Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: Sandoz6G16 on September 20, 2013, 07:14:54 pm
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Does anybody know if I could run into problems if I get a marsh 5g9 kit and throw in a JTM 45 OT, they would both be 8K. Also KT66 tubes if workable. Then I would put one or two 15's on it. Just thought of this looking at my 45 next to marsh kit with pro cab. Any suggestions would be awesome, novice here , thanks a lot.
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The PT for a 5G9 won't have the heater current or the B+ current KT66's.
The OT would be over kill for a pair of 6V6's, but I guess your wanting to use the KT66's?
Brad :icon_biggrin:
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I *thought* the JTM-45 OT was 6.6K to mate with the KT66's.
I would ask Marsh if their supplied PT has the heater current and B+ current to make this swap worthwhile. You may also find the KT66's slightly harder to trem than 6V6's.
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On the magnetic comp. (classictone) they say their jtm 45 OT is 8k, I basically just want to try this for #1. I can run two 15's, #2. it will have 28 watts output ( that's what my jtm 45 puts out with this OT) and I can use the half power switch to bring it back to slightly under normal wattage. I was thinking about the KT 66 just cause I got this idea looking at a jtm 45 and thought it would be bigger sounding but I like 6v6 too. I was pretty sure the trem came from a 12ax7 on the 5G9 but I could be wrong
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I was pretty sure the trem came from a 12ax7 on the 5G9 but I could be wrong
It does. But it goes to the output tubes.
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Yes the 5G9 trem circuit is unrivalled for wiggling those 6V6s grids, but I'm afraid it won't do a thing for KT66s or even 6L6s. There's just too much tube current and/or bias voltage in those other tube types.
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if you use the trem. ckt. copied from a 6G11 vibrolux, it will work with KT66/6L6GC. they both make use of about 360V B+ so that shouldn't be an issue. if you want to switch back to 6V6 that could be problematic. you could craft some switching arrangement to accommodate both valve types since the major difference are the values of two components for the just the TREM. ckt. the bias supply is another can of worms. IMO, it would be best just to use one valve type permanently.
http://www.el34world.com/charts/Schematics/files/fender/TREMOLUX_5G9.pdf (http://www.el34world.com/charts/Schematics/files/fender/TREMOLUX_5G9.pdf)
http://www.el34world.com/charts/Schematics/files/fender/VIBROLUX_6G11.pdf (http://www.el34world.com/charts/Schematics/files/fender/VIBROLUX_6G11.pdf)
--pete
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The earlier 5e9-a used a paraphase inverter and the trem wiggled the bias on the paraphase. Its a nice trem different but cool. The PI gets a bit over loaded at max trem settings but its still cool. similar amp in many respects.