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Post by taylordaly on Sept 7, 2007 18:51:11 GMT -7
I really couldnt think of any clever way to title this thread, so thanks for taking the time to read. Ive been trying to educate myself on tubes (my new adventure) and it seems like a few things are common to "improving" the Maz Jr:
*5751s in v1 and v3 or v5 *NOS Rectifier *Matched Phase Inverter" tube for V3
Please forgive my ignorance. Im learning as I go here, and have been trying to research these but hoped someone could answer them in simple terms (if possible).
Can someone explain to me in simple terms the significance of a "matched phase inverter"? What position is the PI slot? Whats the significance of a Black Plate?
Thoughts? I think Id like to pick some of these tubes up. I like the idea of 5751s based on others' explanation of them. Can anyone recommend one or two of each of the above for me? Im not trying to spend tons...just enough to get a reliable tube and some improvement. I also shot an email off to Mike at KCA so hopefully he will have some tube suggestions for me.
Thanks for reading and helping!
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Post by dixiechicken on Sept 8, 2007 1:49:44 GMT -7
DC here!
1) It is not matched really that's a term usually reserved for the power tubes. ( although you could argue it's the same thing ) You usually use the term balanced for the PI-tube - that means the two halves of the double-triode tracks the same, same amplification factor, same transconductance, same plate dissipation same idle current etc etc.
This is to insure that the PI-tube drive the output-tubes the same way. If the PI-tube is UN-balanced it will drive the power tubes unevenly - then it wont matter very much if you try to bias and find a matched pair of power-tubes.
2) The PI-slot is the tube driving the power-tubes - it is usually located closest to the power-tubes. Better check the wiring or schema of the amp.
3) Black Plate is plate commonly found in old RCA NOS tubes, don't know if it was special alloys or materials in the plates. However some RCA 6L6 black plate power tubes were put into old Fender amplifiers aka Fender Bassman 59 or so.
This is considered - the by some people at least - to be the holy grail of all 6L6 tubes. Often when we nerds/geeks speak of the Fender sound this often is what we mean, Fender Bassman 59 equipped with the RCA black plate tubes and the Jensen/Eminence speakers 4x10".
Ask Myles these questions he can correct my mistakes and flesh out his subject until your ears fall off. ;D
Cheers: Dixiechicken
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Post by taylordaly on Sept 8, 2007 7:05:20 GMT -7
Thanks buddy!
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Post by chipstar75 on Sept 8, 2007 13:37:49 GMT -7
what he said........in addition I would further say......"youve heard the term "push-pull" curcuit? Well the phase inverter tubedoes just that. It is the only position tube to use both sides of the tube , in that push -pull analogy. Ideally, you want the same push as you do pull. A ballenced tube gives you a noticable improvement in any amp. As for other tube subsitutions and changes, its fun to experiment, but in the end, its what you like best based on alot of factors ie. guitars used, pick-ups, playing style, etc. I personally like the stock set up. Ya gotta figure, Doc did alot of experimenting before he came up with his recomendation for tubes and speakers. I just add the matched phase inverter tube and Im happy.
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Post by taylordaly on Sept 8, 2007 17:03:07 GMT -7
Any suggestions for a matched phase inverter tube?
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Post by dongiesen on Sept 8, 2007 17:21:18 GMT -7
The Doc uses a Sovtec 12AX7LPS. Get ahold of Mike at KCA (experts section this site) and on the site when you order there is a line that covers the matching aspect. I believe there is also a comment section wherte you can specify what your doing and what your doing it with etc
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Post by dixiechicken on Sept 9, 2007 2:14:00 GMT -7
This is what Mike at KCA NOS said to me.
Cheers: Dixiechicken
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Post by Stylemaster on Sept 14, 2007 15:33:36 GMT -7
+1 for the Sovtek 12AX7LPS in PI socket.
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