LA-2A - puzzled

[MartinDorr]

Thought I had a good handle on the HD500 model of the Studio Compressor, but the Helix one puzzles me.

 

What I found so far is this:

 

Needed a Gain value of ~3.7 to match output to input level as long compression is not engaged (that's fine).

The PeakReduction dial shifts the start of compression up and down the input signal level scale, e.g., a value of 10.0 starts compression at -33dB peak and at a value smaller than 2.4 prevents any compression unless you peaks above 0 dBFS (that seems like a strange scale range considering that >25% of the parameter values are not usable).

If you are curious about the mapping - a change of ~0.23 on the PeakReduction dial shifts the start of compression by 1dB, e.g., a value of 10-3*0.23=9.7 makes the start of compression kick in for peak signals above 33-3*1=30dB

 

So far no biggies, but when I checked for compression of peak signals I only get ~1.3:1 compression essentially constant across the whole range no matter whether I use a Type selection of Compress or Limit, i.e., I do not find any limiting function at all.

I also expected that the compression rate would be variable dependent on the setting of PeakReduction and type set to Limit or Compress and at least reach 4:1 (all features described in the L-2A manual).

There is also no slow start of compression - it goes into full effect on the first dB above the threshold set by PeakReduction.

 

Emphasis settings seems to do hardly anything if you run your guitar right into the LA-2A model (for clean tones - have not tried anything else yet), but that kind a makes sense because there is not a lot of activity in 15KHz band coming from an electric guitar.

 

Anybody out there having more luck or found the magic setting to get different compression rates or a limiting effect?

 

PS: I measured using a re-amped track and run it through 2 gain stages to lollipop the levels up and down over a 34dB range before driving the LA-2Aand measure the output with Logic's level analyzer.

[DunedinDragon]

I use the LA Compressor quite a bit to achieve that kind of mildly compressed tone on slightly crunchy songs typical of 'Start Me Up' or 'Honky Tonk Women', or even early Doobie Bros. stuff like 'Long Train Running'.  I also use it quite a bit to even out finger picked clean ballads on my Gretsch.  It's a much more subtle, less aggressive compression than you might get with the other compressors and I typically place it toward the start of my signal chain.

 

For my purposes I typically match up volume-wise with the gain a tad below 5.0.  I put the Emphasis (which is really the amount of compression) up around 8.5 to 9.0 and the Mix at about the same range as Emphasis.  Peak Reduction seems to work best to my ears around 3.5 to 5.0 on what I'm trying to do, but that parameter can vary quite a bit depending on the guitar, amp, cab, and mic.

 

I've only really used it as a compressor so I can't speak to it's limiter abilities.  Anyway, that's generally where I've found it to be useful for me.

[HonestOpinion]

...

There is also no slow start of compression - it goes into full effect on the first dB above the threshold set by PeakReduction.

 

 

...

Was trying to get my head wrapped around this comment. This potentially implies a couple of things to me - the attack setting is relatively short/fast such that the compressor kicks in almost immediately when the threshold is crossed, and that the "LA-2A" is set to a hard knee as there is no gradual ramping up of compression (there is no "Knee" parameter on the LA Studio Comp or the original "LA-2A" so this may be as originally designed?).

 

 

Thought I had a good handle on the HD500 model of the Studio Compressor, but the Helix one puzzles me.

 

What I found so far is this:

 

Needed a Gain value of ~3.7 to match output to input level as long compression is not engaged (that's fine).

The PeakReduction dial shifts the start of compression up and down the input signal level scale, e.g., a value of 10.0 starts compression at -33dB peak and at a value smaller than 2.4 prevents any compression unless you peaks above 0 dBFS (that seems like a strange scale range considering that >25% of the parameter values are not usable).

If you are curious about the mapping - a change of ~0.23 on the PeakReduction dial shifts the start of compression by 1dB, e.g., a value of 10-3*0.23=9.7 makes the start of compression kick in for peak signals above 33-3*1=30dB

 

So far no biggies, but when I checked for compression of peak signals I only get ~1.3:1 compression essentially constant across the whole range no matter whether I use a Type selection of Compress or Limit, i.e., I do not find any limiting function at all.

I also expected that the compression rate would be variable dependent on the setting of PeakReduction and type set to Limit or Compress and at least reach 4:1 (all features described in the L-2A manual).

There is also no slow start of compression - it goes into full effect on the first dB above the threshold set by PeakReduction.

 

Emphasis settings seems to do hardly anything if you run your guitar right into the LA-2A model (for clean tones - have not tried anything else yet), but that kind a makes sense because there is not a lot of activity in 15KHz band coming from an electric guitar.

 

...

 

 

Thanks for testing this! I have not seen any response from Line6 regarding your testing. If your testing results check out, particularly regarding the issue with compression ratio it would appear that the "LA Studio Comp" model might be well served if revisited by Line6 and tweaked/fixed.

 

I have also never seen a response from Line6 regarding how the 'Emphasis' parameter was implemented. As you point out and I have also asked in the past, if it only affects the 15khz area similar to the original "LA-2A" compressor it was modeled on, it will have little bearing on the sound of a guitar which does not generally extend in any significant way up into this range. That means this control really only exists to provide accurate modeling of the original "LA-2A" device and perhaps for use in some specialized scenarios on the Helix where this frequency range actually comes into play. That would be fine, I am just curious as to how it was implemented.