Electro optical vs. Vari Mu - shedding some light on theory and practice ?

[ISedlacek]

Could someone shortly describe the basic principle difference between Electro-optical and Vari Mu type of compressors ?

What would be the main difference in the sound ? Like between using a transparent Electro optical compressor (like Pendulum OCL-2, which I have) and a Vari Mu tube compressor (like Gyratec X etc.) on the same material ?

[thethrillfactor]

Originally Posted by ISedlacek

What would be the main difference in the sound ? Like between using a transparent Electro optical compressor (like Pendulum OCL-2, which I have) and a Vari Mu tube compressor (like Gyratec X etc.) on the same material ?

The only way to really know is try them out and see.

Just talking about the differences mean nothing since most people's idea of a Variable Mu type of compressor harkens back to a Fairchild 670 or Gates Sta-Level but in all honesty most Vari-Mu compressors made today(including the Manley version) is much much cleaner.

The Pendulumn ES8 for example is really clean sounding.

Same goes for Optical compressors.

Most people think of an La2a sound but again most of the stuff made today leans more to the clean side(Pendulumn, Buzz OC, Manley Elop).

[gainreduction]

Many modern designs, in contrary to many vintage ones, also give you variable attack and release times which also plays a big role.

[ISedlacek]

Originally Posted by gainreduction

Many modern designs, in contrary to many vintage ones, also give you variable attack and release times which also plays a big role.

Oh, you have a great nickname for a real insight into this topic

[thethrillfactor]

Originally Posted by gainreduction

Many modern designs, in contrary to many vintage ones, also give you variable attack and release times which also plays a big role.

This could go either way since you can modify a Sta-Level or 436C with variable attack/release and still retain its character.

Part of the sound in some comps is the 6386 tubes which are harder to come by and also the power supplies.

On the older Vari-Mu comps it uses a tube as dual duty and part of the use is for the power supply.

Problem is when using a tube for voltage it rarely fires up all the way so the headroom gets compromised. Its also part of the reason they never sound a like or different from day to day.

[ISedlacek]

I just learned that within cca 10 days I shall have Gyratec X Vari Mu here to try and to compare to my Pendulum... So, it will be first hand practical knowledge .. Very curious. If it is the same sweet as G14, I will bankrupt

[Benmrx]

Please correct me if I'm wrong, but I think that a "vari-mu" is about the only type of compressor that actually uses tubes for the gain reduction. While an LA2A might have some nice tubes in it, it's still using an optical sensor for the actual gain reduction element.

Again, someone chime in if I'm way off here.

[dementedchord]

Originally Posted by Benmrx

Please correct me if I'm wrong, but I think that a "vari-mu" is about the only type of compressor that actually uses tubes for the gain reduction. While an LA2A might have some nice tubes in it, it's still using an optical sensor for the actual gain reduction element.

Again, someone chime in if I'm way off here.

that's my information as well fwiw... and as to the diff in the sound it was explained to me that the tube reacted slower both in attack and release than the optical... not sure as to the acuracy but sounded logical enough...

[ISedlacek]

Originally Posted by dementedchord

tube reacted slower both in attack and release than the optical... not sure as to the acuracy but sounded logical enough...

What I was told is that Vari Mu compressor is generally faster than opto compressor. Correct me if I am wrong

[Benmrx]

I would imagine it would depend on which is slower/faster, etc. because quite a few optical units have a fixed attack/release (LA2A) and some let you set your own (OCL-2).