Ultimate Hammond Conversions thread
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Re: Ultimate Hammond Conversions thread
I spent 5 mins going over the chasis looking for a AO# and couldn't locate anything. The underside has 13 written with a green marker.
Re: Ultimate Hammond Conversions thread
I've never seen that one. The PT and OT are the same as found on the AO-29-13.
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Re: Ultimate Hammond Conversions thread
measured and calculated these awhile back
ao-24924 output transformer 7k4:8
ao-24110 power transformer
red-red/yellow-red 350v-0-350v
brown-green-brown 6.3vct
yellow 5v (3A since this runs a 5u4)
shame didn't come with the ao-43 chassis that was likely in the organ with it. two ecl86 tubes are fun to mess with (especially if you add another 12ax7)
ao-24924 output transformer 7k4:8
ao-24110 power transformer
red-red/yellow-red 350v-0-350v
brown-green-brown 6.3vct
yellow 5v (3A since this runs a 5u4)
shame didn't come with the ao-43 chassis that was likely in the organ with it. two ecl86 tubes are fun to mess with (especially if you add another 12ax7)
PRR wrote: Plotting loadlines is only for the truly desperate, or terminally bored.
Re: Ultimate Hammond Conversions thread
The AO-43 uses 6BQ5/EL84. The PT is AO-24157-1 and OT is AO-24158-0.thetragichero wrote: ↑Fri Jan 01, 2021 10:29 am shame didn't come with the ao-43 chassis that was likely in the organ with it. two ecl86 tubes are fun to mess with (especially if you add another 12ax7)
The AO-44 uses ECL86/6GW8. The PT is AO-24956-1 and the OT is AO-24158-0 (same as AO-43).
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Re: Ultimate Hammond Conversions thread
meant 44, typed 43. hammond's numbering convention seems about as useful as marshall's
PRR wrote: Plotting loadlines is only for the truly desperate, or terminally bored.
- dragonbat13
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Re: Ultimate Hammond Conversions thread
Amp and preamp out of L74 Baldwin. Have all Baldwin tubes. All kinds of extras. Fused leads off power transformer. Flyback diodes on the OT.
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Re: Ultimate Hammond Conversions thread
Hammond S-1 to 5E4A. Thanks for all the knowledge on here. I didn't want this sticky to die
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Re: Ultimate Hammond Conversions thread
Sweet amp, man. I have heard some seriously good conversions using Old Hammond iron.ok_state_blues wrote: ↑Sat Jan 22, 2022 2:51 am Hammond S-1 to 5E4A. Thanks for all the knowledge on here. I didn't want this sticky to die
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Re: Ultimate Hammond Conversions thread
Yes it works great as long as you can tame the voltage. Captain foldback has been a very valuable resource. Now I know what to do with the field coil PT's!Colossal wrote: ↑Sat Jan 22, 2022 1:21 pmSweet amp, man. I have heard some seriously good conversions using Old Hammond iron.ok_state_blues wrote: ↑Sat Jan 22, 2022 2:51 am Hammond S-1 to 5E4A. Thanks for all the knowledge on here. I didn't want this sticky to die
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Re: Ultimate Hammond Conversions thread
Hammond AO-14 to Matchless Lightning.
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Re: Ultimate Hammond Conversions thread
Have any of you Hammond builders run these amps with a mis-matched speaker load? If so, were there any negative effects noticed? I have two AO-43 and one AO-35 converted to circuits for guitar, and I always use a 8 ohm speaker load. Just wondering if these would be fine with a 4 ohm or 16 ohm speaker load. I know that Hammond iron is known to be pretty robust.
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Re: Ultimate Hammond Conversions thread
I have run the AO-43 OTs with 8Ω and 4Ω speaker loads with no ill effects.
Re: Ultimate Hammond Conversions thread
FWIW, I tried both of my AO-43 amps through 8 Ohm and 4 Ohm cabs. A single speaker at 8 Ohms and a pair of the same speakers in parallel at 4 Ohms. They both sounded fine with either load, and the transformers did not get hot. I did notice a slight drop in volume at 4 Ohms. I guess that is to be expected if the OT is designed for 8 Ohm load.
Re: Ultimate Hammond Conversions thread
Here's my latest Hammond conversion. AO-43 to something resembling a modified Princeton reverb with a cathode biased 7189 back end.
I lifted a transformerless reverb driver from Merlin’s site and the LND150 recovery stage (I think) from a fx loop schematic? Cant quite remember where I stole it from or who to credit. The reverb switch is backwards, down being on. Couldn’t figure out how to easily reverse it without making the wiring more of a headache. There’s a foot switch anyway… TMB tone stack, no negative feedback, Vox cut control (sparkle). Planning another with a master volume, neg feedback, and no cut control.
I’m pretty happy with the layout, aside from the upside down reverb switch. Kept the original PWR and REVERB SW. markings/functions. Used every original eyelet and tag strip (excluding grounds) and only one added turret attached to the treble pot. I kept the reverb choke in place and added another dropping resistor before it for good measure. The amp has a very low noise floor and sounds pretty good to me. Reverb is very surfy. I would be happy to hear suggestions for improvements if anyone has them. Not all of the values on the layout are exactly what I ended up with. I tend to change my mind on details mid build. I made a time-lapse video of this and a handful of other hammond conversions I’ve done this year if anyone is interested.
I’m pretty happy with the layout, aside from the upside down reverb switch. Kept the original PWR and REVERB SW. markings/functions. Used every original eyelet and tag strip (excluding grounds) and only one added turret attached to the treble pot. I kept the reverb choke in place and added another dropping resistor before it for good measure. The amp has a very low noise floor and sounds pretty good to me. Reverb is very surfy. I would be happy to hear suggestions for improvements if anyone has them. Not all of the values on the layout are exactly what I ended up with. I tend to change my mind on details mid build. I made a time-lapse video of this and a handful of other hammond conversions I’ve done this year if anyone is interested.
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- dragonbat13
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Re: Ultimate Hammond Conversions thread
That's a very nice conversion. From what I've heard conversions are difficult. Yours makes it look even more challenging. If I could ever get caught up I want to mess with my Baldwin.