Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => AmpTools/Tech Tips => Topic started by: lego4040 on August 22, 2018, 04:12:20 pm
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Hey Folks, how has everyone been, Summer has been HAB here in Manhattan. I've been on hiatus, picking up OT shifts trying to make up for the 7 months my wife has been out of work but I'm finally back in amp mode! I recently got my two Edcor Ot's and My Classictone PT in for BlueGlow's SE 807 Stereo amp https://www.youtube.com/playlist?list=PLo7DGF0CxJGmfOv4KSSgpp7vrxrC7cdoR (https://www.youtube.com/playlist?list=PLo7DGF0CxJGmfOv4KSSgpp7vrxrC7cdoR). I took them apart and gave them a beautiful repaint but I busted some of those nylon bushings that go through the tranny's and I cant source them out? So today I called Classictone since it was the PT ones that I broke but they don't sell them separately. I reached out to Edcor and they no longer offer them. Does anyone know of a source? Ive been looking and cant find anywhere, These are for 8x32 screw size I.D.
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look here...
https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=%238+shoulder+bushing+washer&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=%238+shoulder+bushing&LH_TitleDesc=0 (https://www.ebay.com/sch/i.html?_from=R40&_trksid=m570.l1313&_nkw=%238+shoulder+bushing+washer&_sacat=0&LH_TitleDesc=0&_osacat=0&_odkw=%238+shoulder+bushing&LH_TitleDesc=0)
Or go to Grainger and search for "#8 shoulder bushing washer".
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Thanks Steve, I will mic out the OD again and order some. I have some nice brass ones for our pneumatic lines in my shop but the OD is to big
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Maybe it's possible to run a bolt through the bushing; lock the bushing with a nut at the head of the bolt; chuck the other end of the bolt in a drill press. Reduce the OD of the rotating bushing with the edge of a file. (Could also use a lathe.)
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for the nylon shoulder washers / nylon bushing washers.
https://www.mouser.com/Electromechanical/Hardware/_/N-5g2c?Keyword=nylon+shoulder+washer&FS=True
for chassis wire strain reliefs.
https://www.mouser.com/Wire-Cable/Wire-Protection-Management/_/N-5ggy?Keyword=nylon+wire+bushing&FS=True
--pete
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So the nylon washers came in and the new #8 star washers as well. They fit perfectly and added the finishing touch. Thanks for the tips guys. Slowly my stereo amp is coming together, gotta mark out chassis and punch next
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been chugging along with the stereo SE 807, stepped away to get some fishing gear ready and some fishing in. Only got out once so far but the stripers are running. So I am painstakingly working at the grounding and not sure how I want to got with the first main 33uf/500v. another post coming
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This is the 6.3 floating ground part which is on a terminal strip by the right channel. The 390K I was thinking I was going to tie at one point off pin 2 on the 5u4 where L1,L2 and 33uf/500v come from, I think i got this right, its late so I wont finish that yet. Oh, and I believe I need to relocate my red/yellow
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I'd take the dcv bias for the heaters from after the choke. It's cleaner there. In fact I'd probably take it from as far down the B+ rail I could.
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Willabe, Mark is the fella who has built this and as he is going along wiring up the amp said the exact same thing. He wound up not doing it tho and had no problems with noise. Now I would love to do that but what I don’t understand is after L1/L2 I have two B+. One for left, one for right. Would I just do tie in after say L1 or “Y”it into both
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Tie in to only one filter cap. Either left or right, doesn't matter which. But don't "Y" into both.
It's OK to go even farther down the B+ string. The farther you go, the cleaner (better filtering) the B+ is.
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I tried drawing out what I have built so far. Drawing out layout while on Bus heading to work doesn’t really work out, it’s like a chicken on caffeine and speed got hold of a pencil. I’ll redo at work, it’ll also serve me later on if I have to troubleshoot. I also realized I wired switch before fuse, will reverse that. I’ll draw that out as well.
Here is direct link to Blueglow schematic https://blueglowelectronics.wordpress.com/diagrams/ (https://blueglowelectronics.wordpress.com/diagrams/)
He’s Working on a good SE KT88 Stereo as well :huh: at moment
{EDIT-- un-munged URL -- PRR}
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That direct link doesn't work for me.
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> direct link doesn't work
Had some too many "http" in front. Fixed now?
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> Tie in to only one filter cap. Either left or right, doesn't matter which. But don't "Y" into both.
> It's OK to go even farther down the B+ string. The farther you go, the cleaner (better filtering) the B+ is.
What I am thinking, with 333K(?) feeding 100uFd, that node will be dead-clean even if fed with crap.
Also with the heavy filtering it can't matter which channel it feeds from.
However if you truly obsess about channel/channel symmetry, you could change one 333K to two 666K, one from each side's filter chain.
To truly make an obsession, it "should" have separate heater windings for each channel. Of course you can also build two Mono-Blocks. There's no end of ways to fancy it up.
Considering that, in the end, both speakers are in the SAME room, I have doubts about how much it matters.
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I just tried that link and it worked. Of coarse tonight starts of busy at the plant.(https://blueglowelectronics.files.wordpress.com/2018/02/se807-amp-td-blueglow1.png?w=640)(https://blueglowelectronics.files.wordpress.com/2018/02/se807-ps-td-blueglow1.png?w=640)
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Doing this via mobile, I’m on chemicals tonight. No not me physically, testing my to chemical plants for our two separate tower systems. The picture I drew out represents what I’ve done so far except 33uf main. On bottom of page in highlight is the floating ground, so Like you have said I will bring the leg off the 390k to B+ after choke since it’s cleaner. I also realized I put switch before fuse. I’ll fix as well
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:happy1: After quadruple wiring checks and finding one mistake I threw the switch. I used the current limiter for safety precautions, made some measurements and let it her warm up on a dummy load for about a half hour then took some more measurements. I then removed the limiter, plugged in my speakers and music source. I am so Thrilled at the sound, I need to step up my speakers next. They are a pair of old Infinities and I want to rebuild some 12" pair next. This was my first attempt at point to point, it went well. Using the knowledge I got from you guys here I also did the left and right power boards separately
https://www.facebook.com/lionel.berthelon/videos/pcb.10218448512473974/10218448293228493/?type=3&theater (https://www.facebook.com/lionel.berthelon/videos/pcb.10218448512473974/10218448293228493/?type=3&theater)
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So damn cool! I'm late to the thread, but congrats on a great project. I picked up an 807 monobloc at an estate auction. It had been an electronics instructor's project. My intent when I get to it, is to make another for a stereo pair. The circuit is very close to the one you used. Do you have speakers you intend to rebuild? I was not clear on that. I have some vintage Fisher and Grommes tube stereo gear and use HSU research MKIIs and older Unity Audio towers with them. Using tube friendly high efficiency speakers really makes a difference. Like you, I used to have infinity speakers.
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I’ve been away for awhile not building. I plan on Diying a set of better speakers. I have infinity’s now but I’d like something like this https://www.madisoundspeakerstore.com/full-range-speaker-kits/fostex-bk-16-folded-horn-kit-pair/ (https://www.madisoundspeakerstore.com/full-range-speaker-kits/fostex-bk-16-folded-horn-kit-pair/)