Skip to main content

LA-2a as an overall compressor?

tracking with an LA2A is amazing.

Wow, smoke

Right in your face.

Trying to get the same sound after vocals are printed doesn't compare. What a glorious sound tracking with an LA-2A.
It makes me wonder how the Apollo and the LA-2A plug-in would stack up to the hardware. My guess is no contest to the real deal but if you have an Apollo, please chime in and let us know what you think.


Serpentarius Sun, 11/11/2012 - 09:05

audiokid, post: 393585 wrote: Wow, smoke

Right in your face.

Trying to get the same sound after vocals are printed doesn't compare. What a glorious sound tracking with an LA-2A.
It makes me wonder how the Apollo and the LA-2A plug-in would stack up to the hardware. My guess is no contest to the real deal but if you have an Apollo, please chime in and let us know what you think.

As soon as I've got the stuff I'll let you know. By the end of next week I should have it in the flat and like I said, I intend to re-record the vocals for "Eagle". At least, I want to record another set of vocals and compare to the original. The difference in overall sound should be substantial, with the Peluso mic and the Apollo versus the TSM mic and the Babyface.

Serpentarius Sat, 09/23/2017 - 00:06

Hi Chris!

Long time no write. Yes, I did in fact get my stuff set up—just in time for the birth of my second child. Need I say more? At the time I wrote the above response by boy was a little over a year old and I thought I'd find the time to record and produce. Now my boy is 6 and my daughter is 3 and I've hardly produced or composed any new music. I still have the gear, although I did contemplate selling it and wait until the kids are a little older and re-buy it or equivalent stuff. I opted to keep it though, for now. So I'm sorry to disappoint but I've not had any opportunity to try tracking with the UA LA-2A.

On another note, have you heard of AudioJungle? I was thinking of maybe trying to earn a bit of money on the side selling music clips there.

audiokid Sat, 09/23/2017 - 07:47

Serpentarius, post: 452970, member: 45049 wrote: just in time for the birth of my second child. Need I say more?

Been there too! Being a Dad and there for you kids is more important. Congratulations!

Serpentarius, post: 452970, member: 45049 wrote: So I'm sorry to disappoint but I've not had any opportunity to try tracking with the UA LA-2A.

Understandable! I look forward to the time you are back at it and share your experiences again. The LA-2A is a wonderful tool. Glad to hear you kept it!

Serpentarius, post: 452970, member: 45049 wrote: On another note, have you heard of AudioJungle ? I was thinking of maybe trying to earn a bit of money on the side selling music clips there.

I haven't. Thanks for the link, we shall check it out!

audiokid Sat, 09/23/2017 - 09:35

DonnyThompson, post: 452979, member: 46114 wrote: I wonder how the Warm Audio WA Opto compares to an LA2? Any RO members have any experience with it?

I've tried to get one here 3 times now. Can't seem to inspire Warm to do that without buying it. I suspect its pretty good for the price.

Tony Carpenter Sat, 09/23/2017 - 10:35

@DonnyThompson like Chris says UA stuff is nice. My only experience being UAD of course, since I have the UAD2 quad card. I was discussing the relevance of more modern plugins using modelling with a second year audio engineering student on Thursday. His example was an 1172 that they have a real one of. He commented you simply couldn’t separate them enough worth talking about.

I think the important thing still is, how does the overall sound of the song rate when all is said and done.

DonnyThompson Sat, 09/23/2017 - 12:38

Kurt Foster, post: 452995, member: 7836 wrote: @DonnyThompson

you should contact Warm Audio and ask them for the loan of a demo unit to do a review. i'm sure theres a lot of interest and a nice review on RO can help them sell a few units.

meanwhile, there's this from Tape Op

I dunno Kurt ...Chris mentioned in his post above that he has has tried several times to get one to do a review; I doubt they'd give one to me to try if the administrator of RO couldn't get them to do it for him.
I'd love to try one, though. Along with their 1176 Rev D clone and also the Pultec clone they make as well. I guess I could ask... The worst that happens is they say no, which would be the answer I would expect to get anyway.

audiokid Sat, 09/23/2017 - 12:49

(My 19 year RO policy)
I won't do anything here unless, at the very least can keep what we promote. That is assuming we endorse it for what it is targeted for as well. I also don't, under any circumstance renew ads that don't live up to what they say they are. Which has only happened a few times in 19 years.

