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Overview

The Synsonic will form the "core" of my Drum set: Snare, Hi-Hat and Bass. (Not anymore.) It will be primarily manually playable, with some provision for electronic triggering later on. I do not plan to use its programmability. I'll be adding more voices in the form of d.i.y. circuits, utilizing some of the Synsonic's resources: the noise source, summing op amps and the DC-to-DC converter which converts a single-ended 9volts to bipolar +/-9volts.

Of course, the Synsonic's case cannot contain all I want to add. It can't even contain the little I've done so far, so I'll be putting everything in a bigger box, to hold everything.

My Modifications
Most of the following has been posted at burnkit2600, beginning here, so here I'll give a brief summary of my mods and future plans. As much as possible, I've tried to accomplish things by adding components, rather than changing or removing parts from the Synsonics board. Some desoldering was unavoidable; moving Tom-1 Tune off the circuit board, for example. Also, wherever possible, connections were made to components connecting to IC pins, rather than soldering to the pins themselves. More details are available on the Update page.

Decay is a simple mod that involves adding an electrolytic capacitor to lengthen an instrument's decay and a potentiometer and fixed resistor to vary the length from shorter than originally to longer. The resistor and cap can be mounted right on the pots' terminals. Values differ for Snare and Tom Toms. See the Update page for suggested values.

Snare Tone is also simple: A .001uF capacitor and pot allows more of the noise high frequencies to be heard.

Impact, Snare and Tom-2
Another simple one. A capacitor, pot and resistor in series, paralleling already existing Impact components.

And that concludes the simple mods that can be described simply.

Tom Toms Frequency
I will not be using the Synsonic Toms as Tom Toms, I'll use D.I.Y. circuits, probably Thomas Henry UD-1s for those. (His Bass++ is also a possibility.) My mods leave the Synsonic Toms still usable as Toms, however.

In my opinion, the Synsonic Bass is miserable, so I'll be using Tom-2 for that function. For that, I've added a capacitor to lower its frequency and a pot to make the frequency adjustable over a limited range. The Tom-1 mod is a little more complicated.

Tom-1 will be used for a "shell" sound for the snare. The drumpad I've made for the Snare has 2 piezos, one near the edge and one in the center, both can be struck independently or linked electronically via a switch.

Tom-1’s frequency range was too high for my taste: I lowered it by putting a .1µF cap in parallel with C4. But that wasn't enough. Tom-1 has a built in frequency sweep-swoop that may have been de rigueur in the 1980s but now sounds trite, hackneyed, and simply irritating. I've added a circuit that gives control over the sweep depth that can reduce the sweep to a less disco-ish amount, completely cancel it for no pitch sweep at all, or sweep in the opposite direction from normal; that is, a very unnatural sounding down then up.

Like everything else on this page, schematics and more details are available on the Update page.

Cymbal/Hi-Hat
The Synsonic includes an "Accent" button and foot switch input to shorten the Cymbal decay, simulating the sound of a closed Hi-Hat. The choice of long or short decay seemed too limiting to me, so I added components to allow a foot pedal to control how much the Decay can be shortened. This mod is only a partial success.

For more control over the tone of the Cymbal sound I added a Bass/Treble Boost/Cut tone control.

Blend
The Synsonic sends a reduced level of the Left Channel signal to the Right Channel and vice-versa. I didn't like that, so I clipped out resistors R50 and R51 to give total Left-Right separation. It should be possible to implement Blend Amount with a dual linear pot, but I have not tried that.

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