Cgs synth

The passive ring modulator sounds different because of the losses
inherent in the transformers and to a lesser extent, the diodes.
However, these losses are frequency specific, making the circuit
very "organic" sounding when compared to an active balanced
modulator. I liked the sound so much I made a dual RM module.

The signal loss is enough for most to add a make up amp. I went with
a non-inverting op-amp with a gain of about 3, followed by a buffer.
This arrangement uses a single TL072.

A "ring" modulator is a nickname for a diode-based balanced
modulator. Ken's article on his website clearly points out why.
This is a very old radio circuit (from the 30's) designed to improve
radiotelephony by using the sidebands of modulated speech. Sideband
information is of higher frequency, and therefore covers a much more
narrow band of radio frequencies. An AM signal is over 6KHz wide,
while a single sideband signal is about 1.5KHz wide. It is also much
easier to filter the sideband signal.

Any information you'll need is available in the message archives of
this list. Also, I still have a small cache of germanium diodes and
I'd be happy to send you a matched quartet.

Chub


--- In cgs_synth@yahoogroups.com, "martinjbeer" <martinjbeer@h...>
wrote:

> Hi, I've just come across this group, and have some questions about
> Ken's passive ring modulator boards (I like ring mods, so I'm

tempted

> to try one). Does a passive ring mod drop the signal level enough

to

> need some sort of gain stage after it (and if so, does it need
> anything special, or would a basic op-amp stage do the job?)Also,

how

> does the sound differ from a standard balanced modulator? My
> intended use is to modulate the output of two VCOs with each other,
> or one VCO against a preamped signal from another instrument.