A Little help Needed To Identify

[dorrisant]

I have an organ amp of unknown (to me) origin...

Someone gave this to me with a 12" field coil speaker that seems to be original to this amp.

Tubes are (from left to right):
5U4, 6BA6, 6V6GT, 6V6GT, 6SN7, 6SC7, 6SJ7, 6SJ7

TX Numbers:
H-AO-20994-4 and AO-20936-0

Speaker Numbers:
AO-21055-2, 285305 and 8835 stamped on the frame
42H8001 stamped on the cone

Does anyone have any clues? I'm trying to find a schematic...

[dorrisant]

More pics of the chassis...

[dorrisant]

Some pics of the speaker...

[victubeamps]

My guess would be a Hammond Electric Organ amp.
I had parts from a Hammond (M-2?M-3?) amp that looked similar -I used the field coil speaker to rebuild a Valco amp.
AFAIK- Hammond organs have nothing to do with Hammond Transformer Mfg (Guelph, Canada) - different companies.

[sluckey]

It's a Hammond Organ M2 Amplifier AO-14. Schematic is on Captain Foldback's website.

Here's one on eBay...

http://www.ebay.com/itm/Vintage-Hammond ... SwFqJWnVYE

[dorrisant]

Thanks guys, I'll take it from here...

[The New Steve H]

Arrgh. I hope that wasn't out of a decent Hammond. There are so many crap organs out there that aren't worth saving; it's a shame to wreck a nice one.

[DenDanger]

Yes, field coil speaker.
Seen them in schematics, never seen one in person.
The AO numbering is all Hammond Organs. They put them on everything.
Have fun with it!

Denny

[Stevem]

And it's a Rola made speaker.

[dorrisant]

Great! I scored some good stuff here... and no I did not kill a whole organ to get it... This got passed along to me from someone who yanked all the parts he could out of a badly damaged unit. Seems it fell off of a loading dock many years ago... been sitting on a shelf for over 30 years. Glad he had the presence of mind to pull all he could.

I'm thinking of trying a 65 Amps Soho with these parts... maybe reuse the terminal boards and anything else I can recycle. I have an Epihone Valve Standard chassis and cab (1x12") that are near perfect for this project...

Possibility... I could use something along the lines of a VVR circuit to raise and lower the voltage to the field coil... This would reduce/increase the SPL from the speaker. Any ideas on this? If so I may just start a new topic and sort out the details there.

[victubeamps]

Great! I scored some good stuff here... and no I did not kill a whole organ to get it....

Even if you had dismantled an old Hammond, you needn't feel any guilt IMO. If I had a truck and some strong helpers, and the ambition, I could intercept a half-dozen Hammonds on their way to the landfill every year - and I don't live in a very big city. People can't give away organs nowadays. A piano or (for the more wealthy) an electric organ was a standard thing in many homes in the 50s and 60s. Not today - and when the old folks move into the seniors place or downsize into a condo, nobody in the family wants the organ/piano. (It's sort of the same story with console hi-fi units, but that's another side of 'scrounging' .. )

Possibility... I could use something along the lines of a VVR circuit to raise and lower the voltage to the field coil... This would reduce/increase the SPL from the speaker. Any ideas on this? If so I may just start a new topic and sort out the details there.

Are you planning to power the field coil 'independently' or use it as a choke in the power supply?
Looking at some old Valco and Premier schematics may give you some ideas.
I'm not sure that dropping the field coil voltage will give you a good decrease in 'volume'. Would swapping in a lower-power permanent magnet do the job in a regular speaker? I'd be wary that 'user error' would end up over-driving the voice coil when the field was 'down'. But, it's an interesting idea.
I have field coil speakers in a couple of amps - the Valco with the Hammond Rola and also a Premier 76 which I rewired to a Tremolux. The Valco/Hammond is more 'bassy'.

[Leo_Gnardo]

Not today - and when the old folks move into the seniors place or downsize into a condo, nobody in the family wants the organ.

There's always a home for wayward Hammonds & Leslies around here. Could it be a coincidence the biggest Hammond buyer/seller is also one of the biggest - funeral home owners? (Put big sad sounding organ lick here.)

[dorrisant]

The idea stems from what Fluxtone is doing... Not using the field coil as a choke but feeding it a variable DC supply to get the SPLs down. I may not do it... I may just use it as a choke in the PS and leave it at that. I just like to take the opportunities given to experiment when the stars line up.

https://www.youtube.com/watch?v=iWINn9sy8xQ

[victubeamps]

The idea stems from what Fluxtone is doing... Not using the field coil as a choke but feeding it a variable DC supply to get the SPLs down. I may not do it... I may just use it as a choke in the PS and leave it at that. I just like to take the opportunities given to experiment when the stars line up.

https://www.youtube.com/watch?v=iWINn9sy8xQ

Thanks for giving me a 'heads up' on that whole idea. Lots to think about...that Valco is too loud for me, so maybe (one day!) I'll play with the Fluxtone idea with the FC speaker.
Watching and listening to a few YT videos on the Fluxtone, it certainly seems like an effective system.
Is anybody still making FC speakers for instruments? (I know there are hi-fi FC speakers, but expen$ive.)

[dorrisant]

Last I knew Fluxtone will pull the magnet off of some of the more popular speakers (Celestion for sure) and replace the mag with a field coil and variable supply. The cost was prohibitive, don't know if they are still priced the same.I don't know if FC speakers are manufactured by others but there is no reason they cannot be made by modifying an existing speaker. It may not be easy to do but is certainly possible.