Balanced Modulator or Ring Modulator?

[Peter Snowberg]

Could somebody please explain the difference between balanced and ring modulators?

Some people say they're the same, but the Anderton's EPFM says (from memory, I lost the book ) that he is presenting a balanced modulator beacuse it is a simpler build.

I've always wondered about that.

Thanks!

-Peter

[moosapotamus]

OK... If I get this wrong, maybe some really intelligent folks will chime in and correct me. So, here goes...

I think a balanced modulator circuit does not have an internal oscillator (or, carrier). It just multiplies ("balances") the input signal against itself (like the green ringer does), much like an octave-type effect.

In contrast, a ring modulator has an internal oscillator (carrier... or, is it the modulator?) and actually does the math, creating a combined output that consists of the true sum and difference of the frequencies of the internal oscillator (carrier) and input signal (modulator).

Or (maybe), not. Anyone with an educated opinion care to respond?

~ Charlie

[Tim Escobedo]

As I understand it, a ring modulator owes it's name to the diode ring architecture used in classic ring mod design, usually part of a RF mixer of some type. A well designed ring modulator is a balanced modulator, but a balanced modulaotr may or may not strictly be a ring modulator. I guess the meaning of "balanced" in this context is the ability for the inputs to null each other out regardless of circuit topology.

Though the term "ring modulator" is usually generically applied to any effect that'll do this kind of mixing of signals.

Sounds like a good enough explanation to me, anyway. Got any better ideas?  :wink:

[tboy]

There is no difference. The term "ring modulator" comes from a common method of implementing a balanced modulator using a "ring" of diodes.

[Peter Snowberg]

Thanks for the replies everybody!

-Peter

[zeppenwolf]

As I understand it, a ring modulator owes it's name to the diode ring architecture used in classic ring mod design, usually part of a RF mixer of some type.

That's possible, I guess, but I'm pretty sure the "ring" in a ring modulator is a ring in the sense of abstract algebra.  It's referring to the cohesiveness of the modulation of inputs in all four quadrants.

For example, the set Z of totally normal integers, with the totally normal concepts of "addition" and "multiplication"... when you talk about that whole thing taken together, it's called "the ring of integers".

Eden

[puretube]

IMHO, Tim is right:
the original RM is just 4 diodes heads to tail, switching the carrier
on and off (or vice versa) at the modulation`s rate -
no deep mathematics involved in there.




//www.puretube.com

[Paul Perry (Frostwave)]

Puretube, I don't think the 4 diode ring modulator is all THAT simple, because if yuo are simple switching the diodes on & off, you wouldn't be applying any level modulation via the switching signal! Yeah, you would get a RF signal..(if the switching was at RF) as in the early applications. But for actual multiplication, you have to be using the square law prt of the diode characteristics. And the maths loo pretty hairy to me!
But, I agree, number theory is not really needed (thank God!)

[puretube]

IMHO the RM doesn`t intend to multiplicate.
The output of it is just (almost) the same as if you multiplicate with
a 4-Q-Mply.

[ExpAnonColin]

My 2 cents:

They're the same thing, both of them do exactly the same thing...  But...

Oftentimes when someone says that they made a balanced modulator, it doesn't include an internal CV oscillator, while a ring modulator does.  You'll notice on a lot of commercial ring mods theres a CV in, qualifying it for both categories...  But actually, some modular synth ring mods have no knobs, just 3 jacks:  Input, CV in, and out.

They are exactly the same thing... different words meaning the same thing applied to similiar devices, I guess.

Oh, and "mod" means "modulator", so when someone says "ring mod", they actually mean "modulator".      :roll:

-Colin

[puretube]

I think there is a need to clear the differenent opinions on RM.

Since this (luckily) is not the HC FX-forum,
this is the right place to clear things up:

Musician`s opinions on RM are different from EE`s RM.

RM should better be called a special kind of "Double Balanced Mixer", in contrary to just a "Balanced Mixer".

A balanced or a double balanced mixer is not neccessarily a RM.

A RM is not neccessarily a 4-quadrant multiplier, nor vice versa.


more on this later.....   (any old Ham`s in here ?)