Organ amp guitar conversion

[Crossfire]

I have a question meant for someone who has great knowledge in these old Hammond organ amps. I have a 56 s6 that I acquired several years ago. It worked great while I had it and ran out of room and tried to store it somewhere and upon research into I found that the speakers were Jensen so I pulled them for my extension cab, which leads me to the actual organ itself. I've been reading that converting them can be good but everyone I speak with says to leave it all intact and not mess with it, but the problem is these old organs just ain't worth that much even to a good collector so there's not many options for them, and I don't really want to see this in the scrap yard so if it can be converted to a guitar amp then I would love to pursue that. My question is would this all be a waste of time to do this? If it would not be a waste of time, can someone with some experience share with me the tonal characteristics of such an amp? I found several schematics online for this chord organ, and I know there's 2 6v6 power tubes on the amp part itself, but I'm not sure what all this means. Much assistance can someone provide into this matter? I hate to take this apart actually but selling it just hasn't been an option lately as no one is interested in buying it, not even trade the entire thing with the old CBS tubes in it for an amp.

[selloutrr]

It's incredibly wasteful and once you start it's not something you can back on as easy as oops I changed my mind. With said the ones I've debt with you basically have to build a preamp. The organ donated the power amp. So you are half way when you start. Does the organ offer any benefit like rotating speakers? Or are you just making an amp? It's hard to say what it will sound like since the bulk of the tone is going to be from the preamp

I hope that helped

[Crossfire]

No rotating speaker or nothing like that. The chord organ is just a smaller type machine with an array of tubes down one side of the back of it. A guy told me about a year ago that it would require a gain stage and that may be what you said. I'd just rather sell it instead of trying to convert it but that's not working too well.

[M Fowler]

I've only stripped one complete organ and thought it was a shame until I looked around and just in my small town there are lots of them. Because people don't want them they end up on trash pickup day in May where us TAG guys strip the tubes and power chassis out.

Now days I just buy the transformers off ebay and put them into a blank chassis. The old iron sounds great but too many times the OT's are bad probably the reason people stopped using the organ huh!

With good price from Magnet Components transformers I tend to not use old iron as much as did previously.

A few photos of old organ transformers made into a guitar amp.

Mark

[Crossfire]

Here's a few photos of what I am working with currently. I mean if it'd work I'd love to give it a shot and see. I've never seen an amp ADR from an s6 chord organ, but plenty of m3s. A guy once told me I'd have to add a gain stage but it'd be a push/pull style like the old princetons. I've never played one so I'm not quite sure what they're like. I have a new super reverb re-issue and I just don't like it that much because it doesn't break up like the older ones of the 60-70s, so I the princetons are like that it won't do me much good

[M Fowler]

In the first picture the only thing to save is the tubes. The second picture is what I buy off ebay the power transformer with 5U4 rectifier tube.

Picture number three shows the output transformer lower left corner. I have that same chassis and haven't thrown it away yet.

[Crossfire]

I kind of figured there'd be parts that's not even used or considered to be used on it. The two power amp tubes are 6V6. I'm gonna ask a stupid question, what's the difference in using a rectifier such as one that's in this? And assuming this is converted, would it offer a better quality 'tone' than say a peavey classic 30? I play blues mostly so clean is not a sound I really on but I don't grungy at all either. Just looking for a good tone and if I can accomplish it with this rather than forking out 2K on a prs that'll be worth it to me. And would it need a preamp stage added or ran straight?

[Phil_S]

In addition to what's been said above....
Conversion has to be a labor of love. You will spend countless hours doing things that you don't do when you can buy a blank aluminum chassis from Dirty Dawg (best price, decent item) and make it a DIY project from scratch.

First there is all the work of stripping the chassis because it is rarely worth keeping what's there. You may want to harvest and recycle the good parts, which takes time and care.