Being said, they would likely lend it to you in exchange for a good review though (good trade for them and likely you). If you liked it, the norm would be to give you the accommodation pricing, after the review.

audiokid Sat, 09/23/2017 - 13:03

Kurt Foster, post: 452995, member: 7836 wrote: you should contact Warm Audio and ask them for the loan of a demo unit to do a review. i'm sure theres a lot of interest and a nice review on RO can help them sell a few units.

I think you would do a respectfully fantastic review that was earnest and informative. I think the timing is perfect for it, I'd be sure to mention the project you are on right now and (to help) I will put it in our resource section as my contribution towards your project as well!

I actually think you could have a great career doing reviews.(y)

DonnyThompson Sat, 09/23/2017 - 15:05

Thanks Chris.
I've done very few reviews, mostly what I've done here is to go over the history of famous pieces; their origins, revisions, explanations of what the various functions and settings do. I'm the son of a history teacher, I guess that must have rubbed off on me. ;)
I'm happy to try... though I don't know how much credence or weight I could lend, certainly not as much as you, having owned all the real hardware they are cloning, as well as being RO's CEO.... or Kurt or Boswell's knowledge of all things analog. I'm happy to admit that I'm a fairly good writer, although I'm not sure that's enough to qualify me.
I'd be happy to contact them and ask, though, if you guys think I should. If you have any contact info for the company that would be helpful.


Teletronix LA2A - History and How it Works

With the advent of classic gain reduction units in software/plug-in form, I thought I would start a series of threads explaining how these original classic units worked - kind of a "what makes them tick" series of threads, for those who are using emulations from companies like…

I believe that knowing how these original models worked, and what they were/are designed to do, will perhaps help those who are using the plug-in versions of them to better understand them, and hopefully, to use them to their optimum.

Part2 in the series...

The Teletronix LA2A

The LA-2A Leveling Amplifier is an audio gain reduction device, invented by James F. Lawrence II, founder of the Teletronix Engineering Company in Pasadena, California in the early 1960s. Teletronix was sold to Babcock Electronics of Costa Mesa, California in 1965. In 1967, Studio Electronics (eventually renamed UREI), picked up Babcock's broadcast division, including the Teletronix brand. Three versions of the LA-2A were made until 1969. The LA-2A was inducted into the TECnology Hall Of Fame in 2004.

The LA-2A has simple controls: a Peak-Reduction knob controls the gain of the side-chain circuit, and therefore, the gain reduction; a Gain Control for make-up gain; and a Limit/Compress switch which alter the compression ratio. The VU meter may also be switched to show gain reduction or output level.

Compared to other gain reduction devices, the LA2A is considered to be "slow" in reaction time, with the attack set for 10 milliseconds. The LA-2A has a sonically "smooth" character that has made it sought after by many recording engineers over the years. Widely used on vocals, but compatible with all instruments, it is often found as a second stage compressor/limiter located after a "faster" type GR is used first (FET-style such as the Urei 1176).

The Teletronix Leveling Amplifier will automatically reduce audio peaks which might otherwise over-drive broadcast or recording equipment.

How It Works:
The LA-2A is a hand-wired, tube-based, compressor. It uses an electro-luminescent panel, together with a cadmium-sulfide light-dependent resistor, to provide gain reduction, which, in the LA-2A, is called the T4 cell. The properties of the T4 give the LA-2A its unique character by making it an entirely program dependent design. The attack time is 10 milliseconds, and the release time is about 60 ms for 50% release and 0.5 to 5 seconds for full release, depending on the previous program material.

Automatic gain reduction is accomplished by the use of the T4 Cell, which is placed ahead of the first amplifier stage. The attenuation is controlled by the amplitude of the LA-2A input signal.

