Hammond Auto-Vari 64 Drum Module Project

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Hammond Auto-Vari 64 Drum Module Project

Post by Uncle Screwtape » Sat Jul 02, 2016 8:44 am

Not sure if this is a big deal, but it is for me. I just finished figuring out how to trigger the Auto-Vari 64 voicing board so I can turn it into a module! I'm so excited, and think this is the only place (esp. at 3am) that I could tell anybody who might give a $#!T. Anybody around here would be like :? -uh... cool.

I've only got a circuit set up for a single voice so far. Will be breadboarding the other 10 over the coming days while I order and await some other items I'll need to move forward. More news (and maybe a few pics) to come.

Time for a nap.
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Re: Hammond Auto-Vari 64 Drum Module Project

Post by commodorejohn » Sat Jul 02, 2016 7:35 pm

Awesome :) Post a demo when you've got it all up and running!
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Re: Hammond Auto-Vari 64 Drum Module Project

Post by Virgule » Sat Jul 02, 2016 7:43 pm

Very interesting. I had one when I bought my first Hammond (and an Acetone FR8L with my 2nd purchase).

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Re: Hammond Auto-Vari 64 Drum Module Project

Post by Blue Monster 65 » Sun Jul 03, 2016 3:56 am

Yeah - I'll look forward to a demo of this when you're done as well!
Muhahahahahahahahaha!

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Re: Hammond Auto-Vari 64 Drum Module Project

Post by Uncle Screwtape » Tue Jul 12, 2016 7:41 am

OK. I've wired up all 11 voices. Here's a brief "proof of concept" video with the results:

https://youtu.be/YXu3Ndh4FeA

I've got some other plans in store, so it will be a while before I build this into a finished box. Once I check this board against a known working unit, I'll make the required tweaks and at least solder up the trigger circuits.

As for moving forward, I've got a couple of questions. I'm looking to add pitch and decay adjustments to some of the voices. In doing so, I also want to build in options that will retain the original character of the unit, so:

1) It would be very easy for me to include a switch that provides, "original, 2x and, (3 or) 4x" decay options. Would that be acceptable, or would it be preferred that the decays are continuously variable. So far, I have found that in order to retain the original voice, and add a decay pot, there would still have to be a switch to enable/disable the decay adjustment anyhow, since the original sound can't be attained (within my abilities) if the pot is always active.

2) Same thing here for the pitch. I can (a) use the original "base" pitch, with a pot to increase it (bot not lower it), (b) add a switch that just has a "low/original/high" option, or (C) a switch+pot that has the option of original pitch, and continuously variable.

3) On trigger jacks, is 1/4" still the standard, or is 1/8" becoming the norm?
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Re: Hammond Auto-Vari 64 Drum Module Project

Post by cornutt » Thu Jul 14, 2016 9:11 pm

Uncle Screwtape wrote:3) On trigger jacks, is 1/4" still the standard, or is 1/8" becoming the norm?
If you're going to format it into an actual module for a modular synth, stick with the standard for whatever format you choose. 1/4" for MOTM and MU, 3.5mm for Euro and Frac, banana jacks for Modcan-A. If you're going to make it a tabletop or rack module, pretty much everything I see like that uses 1/4".
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Re: Hammond Auto-Vari 64 Drum Module Project

Post by Uncle Screwtape » Tue Jul 26, 2016 3:27 pm

Thanks for the input cornutt. For my own purposes, I'm building a desktop unit primarily for use with my BeatStep Pro, so the 1/8" triggers were going in no matter what. Since I wanted to add versatility (and future sale value), I was originally wondering what the "drum synth" standard currently was (if any). For example, those old Tama units and my DRM1 both use 1/4" - but there seems to be a lot of movement to 1/8" these days, so it had me doubting a need for 1/4" inputs. That's no matter now though. Since the cost of 1/4" jacks is comparatively negligible, I will just be putting both into the final build.

Anyhow, here's a new demo with the board under control of my BeatStep Pro - and some yapping:

https://www.youtube.com/watch?v=aBvkvYsNiow
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