Chopping my Leslie speaker

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andrew embassy
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Chopping my Leslie speaker

Post by andrew embassy » Fri Feb 10, 2006 4:27 pm

Okay, so I'm not chopping the actual cabinet, but I am going to pull the innards and stick them in a new cabinet for it so I can bring it to gigs. I've got a Leslie model 44W, which is a single speed tube amped leslie.

I'm going to build a cabinet with rotating horn chamber similar (hopefully slightly smaller than) my existing one, and then sacrifice the rotating bass speaker and just go for a standard bass cabinet in a chamber immediately below.

You can see what I mean here:
Image

It won't sound exactly like my current Leslie, but we'll be playing a farfisa into it anyway and I'm into creating new sounds.0 I spoke with an amp tech near me and he's going to modify my existing leslie amp to take a 1/4 jack and use a standard footswitch to turn the rotor on and off; all I'll need is a preamp to bring the signal up to the right levels. I'm tempted to find a preamp and put it in the cabinet too, essentially making it a combo amp...

If you have any suggestions or thoughts or anything, I'd love to hear them. I'm planning on using 3/4" void-free plywood and finishing it with a hard clear laquer, possibly something really hard like epoxy, then a silver Fender-style grille cloth.

One thing I'm thinking about is how large the box is for the bass driver in the original- I'm worried that because my box will be so much smaller, I'll lose some important quality or something- I recognize that the sound is going to be different from a true leslie anyway, with a non-rotary bass speaker, so maybe I shouldn't worry about it. I'm glad I get to use the real drivers and amplifier though, I think that'll keep a lot of the sound intact.

Anyway, if you've got any tips or tricks for the construction I'd be very interested. I think I'm just going to router the louvres on three sides and then leave the fourth side mostly open with a grille cloth covering.

Anybody got any ideas? Words of wisdom? Caution?

Andrew
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Post by andrew embassy » Mon Feb 13, 2006 10:23 am

I pulled the amp from the leslie- my goodnes those transformers are huge. I took it down to Condor Electronics in Freemont, and Kevin is going to put a 12ax7 preamp in it, replace the 9-pin jacks with 1/4" jacks, and put a standard power cable on it.

You better believe I'm going to hook this thing up to pretty much every speaker in the house to hear how it sounds. Anybody ever do this before? This amp is beautiful, here it is (not mine, but it looks exactly like this one- mine's a little nicer, actually). 6V6 tubes and 5Y3 rectifiers = sounds like what amp?

Image

Once that's done it's time to figure out the cabinet is going to be constructed. I think I'm going to use a 12" speaker for the side, to keep the size down. The dimensions are going to be 22x20x22 (L/W/H). I like the idea of it being a cube of sorts. Right now I'm thinking standard 3/4" plywood with 1x1 for supports - anybody suggest anything different?

That means that the interior of the woofer compartment will be basically 14x20x22; anybody have any idea how to figure the port size (or if I should have one at all)? Any suggestions on relatively cheap (< $100) 12" speaker? Damn, I just thought of something, what about 2 12's, on different sides of the cab? That could be interesting. Maybe even do one on each side. Crazy sound.

Anyway, I'll keep you guys posted. Any tips/tricks would be really appreciated.
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Post by apropos of nothing » Mon Feb 13, 2006 3:48 pm

Wow! Color me jealous.

I have nothing useful to add. But I'd sure love to hear some sound samples once y'r done.

I've always fantasized about analog synth through a leslie.

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Post by blakbeltjonez » Tue Feb 14, 2006 9:38 pm

be careful how much signal you put through that amp, the horn driver is probably an old phenolic Jensen and they are typically about 10 watts - too much and the driver will flail. not that it's the end of the world, but it'll be tough finding another original, and tougher still finding a replacement that sounds as good as the Jensen - replacement diaphragms are not made anymore. if you want more durability, get a bigger driver. you may need an adaptor plate though..

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Re: Chopping my Leslie speaker

Post by lg » Sat Mar 24, 2007 8:27 am

andrew embassy wrote:Okay, so I'm not chopping the actual cabinet, but I am going to pull the innards and stick them in a new cabinet for it so I can bring it to gigs. I've got a Leslie model 44W, which is a single speed tube amped leslie.

I'm going to build a cabinet with rotating horn chamber similar (hopefully slightly smaller than) my existing one, and then sacrifice the rotating bass speaker and just go for a standard bass cabinet in a chamber immediately below.
curious how this one turned out- sounds like a great idea. i'm thinking of doing something similar for my compact duo. btw, in terms of a preamp, dumb question, but wouldn't the F/AR unit with a 1/4 out do the job?

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Post by b3groover » Mon Mar 26, 2007 12:13 pm

I missed this the first time around as well. He probably found out very quickly that you cannot just hook any old woofer up to that amp. That series of amp uses a Jensen Field Coil woofer as a choke in the circuit. Without that field coil, the amp will not work.
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Post by WillMorgan » Tue Apr 03, 2007 10:52 am

Regarding port size calculations google is your friend, i think... in any case i found a calculator
http://www.carstereo.com/help/Articles.cfm?id=31

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