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Amp Stuff => EZ Board postings => Topic started by: Geezer on June 17, 2005, 09:31:12 pm
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> BF Showman 6v6's conversion?
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gibsonchild
Junior tube assistant
Posts: 40
(2/19/04 5:43 pm)
BF Showman 6v6's conversion?
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I have a '63 Showman that came from the factory w/ 7355's. I love the tone, but they are too hard to come by and so far have been very unreliable (3 sets in 18 months). I switched it over to 6l6's and it works great but sounds kinda sterile. Doesn't have the smooth breakup that the 7355's do. I've read that 6v6's are very similar sonically to the 7355's, so I was thinking of trying them out. Anything in particular that I should look out for other than plate voltage? Any help or suggestions would be greatly appreciated! THANKS,
Garrett
wayneosdias
Senior tube assistant
Posts: 240
(2/19/04 6:58 pm)
sadf
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Hey Garret,
Ive been researching the 6l6 to 6v6 swap myself but in a bassman config. After everyones help here and then what ive read ib oconnors tut, the tubes "can be used in identical voltage envirenments w/identical bias conditions, provided the plate voltage is less than 420v." Dunno what youve got on the plates now, but if you drop it below 420 you should be good.
wayne
Rotting27
Junior tube assistant
Posts: 119
(2/19/04 7:12 pm)
Re: sadf
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That info is almost a decade old. Electro-Harmonix makes a 6v6 capable of running at nearly 500V. 475 is their rating.
wayneosdias
Senior tube assistant
Posts: 241
(2/19/04 7:47 pm)
asdf
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that info is more likely over 6 decades old and still applicable today.
wayne
GroundhogKen
Forum Moderator
Posts: 2288
(2/19/04 8:50 pm)
Re: How 'bout trying 7591s
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I like 7355s too. I have an old Stromberg stereo that uses them. They are impossisble to find.
Why not try some 7591 tubes? I know you've already re-wired for 6L6 or 6V6, but you could revert back to the old wiring--7591 and 7355s have almost exactly the same pinout.
A lot of Ampeg users have good things to say about the EH-7591A. It's about half way between a 6v6 and a 6L6.
I personally would not run EH 6v6 above 430-440v. It's not the plate voltage you need to worry about, it's the screen dissipation. If you go with these, increase your screen resistors to 1K.
The new JJ 6V6S would probably work fine. They sound nice, but they don't really look like a typical 6v6; they're about 15-20% larger. I was considering disconnecting two of the speakers and giving these a try in my Super Reverb.
Ken
Rotting27
Junior tube assistant
Posts: 120
(2/20/04 12:26 am)
Re: How 'bout trying 7591s
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No, Wayne, info found in TUT is only....about a decade old. If O'Connor was writing the book today he'd note that current production Russian 6V6s are more reliable and can take higher voltages, and are not limited to a 420V safe operating range anymore.
He has been very clear that each new volume's data replaces contradictory information from earlier volumes. So, using info from TUT1 only applies to the context in which is was written.
So, to reiterate, current production Russian 6V6s can handle nearly 500V.
lowtech
Senior tube assistant
Posts: 182
(2/20/04 1:11 am)
Re: How 'bout trying 7591s
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I'm with Ken on this one. The 7355's are extremely close to 7591's - heater current, plate disipation and output impedence is a closer match than either the 6L6 or the 6V6. And I think the 7591's are more ok with the higher plate voltages than the 6V6. But if you've got the sockets rewired for a 6V6, I'd trying hooking up an 8 ohm to the 4 ohm output ( or some similar logic) to provide maybe a better impedence match.. me thinks thats Ken's logic for unhooking two speakers in his super in the above post
wayneosdias
Senior tube assistant
Posts: 243
(2/20/04 1:18 am)
asdf
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not to quible, but what i meant was that the fact that these tubes are interchangeable has most likely been known since their inception. i made reference to the tut as it the only reference re this that i have.
also, are you talking about the Eh gt's?
wayne
ganzonimx
Hey get your own solder
Posts: 399
(2/20/04 11:36 am)
&V& EH rating
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My 6V6EH data sheet I got from New Sensor Corp rates them
Vp max = 450 V
Pd max = 14 W
If the voltage rating is effectively higher, what about the plate dissipation? How high is safe? any experience?
The ones I use are the EH6V6GT's from Doug.
Cris
crashtm1
Senior tube assistant
Posts: 115
(2/25/04 9:05 pm)
4 x 6V6 in a '66 Bandmaster....:beam
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I have a '66 bandmaster... this chasis is already setup for 4 power tubes.. if you refer to the schematics with 4 power tubes,, you will easliy see how to wire up the 2 new sockets...Now instead of 2-6L6s,, I run 4-6V6's... I am currently using jj's..... I love the change of tone these offer.......:)
6G6
Junior tube assistant
Posts: 93
(2/25/04 10:13 pm)
Re: 4 x 6V6 in a '66 Bandmaster....:beam
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Ahh, but can you describe it?
wayneosdias
Senior tube assistant
Posts: 244
(2/25/04 10:19 pm)
asdf
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casy4s did the 4 6v6 thing to his 5f6a, you should look for his site on yahoo.
wayne
crashtm1
Senior tube assistant
Posts: 116
(2/25/04 10:20 pm)
4 x 6V6 in a '66 Bandmaster....:beam
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To be continued.:))
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