MOTM

----- Original Message -----
From: <Konkuro@...>
To: <analogue@...>
Sent: Monday, June 17, 2002 3:56 AM
Subject: [AH] REVIEW: Synthesizers.com Q127 FFB, Q140 FFB Aid, and Q123 Standards


Lest this review appear as entirely negative, let me remind the reader that
Synthesizers.com remains my favorite synthesizer manufacturer.  The company's
customer service is legendary and the overall product is excellent.  True,
the modules are "vanilla," but it is rich French vanilla.  If you eschew
gewgaws and gimmicks on synthesizers and seek well-built modules for serious
synthesis, this is it, kids.

Warning: This review is way too long.

Given the historical quality of the Synthesizers.com line, the announcement
of several new modules (after a bit of a lull) was rather
exciting--especially given that the last new offering from Synthesizers.com
(the Q150 Ladder LPF) was simply outstanding (highly recommended).
Unfortunately, the latest crop of modules is marred by what I call
why-the-hell factor or WTH.  That is, they would have been excellent, but a
certain lack of planning impacts their desirability.  They leave you
scratching your head and wondering why the hell the creators made the design
choices they did.  Some examples:

Q161 Oscillator Mixer and Q162 Filter Mixer:  The former enables you to mix
waveforms from a single oscillator to "easily create new waveforms," and the
latter allows you to mix LP, BP, HP and notch outputs from the Q107 State
Variable Filter.

WTH Factor:  Mixing waveforms from a single oscillator doesn't sound like
much, even though the waves might look interesting on an oscilloscope (you
can use a mixer to do the same thing but the result is hardly worth the
effort).  As for the Q162 Filter Mixer, notch and BP responses are mutually
exclusive as are LP and HP, so what's the point?

Q 143 Presets Module: Enables switching of 2 voltage sources and 2 routing
paths.  Useful for live performance situations where quick changes need to be
made.

WTH Factor:  If ever a module needed footswitch control, it is this one.  Yet
only a toggle switch is provided.

Q146 Normalization Module:  Cuts down on patchcord clutter by enabling common
sources (oscillator CV, ADSR triggers) to be shared internally, unless
patched otherwise.

WTF factor:  One of the reasons Synthesizers.com says they didn't offer such
a module in the past was because it would lock customers into placing their
modules in specified areas a la Moog.  So what did they do?  Instead of
creating a module that could have been used to normal a wide range of modules
(VCOs, ADSRs, VCAs, Filters) they created a normalization module that is
specific to VCOs and ADSRs.  This is not only functionally limiting, but also
locks customers into placing their modules in specified areas a la Moog!
(What if your VCOs and ADSRs are located in separate cabinets?)

All this is simply to set up a context for the modules in this review, each
of which has its own WTH factor.

Q 127 Fixed Filter Bank and Q140 FFB Aid.

A fixed filter bank (FFB) is one of the most useful-and misunderstood-of all
modules.  People often confuse them with equalizers, but the job of the fixed
filter bank is not to smooth out an audio spectrum, but to accentuate certain
portions of it.  Thus an FFB is particularly useful for formants.  For
example, to synthesize the vocal sound "Ah" you need a passband centered
around 1000 HZ.  To synthesize a bassoon, you might start with a sawtooth
wave and select a passband centered around 500 Hz.

The Synthesizers.com FFB gives you 12 fixed BP filters (-12 dB) spaced \ufffd
octave apart, plus a -24 dB fixed LP and HP filter.  A bypass switch lets you
select filtered or unfiltered output.  The FFB is complimented by the
optional Q140 FFB Aid, which gives you outputs for each individual filter (a
very useful feature which, to my knowledge, no other manufacturer offers).

Although the Q127 FFB is built to typical Synthesizers.com high standards,
one must keep in mind that the Synthesizers.com synthesizer is *Moog format*,
but is not a Moog clone.  The Synthesizers.com FFB is an RC design and does
not use inductors, so it will not behave exactly like a Moog FFB if that is
what you are looking for.  But it does perform the function it is built to
do.  Well, almost.

An easy way to demonstrate what an FFB does is to introduce a noise signal to
the input.  With all the knobs set at zero, the output should be bupkis.  As
you turn up each individual band, you will hear the specific coloring of that
band.  This will work for any FFB including the Synthesizers.com FFB.  Well,
almost.

