DIY: Leslie Combo Preamp

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lanxe

Well-known member
Joined
Jul 15, 2004
Messages
107
Location
Carson City, Nevada USA
I did a search on schematics and didnt come up with anything

Rather than spend the $350 for one, it doesnt seem to crazy to make one. maybe?

BTW its a Leslie 147 that i want to jam some guitar into. I have heard of people putting a 1/4" jack in there and just using their guitar amp to drive the horn/speaker but i am not intrested in that. i want to use the leslie amp.

Thanks,
Ryan
 
I have a schematic of what you seek... As well as alternate(modern) trasistor replacements. We have one at work that is currently sick... When you run it with anything 1/4 it trips the internal circuit braker and shuts off... currently looking into the cause... I can get that schematic to you as well as circuit board graphics
 
As far as I know the leslie input is kinda symmetrical ('electronically balanced' with a tube). I used to use a normal xlr as line input for the leslie because I wanted to get rid of the bloody cable. Nevertheless the preamp has a higher sensitivity and might add some distortion as well.

Michael
 
I've been wanting to do the same thing. I like running my rhodes through the leslie, but I'm having to pass the rhodes through the hammond right now. I'd love to have the standalone preamp so I could take the lesle and rhodes places and leave the organ at home. I'd love to hear if anyone manges to build one (especially a tubeless version), cause I'll probably try myself at some point.
 
[quote author="fazeka"]FWIW, it's available here.[/quote]

Yes that is the schematic... Here are the new replacements for the transistors/DIODE. they are all made by NTE


For the Diode use a NTE 117 which is a general purpose rectifier

For q1 and q2 on the schematic, Use a NTE123AP which is an npn transistor

For q3 and q4 use a NTE199 which is a high gain amplifier another npn transistor

lastly for q5 use an NTE128(NPN) audio output/video driver...
 
[quote author="pucho812"][quote author="fazeka"]FWIW, it's available here.[/quote]

Yes that is the schematic... Here are the new replacements for the transistors/DIODE. they are all made by NTE


For the Diode use a NTE 117 which is a general purpose rectifier

For q1 and q2 on the schematic, Use a NTE123AP which is an npn transistor

For q3 and q4 use a NTE199 which is a high gain amplifier another npn transistor

lastly for q5 use an NTE128(NPN) audio output/video driver...[/quote]

Cool, thats waht i needed to know. Thanks pucho.
Ryan
 
Ok,
I am going to mill some PCB's soon (i may make a couple if anybody is interested in one). It will be the same layout as the links provided from captainfoldback.

I had a couple of questions though.........just double checking.

for the transformer T1
is the secondary 34VAC ? or is that after D1.....ie if i buy a 34VAC trasformer, i will be ok?

some of the capacitor labels are throwing me off too. like look at C8 that is labeled 200/50 ...... does that mean a 200uF 50V cap? how about C5 that is labeled 50/15.......50uF 15V? i am a bit confused with that.

Other than that, i think it should be pretty easy to do. oh, here is the schematic.
schematic.jpg


Thanks again,
Ryan
 
yes it's a 34V secondary on the transformer. Yes the cays are 200UF/50V and so on...

We have a guy right now at work who is making one on breadboard. Only problem he ran into was he was sent a 8 pin Amphenol instead of a 6 pin. mistake on the company he purchased it from... But it happens
 
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