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What kind of tube did I use back then?
What kind of tube did I use back then?
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Old 5th March 2011, 08:28 PM   #1
sprinter is offline sprinter  United States
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Default What kind of tube did I use back then?

Back when I was 18 and going off to school, I decided I would need a little stereo for my dorm room. I built a little stereo amp (and speakers) with just two tubes. They were twin tubes with one half as a preamp driving the other as a power amp. I'm trying to remember what tubes I used for that. I remember that it worked surprisingly well. I think they were small 7-pin jobs, but I'm not certain. The B+ may have been derived from the 120VAC without xfmr. I do know that cost and simplicity were important.

Anybody know what they may have been? I'm thinking that they may have been specifically designed for that purpose in mind. But they may have just been like a 12AX7 or something, then it could have been anything. Do people still do this? Most designs I see now use at least 3 tubes.

I'll expand this question to include any known ultra-simple transformerless designs.

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Old 5th March 2011, 08:59 PM   #2
Eli Duttman is offline Eli Duttman  United States
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The 6BM8 is a Noval (9 pin mini) type suited to a "spud" (1 tuber) circuit. FWIW, I've been involved in such a project. Look here if you're interested.
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Old 5th March 2011, 09:07 PM   #3
mashaffer is offline mashaffer  United States
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6GW8, 6GV8 et.al. also possible.
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Old 5th March 2011, 09:39 PM   #4
Ty_Bower is offline Ty_Bower  United States
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Quote:
Originally Posted by sprinter View Post
Do people still do this?
Sure. I'm building a 6BM8 amp that I'm gonna finish any day now, I swear...

Click the image to open in full size.
http://i69.photobucket.com/albums/i4...E/P1140836.jpg
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Old 5th March 2011, 10:29 PM   #5
sprinter is offline sprinter  United States
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Quote:
Originally Posted by Ty_Bower View Post
Sure. I'm building a 6BM8 amp that I'm gonna finish any day now, I swear...

Click the image to open in full size.
http://i69.photobucket.com/albums/i4...E/P1140836.jpg
Yeah, yeah, I've heard that before (usually from me to my wife)...

Thanks guys. I'll take a close look at your projects. I imagine there are some spud threads here. I'd be interested to see any such projects. I've heard the term "spud" but didn't know that's what I did (ahem) years ago. Big question is, how do they compare sound-wise to other, more conventional SET designs? I know they'd be flea power but I will have some 94 dB full-rangers to try it on. Maybe I could even find something more sensitive. I like simple. Simple is good.

Boy, that 6GW8 sure sounds familiar, but I'm not sure.
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Old 5th March 2011, 10:49 PM   #6
woodturner-fran is offline woodturner-fran  Ireland
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Maybe Ecl82 or ecl86? Can't recall the US numbering........ but very like half 12ax7 and half el84.
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Old 5th March 2011, 11:12 PM   #7
sprinter is offline sprinter  United States
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Quote:
Originally Posted by woodturner-fran View Post
Maybe Ecl82 or ecl86? Can't recall the US numbering........ but very like half 12ax7 and half el84.
Yeah, that's the kind of thing I had in mind.

Oh, I just found the ECL82. It's a 6BM8. Sounds like a really nice project tube.

Last edited by sprinter; 5th March 2011 at 11:18 PM.
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Old 5th March 2011, 11:19 PM   #8
woodturner-fran is offline woodturner-fran  Ireland
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ecl86=6GW8
ecl82=6BM8


There's also PCL86 and 82, exactly the same valve but with 14V heaters I think.
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Old 5th March 2011, 11:23 PM   #9
Wavebourn is offline Wavebourn  United States
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What kind of tube did I use back then?
6Ф3П (6F3P) is the same, still available.
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Old 5th March 2011, 11:26 PM   #10
woodturner-fran is offline woodturner-fran  Ireland
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I just picked up a ECL82 amp the other day and am about to start restoring it....

see: ECL82 mullard 4-7
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