Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: scstill on November 22, 2023, 05:31:09 pm
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I recently came across a 12pin 6M11
http://www.r-type.org/pdfs/6m11.pdf
It has a pentode and two triodes in one tube.
Anyone ever use this?
Could it be worthwhile making a 5F1 (or similar) with it?
Gain would be lower but that might be a good thing.
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It wants to make a gain of 40,000 from first grid to power plate. (Say 25*25*70) It may be VERY difficult to keep it from squealing.
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If you do a search you can find a project who's name is Squirrell Monkey, it uses only a Compactron tube (two triodes and one pentode in the same envelope) a 6AF11
I don't know of projects that uses 6M11 tubes and if you can give it a try with the Squirrel Monkey project
Here you can find info and projects about the use of Compactron tubes, including 6M11 tubes (but for 6M11 not in the way you are looking for)
https://www.junkbox.com/electronics/CompactronTubesIndex.shtml (https://www.junkbox.com/electronics/CompactronTubesIndex.shtml)
Franco
p.s.: if you are interested I think I've in my archive some good and complete documentation about one other small 6AF11 amp (kit), the Percolator
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Here's a way to make a Tweed Champ(5C1) with one tube. Start with the schematic in the middle of the page but use the first section of the tube as a pentode instead of a triode. Also an isolation transformer is a must along with a full wave bridge rectifier. Also add a volume control between the 2 tube sections. I built one of these years ago and it turned out pretty good. Gives about 1.5-2 watts.
https://www.angelfire.com/vt/audio/compactron.html (https://www.angelfire.com/vt/audio/compactron.html)
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I'm new to compactron tubes, might be worth a build sometime.
Wikipedia says it was in response to the "new" transistors.
Thanks for the resources - good to see the interest (some junkbox tube links might be broken)
The pic of the anglefire "breadboard" is a pretty interesting setup.
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I think I've find something you can use as a base to experiment to obtain a guitar amp from those 6M11 tubes
https://www.diyaudio.com/community/threads/6m11-push-pull-spud-amp.245813/ (https://www.diyaudio.com/community/threads/6m11-push-pull-spud-amp.245813/)
(https://www.diyaudio.com/community/attachments/spudamp6m11nt-png.382090/)
(https://www.diyaudio.com/community/attachments/spudamp6m11-png.382091/)
https://electronbunker.ca/eb/TubeAudio_01a.html (https://electronbunker.ca/eb/TubeAudio_01a.html)
May be a 5C1 with a Paralleled Triode SE instead of a Pentode as Power Tube ?
Franco
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That is very interesting approach to Push Pull; think it could work for guitar?
as well I like the idea of pentode preamp with parallel triode single ended
Many options. Maybe three 6M11 with on-on-on switch one is T-T-P (SE) two is P-T|T (SE) three is P-T-T (PP)
Could also run the pentode as triode for single tube T-T-T (6AV11 does this too)
Need to buy some tubes first.
6AF11 another candidate claimed to be great as Champ style amp
https://zeppelindesignlabs.com/product/compactron-tube-6af11/
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About the 6AF11 Percolator I've documentation if you are interested
Franco
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Haven't been able to find the 6AF11 datasheet with plate voltage curves...
This schematic for the percolator was online, if you have a schematic that would be great
https://music-electronics-forum.com/forum/schematic-requests/52075-
To me the 6M11 and 6AF11 seem close. Any thoughts one vs the other
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http://www.r-type.org/pdfs/ge1964.pdf
Explains the normal versions of the compactrons.
6AL11 has a mini-6V6 in it.
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Haven't been able to find the 6AF11 datasheet with plate voltage curves...
See the GE attached datasheet
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On the Percolator B+ on 6AF11 is ~175V DC and load to be applied is around 6K (or a bit more)
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The Percolator schematic you found is a good version, I've it and also have this
(https://i.imgur.com/HhHZ7Za.png)
(https://i.imgur.com/I9Pchm8.png)
(https://i.imgur.com/bjtCuCe.png)
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I've also some other documentation (I worked on a modified schematic and some Turret Board versions, 3 years ago, but you must revise it because I don't remember if Turret Boards were correct or not)
Measures are in mm not inch
(https://i.imgur.com/14ZImwj.jpg)
This one is my preferred
(https://i.imgur.com/HnzLfmp.jpg)
(https://i.imgur.com/5jqXhQQ.jpg)
(https://i.imgur.com/IsOgAk5.jpg)
Note that the Tone Control was planned to have components on the pot or rotary switch (if used) and a choice about a kind of tone control wasn't done, I think it will be used something like the control in a 5F2A or a 6 position rotary switch with capacitors like in the mtchless DC30 (to have a low signal loss)
Franco
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Thanks a lot...
Now to get some tubes.
I have used findatube.com before for some decent prices.