Little Labs LL2A - anything similar (sounding)?

[altfidelity]

How would you describe Little Labs LL2A sound-wise?
To me it sounds somewhat "fairchildish" / varimu-ish, very thick and pumping/thumping in an old school way.




Yet it is completely solid state, not a tube, vactrol, T4B, or a transformer in sight.
The board looks like a budget Alesis Microlimiter, very simple & compact....

https://www.soundonsound.com/reviews/little-labs-ll2a
Anybody heard/build anything similar?

 

[gyraf]

I thought it was a pwm - it sounds really really good. Tried it at NAMM a couple of years ago..

/Jakob E.

 

[living sounds]

Interesting, its rare that companies go to the lenghts of employing Nichicon Muse capacitors and Dale resistors. The examples sound really nice. I would prefer a more conventional form factor though. With the right settings the Haikki Trafoless Varimu can sound quite similar, I think. The latter is a lot more flexible, of course.

 

[altfidelity]

It suppose to be the only compressor IN THE WORLD ( ) that's using analog multiplier. His words not mine.
Anyway, that doesn't mean anything to me, maybe it means something to you tech folks.

 

[gyraf]

e.g. MC1496 as a VCA? Doable, but for theoretical reasons ("it'll distort too much for audio, in a way that has no linear relationship to audio levels") it hadn't been tried out irl. Jonathan did, and won..

/Jakob E.

 

[altfidelity]

Why do it sound so weighty, thumpy for lack of better words?

I always thought this sound perception comes from transformers, but it certainly isn't the case with this one.

Obviously it uses soft knee and slower attack and recovery timing, but majority of budget vca compressors set this way, just sound lame and boring.
I know this is objective and untechnical quality, but it must be measurable in some way.

What is it, slew rate, shape of the envelope, sidechain dc signal leaking into audio path?

 

[Michael Tibes]

It suppose to be the only compressor IN THE WORLD ( ) that's using analog multiplier. His words not mine.
Anyway, that doesn't mean anything to me, maybe it means something to you tech folks.

Analog multiplier - Wikipedia

A VCA is kindof an analog multiplier with limited features (the two inputs do not have identical features / are not 4 quadrant). Just trying to separate the marketing bs from the possible circuit... Also I don't believe that the dale resistors or choice of caps are the key essentials for the good sound, though they might be the very thin icing on the cake.

from: Little Labs LL2A

' Here, the gain‑reduction element is an analogue signal processor called a ‘four‑quadrant analogue multiplier’'

' the particular four‑quadrant analogue multipliers used here are Analogue Devices’ AD633s, and I counted five of them altogether, although I believe some are serving in the side‑chain as the maths involved in generating the required multiplier control signal is quite involved. '

Always interesting what can be done with the little bugger: https://www.analog.com/media/en/technical-documentation/data-sheets/ad633.pdf

Tape op: LL2A Compressor Limiter

 

[altfidelity]

From the manual:https://static1.squarespace.com/sta...5dc45f0b/1611004856882/LL2A_MANUAL_040220.pdf

"The LL2A is fully differential...

.... To make it clear, what is fed to the + input is processed 100% separately from what is fed to the - output throughout the whole LL2A. Most Little Labs products use that topology. "

"The LL2A has a fast 400-microsecond attack and a 0.9-second release."

 

[gyraf]

..some of the real niceyness here is probably a wee bit of control-voltage feeding through to audio. Our ears tends to like this for certain types of material..

/Jakob E.

 

[altfidelity]

..some of the real niceyness here is probably a wee bit of control-voltage feeding through to audio. Our ears tends to like this for certain types of material..

/Jakob E.

That's probably from diferential "floating" topology right? Same as push-pull cell in vari-mus...

The + and - "branches" don't cancel each out 100%, which create slight DC offset, which our ears percive as thump/weightiness.
We may have pinpointed why I like vari-mu compression.

