Leslie Preamp Options

[Drawbar Dave]

I bought a combo preamp for my 147 a few months ago because I wanted to be able to run my Farfisa Compact Duo through it occasionally. Well the combo preamp makes it sound nasty and shrill (even for a transistor organ). I knew that combo preamps had a reputation for being noisy and primitive and I totally agree.

I don't want to spend a lot of money on a Trek preamp because I'm unlikely to stray from a 147 and I don't need the extra hookups. I'm interested in using a spinet tube amp as some people on here have done. So what's the deal with the L100 amp? I believe Pete has gone this route. Do you use just the preamp or do you need the power amp too? Is there a better Hammond preamp to use? I am unfamiliar with anything other than the AO28,29 and 44!

[Sweet Pete]

This L100P amp chassis really drives a Leslie the way it was intended.
This one has different molex pinout configs than a stock L100.
That being said thanks to Adam M who helped me out on that! That it has a working 122 kit already on it was pretty cool!
Added bonus is the ability to run a spring verb properly.The 12BH7 tune on 'verb to me sounds more like a useable effect.
Your Farf or any organ 'clone' will be much happier at it's destination sent through those tubes than a CP pedal.
I also removed the treble click filter disk caps.This thing screams great tone with my C2D also.
I needed to run three Nord 'organs' and the high level output on the C2D can't be shared.....so this little puppy sums them no problem.
Makes the 'drive' dial on the C2D laughable for sure.....you'll need less of that......haha.

[Drawbar Dave]

Thanks Pete! So this is basically an AO-43 with extras in the case of the L100P? So the output of my Duo or line level from a synth should be hot enough to drive it without a preamp? I need to try and find out what kind of signal I'd be putting in. The Duo is run at a third of its master volume into a Binson Echorec. The Binson distorts if I hit it any harder. This would be a rewarding winter project. My first organ was an L122 but I never really delved into it other than rebuilding the motor so I'm not familiar with this amp.

[Sweet Pete]

Even though the L100 is considered a 'light weight' by many,that AO43 is an absolute tone monster IMO.
Removed the click filters,added a little more gain.Best for a clone Leslie preamp I've used in every way.
Farf is a little brighter so remove those disc caps!
Doon has one I sent him and uses it for guitar I believe?
That includes running clones through the A100 preamp!(AO28)!

And it was inexpensive.
Modern keys are line level just like the L100 preamps,give or take.
So many have been parted out,might as well redeem the amp at least.

[Sweet Pete]

Regular L100 has no Leslie kit built in. This '69 L100P unit has the 122 type along with an extra outlet!
A 40 dollar 'Leslie kit' with a great little amp on it!Add tubes and a few more things,I'm all in for 100.
I still use my CMP's for Leslie motor rebuild jigs.... ;>),and test an amp occasionaly.

There must be an unused L100P in the UK somewhere?
Or in mainland Europe?

[Drawbar Dave]

Awesome! I will look for one of these. It sounds perfect.

[dbsoundman]

Another simpler option is the "classic" technique of using the ART Tube Pro MP preamp (like $50) to boost the output of your Farfisa into the Leslie. However the L100 amp sounds like more of a fun project!

[Drawbar Dave]

I have managed to find an AO-43 from a stock L100 that someone had left over after chopping their organ. I'm really looking forward to this project when it arrives.

[Drawbar Dave]

I've managed to figure out what changes to make from the schematic and do not have to worry about the B+ as it will be driving a 147. The only thing I want to check is whether the speaker output on the AO43 needs a 16 ohm load across it when I send it to the 147?

[Sweet Pete]

Funny,I never actually measured the ohms out of the 'AO43'......however,the green+ and black- speaker wires hang directly off 147/6W pins 1 and 6 no problem!
Your Farf should sound awesome through it!

[Drawbar Dave]

Thanks Pete I saw the speakers on the schematic attached but was wrong anyway as they were parallel so it would have been 8 ohm load. Good to know I won't have to worry about a load resistor.

[Drawbar Dave]

Got it today. Already converted and working although I still have to replace the electrolytic and snip out the click filter disc caps. It appears to have too much gain for the output of the Binson Echorec or even the Farfisa on its own. I wonder if I can swap out the gain pot to a different value or change the adjacent resistor. Thoughts? Bags of power like you said Pete!

[Sweet Pete]

I use a little passive 4 channel 'mixer' on the input of the AO43.It sums whatever I need to put through a Leslie.
It's about 30 years old,made by DOD.It was 30 bucks back then.Has really good 1% resistors along with 100K pots.
Switchcraft 1/4" too! Back when they were made in North America.....have played some big shows (40K people)
and used it no problem.Keys sound great through it at line level.I have three of them.....a whole 75 bucks back then LOL.
You can see one of them at the 'front' of my pedalboard.They are blue......
I suppose one could change the input levels on the AO43.....I need a passive mixer though.
I actually tried 'keyboard mixers' and owned an Ashly,and a Tapco.These passive boxes sound better.
The only other mixer I recommend is the Key Largo that is not cheap.....it also handles line level with ease.
All they do is adjust levels.I stopped using EQ on a mixer as soon as I could......about 1990.
I ran my keys through them at a recording session in December.I trust them that much.And they were cheap......

[Sweet Pete]

[Drawbar Dave]

Thanks for the info. I added a 100K input pot and it's perfect now. Set at 12 o'clock position.

Also it didn't come with the 12AX7 shield. Is this worth getting?