MOTM

A recent (unsigned) post asked for WAV files of MOTM VCO outputs, 
presumably for comparison with other VCO makes.  I would be interested 
to know whether anyone thinks that recordings suit this purpose very 
well.  Problems would surely dog this approach, vs. actually having the 
modules side-by-side in the same system and doing A-B listening tests.

The files being compared could have been produced with different 
sampling rates.  The recording levels most likely would have been 
different.  The psycho-acoustic effects of simply playing back the 
*same* recording at different levels of amplification can be 
significant.  If it is indeed reasonable to make comparisons this way, 
it seems to me that the recordings being compared would all have to have 
been made in the same studio with all parameters kept as equal as 
possible (as when Paul S. posts samples of different sounds for 
comparison).  Thoughts?

Thanks,

Richard Brewster
http://www.pugix.com

I know that the person asking is pondering a MOTM system, and that such 
requests are common. So, why *not* have such things posted on the site?

Several thoughts:

a) to me, it's like buying guitar strings not attached to a guitar, effects 
or an amp. Sure, the strings have their own "sound", but to what degree do 
they contribute to the final tone?

b) in theory, pretty much any manufacturer's VCO will sound the same coming 
straight out of the outputs. OK: the sine of 'X' may have a few more 
partials that are audible than 'Y'. If you want a REALLY clean sine, use a 
MOTM-440 VCF. It can track quite well and has <0.15% THD. Or, run the sine 
out through a '440. Those 4 poles will attenuate any extra harmonics quite 
well.

c) There are some specific cases that *more complex* audio will sound 
*quite* different from 1 VCO to another. Things like linear FM, audio-rate 
PWM and hard/soft synch. These types of demo files are more useful, IMHO.

d) how often are raw ouputs used from VCOs in audio tracks? Bueller....?

Usually, some sort of VCF is in the signal path, and more than likely that 
is a low-pass filter. So, any additional harmonics present by slight 
'wiggles' from 1 VCO to another will "go away" after the audio comes out of 
the LPF.

Paul S.

You make sense to me Richard.  There are obviously many variables in the
signal chain and the recorder.  Impedance mismatches, different opamp output
stages on mixers, etc. will all have an effect.  Perhaps one could compare
oscilloscope images? :)  For example there is usually a little glitch on the
top of the triangle wave (from the waveshaper) of a saw-core VCO.  There
could be differences in the rise and fall times on the triangle wave for
triangle-core VCOs.  Turn up the freq past 20KHz, what is happening to the
amplitude, to the rise-time on the square wave?  These all are inducing
changes in harmonics.  But good luck translating what you see to what you
will hear.  Side by side hearing tests - there is no good replacement for
this IMO.

George

Richard Brewster wrote:

> A recent (unsigned) post asked for WAV files of MOTM VCO outputs, 
> presumably for comparison with other VCO makes.  I would be interested 
> to know whether anyone thinks that recordings suit this purpose very 
> well.  Problems would surely dog this approach, vs. actually having the 
> modules side-by-side in the same system and doing A-B listening tests.
> 
> The files being compared could have been produced with different 
> sampling rates.  The recording levels most likely would have been 
> different.  The psycho-acoustic effects of simply playing back the 
> *same* recording at different levels of amplification can be 
> significant.  If it is indeed reasonable to make comparisons this way, 
> it seems to me that the recordings being compared would all have to have 
> been made in the same studio with all parameters kept as equal as 
> possible (as when Paul S. posts samples of different sounds for 
> comparison).  Thoughts?
> 
> Thanks,
> 
> Richard Brewster
> http://www.pugix.com
> 
> 
> 
> 
> ------------------------------------
> 
> Yahoo! Groups Links
> 
> 
> 
>

I agree with all of your points, Richard!

To Argitoth (OP), I think you could not go wrong with the MOTM-300 /
MOTM-310 oscillators! They sound fantastic and are very stable! As an
alternative I've read a lot of good things about the Oakley VCO's but I
haven't tried one. So, just get a few of the ones mentioned above and move
ahead with your synth, any exercises in analysis/comparison will just be a
waste of your time IMHO . . .unless you are mainly interested in
analysis/comparison exercises instead of making music? (Nothing wrong with
that, just sayin' . . .)

John L Rice

-----Original Message-----
From: motm@yahoogroups.com [mailto:motm@yahoogroups.com] On Behalf Of
Richard Brewster
Sent: Sunday, February 08, 2009 12:35 PM
To: MOTM List
Subject: [motm] Comparing VCO modules by recording

A recent (unsigned) post asked for WAV files of MOTM VCO outputs, 
presumably for comparison with other VCO makes.  I would be interested 
to know whether anyone thinks that recordings suit this purpose very 
well.  Problems would surely dog this approach, vs. actually having the 
modules side-by-side in the same system and doing A-B listening tests.

