Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: jonyoungyi on August 25, 2019, 11:47:35 pm
-
Hey all, per usual, I found a decent deal on a Mojo761 Power Transformer (attached PT specs). I remember how much I liked the 6L6 BluezMeister, so I thought I'd give the 6V6, Clean Only, version a shot.
My question is, is that the Mojo761 has a 360-0-360 secondary voltage. Using https://thesubjectmatter.com/calcptcurrent.html (https://thesubjectmatter.com/calcptcurrent.html) my B+ is going to be 460v! vs the 6V6 BluezMesiters B+ of 374v (attached schematic)
Even if I were to use a tube rectifier that'd drop the voltage by 60v (not to mention one that'll handle that high an input voltage), it'll be pretty far from the original schematic.
I'm wondering what my options are, if changes to the BluezMeister's schematic can be made, or if I should look at building another amp, perhaps Sluckey's AB763 Lite (built that one before!), or if someone can recommend something that'll fit the Mojo761's bill?
-
I think it would be fine to build the Tweed BluezMeister with a tube rectifier.
360 x 1.1 (5Y3GT) = 396v
360 x 1.2 (5V4) = 432v (probably fine with JJ 6V6)
You can just change the dropping resistor between node B & node C. Shoot for between 160-200v on the plates of V1 using a 12AX7. (12AY7 will give considerably lower voltage).
Sluckey's AB763 would be a good choice also. AND if you wanted to, you could build it with a Dumble tone stack? Not saying you "should" do that just throwing out thoughts.
I've attached another idea for you for your consideration.
With respect, Tubenit
-
OR ……….. IF you're wanting something different, you could consider Geezer's HoSo56?
Shoot for 140-160v on the 5879 pentode for a FAT tone. Use the mosfet as the CF follower so you can also have active FX loop. You can use the suggested tone stack or simply substitute a traditional Marshall tone stack.
And use a 5Y3GT for your tube rectifier. With respect, Tubenit
-
tubenit, you've done it again! Thank you for your always helpful suggestions! I'll take a look at that HoSo56 (I think you mentioned it in another post of mine, too)
Thank you!
-
IF you decide to go the HoSo56 route, I have a SCH layout that can be easily modified for the 6V6's.
-
I think I'm going to go the Bluezmeister route! I remember I really liked the sound of that amp (at least with 6L6s) and it's such a simple build!
Thank you!