This is my first post here, but I've been a 'guest' for a while now.
I found 2 organs on Craigslist in my area for $20.. One was a 60's Wurlitzer with a Leslie speaker unit, no amp, and the other was a Silvertone model 4722, manufactured in 1961. The Silvertone I actually got to make some noise before I started tearing them apart. I've checked these and other forums for some good info on this amp but haven't come up with anything I can use right now. What I would like to do is take the amp from the silvertone and the speakers and spring reverb unit from the Wurly and make it into a good guitar amp. (With the leslie as an add-on) I've got some electronics experience but am fairly new to tube amps. I have a 1968 Alamo that I've recapped and such, and know about the whole capacitor charge danger. I just want some input as to how to go about setting up this amp for guitar. I'm not afraid to rewire the whole thing, as I think there's a lot of organ effects I'm not going to take advantage of. I'd like to wire in all the 12 AX7's in series, to increase the output of the amp, and I'd like to add as I said a reverb channel. Is this do-able? Lots of extra wiring... So, I guess, my question is what amp should I build from these parts? Any thoughts would be greatly appreciated. Here are some pics of the unit, as well as the tube layout. thanks!
I found 2 organs on Craigslist in my area for $20.. One was a 60's Wurlitzer with a Leslie speaker unit, no amp, and the other was a Silvertone model 4722, manufactured in 1961. The Silvertone I actually got to make some noise before I started tearing them apart. I've checked these and other forums for some good info on this amp but haven't come up with anything I can use right now. What I would like to do is take the amp from the silvertone and the speakers and spring reverb unit from the Wurly and make it into a good guitar amp. (With the leslie as an add-on) I've got some electronics experience but am fairly new to tube amps. I have a 1968 Alamo that I've recapped and such, and know about the whole capacitor charge danger. I just want some input as to how to go about setting up this amp for guitar. I'm not afraid to rewire the whole thing, as I think there's a lot of organ effects I'm not going to take advantage of. I'd like to wire in all the 12 AX7's in series, to increase the output of the amp, and I'd like to add as I said a reverb channel. Is this do-able? Lots of extra wiring... So, I guess, my question is what amp should I build from these parts? Any thoughts would be greatly appreciated. Here are some pics of the unit, as well as the tube layout. thanks!
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
First, this discussion belongs on the musical instrument "board".
The 12AX7 is a small signal, not power O/P, type. The 6AQ5, which is a member of the 6V6 family, is the power O/P device in that unit. Figure on an approx. 5 W. yield.
A cheap phenolic printed circuit board (PCB) was used. You will probably have to discard that, install a piece of sheet metal in the opening and rebuild using point to point wiring.
I suppose the Fender "Champ" 5F1 is a good place to begin. You did mention spring reverb. So, the "Vibro-Champ" AA764 may be worth looking at too.
The 12AX7 is a small signal, not power O/P, type. The 6AQ5, which is a member of the 6V6 family, is the power O/P device in that unit. Figure on an approx. 5 W. yield.
A cheap phenolic printed circuit board (PCB) was used. You will probably have to discard that, install a piece of sheet metal in the opening and rebuild using point to point wiring.
I suppose the Fender "Champ" 5F1 is a good place to begin. You did mention spring reverb. So, the "Vibro-Champ" AA764 may be worth looking at too.
Thank you Eli. Would it be reasonable to upgrade to a 6V6 power tube instead? I would prefer something with a higher yield than 5W, and if I'm going to do this p2p, I guess I'm just using this for parts at this point.
For all practical purposes, the 6AQ5 is a 6V6 in a 7 pin mini package. Approx. 5 W. is what you get from either type. Switching to a 6V6 makes sense from a replacement point of view, as that type is currently being produced.
The magnetics in the Silvertone carcass will not support higher O/P power. I strongly suggest you build something along 5F1 style. The 2nd 12AX7 on the chassis would allow you to add a tone stack to the minimalist circuitry. To get more "sock" from such little power requires the use of the most efficient speaker you can get your "mitts" around.
The magnetics in the Silvertone carcass will not support higher O/P power. I strongly suggest you build something along 5F1 style. The 2nd 12AX7 on the chassis would allow you to add a tone stack to the minimalist circuitry. To get more "sock" from such little power requires the use of the most efficient speaker you can get your "mitts" around.
Eli, thank you for the info. Yes, I'm going to try and build an AA764 from these parts and not add the reverb tank right now. Maybe I'll use that in a future project. I have another question now. I've removed the PCB from the chassis and left the power side largely untouched. I'm in the process of removing components from the PCB but I got to thinking- how can I reuse those tube sockets since they were soldered on the board? Are these reusable practically for a homebrew amp? Most of the sockets I've seen are riveted to the metal, but these are soldered in.