 

[gyraf]

Imprecisions in the analogue math does this - data sheet mentions errors in the order of 1-2% of full scale signal iirc

but it's not a linear add were hearing, I tried that (off course ) and it didn't at all feel the same

/Jakob E.

 

[altfidelity]

Imprecisions in the analogue math does this - data sheet mentions errors in the order of 1-2% of full scale signal iirc

but it's not a linear add were hearing, I tried that (off course ) and it didn't at all feel the same

/Jakob E.

I agree, surprisingly small differences (academically speaking negligible), makes audible difference.
Boosting +3db @ 10kz on left and right channel sounds perceivable less 3D (or whatever) than lets say +3.1db @ 9997hz on left and +2.95@10020hz on right channel.

I see, you can use the same "floating" trick with IC-chips.
How is this topology called officially?

 

[gyraf]

..this gives you 6dB more headroom (in theory), but as the vca distortion products are not linearly distributed, there's no real hope of it actually reducing distortion as claimed..

 

[jensenmann]

IIRC EMT were the first to use the four quadrant multiplier principle in their EMT266 Transient Limiter. In 1980 that was.... A Valley People transistor array has been used as multiplier. The manual contains schematics and some technical descriptions: Schematics and Manuals

 

[Gold]

The Neumann BSB74 Acceleration Limiter (HF limiter) used a four quadrant multiplier as the gain reduction element. That was designed in the very early 1970's.

 

[altfidelity]

..this gives you 6dB more headroom (in theory), but as the vca distortion products are not linearly distributed, there's no real hope of it actually reducing distortion as claimed..

But would the double floating IC topology produce this thump-ier response similar to those in push pull configurations?

Or would be this effect less pronounced because IC chips are more linear anyway?

 

[richiyobs]

https://patentimages.storage.googleapis.com/fa/79/86/efd183eb1c5423/US3241078.pdfHoward e. Jones

https://patentimages.storage.googleapis.com/a7/d1/7d/56d59fbc7b4bf7/US3689752.pdfBarrie Gilgert

are these useful for understanding the basic concept of the 4 quadrantMultiplier?

 

[Michael Tibes]

..this gives you 6dB more headroom (in theory), but as the vca distortion products are not linearly distributed, there's no real hope of it actually reducing distortion as claimed..

I remember an article by Mr. Matthias Carstens (later co-founded RME) in the German Elrad magazine (my electronics bible as a teenager in the 80s....) which used exactly that technique. It stated a significant reduction (but obviously not elimination) in distortion and CV feedthrough plus the obvious improvement in noise floor. He also posted measurements. I guess someone at SPL did also read that magazine and 'had an idea' later ;-)

If it is really having an audible effect, it should make the vca less 'audible', but probably not 'meatier'.

..some of the real niceyness here is probably a wee bit of control-voltage feeding through to audio. Our ears tends to like this for certain types of material..

/Jakob E.

...which would result in 2nd order harmonic distortion, wouldn't it? Could be a road to artificial meat...

 

[altfidelity]

I remember an article by Mr. Matthias Carstens (later co-founded RME) in the German Elrad magazine (my electronics bible as a teenager in the 80s....) which used exactly that technique. It stated a significant reduction (but obviously not elimination) in distortion and CV feedthrough plus the obvious improvement in noise floor. He also posted measurements. I guess someone at SPL did also read that magazine and 'had an idea' later ;-)

If it is really having an audible effect, it should make the vca less 'audible', but probably not 'meatier'.



...which would result in 2nd order harmonic distortion, wouldn't it? Could be a road to artificial meat...

Do anybody know any other IC based compressors that use this so-called dual VCA floating topology?

 

[gyraf]

As I see it, paralleling vca's would reduce distortions caused by nonlinearities, but running opposite-phase won't do this (unless we have a strictly predictable and evenly distributed level-dependent non-linearity - but such one would have been compensated already because this would be easy)