D.I.Y. Hammond Leslie Horn

Compression Horn for Leslie in Hammond T-202


D.I.Y. Hammond Leslie Horn
D.I.Y. Horn made from broken Trumpet for Leslie in Hammond T-202


Getting that Honky Sound

The Hammond T-202 has an inbuilt Leslie speaker which sounds pretty good but only has a 10″ cone with a 2 speed rotating baffle – no horns for that high end and honky air distortion. To modify it I bought a compression driver for £7 (plus around £6 delivery!) from Blue Aran (here) and fitted it with a horn from a broken trumpet. By pointing the horn at the inbuilt Leslie’s rotating baffle I get some modulation too. It works quite well – here is a video recorded on my phone with and without the horn.

Tech Stuff

The compression driver is 8 ohms and I put it in parallel with my 8 ohm Leslie speaker. (This may seem rash since it now presents only 4 ohms to the amp but the non-Leslie speakers in the T202 present 4 ohms so I know that’s OK.) I also put a 22mf capacitor in series with the compression driver to knock out the bass – this capacitor should not be electrolytic since it has to work both ways round.

7 thoughts on “Compression Horn for Leslie in Hammond T-202”

    1. Yes it’s too big to bring to the Dingle! (without help) it weighs in at 235lb! (Also it isn’t acoustic!) G x

  1. Hi George!
    How did you connect it? Do you think this might would work to my L-200? Which also has a built in Leslie.

    1. Hi – the tweeter and it’s capacitor is in parallel with the main speaker. In other words I took the positive terminal of the tweeter straight to the positive terminal of the main speaker, and the negative terminal of the tweeter to one side of the 22mf ceramic capacitor, and the other side of the capacitor to the negative terminal on the main speaker.

  2. Hi George, been reading your stuff intently the past few days as I’m about to pick up (Tomorrow) a “relic’d” T202 to use (in another location) in parallel with my (home) RT-3. Noticing this, and questioning the impedance.. if the driver is piezo based, and you have the capacitor /just so/, that should not be much of a problem. (except the impedance of a piezo/cap pair decreases madly at high (distortion) frequencies, so ma cause the amp some problems) If it’s got a coil in the driver, you really need a proper crossover. (at about 1KHz I’d guess, the xovers in Leslies seem to be 800Hz.)

    I also have a “spare” set of A100/D100 preamp/amp/reverb amp, which i’m thinking of grafting into the T202. The 202 had it’s speakers taken out and was connected to a 145 for the last 30 years. I have a rotor and speaker from a de-amped 130 I’m thinking of grafting in, and probably going to try this driver mod (with a coil-based driver/xover/plastic off the shelf horn) of yours too. Looks very cool! Cheers! Mark.

  3. Hi George. I tried to email you regarding the compression driver idea but your spam filter doesn’t like my roy@royashby.com address.
    I hereby try again with my alias. Hope to establish comms as I intend to build your distortion unit into my T202 along with the horn leslie mod. Thanks for your great site.

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