Vintage Simmons Drums (UK) Users Group

i did a search on analogue heaven

there is more so i will keep searching


Isn't it funny how when you go to sell stuff and
nobody wants it you start looking at it again. Since
there was little interest in my TS305/306 I thought
I'd better evaluate whether or not I was asking too
much for them. In the process of looking for info on
them, I stumbled across the schematics. I was
planning on buying some percussion modules with some
of the proceeds from my gear sales, but those plans
have changed.

The TS305/306 are early eighties analog drum brains.
Although many people seem to like them as is, frankly,
I think they have a very dated sound and while they
have more capability than the intended use, i.e. a TOM
can be more than a TOM, the sound has always been a
bit limited for me.

I got the 306 first which has 4 TOMs, SYNTH, and
HANDCLAP. I have always loved the handclap, enjoyed
the synth and tried to find uses for the toms without
lots of processing. I have never really used the 306
much in my setup but thought at some point I might do
something with it. I ended up with the 305 in a
complicated trade some time ago. The 305 has BASS,
SNARE, RIMSHOT, and 3 TOMS. The BASS is really usable,
as are the SNARE and RIMSHOT. Alas, those three TOMS
don't do much for me. I thought several times about
just pulling those modules out, putting them in my 306
and then trying to get rid of the 305 as a TOM only
box.

It's not just the sound that I didn't like. They take
a lot of rack space and the inputs/outputs are at the
top so they take, realistically, at least two,
probably three more than the seven spaces the box
itself takes. In addtion, every time I have wanted to
use them I'd have to find something to go from
whatever sequencer I was going to use to 1/4 inch
plugs for the triggers.

As the schematics show, there are only four variations
on the sound modules. The HANDCLAP, SYNTH, and
RIMSHOT each have their own design. The TOMS, BASS,
and SNARE, however, are ALL THE SAME MODULE. Just a
few parts changes and any one can become any other.
If that's all there was, I'd still think these were
really neat, no more toms, just a lot of kicks and a
couple of snares, but, the best part is that the
design seems to be made to be modified. These boxes
are a percussion diy'ers dream come true. For the
record, I'm not selling either of mine, I have plans
for both of them.

Since I like the HANDCLAP/SYNTH and the RIMSHOT is ok,

I wasn't too concerned about modding those much, other
than adding front of box inputs and outputs, but those
TOMS, they had to go.

The SYNTH is fairly capable, but you only have one of
those so it's probably best left without too much
modifcation. The rimshot and handclap have simpler
configurations and there isn't much modding to be
done. But the TOM/SNARE/BASS is complete enought that
it can be configured into many different things. Each
module contains:

TE: Trigger extractor
EG: Simple Envelope
INV: CV Inverter
VCO: Linear VCO
VCA: VCA
NOISE: Noise
LPF: LPF (connected to noise)
VCA2: Second VCA, configured as "Attack"
NF: Fixed notch filter configured as "emphasis"
MIX: Several Mixers

(The acronyms are mine to aid further discussion)

Now I realize that this may not seem particularly
useful. I think trying to separate the components of
say the 909 kick and use them separately would give me
a major migrain. But, that isn't the case with the
techstar. Because it is a single sided pc board layed
out in a very linear fasion. It is almost trival to
separate and reroute each module. In almost all cases
it simply means lifting a jumper or moving a passive
component. As it comes it's configured like this:

TE -> EG -> INV -> VCO -> MIX ->NF ->MIX ->OUT
| \ /-------/ /
| ---\ / /
| NOISE -> VCF -> VCA2 -----------/
\ /
------------------/


One of my favorite features is the "emphasis" filter.
It sounds like shit. But that's not the point. It is
two op amps. Remove it's passive components and two
jumpers and it's two completely isolated opamps in the
output chain. For my first module mod, an 808esqe
kick, I configure these opamps as a tri->sine
converter and now the emphasis mixes between the sine
and triangle waves.

Throughout the board you can create various sounds
simply by changing the passive parts on the board.
The values for the TOMS, SNARE and BASS are printed on
the schematic. Some other mods you can do:

Increase/Decrease tuning range:
Resistors Ra and Rb control the range of the tune
control. You could, I suppose, just replace them with
jumpers for the max tuning range. I tested with Ra =
100k and Rb = 1k, and with that the VCO will go from
quite sub audio to about 8khz to 10khz or so.
Frankly, I find a 6khz blip with a bit of a bend far
more useful than a sproingy tom. Nevertheless, for my
bass/kick I didn't want such a large range as much as
I wanted a lower range. I replaced Ra with a 3m
resistor and Rb with a 1.5k. This allows the bass to
go sub audio but is not so sensitive that you can't
adjust pitch on the fly.

The Techstar comes with a nifty memory feature. I'm
sure it was a selling point. In manual, you control
the sound, in Memory, you get early eighties Tama crap
sound. This is meant for drummers who can't count
past four, and like guitar players, think every knob
belongs on ten. With the flick of a switch you get
instant boring sound. Since I have no use for this
feature I thought about what could be done with it.
It is implemented as a spdt switch connected to pairs
of FETS that accomplish the switching. So, for each
programmable sound, you can either replace the
existing passive components with more useful ones,
simply make both options go to the front panel
control, or in cases where it is switching a control
voltage, choose a different cv source. The best part
about this is that with the addition of two
transisters and an inverter, the switching can be
accomplished via a gate signal.

Some ideas for this include open/close hihat, accent,
extending the decay etc. In some cases it could
switch between two completely different sounds in the
same module. If you, for example, configured the VCO
section as some sort of tone drum, bass, tom,
whatever, and the noise section as a cymbal, you could
use the FETs to route the knobs to the active
instrument and passive components that kill the sound
for the inactive one. I plan to do this for sounds
that I don't use dynamically in real time such as
cymbal or woodblock.

Lowering the cutoff of the noise filter allows for
some really nice sounds with a low kick. Simply
change the value of R9 to about 150k to allow the
filter to adjust almost subaudio.

The schematics are on Florian Anwander's page

http://home.camelot.de/fa/diy/BR>
If you are looking at this in the archives, years from
now, and his page isn't up, try www.planetp.org. No,
they aren't there now, but they will be in the future
:)

For my fist module, I changed about twenty parts on
the board, added a small (1 inch square) board with
the wave processor parts, and another board for the
trigger IC. This turned a fairly boring TOM sound
into a warm and evil bass/kick with really usable real
time controls. Just triggering it with a function
generator on the bench is fun.