PLAN B analog blog

I've turned my attention to finalization of the Model 25 (now off the
bench and well into PCB design) and I'd like to let you in on some
fundemental changes from what was previewed at the Winter Namm show.

Before the top section (attenuator/waveshaper) was designed so that
when nothing was connected to it, it's output could be used as a
variable fixed voltage source, much like the Deopfer A-176.  As useful
as that is, I've come to feel that was a bit of a cop-out and have put
that configuration to better use. In the final production release of
the M25, when nothing is connected to the input of the
Attenuator/Waveshaper, the output will be normalled to a White Noise
source.  The pot will act as an attenuator.

I've also totally re-vamped the Ring Modulator.  Before I was doing
the multiplying using two 13700 VCA's.  I've now changed the basic
engine to a 1496 design configured as a dual-sideband multiplier. 
Much better.  Further, I've removed the done-to-death AC/DC select
switch and instead incorporated a unique cross feedback function which
is like no other out there. It's unique because it adds harmonic
content without introducing additional sidebanding. I think it sounds kind of interesting.

I've updated M25 page on the EAR site showing the new faceplate design
(subtle, but they're there) and added some audio examples of Ring, it's Feedback function and two others of the waveshaper.

enjoy (or not!):

http://www.ear-group.net/model_25.html

The Model 25 is part of the next wave of releases, along with the
Model 28A and B companion modules coming in July.

- P