Schematics for Earth Sound Research amps

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Joined: 2007-04-23
Schematics for Earth Sound Research amps

I have an Earth Sound Research bass head (think it's 50 watts, a solid state/tube hybrid) that I bought at a used guitar shop. Can't find a model # on it, just a serial#. Anyway, I LOVE its sound, especially for upright bass, but it stopped working and after three fruitless trips to the repair shop (triple S), they finally told me that something was wrong in the driver section of the circuit board (I know nothing about this stuff), and said that to diagnose the problem, they would need to see the amp's schematics. I realize this is a tall order given that the company hasn't been around for a long time, but I'd really love to resurrect this amp. So, I'm throwing the question out there: does anybody know if these schematics exist OR are there any repair people out there who might be familiar with these amps and can fix it? Thanks--my fingers are crossed.

Joined: 2007-05-05
Earth Amp Repair

I'm working on one right now in Houston, a model M1952D (the number was on a metal tag on the back panel.
Its a two-tube output tweed amp with transistors for the inputs.
I don't have a schematic, but I don't always need one.


Joined: 2007-05-06
additional repairs


You did the repair on my amp, and it still is working strong. I salute the work you did. I did have another device that needs repair. It is a Digitech GSP-21 Rack Mounted Effects Processor. If you get this message, please contact me. I can tell you what is going on with it. I dont know if you work on these types of electronics as well, but I can say I trust your abilities more so than anyone else I have ever met.

W: 713-507-5638 (M-F 8am - 5pm)

H: 281-419-0338 (after 7:30ish weekdays)

Thanks mike. I will snuff this reply if possible after your call. I tried to send a personal message to your account, but I dont think this site supports that function.

Joined: 2007-05-06


I am as well in Houston, and have an Earth Sound Research amp. I need to relocate the back panel which I still have, however I dont remember my rig having a model number. It was an amp integrated into the speaker cabinate (all-in-one) unit. It was a guitar amp featuring two(2) 12" speakers. I would love to do the repair on this unit, however my tubes are old and no longer have the identifying marks on them. It was purchased in 1979 if that is any help. If you do amp repairs, and are familure with the Earth Sound Research line, I may be interested in having some repair done. My only hitch is that I want to know that I can prevent further amp failure by having fresh tubes in place before I repair it again. Your insight is appreciated. Thank you in advance.

Ronald C. Elbrechter

PS - I think in doing a bit of further research, it is an Earth Sound Research 1955 Revival 212 Combo. When it is operational - it flat howls. It is indeed one monster amp.

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