Hammond AO-43 Guitar Amp Build Options with Amp Layout

[Yamariv]

Hey Guys,

I'm new to this forum, first post! I've just picked up an AO-43 chassis with original Hammond tubes and would like to convert it to a guitar amp. I was hoping to do an 18 Watt Marshall conversion using the Hammond PT, OT and choke if possible. I've been researching for the past couple of days and am reading everywhere that the PT is too hot to just run the EL84's and am wondering if this conversion can be done reliably and safely?

I'm thinking that a 6V6 Plexi conversion is the best option for this iron but I'm not sure if it will be worth it as I already have a JTM50 Clone in my amp arsenal. Would I notice much of any sound difference just by having 6V6's? Any other amp suggestions? I have a VOX AC30 as well so doing an AC15 clone would be a bit redundant for my needs as well.

I have great soldering abilities and have build many pedals and just finished restoring my Dynaco ST70 Stereo amp and am confident working around high voltage electronics and know how to drain the caps etc prior to working on the guts. My theory and diagnosing skills are to be worked on though as I have no formal electrical training which is why I'm hoping to find an amp layout instead of a schematic for this conversion that I'm hoping to do.

Anyone know of someone who's done an 18 Watt Marshall or a 6V6 Plexi and has a layout diagram done? If so, please send me the link as I haven't had much luck on finding any.

[thetragichero]

hello
i believe there's a Hammond conversion sticky thread that may have ideas for you
in a bit perplexed by the concept of the power transformer being *too hot* to run el84s... isn't that what the stock amp is made for? were you planning on going with solid state rectification?
i've been wrapping up the speaker cabinet and headshell builds for my own ao-43 conversion... it's a little bit vox, a little bit orange, with a one tube reverb driver/recovery (made use of the 12dw7 from elsewhere in the organ and the killer gibbs reverb tank). no layout because i did point-to-point/terminal strips and figured it out as i went
i guess figure out what you want it to sound like and go from there? I'm not nearly as up on the theory as i should be... i piece together a little bit of this and that and plug stuff into online calculators

[Yamariv]

Yeah that's what I first thought about the AO-43 being perfect for a nice 18 watt Marshall clone but in all the research, I guess the PT puts out about 30v per side too much. It's rated at 320v where an 18 watt Marshall would need 290v per side. I'm no technical guy but I'm learning and from what I understand the voltage was a bit higher in the A0-43 to run other things in the organ as well as the EL34's.

So given that, I'm looking at something cool to build with a 6v6 platform which will suit the A0-43 better. I have a JTM50 so going with a 6v6 Plexi build won't sound different enough to me I'm guessing. I'm kind of intrigued by the 6v6 Jubilee amp Dorrissant built a few years back.

Anyone have any other suggestions?

[sluckey]

I built a Supro S-6424 using an AO-43 as a donor.

[M Fowler]

Make a 6v6 Marshall fire breather!

[sluckey]

Fender has several 6V6 amps that would do well with the AO-43 iron... Deluxe (tweed or blackface), Deluxe Reverb, Princeton, Princeton Reverb, Harvard.

[Yamariv]

Does anyone have or know of any good wiring layouts to do a 6V6 Plexi? My schematic reading needs alot of work Do the 6v6 Plexi's sound any different than say my JMP50 clone?

Yeah, I'd love to do a Fender but I have a 5E3 on the way already unfortunately..

Could this amp support a 6L6 Duluxe maybe or are 6L6's just too power hungry? Maybe a non GC 6L6 style Fender amp could be powered properly by the Ao-43?

[pompeiisneaks]

any plexi layout would work, just change the components around the power section. It's not a massive change to change the power section, new grid stoppers, new screen resistors, different PT and OT but the rest of the layout is going to work as previous.

~Phil

[M Fowler]

The amp can support a pair of 6v6's whether you want Fender Deluxe Reverb or Marshall Plexi which to me the Marshall Plexi is not very exciting as a high gain would be.

If you don't have a Fender Deluxe Reverb then this AO-43 would be a good candidate like Slucky said.
Slucky has great build info, board making, layouts and schematics.

Mark

[Yamariv]

Ok, cool makes sense! Since I already have my JMP Plexi I'm not sure it would be worth making a 6V6 Plexi, plus I have an AO-50 on the way from Ebay to make an 18Watt Marshall clone so I think I have most Marshall stuff covered.

Member on here @Dorrissant had built a Silver Jubilee which would be a bit more high gain..that's still an option..

Interesting about @slukey having some layouts and possible turret boards A 6V6 Deluxe Reverb might be in order then as I don't have one of those! I always thought the Deluxe Reverb was a 6L6 power tube amp..interesting

[sluckey]

It would be worthwhile to take a look at this web page...

https://el34world.com/schematics.htm

[Yamariv]

Awesome Sluckey, I checked out your page! Very cool that you have all those layouts and amp options for us! One question, are these amps all your take on original circuits ..as in you've changed the circuits alot from the originals or are they true to the original circuits?

[sluckey]

Awesome Sluckey, I checked out your page! Very cool that you have all those layouts and amp options for us! One question, are these amps all your take on original circuits ..as in you've changed the circuits alot from the originals or are they true to the original circuits?

That's not my website. Belongs to Doug Hoffman. Everything you see there is available in his web store.

[Yamariv]

Oh ok cool, sorry my mistake. Does anyone know if those circuits are true to the originals or his take on the circuits with mods done?

[sluckey]

Some are true to the original schematics. Others incorporate some of Hoffman's own ideas. All use Hoffman's own layouts.