As for the speaker, I've got 3 options right now in my garage- 2 12" speakers pulled from a 60's wurlitzer organ, the one 12" from this Silvertone organ, and a 12" sub I pulled from a non-functional Line6 Spider III guitar amp. I'll have to check impedance of course but I'd be willing to bet they're all 8 ohms. Thoughts?
As for the speaker, I've got 3 options right now in my garage- 2 12" speakers pulled from a 60's wurlitzer organ, the one 12" from this Silvertone organ, and a 12" sub I pulled from a non-functional Line6 Spider III guitar amp. I'll have to check impedance of course but I'd be willing to bet they're all 8 ohms. Thoughts?
The moderators must be sleeping, usually guitar amp posts have been sent into exile (the musical instruments board) by now.
First, get a blade for that saw that will cut metal. Then saw off the part of your chassis that has the circuit board. 8^)
Most of the components on the PCB are likely out of spec and I doubt the PCB mount sockets could be adapted for use on a metal chassis.
I see two options if you want to use the existing chassis.
First would be to replace the 5Y3 rectifier with SS diodes and then rewire the 5Y3's octal socket for a 6V6 output tube. Then the two remaining 7-pin sockets, which are currently used by the 0A2 and 0B2 voltage regulator tubes, can be converted to use a pair of 6AV6s, which are essentially half of a 12AX7 each. The 6AV6s can be ordered from any of the large tube dealers for about $3 each.
The second option: Keep the 5Y3 rectifier and remove the can cap (C34). Then install a second octal socket for a 6V6 in the space where the can cap was. Install new individual caps underneath to replace those in the can - something you would generally do anyway.
. . . Charlie
First, get a blade for that saw that will cut metal. Then saw off the part of your chassis that has the circuit board. 8^)
Most of the components on the PCB are likely out of spec and I doubt the PCB mount sockets could be adapted for use on a metal chassis.
I see two options if you want to use the existing chassis.
First would be to replace the 5Y3 rectifier with SS diodes and then rewire the 5Y3's octal socket for a 6V6 output tube. Then the two remaining 7-pin sockets, which are currently used by the 0A2 and 0B2 voltage regulator tubes, can be converted to use a pair of 6AV6s, which are essentially half of a 12AX7 each. The 6AV6s can be ordered from any of the large tube dealers for about $3 each.
The second option: Keep the 5Y3 rectifier and remove the can cap (C34). Then install a second octal socket for a 6V6 in the space where the can cap was. Install new individual caps underneath to replace those in the can - something you would generally do anyway.
. . . Charlie
Charlie is right about "ditching" everything on that old POS PCB. You need new chassis mount sockets to go on the sheet metal you are using to fill the opening left by PCB removal.
Several sources of sockets and other parts are at your disposal. The vendors list includes (but is not limited to) AES, Jim McShane, and Triode Electronics.
Definitely retain the 5Y3. Part of the "tone" of a tubed guitar amp is the sagging B+ rail associated with vacuum rectified B+.
A possible use of the 0A2 and 0B2 gas discharge regulators is in the O/P tube screen grid (g2) B+ supply. Regulated g2 B+ holds intermodulation (IM) distortion down. As IM distortion is most definitely unmusical, such a tweak could be of benefit even in guitar amp service.
UPDATE
UPDATE! Well, I Finally got it done. I Ordered some new caps from Mojotone and had the extra breadboard laying around from an LED project. I made a modified champ clone with a tone knob. This is my first ever tube amp and I couldn't be happier. It sounds great! There are two little issues though- if I turn my tone knob up all the way, the volume cuts out. Well, I should say that about 8 on the tone knob the volume slowly fades down to no volume when turned from 8-10. Not sure what that's about. I'm going to try a different 12AX7 in there because I'm getting some loud squealing when the volume is on 10- 1 thru 9 works perfectly. No hum, just good warm tone. I'm quite happy with it other than those two issues..
If I had it to do over again I'd drop the 12AX7 in the hole where the old cap can was. Not sure why I didn't do that to begin with, but again it's my first go. This one was more for the theory and experience than anything.
Eli, I'd love some further info on the 0A2 and 0B2 circuit - I would love to toss them into service. I'd have to rewire my 6AQ, and if I did utilize the others I'd probably go with a 6V6 as mentioned earlier. I just wanted to use as many of the original parts as I could. Even the wire is from the organ.