This system permits up to 40 DB of instantaneous gain reduction, yet causes no wave form or harmonic distortion. The amplifier provides sufficient gain and output level (10 DBM nominal) to be used as a line or program amplifier, or for direct connection to the transmitter in the case of radio and TV operation. Provisions are made for interconnection of the optical attenuators to provide equal gain reduction in both channels when two of the LA-2A Leveling Amplifiers are used for FM stereo broadcasting.

The LA-2A Leveling Amplifier will produce essentially instantaneous gain reduction of over 40 DB with no increase in harmonic distortion.

Compressor action occurs from the breakaway point at -30 DB input and up to -20 DB, at which point the curve becomes horizontal to exhibit limiting action. The input increases an additional 20 DB, but the output increases less than 1 DB. The leveling amplifier thus combines the the characteristics of a compressor and a limiter. A reasonable amount of care in gain riding will restrict normal operation to the compression region, but uncontrolled output levels will be prevented by the limited action.

Let There Be Light...
The heart of the leveling amplifier is the electro-optical attenuator which is placed ahead of the first amplifier stage. The actual stage gains and and tube operating parameters are not varied, permitting the tubes to operate at optimum conditions regardless of the amount of gain reduction. The optical attenuator consists of a photo-conductive cell, which is optically coupled to an electroluminescent light source. The electro-luminescent device provides a light intensity which is proportional to the audio voltage applied to its terminals.

Not unlike a capacitor in construction, the electro-luminescent lamp consists of a plate of glass or plastic coated with a clear conducting material on one side and a thin layer of phosphor on the other side. A metallic plate contacts the phosphor coating. As alternating current is applied to the conducting plates, the phosphor particles s are "excited" by the voltage across the dielectric and light is produced. The amount of light depends upon the applied voltage and frequency. The gain or level controlling element is the photo-conductive cell. The resistance of the cell decreases with an increase in the impinging light. Since the light is produced directly from the audio voltage, the response is instantaneous. Rectification and filtering of the audio to produce a control signal, are not necessary as in the case of conventional limiters. This system results in automatic level control whose speed of operation is limited only by the response of the variable resistance photo cell used.

A cell is selected which provides a minimum attack time, and a release time which requires about 60 milliseconds for 50% release, and then a gradual release over a period of 1 to 15 seconds to the point of complete release.

The input signal is applied directly to the optical attenuator from the high impedance winding of the input transformer. The amount of introduced by the optical attenuator is controlled by the audio voltage applied to the 6AQ5 which is the luminescent driver amplifier. The amount of signal applied to the 12AX7A voltage amplifier is also controlled by the manual gain control. The voltage amplifier stage provides a gain of 40 DB. Overall amplifier feedback of approximately 20 DB provides low distortion, flat response, and gain stability.

The output stage is somewhat unconventional, in that a totem pole or double cathode follower is used. This output stage can tolerate great amounts of output impedance mismatch, but retains low distortion and flat frequency response.

For stereo broadcasting applications, a portion of the input signal is fed through the gain reduction control to the 12AX7A control amplifier. The output at this stage is applied to the stereo balance control and is brought out out to a terminal on the chassis. For stereo operation, this terminal is connected to the same terminal on an identical amplifier and control voltage becomes common to both units. A gain-reduction control voltage in either amplifier will cause equal gain reduction in both units. The control voltage is applied to the stereo balance control to the 6AQ5 driver amplifier. This stage provides the necessary voltage to operate the electro-luminescent light source.

sources: Wiki, Teletronix/UA, Dreamhire

Attached files

Hi I currently use a RNC compressor for overall mixes. Would an LA-2a either alone or after the RNC be a good second compressor to purchase for overall mixes?


hollywood_steve Tue, 05/29/2001 - 13:51

Well, one thing to consider is that you will need two of them; unless you are printing mono mixes. Even at the biggest discount pricing, that will run you $5k for a pair of the new reissues, more for originals. I'm sure others will suggest other compressors that would work better than the LA2A in this situation for well under $5K.


hollywood_steve Tue, 05/29/2001 - 14:08

I don't want to hi-jack this thread, but while we are on the subject of stereo bus compressors, what does everybody think of the AMEK 9098 compressor? Is this a "contenduh" in the 2-bus compressor rankings? I've yet to actually see one in person (or hear it), so I'm looking for opinions from anyone who has. Thanks.


