Tube Practice Amp Adding Reverb

[nickb]

Ok guys the circuit board is the reverb driver and preamp can I use this?
This is the reply that named the pins.

It is the tank driver and receiver circuit.
Pins 4,5,and 8 are ground.
Pin 3 25Vdc.
Pin 6, 7, and 9 inputs.
Pins 1 & 2 output.
Takes about 1Vac at the input and has a pot on the board to adjust the output level.

You'd need at least an extra power supply and a gain stage. Therefore you would still loose the tremolo. Doesn't seem like it saves anything. Even if you were to make a stand alone reverb and keep your practice amp intact it doesn't add much to the mix other than using an unusual tank of questionable quality.

[Chuck H]

This^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

I can't tell just what that board is doing. Is it a driver or recovery stage? I don't know. We would need a schematic for that. If it were on my bench I could trace it I suppose. Honestly though, even with an image of the board traces and high res photos to determine component values here I'm not likely to do that over the internet. It's and old tank and an old board (that would need to have the electrolytic caps replaced, at least) and as noted, requires a different power supply than the one in the existing amp.

[Chuck H]

My plan is to put the input jack on the Silvertone where the original input I use on the Kustom then convert the speaker out on the Silvertone into a line out and solder the leads to where the original input goes on the board of the Kustom.

???

Really? What do you plan to house all this in? Honestly, this seems like a very cumbersome arrangement. Just my opinion, but I think it would be much easier to add the dummy load/line/low out to the Silvertone such that it's rendered into a preamp. Then use it as such to feed the input of the Kustom and leave that amp whole. The dummy load and signal output on the Silvertone could even be put on a switch so that the amp could be used as the stock combo at will.

[Wolfman88]

Its a driver/preamp. Losing the trem is no big deal I never use it anyway. Here's a schematic

https://archive.org/stream/23001/230...e/n16/mode/1up

Also I know it works. It was one of the few things that worked on that organ.

[nickb]

???

Really? What do you plan to house all this in? Honestly, this seems like a very cumbersome arrangement. Just my opinion, but I think it would be much easier to add the dummy load/line/low out to the Silvertone such that it's rendered into a preamp. Then use it as such to feed the input of the Kustom and leave that amp whole. The dummy load and signal output on the Silvertone could even be put on a switch so that the amp could be used as the stock combo at will.

After sifting through 53 pages of almost illegible drawings...Ta da! Not that it changes my opinion one iota.



Hmmm... does the Kustom have parallel FX loop? If it does then the board with a suitable power supply could be used in that position and you get to keep the little amp.

[Chuck H]

I've only worked on one Kustom. But I did have to replace parts on two boards and correct the reverb circuit which some other tech had kludged. As far as I can tell they're very "modular" in design. It would probably be easier to add reverb to the Kustom than the Silvertone. And it would make more sense because it would put the reverb last for effects (if any were used between the Silvertone and Kustom).

I don't remember an effects loop on the Kustom I worked on. But as I said, they're sort of modular. So the effects loop is sort of there, it's just that it's idealized for Kustom boards rather than whatever you buy at GC. Maybe. Maybe it would work just fine wired up to a pair of jacks.

[Wolfman88]

The K100-1 is a bare bones amp so no fx loop. I'm open to adding the reverb to the kustom but how would I go about doing that? My plan on the housing in the kustom I'm building custom mounts and the Silvertone will be housed inside of the Kustom so the tube preamp and reverb tank will all be inside of the Kustom head. If I used the driver/preamp board on the reverb tank how could I get the 25v dc to run the board? So far all my fx are running into the input on the Kustom I have a Behringer V-amp 2 and a Digitech RP300 running my fx and overdrive channels like I said bare bones amp it just has a clean channel a bright and normal high and low for each a volume bass and treble and a speaker out that's all it has. But like I said I'm not opposed to adding the reverb tank to the Kustom. I do have a really small practice amp maybe I could use it to drive the reverb. I'm just trying to shape my sound on my dream amp the Kustom K100. The tube preamp would give me the tube sound and the spring reverb I just prefer the real thing over the digital reverb on my fx processors.

But if you guys think its best to run the reverb from the kustom I'm all ears.

[Chuck H]

My plan on the housing in the kustom I'm building custom mounts and the Silvertone will be housed inside of the Kustom so the tube preamp and reverb tank will all be inside of the Kustom head.

