Silvertone Solid State 100 Tremolo & Reverb

[Mars Amp Repair]

Hey folks,
This just for info on the trem bulb replacement. I found that the bulb mfg#12ESB or Mouser#606-CM12ESB works great as a exciter bulb in this trem bug. It is actually one of those push in bulbs that they used to have in the old multi-line telephones that you see in old movies. I only happen to have one from when I was looking for a replacement for the ballast bulb in my Heathkit Audio Generator. I bought a number of different voltages to see which one it was.
This is a 12V version that did not work in the Generator. If memory serves, that bulb was somewhere around a 60V version.
Anyway, this bulb is cylindrical and fits in the bug assy perfectly.
Just thought this would help anyone trying to source the bulb. Glen

[Mars Amp Repair]

Here's the innards of the tank. I just had to reattach the spring & repair connections to the coil on the rightt.
You remove the end-cap that is stapled on. Then rotate the tank I think clockwise which loosens the circular springs that suspend it in the cylinder and pull it out. The other tank I had from a donor amp the cust brought to me had a piece of red thread that was attached to the center of the spring and attached to the bottom plate. Maybe to dampen the action a bit or to limit the travel of the spring. Who knows. I didn't deal with that. Glen

[Helmholtz]

Wow, that reverb is an unusual design.
How does it sound?
Trying to figure out where's the output transducer.
Could you post a pic of the bottomside?

[x-pro]

Perhaps the receiver is a piezoelectric element-plate between the coils of the spring on the left side.

[x-pro]

For example:
https://dzen.ru/a/X1epo8zCNHp2mez_

[Mars Amp Repair]

[QUOTE=Helmholtz;n997765]Wow, that reverb is an unusual design.
How does it sound?
Trying to figure out where's the output transducer.
Could you post a pic of the bottomside?[/QUOTE

Hello Hemholtz,
The unit is already back together, so I cannot do that. The left side pickup is a piezo element. The copper spring that is rivetted to the Masonite board has the shielded cable hot soldered to it. That spring pushes up against one side of the piezo element as a connection. I don't recall how the shield connects to the piezo.
The coil side connects to rivets in the Masonite board where the non-shielded wires connect and that end of the spring connect to a metal piece that then connects to a plate that I believe serves as the primary pickup of the transducer. I'm actually surprised that I didn't think to look at it any closer! More focused on getting the damn thing done (:- )
Oh I can see now that the end of the coil acts like a tape head which picks up the action of the spring being close to the coil.
Glen

[Mars Amp Repair]

Wow, that reverb is an unusual design.
How does it sound?
Trying to figure out where's the output transducer.
Could you post a pic of the bottomside?

Well, it actually doesn't sound horrible, but a bit bong-ie. It is substantially better than the short delay piece of crap the 1484 amps had in them. Those also used piezo elements for both pickup & drive.
I think if anyone were actually going to use this amp to play out, they'd be better off using a digital reverb or an actual reverb unit, albeit the vintage ones are pretty pricey!
Glen

[Helmholtz]

So the reverb uses longitudinal spring waves as opposed to torsional (twisting) waves with Hammond type tanks.
As longitudinal waves travel faster, delay times are shorter.

[Mars Amp Repair]

So the reverb uses longitudinal spring waves as opposed to torsional (twisting) waves with Hammond type tanks.
As longitudinal waves travel faster, delay times are shorter.

Hmm, I never thought of it that way.

[Axtman]

Yeah those Silvertone reverb tanks have a reputation of being not that good sounding.

To slightly sidetrack this thread. Mars, does your amp have a noticeable hiss when the amp is turned down? I have a Sivlertone 1464 that has an annoying hiss like a high gain amp cranked, but my amp has all the controls rolled back. I think the amp should be dead quiet. Another tech told me that the hiss might be characteristic of the two Germanium output transistors.

[Mars Amp Repair]

Yeah those Silvertone reverb tanks have a reputation of being not that good sounding.

To slightly sidetrack this thread. Mars, does your amp have a noticeable hiss when the amp is turned down? I have a Sivlertone 1464 that has an annoying hiss like a high gain amp cranked, but my amp has all the controls rolled back. I think the amp should be dead quiet. Another tech told me that the hiss might be characteristic of the two Germanium output transistors.

Hello Axtman,
Well, the amp actually came back with a low motorboating symptom, so until I ferret that issue out, I really can't check it for hiss, but I don't recall it having any appreciable hiss. I agree that the germanium xistors could be your source. You should try heating/cooling them to see if the hiss changes. Be mindful tho, of over cooling or overheating them as any xitor will move out ot it's designed operating range if heated/cooled radically, ESP the germanium variety. That can give you a mis-diagnosis.
Once I get the motor-boating resolved, I'll check & post the hiss results.
BTW, I jumped all the major filter caps & that is not the issue with the motorboating. I'll also post those results when I get it weeded out.