Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: kagliostro on May 08, 2011, 11:54:47 am
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A friend give me 4 chassis that were part of a military modem unit
I disassembled it, the most components were transformers with a restricted bandwidth, so I think not reusable for guitar amps
there were 3 x 5654 tubes and 1 x 6AK5 tube (near the same tube I've read)
here the data sheet for the tube http://tdsl.duncanamps.com/pdf/5654.pdf
I recovered also some nice shielded Gudeman caps
12 x 1.0 100v
4 x 1.0 200v
8 x .82 100v
4 x .47 300v
4 x .47 200v
4 x .047 300v
I suppose they are fine for guitar amp (??)
about the tube ................ can you tell me if I can use and how ?
I was looking for 5879 tubes but till now I've find no one, are the 5654 usable in a project like TOS ??
Thanks
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The 5654 tube sounds FABULOUS and is a good substitute for the 5879 if you can't find it, IMO. I used a 5879 and 5654 paralleled in the HoSo56 I built. I could pull one tube or the other if I wanted so I got a very good A/B comparison. \
And yes I think you could use them in a TOS project. Just watch the voltage ratings on the plates.
Reasonably comparable tube. The 5654 can also be used in vibrato circuits like on the silvertone 1482 or DanElectro Centurian 275 in place of the 6AU6. I tried that also with reasonable results.
With respect, Tubenit
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Hi Tunenit
The 5654 tube sounds FABULOUS and is a good substitute for the 5879 if you can't find it, IMO. I used a 5879 and 5654 paralleled in the HoSo56 I built.
you make me an happy man :smiley:
I used a 5879 and 5654 paralleled in the HoSo56 I built. I could pull one tube or the other if I wanted so I got a very good A/B comparison.
since you have opted for 5879 what were the differences ??
can you post the values of components you used for the 5654 or that was only a preliminary test with no definitively results ?
Just watch the voltage ratings on the plates
in the schematic you posted here
http://www.el34world.com/Forum/index.php?topic=9636.0
the 5879 tube is connected to the F node that gives 208v and at the plate of the tube you measured 145v
as the 5654 plate is rated in the data sheet at 200v can I assume that is ok ?
Thanks again
Kagliostro
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I recovered also some nice shielded Gudeman caps
12 x 1.0 100v
4 x 1.0 200v
8 x .82 100v
4 x .47 300v
4 x .47 200v
4 x .047 300v
I suppose they are fine for guitar amp (??)
I believe those caps are called feedthru caps. End terminal to end terminal is a straight wire. The capacitor is connected between the metal body of the cap to the straight wire. Very common in quality built industrial or military equipment. Not very useful in a guitar amp.
These feedthru caps are used to make connections to a chassis and provide a shunt filter cap all in the same component. You can test to see if what you have is indeed feedthru caps by connecting an ohm meter between the end terminals. If you read zero ohms, you most likely have a feedthru cap. Now, if your VOM has a capacitance function also, connect one lead to either end terminal and the other lead to the metal shell. If you get a capacitance reading close to what's stamped on the body, you most definitely have a feedthru cap.
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Hi Sluckey
I believe those caps are called feedthru caps
I've measured the caps with my cap tester
I measured from the two terminals, not the shield, and they give a capacitance near the stated value
in this moment I don't have under hand my capacitance meter (it is in my garage and now I'm at home)
I have only under hand a digital tester and used that to measure if there is continuity between the shield and the terminals
response: no one of the two terminal of the cap is connected to the shield also there is no galvanic continuity between the two terminals
can I assume that is NOT a feedthrough capacitor and I can use for guitar amps ?
Thanks
Kagliostro
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can I assume that is NOT a feedthrough capacitor and I can use for guitar amps ?
Yes. Please disregard any of my comments about feedthru caps.
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Hi Sluckey
I took the cap meter in garage (it is beginning to rain) and I measured the capacitors
between terminals I measure the stated capacitance
between terminals (both) and shield there is no capacitance
I think that is nice for my intentions .................
About feedthrough capacitors I've seen many in High RF units, but they looks very very small and those I've seen had not screw mounting, they were to be soldered to the chassis
now I've seen that there are also big feedthrough capacitors, I've never seen one before (every day I discover something new)
Thanks
Kagliostro
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since you have opted for 5879 what were the differences ??
9 pin socket instead of 7 pin socket. The 5879 sounded a little sweeter to me but not by much.
With respect, Tubenit
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Thanks Tubenit
I remembered I've seen a schematic with both tubes on it and I've found it :smiley:
http://www.el34world.com/Forum/index.php?topic=10933.0
http://www.el34world.com/Forum/index.php?action=dlattach;topic=10933.0;attach=21691;image
this forum and you friends are really an inexhaustible mine of information
Kagliostro