Picked this up today

A friend of mine had one of those amps, never got to try it out, though. Back in the late '70's, I had the older model that Phil X uses, it was nice, but got burned up in a fire.

Hopefully those reissues aren't rebadged Crates at inflated prices, I have my doubts.
 
What a bizarro implementation of, "stereo"!

"Each input channel has its own pre-amp, and both of these signals are equally mixed together on both output sections. There is Stereo vibrato, but it only applies to the signal from Channel No.1 input. That signal is send to two different vibrato units, which each go to one of the two output sections."
 
Plastic. Found that that the power tubes cost and arm and a leg. Got a power cord on her and she fired up, all tubes lit up, and a real nice hum, so caps first. Anyone have any 7189A tubes? I can trade some nice 6L6s
 
Plastic. Found that that the power tubes cost and arm and a leg. Got a power cord on her and she fired up, all tubes lit up, and a real nice hum, so caps first. Anyone have any 7189A tubes? I can trade some nice 6L6s


I'll go to the barn later this week and take a peek for you, DR.
 
Plastic. Found that that the power tubes cost and arm and a leg. Got a power cord on her and she fired up, all tubes lit up, and a real nice hum, so caps first. Anyone have any 7189A tubes? I can trade some nice 6L6s

I have an extra leg I can send you but you'll still need to come up with an arm!
 
Power supply is now rebuilt. I had to buy some tubes. When I took her apart there were 3 7189As and one 7189. They are not interchangeable. I have to buy a 3 prong receptacle for a new plug, throw her back together and see where we are at.
 
Those old magnatone's do the clean thing real well. If you're lucky, the vibrato is in working order. If not, those varistor's are listed under unobtanium in any catalog I've seen. I had a Magnatone 260 12" twin for many years. It sounded it's best with a Farfisa organ. When they were re-issued the prices of the originals' spiked, and I sold it.
 
don't know what works and what doesn't. I am not really an amp tech but am always tinkering around. The wife is going to come down to the basement one day and find me electrocuted. I am still waiting for parts in the mail.
 
I know the reverb won't be working because I a can see one of the springs poking out loose from under the tank. Have to pull that out and if it cannot be fixed, which it probably cannot, will have to be replaced. I have one reverb tank hanging around here and will see if that will work
 
Well, the power supply is in and the amp powers up and works. There is still a hum but about 1/100th of what it was, will have to try and track that down. The vibrato works. One of the clips that hold the end of the springs in the reverb tank is broken, don't think I can fix that. The reverb unit is not hooked up and the in and out are just hanging loose in the amp, don't know if that would cause any hum? Don't think so. But, so far, so good. Bought two new 7189As from ebay for 25.00. Made in the old Yugoslavia.
 
I see you now have some 7189As now but I think you could get away with EL84s?

The original valves have a Pa rating 1.2W above the 84 but since everybody and their uncle overuns them in amps such as the AC30s, I think a set of JJs would be fine. The valves are fixed biased(?) so don't run them too hot.

Dave.
 
I see you now have some 7189As now but I think you could get away with EL84s?

The original valves have a Pa rating 1.2W above the 84 but since everybody and their uncle overuns them in amps such as the AC30s, I think a set of JJs would be fine. The valves are fixed biased(?) so don't run them too hot.

Dave.

7189As will not cross reference with any other tube when the power supply is delivering the higher voltages. You can look this up on the interwebs. They can withstand higher plate voltages and higher plate dissipation. The plate voltage to these tubes is in this amp is around 540 volts, that would fry up the EL84s fairly quickly which are designed to run under 400 volts to the plate.
 
7189As will not cross reference with any other tube when the power supply is delivering the higher voltages. You can look this up on the interwebs. They can withstand higher plate voltages and higher plate dissipation. The plate voltage to these tubes is in this amp is around 540 volts, that would fry up the EL84s fairly quickly which are designed to run under 400 volts to the plate.

Right, if they are running at that voltage I take your point! This:
TDSL Tube data [7189-A] suggests the EL84 as a replacement but does give a warning.

Hmm? Naughty! This: http://www.mif.pg.gda.pl/homepages/frank/sheets/135/7/7189A.pdf gives a design maximum Va of 440V and g2 max of 400. Still! As I indicated before, the guitar amp industry has been abusing valves forever!
Dave.
 
I may have fixed the reverb unit, will have to put it in and see. I took a paper clip and cut it then bent it to shape. I soldered it to the back side of the terminal so it would come up and over the small plastic housing and down and then hooked the spring to the bend I put on the other side.
 

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