EMT Gold Foil pics

[djgout]

So, last week I had the task of opening up the tank on a 240 gold foil reverb and took some photos.....the problem we were having was the channel 2 pick up wasn't working.  It turned out to be the voice coil had come unglued from the pickup and was stuck in the magnet.  Luckily we were able to reattach it without breaking the magnet wire that it is wound from. It's impedance was about 24 ohms and the coil just barely fit around the small end of a standard pot tweaker. I hope it's not something we have to do again but we do know it can be done. Lining the magnet gap back up was almost impossible visually but we brought in a much more experienced tech to help out on this one. There is an x-y adjustment for lining up the magnet and he did it by ear and with some dental mirrors.

The squares on the foil are the piezo drivers and the motor mounting plate is below with the round magnets sticking out.  I did get a good photo of the voice coil after it was re-attached.  The round thing with the holes in it on the center of the motor mount appears to be a moisture packet of some kind....

-justin

 

[abechap024]

Holy wow. Those things look more like something that was sent to the moon than reverb tanks. I remember a while back I was messing around with aluminum foil as a reverb device with mixed results....
Thanks for the peek!
Abe

 

[Stagefright13]

I agree with Abe. Moon landing all the way! Thanks for the pics. Very cool to see inside.

John

 

[shabtek]

like wow: thanks or posting those pics.

 

[haima]

THANKS! these are the best images i've seen of the inside of the 240.

Any chance you could post the full rez images? I can host them if you have no web space...

 

[gyraf]

I was thinking about asking the same, but didn't want to look greedy  ;D

Yes, high-res pics would be great (and I see you use a more than halfway decent camera)

Maybe use the gmail account?

Jakob E.

 

[sunnen1]

weren't those under a vacuum, or gas filled?

 

[djgout]

not quite under a vacuum but close to airtight. it did take a small prybar to get the tank open. I'll try to post some more high res stuff on the gmail account, just don't know how.  our other tech got some good photos of the damper side as well. I didn't have a chance to snap any myself.  the damper is actually several strips of what i believe to be fiberglass that are spaced evenly on a frame, they don't touch the plate, just move closer by means of another set of transducers just like a voice coil.  we had to open that side up to lube the rods that align them on the frame.

-justin

 

[haima]

not quite under a vacuum but close to airtight. it did take a small prybar to get the tank open. I'll try to post some more high res stuff on the gmail account, just don't know how.  our other tech got some good photos of the damper side as well. I didn't have a chance to snap any myself.  the damper is actually several strips of what i believe to be fiberglass that are spaced evenly on a frame, they don't touch the plate, just move closer by means of another set of transducers just like a voice coil.  we had to open that side up to lube the rods that align them on the frame.

-justin

Interesting! the older 140's dampener doesn't touch the plate either... but it's mechanism is very simple compared to what you describe. Seems like EMT really took everything they had learnt from the 140 and took it to the next level with the 240 - as well as miniaturising it!

 

[Dark1]

Nice pictures! I was putting mine together about a year ago but, luckily, nothing was wrong inside the tank. I would not want to mess with... that... The glue between both sides of the shell/tank is for sound isolation, so are the springs, the foam inside, the sealant that was originally between the main unit and both side covers, even the paint on the outside - all there to tune the resonance points and absorb/block surrounding noise...

Damper: No vacuum inside, otherwise, the damping mechanism would not work. According to the manual, this linear-response damper is moved via motors suspended in silicon for noiseless operation... Works great!

Attached is a photo of the amplifier and the PSU inside (my unit was pretty rusty here and there, hence the oxidation in the PSU)...
Anyone has a full service manual for these, by the way?

 

[ethervalve]

RE those pictures:
i think i was just sick to my pants

 

[mrclunk]

Great pics! I've never dared look inside ours.

 

[pucho812]

looking at that makes me think of das boot and launching a torpedo

 

[daggertX]

That thing is a pretty awsome piece of engineering thanks for the peek 

 

[mrclunk]

Had to delve into ours and though i'd post some pics of the dampener side.

 

[jensenmann]

Holy moly, what a piece of precision engineering.