I had to redo a few little things, like running one wire to the preheater circuit and grounding the other, not taking into account it was AC, (That's how the PT was rigged in the amp originally, they must have had a different way of doing things) and physical placements for components like jacks as I didn't lay them out with the breadboard in mind- rookie mistakes- but I learned.
Now it's time to build a wooden cabinet now for the Silvertone 12" and get playing.. Thanks guys for all your help.
On a side note, I picked up for FREE on the side of the road just yesterday a Zenith hifi stereo system, circa 1962 that, once I got it home and cleaned off, discovered it works perfectly. I may start another thread on this one, as I'm not sure if I want to gut it or not. It's still in really nice shape and I'd hate to tear it apart for the sake of tearing it apart. Here are a few pics if anyone cares.
UPDATE! Well, I Finally got it done. I Ordered some new caps from Mojotone and had the extra breadboard laying around from an LED project. I made a modified champ clone with a tone knob. This is my first ever tube amp and I couldn't be happier. It sounds great! There are two little issues though- if I turn my tone knob up all the way, the volume cuts out. Well, I should say that about 8 on the tone knob the volume slowly fades down to no volume when turned from 8-10. Not sure what that's about. I'm going to try a different 12AX7 in there because I'm getting some loud squealing when the volume is on 10- 1 thru 9 works perfectly. No hum, just good warm tone. I'm quite happy with it other than those two issues..
If I had it to do over again I'd drop the 12AX7 in the hole where the old cap can was. Not sure why I didn't do that to begin with, but again it's my first go. This one was more for the theory and experience than anything.
Eli, I'd love some further info on the 0A2 and 0B2 circuit - I would love to toss them into service. I'd have to rewire my 6AQ, and if I did utilize the others I'd probably go with a 6V6 as mentioned earlier. I just wanted to use as many of the original parts as I could. Even the wire is from the organ.
I had to redo a few little things, like running one wire to the preheater circuit and grounding the other, not taking into account it was AC, (That's how the PT was rigged in the amp originally, they must have had a different way of doing things) and physical placements for components like jacks as I didn't lay them out with the breadboard in mind- rookie mistakes- but I learned.
Now it's time to build a wooden cabinet now for the Silvertone 12" and get playing.. Thanks guys for all your help.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
On a side note, I picked up for FREE on the side of the road just yesterday a Zenith hifi stereo system, circa 1962 that, once I got it home and cleaned off, discovered it works perfectly. I may start another thread on this one, as I'm not sure if I want to gut it or not. It's still in really nice shape and I'd hate to tear it apart for the sake of tearing it apart. Here are a few pics if anyone cares.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
wow it's a beauty definitely 60's styling!
what size is the low frequency driver? and is the speaker compliment 2 way or 3 way?
what size is the low frequency driver? and is the speaker compliment 2 way or 3 way?
Yeah it's in surprisingly good shape! And like I said, everything works. Here are some pics of the speaker arrangement. It's an 8 speaker system with 1 12" sub per side, 1 mid, and 2 highs nearest I can tell.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
You wire the 2 tubes in series. You bypass the stack with a 0.47 μF. film capacitor. A current limiting resistor connects the assembly to unregulated B. The screen grid gets connected to the top of the 2 tube stack. Search for GE Glow Tube Data.
The console looks interesting. Quite frequently, the record changers in that sort of product are guano and employ record destroying piezoelectric cartridges. An expert, like Tom Bavis, will tell you what category that changer falls into. If the TT is crap, it's no big deal to get an old Technics, Pioneer, BIC, etc. to take its place. I'd like to see a GOOD look at the power amp.
Okay, clearly I need to do more homework in researching tubes and amp circuitry.. I Have a good handle on the basics after a lot of research and playing with this organ chassis, but don't know the specifics of what you are saying in regards to wiring the 'top' of the stack, etc. Sorry, I'm trying.
The best pic of the amp in the console unit is below. I tried the record player again tonight, and, sadly, it didn't want to work. It kept putting the needle on the record, playing for about 5 seconds, then lifting the needle up and shutting the record player off. Not sure what I'm missing. It played great yesterday.. I may be loading it incorrectly honestly. I'm admittedly too young to have played with record players at all as a 'native'. When i was a kid it was all CD players- that was the only way to go when I was coming of age. you put the disc in and hit play. None of this needle stuff. 🙂
Anyway, here's the pic of the amp itself inside the hifi chassis. After some research it turns out these don't appear to have much value outside their individual components but i'd still hate to break it up for another guitar amp. I do need a really cool overdriven harp amp though.. haha
An externally hosted image should be here but it was not working when we last tested it.
