wire back to the caps without it arcing? How much space do I have to provide? Thanks.
As I look at you amplifier pictures, running a high voltage wire should not be your main concern. That's the easy part if you use the proper high voltage wire. Belden 8899 5KV test probe wire is a good one I like to use. And there are others like Marcal silicone HV wire. The possible problem I see is the tube socket itself and the metal chassis in close proximity.

I'm unfamiliar with the 6D22S, but it doesn't look like a high voltage rectifier I would use just based on it's size. But if it really is like an EY500, and not an exaggeration, then I suppose it will serve. You'll need a good porcelain socket that's rated for several thousand volts. Same for the filament transformer insulation.
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Last edited by HollowState; 15th May 2012 at 12:22 AM.
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Old 15th May 2012, 11:37 AM   #22
djn is online now djn  United States
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Originally Posted by MelB View Post
JBL E140's you say!
Too funny Mel. I didn't think I'd like the E140 but it sounds fairly good.

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I used 1500v rated wire. Then on the chokes and transformers which only had 600v rated wire I bought a roll of shrink tubing (600v rating) and added an extra layer of protection over all the wires. My chokes were all hi-pot tested to 2500v so I'm feeling pretty good about it all. Oh and rubber grommets for anything through the chassis.
Thanks Mel. I just got a handful of grommets just for that reason.

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Originally Posted by HollowState View Post
As I look at you amplifier pictures, running a high voltage wire should not be your main concern. That's the easy part if you use the proper high voltage wire. Belden 8899 5KV test probe wire is a good one I like to use. And there are others like Marcal silicone HV wire. The possible problem I see is the tube socket itself and the metal chassis in close proximity.

I'm unfamiliar with the 6D22S, but it doesn't look like a high voltage rectifier I would use just based on it's size. But if it really is like an EY500, and not an exaggeration, then I suppose it will serve. You'll need a good porcelain socket that's rated for several thousand volts. Same for the filament transformer insulation.
Thanks Hollow. after I read your post last night I look for anywhere around here that sold the 8899 to no avail. I need some other parts from Mouser so I'll add that to the order.

The 6D22S is well up to the job. For all the tubes in this amp I have heavy duty ceramic sockets. I was most worried about the corona effect of running such high B+ around the chassis.
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Old 15th May 2012, 04:24 PM   #23
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I used high voltage wire and in some instances added an additional layer of heatshrink tubing to bolster the insulation. I also covered the plate connection and wiring to the OPT.

I have had problems with Corona discharge in this amplifier, new GM70 tubes seem to need to bake the base to eliminate internal paths, and I have had various other high voltage induced issues. My previous designs operated with raw supplies in the 600 - 700V range, going to just over 1kV seems to have opened a whole new world of issues.

I would run the filaments for about 30 minutes before applying B+ the first time just to bake out the tube bases and prevent internal tracking. (Strange sizzling noises during warm up will otherwise result)

Without a doubt though this is the best sounding (and probably measuring) SE amplifier I have yet designed. Worth the quirks..
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Old 15th May 2012, 04:47 PM   #24
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Thanks K. Will do on the burn in of the filliments. I've ordered a roll of Belden 8899 and have many feet of shrink tube. I am also thinking about epoxying blocks of white nylon with holes drilled through it here and there to make sure that I route all the hv wiring away from the signal path. I thought there was more room in the chassis but as I continue to add parts, it is starting to get tighter than I like for a high voltage amp.
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Old 15th May 2012, 10:50 PM   #25
MelB is offline MelB  Canada
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Originally Posted by kevinkr View Post
I used high voltage wire and in some instances added an additional layer of heatshrink tubing to bolster the insulation. I also covered the plate connection and wiring to the OPT.

I have had problems with Corona discharge in this amplifier, new GM70 tubes seem to need to bake the base to eliminate internal paths, and I have had various other high voltage induced issues. My previous designs operated with raw supplies in the 600 - 700V range, going to just over 1kV seems to have opened a whole new world of issues.

I would run the filaments for about 30 minutes before applying B+ the first time just to bake out the tube bases and prevent internal tracking. (Strange sizzling noises during warm up will otherwise result)

Without a doubt though this is the best sounding (and probably measuring) SE amplifier I have yet designed. Worth the quirks..
Boy I am with you on that last comment. My GM70 amp just sounds fantastic! And with a $25.00 tube! It is after all a "High-Power Low-Frequency Triode" and then some.
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Old 15th May 2012, 10:55 PM   #26
djn is online now djn  United States
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Well, you guys are getting me fired up. It is slow going during the week but I do a little every night.
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Old 17th May 2012, 06:34 PM   #27
djn is online now djn  United States
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well my project got pushed back a week or so.....actually I did it to myself. As you know, being an artist, how things look are as important to me as any other aspect of a build. I kept looking at the color I painted the power transformer, choke, and OPTs and they just don't work well with the over all color of the chassis. So, I am taking them to Ron's to paint them a more better color. He is a tester for House of Kolor so be assured, they will look better when we get done. Because of the color difference, it looks like an amp with a top side and a base......not one amp. If I have to look at this thing for the next 30 years (or more I hope), I'd rather take the time to do it right.
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Old 24th December 2012, 07:34 PM   #28
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Hi All, well its been months since I posted. I put the GM70 aside to do a lot of other things one of which was to lay in bed for three months suffering horrible depression after quitting smoking 2 packs a day. The doc gave me some funny little pills that put me right back on track.

My new room does not have the built in audio rack my old room did so I have been building an audio rack. I hope to have it done in a week. Then the GM70 is on the bench.

Merry Christmas!!!
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Old 24th December 2012, 08:14 PM   #29
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Hi All, well its been months since I posted. I put the GM70 aside to do a lot of other things one of which was to lay in bed for three months suffering horrible depression after quitting smoking 2 packs a day. The doc gave me some funny little pills that put me right back on track.

My new room does not have the built in audio rack my old room did so I have been building an audio rack. I hope to have it done in a week. Then the GM70 is on the bench.

Merry Christmas!!!
Djn,

Occupational therapy is one of the best things to get well quickly from depression. So start the AMP asap.

Merry Christmas
Pawel
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Old 24th December 2012, 10:08 PM   #30
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I agree Pawel. I only took the meds for one month and it snapped me out of it. The doc said it is normal. Here is a link to my rack build. Cheers, Dennis.

Finishing my Audio Rack. Many Pix


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