The files being compared could have been produced with different 
sampling rates.  The recording levels most likely would have been 
different.  The psycho-acoustic effects of simply playing back the 
*same* recording at different levels of amplification can be 
significant.  If it is indeed reasonable to make comparisons this way, 
it seems to me that the recordings being compared would all have to have 
been made in the same studio with all parameters kept as equal as 
possible (as when Paul S. posts samples of different sounds for 
comparison).  Thoughts?

Thanks,

Richard Brewster
http://www.pugix.com




------------------------------------

Yahoo! Groups Links

My thought, upon seeing that post, is that it didn't make a whole lot of
sense because aside from the issues you mentioned, the recordings would most
likely be done through different audio interfaces. One VCO could be recorded
through a Lavry, another could be recorded through the mic input of some
cheap laptop. My MOTM sounds different recorded through my Apogee 800 than
it did through my MOTU 828mkII. So yeah, what you said about "in the same
studio with all parameters kept as equal as possible."
 
--Adam


  _____  

From: motm@yahoogroups.com [mailto:motm@yahoogroups.com] On Behalf Of
Richard Brewster
Sent: Sunday, February 08, 2009 1:35 PM
To: MOTM List
Subject: [motm] Comparing VCO modules by recording



A recent (unsigned) post asked for WAV files of MOTM VCO outputs, 
presumably for comparison with other VCO makes. I would be interested 
to know whether anyone thinks that recordings suit this purpose very 
well. Problems would surely dog this approach, vs. actually having the 
modules side-by-side in the same system and doing A-B listening tests.

The files being compared could have been produced with different 
sampling rates. The recording levels most likely would have been 
different. The psycho-acoustic effects of simply playing back the 
*same* recording at different levels of amplification can be 
significant. If it is indeed reasonable to make comparisons this way, 
it seems to me that the recordings being compared would all have to have 
been made in the same studio with all parameters kept as equal as 
possible (as when Paul S. posts samples of different sounds for 
comparison). Thoughts?

Thanks,

Richard Brewster
http://www.pugix. <http://www.pugix.com> com

periodically there are threads on AH whose intent is largely to 
discover whether people can actually tell the difference between 
various VCOs. this usually springs from a thread on how old Moog 
modular VCOs sound "warmer" than modern or digital ones, and why this 
might be.

the upshot of these threads has invariably been that nobody can 
really tell the difference, and the reasons postulated as to why 
Moogs sound better have turned out to be hogwash - eg, software VCOs 
have measurably more jitter than old Moogs, therefore that theory 
gets discredited (again), etc.

(on a whim i did try swapping output opamps between an Oakley VCO 
(TL072, IIRC) and an MOTM-300 (OP275, IIRC), and i did notice a 
little difference, but i doubt i could tell in a blind test.)

hence, i think even AH has (currently, at least) abandoned the notion 
that the make, model, or vintage of a regular ol' sawtooth oscillator 
makes any real difference to the character of a synthesizer. on to 
blind tests on the filters, then :-) and at least in the last test of 
filters, most people did correctly identify the analogue ones. as to 
*how*....

however there are definitely other differences. MOTM oscillators 
track dead-on over a wide range. it's great to know that my MOTM-300 
will be at exactly the same pitch i left it after a power cycle and a 
suitable warm-up period. the precision makes for great FM. and if i 
want an audio sinewave, the 300 does that trick best (in an 
oscillator). etc...

hth
j

>A recent (unsigned) post asked for WAV files of MOTM VCO outputs,
>presumably for comparison with other VCO makes.  I would be interested
>to know whether anyone thinks that recordings suit this purpose very
>well.  Problems would surely dog this approach, vs. actually having the
>modules side-by-side in the same system and doing A-B listening tests.
>
>The files being compared could have been produced with different
>sampling rates.  The recording levels most likely would have been
>different.  The psycho-acoustic effects of simply playing back the
>*same* recording at different levels of amplification can be
>significant.  If it is indeed reasonable to make comparisons this way,
>it seems to me that the recordings being compared would all have to have
>been made in the same studio with all parameters kept as equal as
>possible (as when Paul S. posts samples of different sounds for
>comparison).  Thoughts?
>
>Thanks,
>
>Richard Brewster
>http://www.pugix.com

I agree that many points of comparison for VCOs are more relevant to 
making a purchase decision than the sound of raw outputs.  Tracking and 
temperature stability are among them.  These aren't really possible to 
evaluate by listening to recordings.

Richard

Jason Proctor wrote:

> however there are definitely other differences. MOTM oscillators 
> track dead-on over a wide range. it's great to know that my MOTM-300 
> will be at exactly the same pitch i left it after a power cycle and a 
> suitable warm-up period. the precision makes for great FM. and if i 
> want an audio sinewave, the 300 does that trick best (in an 
> oscillator). etc...
>
> hth
> j
>