Beginning my foray into tube gear. Looking for some advice
- Thread starter GeneParmesan
- Start date
GeneParmesan
New Member
Wow, what a read. Thank you for posting this!
GeneParmesan
New Member
Hello,
Kinda off topic but just wondering if anyone has a go to site for panel fabric? My current fabric is faded and torn in a few places. And doing a generic Google search can be pretty overwhelming.
A lot of YT videos point to Acoustone fabric. I did request some samples that I received today, but it's kind of thick and doesn't look easy to work with. I only have small areas to do, about 12"×15" and I think the bends won't look good.
Figured i would get started on that while I wait for parts.
Any suggestions would be appreciated!
Kinda off topic but just wondering if anyone has a go to site for panel fabric? My current fabric is faded and torn in a few places. And doing a generic Google search can be pretty overwhelming.
A lot of YT videos point to Acoustone fabric. I did request some samples that I received today, but it's kind of thick and doesn't look easy to work with. I only have small areas to do, about 12"×15" and I think the bends won't look good.
Figured i would get started on that while I wait for parts.
Any suggestions would be appreciated!
I use plain-old thin double-knit polyester on my subwoofer grilles. It's stayed nice and tight for the last 30 years of heavy sub use. Good audio transparency, too!
The key is a tight, wrinkle-free initial fit.
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GeneParmesan
New Member
Well, I decided on Acoustone after all. I wanted to keep the look specific to the period it was built.I use plain-old thin double-knit polyester on my subwoofer grilles. It's stayed nice and tight for the last 30 years of heavy sub use. Good audio transparency, too!
The key is a tight, wrinkle-free initial fit.
I tried applying one of the samples they sent to a piece of plywood, and I think it's going to work ok with a little work.
I will post pictures of the finished product if it looks ok.
GeneParmesan
New Member
Success! (so far anyway.)
Got the new tubes Wednesday night and popped them in and put the amplifier behind a DBT initially. Everything looked good, so I went ahead and plugged directly into mains power.
I let everything sit idle for a few minutes before trying any inputs. Checked for DC offset and found nothing on both channels, so I hooked up a couple of small 8 ohm speakers and tried some inputs.
FM pulls in a bunch of stations with just a pice of wire for an antenna, and the stereo indicator and magic eye are working as expected. Dial appears to be spot-on as far as channel line up goes. Plugged in the aux port to my phone and was able to stream without issue too.
I did notice some scratching coming from the right channel, so I shut everything down and cleaned the controls again (4th time). I also cleaned out the tube sockets and let it dry overnight. That seemed to resolve the issue and the amplifier is as quiet as a church mouse now.
Spent last night letting in burn-in for a couple of hours and listened to streaming on it while I replaced the crossover caps. It sounds very nice with just a pair of small bookshelfs hooked up.
I will say those EL80's get pretty hot!
I was thinking of adding a small computer fan to the bottom of the console to help with the heat, but I wanted to get some thoughts on that. It's pretty open in there so I'm not sure it is worth the effort.
Is there anything else I should do to this amplifier before I consider putting it back in the console? I can't really do a FM alignment because I don't have the gear to do that. I also don't see many other adjustments to make besides the stereo separation control.
I also wanted to thank members of AK for helping me out this far. The tips, tricks and words of encouragement you have provided have helped in ways you will never know!
I will post some pics after I get everything back together and the grilles re-covered. Hopefully everything goes back in nice and easy.
Thanks again!
Got the new tubes Wednesday night and popped them in and put the amplifier behind a DBT initially. Everything looked good, so I went ahead and plugged directly into mains power.
I let everything sit idle for a few minutes before trying any inputs. Checked for DC offset and found nothing on both channels, so I hooked up a couple of small 8 ohm speakers and tried some inputs.
FM pulls in a bunch of stations with just a pice of wire for an antenna, and the stereo indicator and magic eye are working as expected. Dial appears to be spot-on as far as channel line up goes. Plugged in the aux port to my phone and was able to stream without issue too.
I did notice some scratching coming from the right channel, so I shut everything down and cleaned the controls again (4th time). I also cleaned out the tube sockets and let it dry overnight. That seemed to resolve the issue and the amplifier is as quiet as a church mouse now.
Spent last night letting in burn-in for a couple of hours and listened to streaming on it while I replaced the crossover caps. It sounds very nice with just a pair of small bookshelfs hooked up.
I will say those EL80's get pretty hot!
