Hammond AO-35, AO-39, and AO-44 power amp conversion

[Tubelube]

In regards to Hammond Organ amps specifically theAO-35, AO-39 and AO-44 types, these would be great converted into small tube power amps that can be plugged into modern all tube guitar pre amps. The benefit here is having modern stereo tube buffered series/parallel effects loops with channel switching. This means no complicated weeks on end design, fabrication, prototype testing and so forth. Another plus is having more opportunity to play guitar and spend quality time with our families while still filling our need to modify build and enjoy tube tone machines. Everything is a trade off in life; in this case it is a trade up in every aspect. No wasted time building amp chassis because the existing ones are to cramped (remember we are only converting to power amps) which means no extra tubes, filament transformers, power supply stages, tone controls, resistors/caps etc.... We will not have to build wooden amp cabs either. I plan to purchase two 1x12 inch speaker cabs and mount an organ power amp in each one for stereo, no wood working required. The biggest benefit here is; there would be no way for the speaker and amp chain to get unplugged by clue less band mates. No more burned up amps due to no loads on the output tubes. There is another very important aspect also; this paradigm creates two dedicated signal paths (true stereo). No need for a parallel effects loop on your modern all tube pre amp. Most of all the affordable tube pre amps have at least a serial effects loop and channel switching/stacking designed into them. This would mean not having to drop your whole bank account on an over priced tube preamp just to get a parallel effects loop with a mix control (for adjustable wet/dry parallel signal mix). A low cost used B.K. Butler rack mount Real Tube Two with channel switching and stacking and serial effects loops for each channel would work just fine and can be found used for around $100 dollars. If you are going with two organ amp powered speakers (for stereo) go with the even cheaper (under $100 dollars) Rack mount Chandler Tube Driver or equivalent. The Chandler has a series effects loop; it is just a single channel. Get two of them for stereo (Two dedicated effects loops with all the pre amp controls of each pre amp for each channel). All Rack mount preamps have optional foot switches for even more control. There is a device made by Tonebone (Radial) called the Switchbone that can switch between channels or preamps in this case with one stomp, it is a powered pedal that can switch between channel A and channel B or switch both on a the same time. There is a polarity phase switch on the devise that allows you to keep your pre amps in phase and a pickup drag switch. Because the Switchbone is powered (12 volt DC wall wart) it doesn't cut your pick-up impendence in half when both channels are being used at once. Tonebone also makes a device called the Bigshot Mix that allows you to mix any ratio of wet to dry flavors into your signal chains or effects loops. I am not affiliated with any companies in this writing; one of them is even out of production. I am only trying to keep the AO-39, AO-44 and the AO-35's out of the land fills and do my part for the environment. I have personally witnessed at least eight Hammond organs containing these amps thrown out and destroyed over the last five years. I would have saved all these amps if I had known what to do to make them useful with out spending weeks trying to make them into guitar amps. I would happily save them if I knew how to make them into power amps as it would require far less effort and cost and knowledge. If a few of this sites knowledgeable designers could post schematics with the few changes needed to convert these tube rectified organ Jems into cool power amps it would help us all preserve these treasures for our children's children and many other tone aficiacondous to come. Remember there are only so many left, the supply is finite; let's create a demand before they are all trashed out! You can try to keep them a secret in order to get them cheep or you can think of others to come and take the high road! Thanks to all you engineers and enthusiasts who care! Gary

[Phil_S]

Wow, lotta verbage to wade through....the Hammond chassis pulled from an organ retains decent value. eBay price on these is around $100. The only reason to send it to a landfill is ignorance. People who've had these in their basement, living room, house of worship, rec hall, etc., are often clueless about the recycling potential. They just want is gone. I'm not really sure how to reach the audience. Respectfully, I think you'll find plenty of agreement with your main point here, but not people who can change the minds of those who don't know.

[Tubelube]

Phil _s your just the guy who could shed some light on this conversion topic. This would be nothing for you, you could sleep walk and solve this one. I have two AO-39's I want to convert to power amps for stereo got any ideas? I want to install a volume control on them also.

[Structo]

Man, that is a lot of words.

Maybe paragraphs next time?

[martin manning]

There is already a thread on Hammond conversions. See the "sticky" at the top of this sub forum.

[Phil_S]

I see the same rarbling post at AX84. Note to the OP: this is a limited audience. You probably expand your audience by no more than about 20% by that cross post. Also, I wouldn't be surprised if no one at AX84 responds. How many more places did you post that? Really, it is nearly impossible to understand the aim of the post. If you really want help with something, you are likely to get it here if you can express the need clearly.

I'll say this. Anyone who has a good supply of Hammond chassis headed for the scrap heap can sell them on eBait. In a week or so, you'll have enough money to build your dream amp and you won't have to fiddle with repurposing, which, IMHO, can be more trouble than it's worth.

[Tubelube]

I didn't post in any more than the two you mentioned. I didn't realize the same people frequented both sites, I would not have posted in both had I known. It was not my intention to tick people off! Sorry if I offended any one! I will abstain from rambling on in the future. Thank you all for giving me constructive feed back, it is well taken and will be adhered to. Regards!