Silvertone on bench

[Rocks]

Hi everyone,
This is my first post here, I'm somewhat new to working on tube amps but I am learning as fast as I can. I am currently working on an old Silvertone tube amp that was pulled from an old reed organ. Posted below are the pics and schematics from this beast. So far I have added a fuse and a 3 prong cord to it but I am wanting to do some mods to make it more guitar friendly.

As you can see from the schematics it has a strange setup for both the tone and volume controls. The tone is handled by S2, a switch that changes it from "flute" to "strings" and the volume control is actually what they call a swell control and it is late in the chain.

The first thing I'd like to do is add a normal volume control, can I do this by putting a 1M pot after C1?

After I get the volume control in place I want to work on the tone and gain sections, but since I am still learning I want to take this one step at a time. Any help would be greatly appreciated.

Rocks

[Amp Kat]

Theres lots you could do and without hacking it as you have some room there. I would replace all of the E-caps mainly the can cap. What do you want it to sound like is the main question as you are going to have to make some voicing changes. That first gain stage right now is set up as a mu amp and we'll have to add a cathode resistor/capacitor network to voice it. After that what your looking for is strickly up to you. Yes that is a good place for a volume pot and you could even use the fluite and string switch to switch out a voicing if you like but if it were me I'd put that pot right after C1 then a fender type tone stack with the treble wiper going into the grid of the tone recovery stage.You could use another 1/2 triode but we may be able to gain that driver stage up enough to get some more gain. SE Class A should sound real nice. Of course if you just want to add a volume pot and keep the voicing like it is we can do that too but I'd change that first stage some.

[Rocks]

Hi Amp Kat,

Right now I have two good amps for clean tones. One is an old Vibro Champ and the other is an old Kalamazoo model 2. They both sound great at low and full volumes but neither get into that good overdrive unless dimed. So what I'd like to do with this one is to make it into an amp I can get into overdrive at much lower volumes. I don't play out, I only play at home and I can't crank my amps when other people are home. So my goal with this one is to be able to get anything from a nice bluesy overdrive (think David Gilmour playing dogs of war) To a good hard rock/metal overdrive and still be at low volumes.

I've noticed that the SW2 stays rather clean on the strings setting until I crank it a bit and on the flute setting it overdrives at much lower volumes, when dimed it gets farty sounding. So I am thinking that if I can change the voicing on the flute/strings and calm down that farty sound I'd be in the ballpark I am after.

The problem with both settings is the voicing loses a lot of the highs, on flute it is all bass, no mids or treble. On Strings I get a bit more highs but its still not anywhere near as bright as my other two amps.

One question, how would the new volume pot I am thinking of adding interact with the current swell control on the amp? Would it be something like a master volume setup?

Rocks

[Amp Kat]

Well being that the amp is flat out controlled by the volume on the Organ yes I guess it would be a Master. but in reality it is a volume control. The only problem is without hacking the amp and adding controls we'll have to set the midband frequency to a voicing your good with. The problem with making it a gainy amp is you don't have enough preamp stages to do it with however we can get close but it won't sustain until you totally overdirive it into power tube distortion which will tend to get loud. The best thing to do IMO is send a stomp box or processor to the front and use the preamp control as a volume and the amp as a master. Cathode biased Class A amps actually put out more power than your tube rating which in this case is 10 watts so your probably putting out around 20 watts at full power which can be damn loud with the right speaker but that's your call whether at full tilt it's to loud or not. We can just add the pot at first and see if you like it and then go from there.

[Rocks]

I would have no problem with removing the vibrato from this, could I use the rest of the 12ax7 the vibrato uses as another gain stage? I already have two amps with vibrato and I never use it on them, the last thing I need is another amp with vibrato that I won't use.

Thanks for the advice!

Rocks

[Amp Kat]

I would have no problem with removing the vibrato from this, could I use the rest of the 12ax7 the vibrato uses as another gain stage?
Thanks for the advice!

Rocks

Sure you can and it would work out pretty good like that as you can use the Vibrato control for the volume and a tone or master volume for the dwell. Let me draw something up and I'll fax it to you. If anyone else has some ideas please chime in as well.

[Rocks]

Thanks a lot! I have no idea why they made so many amps with vibrato instead of reverb. Frankly I have never had any use for vibrato but a little reverb (very little) is nice to have. I used to play with a lot of effects but now I have outgrown that and I get most of the tone I need by simply switching pickups between bridge and neck. Once I get a good tone dialed in on my amp I am good to go and don't need or want to fool around with it unless I need to adjust for the room.

Rocks

[Amp Kat]

Check your private messages .