If the chassis is steel (depending on hardness/thickness), metal work can be challenging and time consuming. You will want to modify the chassis. Holes will need be closed, and others made. There will be holes in inconvenient places. You'll need bits and other metal working tools, including a step bit that goes to 1 1/8" for octal sockets.

You are pretty much stuck working around the existing socket locations.

Yes, you need a preamp section. The preamp shapes the signal (tone) and boosts it for input to the power section. So, that is where the work is really done, input, tone controls, volume control. You are in for a project.

I don't want to discourage. I'm one who likes doing this sort of thing. I've been lucky, getting it to work out most of the time, though my last one was a disaster and I'm going to strip it down. I want you to have a clear idea what you are in for once you start.

Good results will be quicker and possibilities expanded by doing this without recycling the chassis. Like Mark, I have also been able to pick up decent used power transformers. Output transformers that match a project are harder to come by and like he says, now that there are reasonable cost choices, it is questionable whether one should bother to recycle.

If you can cut the price of the PT and OT by getting used ones that fit your project, you should be able to build it for less than $200, and maybe under $100, depending on what you are building and how clever you are. Of course, if you haven't done this before, costs will be higher because you have no base inventory of supplies. It's like when you move and have to throw out all the refrigerator contents. You'll need start over with basics like mustard and ketchup. It all costs something.

[M Fowler]

It might be just all BS I'm not sure but old iron seems to have a tone of it's own.

What you have is a nice Fender Blackface Deluxe type transformer set in that organ chassis running a pair of 6V6 power tubes and 5U4 tube rectifier. All you need to do is figure out what preamp section you want to marry to that power section. The PT doesn't fit any known Fender chassis it is a lot larger in the mounting bolt pattern.

It is a lot of work and takes tube amp knowledge to pull this off.

Mark

[Crossfire]

To an amateur like me this sounds extremely discouraging. I know it'll be worth it in the end. Of course now I gotta figure if my friend can do it or I have to pay someone hourly for the work. I've been kind of putting it off for a while but now I have to make a decision. Many thanks to the great insight

[selloutrr]

Why not build a seperate preamp chassis and connect the two sections together via a multi cable? Similar to the Ampeg SVT
It would cut down on fabrication you would need to custom build a cabinet but if you were smart about your preamp layout and cable connector you could build several different preamps and make it easy to swap.

[Phil_S]

It might be just all BS I'm not sure but old iron seems to have a tone of it's own.
<snip>
It is a lot of work and takes tube amp knowledge to pull this off.

FWIW, I think I agree about the tone of its own. A while back I built a GA20 variant http://home.comcast.net/~psymonds/GA20.htm with recycled iron. I think the OT might even be the same or very similar to what the OP has in his pictures. I have never heard a real GA20, so I have no way to know if mine sounds anything like a real one, but I think it has great tone. As soon as I plug in, it has that Jimi feel to it.

FWIW2, I'll 2nd your assertion about pulling this off. The GA20 thing is in a recycled chassis. It had its challenges. It is about my 10th build, so by that time, I had the knowledge to do it, modified PTP. Ignore those bits of PCB, it was just handy material for closing holes.
Phil

[Crossfire]

A seperate preamp chassis? That's possible? How would that differ from a pedal? I have a guitar with an active system that just doesn't work with a pedal because the tonal clashes of it an a pedal, but works awesome on a preamp built in. That would be awesome. And what would be the average cost of such?

[Cygnus X1]

There are a few organs that yield a lot of parts.
That's the trick for me...parts.

I don't do conversions but I use what I can after completely stripping them out.
A beginner ought to start with a known circuit and see what might fit.

Be aware the power transformer may push a lot more voltage than you might want.
I tend to separate power transformers for larger projects that will have enough current draw to make them behave properly.
Otherwise you are faced with tricky problems trying to bleed off all of that extra voltage.

I've not found a lot of bad output transformers.
I use those as designed.
Usually.

[Crossfire]

Cygnus:can you pm me?