wasp (was: Re: [sdiy] Comparator = Opamp ??)

[WeAreAs1 at aol.com]

In a message dated 3/7/01 2:00:07 AM, urekar.m at EUnet.yu writes:

<< > (There were some guitar fuzz boxes designed around CMOS chips
> as well, but I don't remember which ones.) >>

Yamaha made a very nice one for just a short time during the early 1990's.  
The name was the COD-100 CMOS Overdrive.  I have one of them, and I like it 
very much.  It's excellent for those times when you wish to add just a little 
bit of "stuff" around your guitar sound, without changing its natural 
tonality (unlike the ubiquitous Ibanez Tube Screamer, which totally messes up 
your guitar's natural sound when you turn it on).  

On the Yamaha, if you turn the Overdrive Amount pot down to 0, you can hear 
absolutely no change in the guitar's tone (though you might see a small 
change on a scope).  As you turn up the Overdrive, your sound just gets more 
distorted, but never loses its tonal character.  At its maximum setting it's 
fairly well overdriver, but nothing like those super-high-gain pedals like 
the Metal Zone or a maxed-out Marshall or Boogie.  

It has active bass and treble tone controls and it also has a NE570-based 
companding noise reduction circuit built around the overdrive section, just 
like we often see on BBD delays and flangers.  The compander seems to be 
quite effective at reducing hiss, and doesn't seem to change the guitar's 
dynamics at all.  I'm not sure that I've ever seen a compander built into any 
other distortion device.

BTW, another excellent box for this type of sound is the BOSS Blues Driver 
(which uses overdriven differential transistor stages to get its distortion). 
 Both of these pedals are great for that sort of Keith Richards/Chuck Berry 
just-barely-distorted rhythm guitar sound (like a Fender amp turned up to 
about 7 or 8).  Great for recording!

I've got the schematic for the Yamaha if anyone wishes to see it.

Michael Bacich