MOTM

This was covered last year in the archives.

Basically, there are 2 factors at work:

a) the MOTM-190 is *extremely* fast. If you have fast envelopes (say 
Attack/Release <2ms) and you put in a frequency less that say 1Khz (which is 
pretty high, musically speaking) what you get is less than 1 cycle of the 
waveform coming out. For example, if you are doing bass notes at 80 Hz, the 
period is 1/80 or 12ms. So, if you are "whacking" the VCA with a 1ms attack/1ms 
decay, only 2/12 or 17% of the waveform is 'getting through'. Well, THAT means 
there is an intristic DC offset associated with that waveform. You hear this as 
a 'click'. The VCA is NOT 'clicking', the *waveform* is :)

b) It depends on your 'signal chain' outside the VCA (mixer, preamp, powered 
monitors, whatever) and how THEY handle DC offsets. For example, and this was 4 
years ago with the '110 (not nearly as fast but fast enough), a user was using a 
SoundBlaster clone card for recording. This card had crappy input impedance 
network, crappy electrolytic caps in the audio path, and overall it 
was.....crappy. The thing 'clicked' like a horde of locusts. When I look at it 
and listened to it on my system, it was OK. He sent me MP3s: yet, sounded awful. 
Same card, same setup here: no problems with *my* setup (it was a Turtle Beach 
card at the time).

I can take my arbitrary waveform generator and run in 'gated mode' with an 
internal square wave. This will 'click' as well, again because the 'note' needs 
at least 1 full cycle to balance the charge in the coupling caps. If you are 
doing basslines, this may be up to 15ms.

Now, I'm *not saying* you *have* to use "slow" A/R times to make the popping "go 
away" as a *general rule*, because my Event 20/20bas speakers can 'take it' just 
fine, and so can my Pro Tools/Digi 002. The best thing is:

1) be sure the CV OFFSET trims are properly set.
2) adjust the A/D/R times
3) upgrade your external stuff :)

Paul S.