Magnatone Amp SE 6V6GTA Model A-646

[Gus]

CJ
what tone control did you end up with post 18 or 19?

I used a tone circuit like post 18 for a SE 6L6 PA amp I changed to a guitar amp.  It had a 12ax7, 6x4 and short 6L6 tube

 

[CJ]

hey Gus! howya doin?

i am currently using the circuit in the red box, i think i will order the correct tone pot/sw and return this thing to it's splendid glory as per the bottom circuit and see how much smoke it makes,

 

[PRR]

> both inputs are self shorting

I'm finding that on other Magnatones as well. Seems like a waste of good signal.

 

[CJ]

this thing again,

got the 500K tone pot/sw to replace the 100K somebody stuck in there, sounds great! tone control works a lot better, vendor on evilbay has Alpha pots for $3.95 plus shipping,

also took out the .005 cap that sits after the 100K input resistors, this was a "transition" amp, built between the switch over from 6SJ7 pentode grid leaker to the 12AX7a dual triode, so we have the octal socket riveted to the chassis as the input tube, which is no longer the 6SJ7, so we have a 6SL7 input tube with the grid leak cap left over from the pentode, so they used up the chassis inventory with the octal socket and switched to the 12AX7a after a brief run with the 6SL7,

replace the first stage ceramic coupling cap with a Mallory Orange Drop, the stock ceramic gets very noisy as you move your finger towards it, so it picks up hum like an antenna, the Orange Drop totally fixed this aspect of the amp, might be some sound difference, but the noise reduction at high volume is worth it,

also put a 100K pot in place of the 22K voltage dropping resistor in the second part of the pi filter and cranked it up and down to see how much volume it chewed, not much, the amp still works great with 100K as the dropping resistance, so we used a 68K to drop noise a bit in stage one and also get some nice distortion out of the second stage at an earlier volume while dropping overall volume a bit which saves the vintage Jensen 8 inch speaker,

here is the final schematic with voltages,

 

[CJ]

this thing....again,

was returning this cute little pearloid Magnatone amp after a complete rebuild, sounds great,  one block from the music store i dropped it and it shattered like a piece of glass, every panel came apart,  ???

this ripped apart the ancient pearloid finish, because it as installed so that it overlapped the panel joints,

interesting history on this finish, highly explosive and toxic, stories about a fire at the Fender plant that scared away further use?
you can buy chunks on evilbay for wrapping drum sets,

there is even a company that makes this celluloid paper>

http://delmarproducts.com/

anyway, we decided to just glue the amp back together, sounded better when it was ready to fall apart, something to be said for floating baffle boards and old worn out cabinets i guess,

this amp use to have a palm tree scene on the front that got worn away,

so we decided that since the cabinet was now fixed with a few dings, why not redo the grill cloth palm tree to make up for it,

you can buy felt at Michael's art store for 33 cents a piece, finding a glue that works was a problem, but contact cement seems to work ok,

so we dialed up the original Leilani scene on the internet and used that to recreate the artwork, you can trace the patterns of the comp screen and make templates, the palm tree trunk was made by coating a square piece of felt with cement, and then cutting it into thin strips, coating the thin strips one at a time is very time consuming,

 

[CJ]

here is the amp before and after, maybe some clear coat finish will protect it from a rain storm,

 

[mjrippe]

Wow, CJ!  You really went the extra mile on this one