Solid State Guitar Amp Forum | DIY Guitar Amplifiers

Solid State Amplifiers => Tubes and Hybrids => Topic started by: joecool85 on March 06, 2008, 04:31:35 PM

Title: How to wire tubes
Post by: joecool85 on March 06, 2008, 04:31:35 PM
How do I know what pins go to what wire?  I'm working from this schematic: http://www.sophtamps.ca/schematics/sopht_12al8-v2.jpg

It says about how to wire the heaters, but that's it.
Title: Re: How to wire tubes
Post by: noobiePT on March 06, 2008, 04:52:12 PM
hey, i found of the 12U7 ( http://tdsl.duncanamps.com/show.php?des=12U7 )
the other couldnt find, do you know if any other type of tube can be used?
Title: Re: How to wire tubes
Post by: joecool85 on March 06, 2008, 05:50:56 PM
hey, i found of the 12U7 ( http://tdsl.duncanamps.com/show.php?des=12U7 )
the other couldnt find, do you know if any other type of tube can be used?

But using that and the schematic I still don't know what wire goes to what pin on the socket...
Title: Re: How to wire tubes
Post by: teemuk on March 06, 2008, 06:07:44 PM
http://www.radiomuseum.org/tubes/tube_12al8.html
Title: Re: How to wire tubes
Post by: joecool85 on March 06, 2008, 06:32:53 PM
http://www.radiomuseum.org/tubes/tube_12al8.html

So what pin goes to R2 for instance?  How do I figure that out?

(http://www.sophtamps.ca/schematics/sopht_12al8-v2.jpg)
Title: Re: How to wire tubes
Post by: numpsha on March 06, 2008, 07:13:21 PM
Check the other thread you have going on this.

http://www.ssguitar.com/index.php?topic=550.msg3811#msg3811 (http://www.ssguitar.com/index.php?topic=550.msg3811#msg3811)

Rob


(http://i272.photobucket.com/albums/jj168/numpsha/firefoxeatiepo1-1.jpg) Use the Force -- Open Source!
Title: Re: How to wire tubes
Post by: teemuk on March 06, 2008, 07:16:48 PM
See the diagram in the link posted by NoobiePT. It shows the socket pinout of the 12U7 and a diagram of which pin is which in the tube. 12U7 is a so-called dual triode so it has two triodes inside it. In the diagram, you can see them at left and right. Pins 4, 5 and 9 are for the heaters and the rest are as follows:

Triode 1 plate: 1
Triode 1 grid: 2
Triode 1 cathode: 3

Triode 2 plate: 6
Triode 2 grid: 7
Triode 2 cathode: 8

Since R2 goes to grid of one of the triodes you use either pin 2 or 7. If you choose pin 2 then you correspondingly use pin 7 for the grid in the next stage or vice versa. The schematic already tells how to wire the filaments.


12AL8 is dual tube as well but it has both triode and a tetrode so you are forced to follow that pattern (tetrode to output, triode to 3rd stage). Diagram in the link again shows the pinout.
Title: Re: How to wire tubes
Post by: joecool85 on March 07, 2008, 07:05:03 AM
Alright, thats starting to make more sense.  Before I wire anything up I will photoshop in the numbers on the schematic and have you guys double check I have it right  8)
Title: Re: How to wire tubes
Post by: joecool85 on March 08, 2008, 08:27:01 AM
This is what I needed:

(http://sub.allaboutcircuits.com/images/03006.png)

Thanks to: http://www.allaboutcircuits.com/vol_3/chpt_13/3.html
Title: Re: How to wire tubes
Post by: joecool85 on March 08, 2008, 09:28:33 AM
I think I got it.  Someone want to double check for me?


Title: Re: How to wire tubes
Post by: noobiePT on March 08, 2008, 09:48:07 AM
hey, nice site you putted there..didnt know it, thanks  ;)

as to the tubes, looks likes its allright
Title: Re: How to wire tubes
Post by: joecool85 on March 08, 2008, 10:06:38 AM
hey, nice site you putted there..didnt know it, thanks  ;)

as to the tubes, looks likes its allright

Alright meaning perfect, or alright meaning it'll probably work?  I want to get it just right before I wire it all up.
Title: Re: How to wire tubes
Post by: teemuk on March 08, 2008, 11:11:00 AM
The final tetrode stage may have an error:

Although the sopht schematic shows it differently I believe that (typically) when tubes are depicted the grid order (from bottom to top) is following:

(control) grid (where signal goes), screen grid (tetrodes), suppressor grid (pentodes), and so on for other tubes.

See...
Tetrode:
(http://www.webace.com.au/~electron/tubes/tetrode.gif)
Pentode:
(http://www.hometheaterhifi.com/volume_1_1/images/pentode.gif)

If that is the case as well in the site showing the 12AL8 pinout (those pics are poor) then you should switch order of the pins 3 and 2. I'm not saying you have it wrong now - I'm just saying there is a possibility for that and you should check it out.
Title: Re: How to wire tubes
Post by: teemuk on March 08, 2008, 11:21:23 AM
Ok... It seems that I was wrong. The pinout is correct as is. See the last page in:

http://www.mif.pg.gda.pl/homepages/frank/sheets/137/1/12AL8.pdf
Title: Re: How to wire tubes
Post by: joecool85 on March 08, 2008, 01:05:11 PM
Ok... It seems that I was wrong. The pinout is correct as is. See the last page in:

http://www.mif.pg.gda.pl/homepages/frank/sheets/137/1/12AL8.pdf

I had looked at that pdf myself, it helped quite a bit.  So the image I posted should be correct?  I just want to make sure before I build it.
Title: Re: How to wire tubes
Post by: noobiePT on March 08, 2008, 08:19:49 PM
the triodes at least are, the other i never worked with but looking through the scheme looked like was right also, but cant be sure about it. anyway, just try, its not like its gonna blow up if you got it wrong(hopefully  ;D)
Title: Re: How to wire tubes
Post by: joecool85 on March 08, 2008, 08:44:23 PM
the triodes at least are, the other i never worked with but looking through the scheme looked like was right also, but cant be sure about it. anyway, just try, its not like its gonna blow up if you got it wrong(hopefully  ;D)

I'll be giving it a try in a day or so, I have a few other projects I need to finish first.
Title: Re: How to wire tubes
Post by: rob_nl on March 11, 2008, 11:38:38 AM
You can find a description of nearly any tube at duncan amps. Check out this link:
http://tdsl.duncanamps.com/
theres a downloadable version of the tube library for free on his site.
Title: Re: How to wire tubes
Post by: J M Fahey on June 05, 2008, 11:25:17 PM
For these and many others check: http://www.mif.pg.gda.pl/homepages/frank/

Noval dual triodes generally go: 1,2,3,4,5,6,7,8,9= plate, grid, cathode, filament, filament, plate, grid, cathode, filament center tap (if applicable)
Title: Re: How to wire tubes
Post by: joecool85 on June 06, 2008, 07:17:20 AM
I forgot to post back, I got it all working - my wiring was correct.  It's very quiet, which isn't surprising considering it's only 40mw output.  I'm considering using it as a preamp.
Title: Re: How to wire tubes
Post by: Jack1962 on June 30, 2008, 01:46:29 PM
go to duncanamps.com and download the TDSL prog , it id's most tubes and isf you click on the last tab to the right it will give you links to data sheets r2 ties to pin 2 on the tube.

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