WTH Factor:  With all of the controls of the Q127 set to zero, you should
hear no output, or almost no output. Unfortunately, you will hear a highpass
"leakage" that the filter passes.  Thus any band you select on the filter
with noise as the input will produce colored noise plus a highpass hiss.  So
if you want, say, to create an earthquake rumble by introducing noise to the
FFB and selecting 175 and 250 HZ passbands, you will have to settle for a
rumble plus a highpass hiss.  By the same token, any waveform rich in
harmonics (such as a sawtooth) will be processed with the band or bands of
coloration you select-plus highpassed upper-level harmonics.  Since the whole
purpose of a fixed filter bank is to accentuate one or more bands to the
exclusion of all others, it is hard to comprehend how the Q127 could have
been let out the door with such an obvious design flaw.  Of course, you can
always lowpass the input or output to get rid of the upper level component,
but that wastes a filter that might be better used elsewhere.  Very annoying.

The highpass leakage does not occur when you use the individual outputs
offered by the  Q140 FFB Aid, because you are dealing strictly with
individual bands.  Thus you could use outputs from the Q140 to avoid having
to filter out the highpass component on the Q127 FFB, but you won't be able
to vary the amount of each passband unless you use an external mixer.  But if
a single band of frequencies is all you need, then great.  Well, almost.

WTH Factor:
The Q127 FFB Aid, for all its usefulness, attenuates each output by 75%.
That's right, 75%!  So you will have to use an amplifier such as the Q116
Instrument Interface to bump the attenuated signal up to acceptable levels.

The highpass leakage on the Q127 FFB ruins what would otherwise have been a
stellar performer.  Sure, it's still useful, but the workaround is an
annoyance the user shouldn't have to put up with and requires an extra LP
filter module.  The FFB Aid is useful, but only if you provide external
amplification.  Consequently, the highest rating I could give these modules
is "fair".  Ditto for the Q123 Standards module.

The Q123 provides precision voltages in whole numbered and fractional (1/12
V) increments.  There is an "add" input and an output.  Also on the module is
a 440HZ reference tone-indispensable for use as a pitch reference.  It is my
understanding that the module is supposed to be a precision summer that adds
voltages incrementally to the voltage on the input.  Thus if you input a
control voltage from the keyboard to the Q123 and route the output of the
Q123 to a VCO, you should be able to switch octaves by switching the Octave
(Volts) switch.  Similarly, you should be able to bump the oscillator pitch
up by one or more semitones by selecting 1/12th increments on the Q123.  Too
bad it doesn't work that way.

Yes, the octave switch does indeed switch by octaves.   But the output
voltage, which should simply be incremented by 1/12th for each semitone
selection, is instead strangely altered. C2 will be twice the frequency of
C1, but the diatonic relationship of the notes in between changes.  In short,
you end up with some strange scale that can be switched in precise octaves. I
guess the module is fine if you're playing in a gamelan orchestra, but it's
useless for the intended application.

The workaround for this module is not to go THROUGH the module.  To shift up
or down in precise intervals, you need to introduce a CV from the keyboard
into a VCO as usual and run the output from the Q123 into another CV input on
the oscillator.  Now summing happens the way it is supposed to, but it eats
up an extra input on your VCO. This is still useful, but it would have been
far better if the circuit just worked the way it is supposed to.

WTH Factor:  Despite its drawbacks, the Q123 is a module that some people
would want to replicate for use with every VCO in their system.  This would
allow the user to quickly and easily shift each oscillator up or down by
octaves and/or semitones.  But the addition of the 440Hz reference to the
Q123 messes things up. What's the point of replicating a 440 Hz reference?
You will never, ever need more than one!  So if you want to buy multiple
voltage references for use with your oscillators or filters, you'll also be
paying for redundant 440 Hz references that will do nothing but empty your wal
let and take up space.  The obvious solution would have been for
Synthesizers.com to have provided the 440 HZ reference as a standalone module
and filled up the extra space with multiples.  But again, they missed the
obvious.  This is another module I won't be buying more of.

One more thing: It would have been nice to look at a schematic or block
diagram to see why the Standards module wasn't functioning as expected, or
why the FFB has that annoying highpass problem.  Unfortunately,
Synthesizers.com doesn't provide schematics or block diagrams, so you are
SOL.  To make matters even worse, the information that arrived with each
module wouldn't fill a gnat's navel.  The documentation on the Q123 Standards
module is so meager it will frustrate even the most experienced users.

Frankly, the current crop of modules from Synthesizers.com baffles me.  They
seem to ignore the most obvious of design considerations. With just a bit
more planning, the FFB, FFB Aid and Standards modules could have been as good
as the oscillators, filters and other module designs that have made
Synthesizers.com my #1 choice.  Let's hope the company doesn't start on a
quantity-over-quality trend and gets back to creating top-notch designs, even
if it means releasing only a few new modules per year.

johnm