That 5L29 in the pic is important, as that's the model #. You have a single ended (SE) 6BQ5/EL84 amp that delivers approx. 5 WPC.
Perhaps member Tom Bavis will provide us with a nice schematic graphic.
With the right speakers, 5 WPC can be enough. You want something at least 94 dB. sensitive that has a reasonably flat impedance curve.
Given the amp, I would not allow irreplaceable LPs on the Zenith TT. I'm thinking low down in the product line.
Here's the GE document I previously mentioned.
A stack is simply cathode of 1 VR tube connected to the anode of the 2nd bottle.
Run a Google search for NEETS, which is US Navy training material available for free off the WWW. NEETS contains all sorts of good info. about both tubes and SS.
Perhaps member Tom Bavis will provide us with a nice schematic graphic.
With the right speakers, 5 WPC can be enough. You want something at least 94 dB. sensitive that has a reasonably flat impedance curve.
Given the amp, I would not allow irreplaceable LPs on the Zenith TT. I'm thinking low down in the product line.
Here's the GE document I previously mentioned.
A stack is simply cathode of 1 VR tube connected to the anode of the 2nd bottle.
Run a Google search for NEETS, which is US Navy training material available for free off the WWW. NEETS contains all sorts of good info. about both tubes and SS.
The moderators moved this thread, just when it was getting on topic for the Tubes/Valves "board".
If you want to continue discussing the console, start a new thread on Tubes/Valves and cross reference this thread.
If you want to continue discussing the console, start a new thread on Tubes/Valves and cross reference this thread.
Hi gtptim, I would advise against using those 0A2 and 0B2 tubes. Coming at this from a hi-fi standpoint, intermodulation distortion does not sound good. But you are not building a hi-fi amp and IMD is an integral part of the guitar tube amp sound. We want distortion, or at least some overdrive. You will be hard-pressed to get much clean signal with only one 6AQ5 output tube. And if you do keep it clean, it will be pretty pathetic in a guitar amp.I know of no classic or modern day guitar amps that use voltage stabilization tubes such as these. When they are present in an old amp like yours, the common wisdom is to dispense with them and get that good tube overdrive sound. If you look at the Champ or Vibro Champ, you will not see any of these. In fact, I know of no Fender amp that used these tubes, past or present.
Could you post a schematic of your finished amp? Of are you happy and just want to get to that next one? You do have to remember that you have a two channel amp and your first one was not. Different problems to solve. Or do you want to keep it as is to use as a console for sure?
Could you post a schematic of your finished amp? Of are you happy and just want to get to that next one? You do have to remember that you have a two channel amp and your first one was not. Different problems to solve. Or do you want to keep it as is to use as a console for sure?
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Hi gtptim, in your update post, you said you would drop the first 12AX7 in the old cap can hole if you could do it again. If that is your first input tube, it should be as far as possible from the power tranny and associated filtering. This part of the amp has the most electromagnetic interference and this is the most sensitive gain stage. Not a good combination. You did well keeping that tube over where it is at to avoid noise problems.
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No worries Turk. Glad to help out! haha
Boobtube- yes after a bit more self-education it turns out that I did the right thing here with the 12AX7 by accident. I'll remember that for future projects. And yes, I'm going to pass on using the other two tubes. I haven't ever seen any others use this type of circuitry and there's gotta be a reason.
I'm still not sure what to do with this console though. Should I try and sell it as a unit, or sell the tuner, keep the amp, speakers, and wood, and build a nice guitar amp from the parts? I even have a leftover reverb tank from one of the torn up organs. This thing's taking up a ton of room in my garage. Thoughts?
You could use the two 12a*7 tubes for your preamp and then feed both OTs and run them to separate speakers, using two output jacks, one from each. You could have one bright speaker and one a little darker to create a nice overall sound. It would be a two 5 watt/ch amp. Swart makes one like this.
If you really want to be adventurous, have a chorus/phasing effect between channels.
I don't think those speakers will be too good for guitar as they are designed for lower freq. woofer duty, but maybe Turk182 will have ideas.
You also probably will need to re-voice the amp with different caps because it was designed for hi-fi. Usually these amps have the RIAA freq. curve to undo. Here is an article on that. What Is The RIAA Curve? | Sessionville
If you really want to be adventurous, have a chorus/phasing effect between channels.
I don't think those speakers will be too good for guitar as they are designed for lower freq. woofer duty, but maybe Turk182 will have ideas.
You also probably will need to re-voice the amp with different caps because it was designed for hi-fi. Usually these amps have the RIAA freq. curve to undo. Here is an article on that. What Is The RIAA Curve? | Sessionville
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