Vintage amp bass rig

[bea]

Well, the Echolette M40 is actually a PA. Yes that little golden cage. But it serves well as a bass rig - really loud for its 32W: You will definitely not want to turn it to eleven.
The amp is well known for its great guitar sound when the power stage is overdriven - but that will kill the screen protection resistors very quickly.

 

[eSGEe]

very cool bea!!! --- we need a sound clip!!!

 

[CabanaBoy]

Cool, looking rig set up...

 

[JohnnyGoo]

Nice

 

[syscokid]

The amp is well known for its great guitar sound when the power stage is overdriven - but that will kill the screen protection resistors very quickly.

Is it a matter of just beefing-up the resistors, or a limitation of the overall circuit?

Are those circular red things covering the speakers dust caps acting like sound beam blockers?

 

[CabanaBoy]

Those red cabs look like they'd move some bass air for sure. I bet that old head and those cabs sound nice in person...

 

[SG John]

Geil!

 

[bea]

This evening i'll take her back home. And possibly also the G-2000.
Reason: the G-2000 just burnt an EL-34. One week later, the replacement tube, also a really old EL34, was also dead (but i had that M40 with me). The G-2000 seems to need some checking and with this opportunity a slight modification: reduce the grid leak resistor somewhat. This will hopefully make the environment a bit more stable for recent EL34 or KT77, which demand for a slightly smaller grid leak resistor if they are fully loaded. Which is the case in that amp - it runs at 790V on the anodes and draws the max possible power from the output tubes, up to 200W RMS from 4 EL34.

Back to the M40: i'll replace her by her little sister which i have sucessfully repaired these days. It's a bit cleaner and has less hum. And it has enlarged screen grid resistors to survive heavy loads on the power stage better. In order to be able to use one of my loud basses, i replaced one of the input tubes with an ECC82 - which reduced the gain less than might be expected. Her sister will achive some work as well - remove the ground loop in the filter chain (a problem with many of these amps), improve the filtering of the bias voltage and check the other electrolytics. After bying it i did only minimal work on her to make her safely usable because my children needed a PA.