baldwin amp conversion

[Cygnus X1]

Thank you LT.
So, to make sure...a 1K5 on pins 5 and 6?

[loudthud]

So, to make sure...a 1K5 on pins 5 and 6?

That will usually do the job in a 6L6 amp.

[rcrmck]

I'm a new guy, so pardon me if I'm giving advice out of place, but I completed the conversion of a Hammond Tone Cabinet that had only rectifier, phase splitter and 6v6 tubes.

I found that it was expecting to see what it called a "Balanced G+G Input". Perhaps yours is expecting the same. I wired it up according to Hammond's instructions for connecting a Line Out to a Tone Cabinet: HammondWiki - Line Out To A Hammond Tone Cabinet

I can now use the line out from my 4-channel mixer to drive it (which sounds amazing) as well as the speaker-out of any of my solid state amps (modifications would be needed to connect a tube amp speaker out). They all give it a very different tone. I just bought a vintage preamp/echo/reverb that was removed from an old 60's amp, and I will be installing that as the permanent preamp section for the organ poweramp.

If you're looking for an easy, sweet sounding way to drive that organ poweramp, this might be something to try. When I did it, I just mocked it up temporarily while I tested diferrent amps to see how it sounded. After the test was done, and I knew it was going to sound good, I soldered it up.

[olddawg]

Here is what I would do. I would pull the power transformer and one output transformer. (It's a stereo power amp right?)
I would buy or make a new chassis. By using only 2 output tubes and an LED power indicator you should be able o free up enough filament current for more preamp tubes. Then I would pick a 2 X 6L6 guitar amp you like and build a new turret/eyelet board. You can try to reuse other parts if you wish, but I would recommend new stuff, especially tube sockets and electrolytics.

[Cygnus X1]

Good stuff guys.
What's a solid state speaker?

olddawg-I'd have to look but I think the PT has enough beef to run whatever
preamp I...or we decided to go with.
It drives the ancillary components such as the tone generator circuit, outboard reverb and Lesley...etc.
Most of the organ amps I have carry PT's twice the physical size than you normally see on a similar
amp in the guitar amp world.
It isn't really stereo, but it's 90% of the way there.
It would need a matching output transformer to make it so.

100 pounds of tone!

[Rhodesplyr]

I'm not sure that your amp does have two output transformers. To me, it looks like you have four 6L6Gs in parallel push-pull, not an uncommon arrangement back then. Another clue is the coils attached to the output tubes to prevent parasitic oscillation--a potential problem with parallel push-pull.

I may be misreading the photo, but I think one of your output transformers (the one closest to the power transformer) is actually a large filter choke. If it only has two wires coming in and out, it's a choke :-)

[Cygnus X1]

I thought it was a choke also until I unbolted it.
The tubes are not running in parallel...and that is another transformer.
Details at 11.

[Casey4s]

I assume mine is just a power amp with dual OTs for running separate cabs but with only a single 12ax7 which I guess each side of the preamp tube drives each set of 6L6s each with a 5U4 rectifier. I haven't fired it up or done anything to it yet and just got a set of tubes for it recently. I have to figure out the PT hot and neutral windings to wire in a power switch.

The "transformer" next to the PT on your chassis is the choke, not another OT. You can see two wires comming in from the grommet, look how many the OT has. Lots of HiFi chokes are as big as the pT sometimes, just look at the size of some of the chokes at hammond.com. Most of us are used to seeing the little chokes on most guitar amps.

[Ran Randle]

Thanks, that makes sense. I didn't realize they were that huge. This project was on hold for a while.

[Rhodesplyr]

High-quality chokes--with high inductance and low DC resistance--tend to be larger. Hammond Manufacturing, the transformer company, makes a 193Q choke: 5 Henries, 53 Ohms DC resistance. It weighs [drumroll] twenty-one pounds! No, I'm not planning to use one anytime soon ;-)

[Ran Randle]

So I got the bladwin working with the original circuit as is but it has very low output.

Is it ok to run 6L6GCs when it takes 6L6Gs? I know the plate voltage for the 6L6G is @ 19w and 6L6GC is @ 30w so is this going to cause any problems or just cause low output because the 6L6GCs aren't getting the higher plate voltage they need? I only have 2 6L6Gs on hand so not able to try it with a set of all four 6L6Gs it requires. I'll post some updated pics soon.

[Ran Randle]

I'm a new guy, so pardon me if I'm giving advice out of place, but I completed the conversion of a Hammond Tone Cabinet that had only rectifier, phase splitter and 6v6 tubes.

I found that it was expecting to see what it called a "Balanced G+G Input". Perhaps yours is expecting the same. I wired it up according to Hammond's instructions for connecting a Line Out to a Tone Cabinet: HammondWiki - Line Out To A Hammond Tone Cabinet

I can now use the line out from my 4-channel mixer to drive it (which sounds amazing) as well as the speaker-out of any of my solid state amps (modifications would be needed to connect a tube amp speaker out). They all give it a very different tone. I just bought a vintage preamp/echo/reverb that was removed from an old 60's amp, and I will be installing that as the permanent preamp section for the organ poweramp.

If you're looking for an easy, sweet sounding way to drive that organ poweramp, this might be something to try. When I did it, I just mocked it up temporarily while I tested diferrent amps to see how it sounded. After the test was done, and I knew it was going to sound good, I soldered it up.

Thanks for that info, I will see if that will work with this amp.

[loudthud]

Is it ok to run 6L6GCs when it takes 6L6Gs? I know the plate voltage for the 6L6G is @ 19w and 6L6GC is @ 30w so is this going to cause any problems or just cause low output because the 6L6GCs aren't getting the higher plate voltage they need? I only have 2 6L6Gs on hand so not able to try it with a set of all four 6L6Gs it requires. I'll post some updated pics soon.

Not a problem to run 6L6GC in this amp. 5881 is also an option. 30W is a maximum rating, the tubes don't need to be run at maximum.

[Ran Randle]

Here is what I would do. I would pull the power transformer and one output transformer. (It's a stereo power amp right?)
I would buy or make a new chassis. By using only 2 output tubes and an LED power indicator you should be able o free up enough filament current for more preamp tubes. Then I would pick a 2 X 6L6 guitar amp you like and build a new turret/eyelet board. You can try to reuse other parts if you wish, but I would recommend new stuff, especially tube sockets and electrolytics.

I think this is the way to go, thanks. I was considering this 5E5 layout but may go with something else. Is this 5E5 a good match for the PT and OT on this baldwin? Can't seem to find any info on the PT windings (512-14512F) stamped on top....

[Ran Randle]

Thanks LT