I was thinking of adding a small computer fan to the bottom of the console to help with the heat, but I wanted to get some thoughts on that. It's pretty open in there so I'm not sure it is worth the effort.
Is there anything else I should do to this amplifier before I consider putting it back in the console? I can't really do a FM alignment because I don't have the gear to do that. I also don't see many other adjustments to make besides the stereo separation control.
I also wanted to thank members of AK for helping me out this far. The tips, tricks and words of encouragement you have provided have helped in ways you will never know!
I will post some pics after I get everything back together and the grilles re-covered. Hopefully everything goes back in nice and easy.
Thanks again!
Yes, 5-inch quiet muffin fans to keep the heat from sitting on top of the unit. I have one blow air across the top (from front to back), then another one in the back blowing upwards.
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tubes are toasters. I made mine have adjustable bias and a test point to make sure it wasn't running itself into an early grave but I'd be lying if I could remember what I set it for. I quite possibly took some direction from the datasheet though
thats per-section, cathode current is plate + screen, and its all on a common cathode. This would read basically 27mA (2x 11 + 2x 2.3) for sheet conditions at 250v. Thats also plate+screen dissipation of 6.75 watts total for both sections. If the voltages in this are too far off 250 I may have simply taken 6.75 / actual plate voltage = target cathode current just to maintain similar conditions to the sheet.
its been long enough ago that I frankly don't remember but that sounds like the sort of thought process I would have used.
I probably wouldn't have used the schematic voltages and tried to work out whatever Fisher had targeted for idle current based on load lines because that sounds like extra work.
I don't recall mine running absurdly hot but its a tube amp so all of that is relative.
thats per-section, cathode current is plate + screen, and its all on a common cathode. This would read basically 27mA (2x 11 + 2x 2.3) for sheet conditions at 250v. Thats also plate+screen dissipation of 6.75 watts total for both sections. If the voltages in this are too far off 250 I may have simply taken 6.75 / actual plate voltage = target cathode current just to maintain similar conditions to the sheet.
its been long enough ago that I frankly don't remember but that sounds like the sort of thought process I would have used.
I probably wouldn't have used the schematic voltages and tried to work out whatever Fisher had targeted for idle current based on load lines because that sounds like extra work.
I don't recall mine running absurdly hot but its a tube amp so all of that is relative.
GeneParmesan
New Member
Hello all,
As promised, I have attached a few pictures of the restoration, all cleaned up and ready to go. I just have to put the rear cover back on and a few other finishing touches, and I should be done. It sounds pretty nice for a little 10 watt unit, and my wife loves it.
The first 2 pictures are the "before" pictures. As you can see, the console was in fairly decent shape as far as the finish is concerned. The unit had been in a musty basement, and started to develop some mold, but not enough to destroy anything.
The pictures with the 1- and 2- are the "before" pictures. They are the first pictures. Some things to note.
As promised, I have attached a few pictures of the restoration, all cleaned up and ready to go. I just have to put the rear cover back on and a few other finishing touches, and I should be done. It sounds pretty nice for a little 10 watt unit, and my wife loves it.
The first 2 pictures are the "before" pictures. As you can see, the console was in fairly decent shape as far as the finish is concerned. The unit had been in a musty basement, and started to develop some mold, but not enough to destroy anything.
The pictures with the 1- and 2- are the "before" pictures. They are the first pictures. Some things to note.
- Besides what has already been mentioned, all caps and diodes were replaced, including caps on the crossovers.
- Cleaned all controls and tube sockets with contact cleaner and/or Deoxit on the amplifier
- Removed and cleaned the dial glass
- Thoroughly cleaned and restored the Garrad turntable, and new stylus from Voice of Music.
- Console was cleaned, then wiped down with mineral spirits. Then a coat of Howard's Restor-A-Finish was applied, followed by a few coats of Howards Feed and Wax
- New grill fabric by Acoustone. Not the worst material I have ever worked with, its just not soft like a fabric would be (and thicker), so it was difficult to get around the corners. Be careful if using a heat gun with this material, it melts easily!
- Installation of 90 mm computer fan with 3D printed stand inside the console. Powered by 12V old modem adapter, and pugged into the switched outlet on the amplifier to power on/off with the unit.
- Installation of Bluetooth adapter with 3D printed cover on the back.
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GeneParmesan
New Member
You know, for days I was racking my brain trying to figure out why the Acoustone felt so familiar. You're exactly right. it is exactly like the webbing in the old foldable beach chairs!
Attachments
Those tiny output transformers actually test and sound a lot better than many other console amp types. Enjoy!