Just so you know, that absolutely will not work. The transformers create too much EMF and the tubes generate too much heat in combination with the Kustom amp circuits for this to be functionally possible. Just the reverb tank alone in the same head sized cabinet as the Silvertone is VERY likely to suffer induced hum and buzz on the tank transducers. All of it together in the Kustom cab (Kustom amp, Silvertone amp, new reverb circuit and dummy load between Silvertone and Kustom) will cause tremendous noise and induced instabilities in every circuit involved. I can't imagine trying to fine tune such a thing and getting on top of it.

JM2C

[The Dude]

[Wolfman88]

I have done something similar with my old Hartke GT60 with the tube preamp it already had spring reverb. As long as its shielded right it didn't cause problems. If it does I will make the preamp rack mountable and put in in a rack. The preamp I pretty much know how to do except what resistors to use on the speaker leads. Its the reverb I need guidance on. You said it might be best to do the reverb to the Kustom amp so how would I go about that way? Like I said I do have a small amp like 1 watt I don't know if I can use this to drive the reverb but that might more hassle than its worth.

[nickb]

The K100-1 is a bare bones amp so no fx loop. I'm open to adding the reverb to the kustom but how would I go about doing that? My plan on the housing in the kustom I'm building custom mounts and the Silvertone will be housed inside of the Kustom so the tube preamp and reverb tank will all be inside of the Kustom head. If I used the driver/preamp board on the reverb tank how could I get the 25v dc to run the board? So far all my fx are running into the input on the Kustom I have a Behringer V-amp 2 and a Digitech RP300 running my fx and overdrive channels like I said bare bones amp it just has a clean channel a bright and normal high and low for each a volume bass and treble and a speaker out that's all it has. But like I said I'm not opposed to adding the reverb tank to the Kustom. I do have a really small practice amp maybe I could use it to drive the reverb. I'm just trying to shape my sound on my dream amp the Kustom K100. The tube preamp would give me the tube sound and the spring reverb I just prefer the real thing over the digital reverb on my fx processors.

But if you guys think its best to run the reverb from the kustom I'm all ears.

Here is the schematic for the K100-1:


I think your reverb board could work so that one of the channels has reverb. An estimate of the signal levels looks to me to make this possible. You connect a 10uF cap +ve to the emitter of Q112 and -ve to your reverb PCB inut. The output of the reverb board goes to another 10uF capacitor -ve to the reverb PCB +ve to a 22k resistor ( guessed value for now). The other side of the 22k resistor goes to the +ve side of C110.

Now you need 25V power for the reverb PCB. It looks to me like the reverb driver could take quite a bit of peak current as its schematic shows 0.76VAC across 5.6 ohms. That's 136mA. It won't be that high all the time so you can use the existing +37.5V supply by using a 7824 type regulator. do a search for the datasheet and a typical circuit. It's going to dissipate only about a watt so a small heatsink should do. Be warned the case of the 7824 is connected to ground the so think about insulation from other things.

Locate the tank output coil as far away as possible from the power transformer.

And you still get to keep your little amp intact. I think I might have an unhealthy desire for not modifying old tube amps.

[Wolfman88]

Kinda Greek to me remember I'm a beginner at this stuff. Could you explain that in simpler terms like you were talking to a child? I think when you say like c110 or q112 you're talking about the k100 schematic right? I know what uF means and 22k resistor means but need things simpler until I learn all this stuff. Is there anyway I could make the reverb like a stand alone where I just solder the output to the input on the Kustom and the input to the reverb solder those leads to the input jack on the Kustom?

If I could make it standalone I could even make it rack mountable.

[nickb]

Kinda Greek to me remember I'm a beginner at this stuff. Could you explain that in simpler terms like you were talking to a child? I think when you say like c110 or q112 you're talking about the k100 schematic right? I know what uF means and 22k resistor means but need things simpler until I learn all this stuff. Is there anyway I could make the reverb like a stand alone where I just solder the output to the input on the Kustom and the input to the reverb solder those leads to the input jack on the Kustom?

If I could make it standalone I could even make it rack mountable.

I think you've understood it correctly. It would be more complicated to put it on the input of the Kustom as you would face signal level, mixing and power supply issues.

[Wolfman88]

What does the +ve and -ve mean and what is the 7824 regulator? Does anyone else have any other ideas? And where do I put the pot to adjust the reverb level?

[nickb]

What does the +ve and -ve mean and what is the 7824 regulator? Does anyone else have any other ideas? And where do I put the pot to adjust the reverb level?

+ve =positive ; -ve = negative

7824 = https://lmgtfy.com/?q=7824+regulator+datasheet&s=g



The problem we've got here is shifting goalposts. First it's add reverb to a small amp. Then it's use small amp as a preamp, then we have to use the organ reverb, then it's a stand alone reverb on the input. I think there's been quite a few workable solutions but now it's time to draw a line, pick one and go for it.