Magnetone Amp MOTS

[CJ]

cellulose is a better name for it, dangerous stuff that almost burned down the Fender factory and got a visit from the fire marshall,

this guy is not on any web pages, 6V6GT push pull, speaker is about a ten inch, palm tree beach scene is worn of,

 

[CJ]

1950 style wiring, not a single soldering iron trace to be seen, unfortunately the two coupling caps to the power tubes are driving the grids positive, one with 5 volts, the otther with 12, Sangamo Type 30 to blame , very common, almost hate to change them,

those dry lytics can sometimes be left alone as their chemistry is different,

 

[CJ]

note input jack resistors, parallel 200 K on all three jacks, this could be for two reasons that i know of, one is they bought a load of surplus resistors and did not have 100 K, or two, the wanted to lower noise by using two resistors instead of one. i suspect reason number one to be more valid.

same thing with the plate resistors on the 6SL7 plates, two 50K resistors in series this time. did they want lower noise or better power handling? probably not, as the were trying for 100 k which furhter solidifies our inventory supposition,

also note that is is hard to find carbon comp in 50K these days, most 10% values go 47K, 51K, 56K,

 

[CJ]

Sylvania 6V6GT's and 5Y3GT, RCA 6SJ7 and 6SL7

Triad pwr xfmr 6308 i believe, and possibly a Triad output marked 1689 with date code marked "(2-50)."

 

[CJ]

this amp highly resembles the front panel of the Kiesel (Carvin guy) 3-HGA, but the circuit is different,

nor is it the same as the Magna M192-5 which has a 6N7 instead of the 6SL7,

https://www.magnatoneamps.com/

 

[CJ]

output transformer has phase shift at 1 K Hz, but comes back into phase later on,

 

[AnalogPackrat]

Looks to be in great condition for a 72 year old amp. Break out your lap steel and make it cry!

 

[CJ]

spk, Permoflux out of Chicago, breaks up nice!

 

[CJ]

jus happen to have on in the house!

 

[ccaudle]

1950 style wiring, not a single soldering iron trace to be seen, unfortunately the two coupling caps to the power tubes are driving the grids positive, one with 5 volts, the otther with 12, Sangamo Type 30 to blame , very common, almost hate to change them,

those dry lytics can sometimes be left alone as their chemistry is different,

How do the components hold up on an amp that old? Are the resistors still close to the right value? Any problems from humidity soaking in, or varnish flaking off, or anything like that from being in storage for a long period of time?

By "dry 'lytics" do you mean electrolytics which have dried up electrolyte, but are still working? Or was there some type of really old electrolytic which did not have liquid electrolyte to start with?

 

[CJ]

sq wave response of OPT>