Rick Powell Tue, 05/29/2001 - 15:04

AMEK 9098

I was at a mix session once that had a choice of AMEK 9098, Logic FX (SSL), Manley Vari-Mu and CraneSong STC-8 available for strapping across the 2-mix. We wound up using the Logic FX followed by the Manley. The STC-8 is also a very nice 2-mix compressor/limiter and we could've gone that route easily.

The 9098 just doesn't seem to make a mix come alive like the other units, in my limited experience. But we did use it successfully as a lead vocal de-esser, sidechained with a 9098 EQ module. It seems to work OK as an "individual track" compressor fairly well.


anonymous Tue, 05/29/2001 - 19:09

I've had similar experience as Rick with the 9098 as a 2-bus compressor...but Nick Launy (sp?) seems to love it...and I like the way his records what do I know.

To each their own I suppose...needless to say, I'm a big fan of the Drawmer 1969 [really? go figure...], but the STC-8 is probably the clearest choice of the lot.

I really don't like what the Manley Vari-Mu does to the 'low end' when I strap it across the 2-bus, kinda makes it a bit mushy and indistinct for my taste. A Pendulum ES-8 on the other hand is a joy to behold.

I'm also not too wild about the SSL "good box" [Logic FX or onboard compressor...or even the Alan Smart], they work well for me inside the mix, but not over the whole mix [taste, or lack thereof I suppose]. for the original question...if you really want to try an 'optical based' 2-bus compression unit...try an Avalon 2044, a 747 even...a Pendulum OCL-2, even a Manley El-Op...but trying to get a pair of LA-2A's to "lock and track" in stereo? Unless you've got a 'black cat bone and a mojo' it ain't gonna happen worth a fuck...not in this life time.

If you really have a hardon to try a "pair of something"...try a pair of Crane Song "Trakkers", in the 'air optical vintage' mode of operation, you get close enough to an LA-2A for my 2-bus requirements...without the unfuckingbelievable frustrating hassle of trying to get those sumbitches to follow each other. Even a pair of Daking 91579's will track better than a pair of LA-2A's.

BTW Nathan...since when does the '69 have a pair of EQ's? I swear the only thing resembling an EQ was on the mono DI...if there's a stereo EQ in there, I better lay off the drugs.

coldsnow Wed, 05/30/2001 - 02:16

When I mentioned LA-2 I meant in style not necessarily the old model. I do have my eye on the Manley El op because it is the only one of the bunch that I have heard and I know I love it. But I have only heard it on individual tracks and wondered how it would sound on an entire mix.

anonymous Wed, 05/30/2001 - 03:01

Depends on the day, depends on the song, depends on alot of stuff. Working with 'optical based' compressors on a mix bus is often a tad tricky. At times not having the ability to get into the 'attack' and 'release' parameters of some models is a plus, more often than not, it's a minus.

I have found the Pendulum OCL-2 to be better than the El-Op in 2-bus applications. The greater flexibility of the timing is marvelous, and the sound of the unit is also the same token, I've had nearly orgasmic experiences with the Manley El-Op...but it was maybe 1 in 35-40 mixes that really shined when put throught the El-Op [if it's left at the end I will often give it a go].

The Avalon 747, also opto based, has the benefit of having 'side chain' controls right on the face panel. This can go along way toward tailoring your 2-bus compression to the song [and frankly, the little 6 band EQ on the back is very often the balls!!].

I've heard very good things about the Tube Tech 'multi-band' compressor. I haven't had an opportunity to play with it, and am not sure if it's 'opto-attenuator based' or not...but I've heard a most excellent buzz on the street about it.

Your best bet is to try a bunch, and see (hear) what works best for the way you work. Some guys find a couple of units that become their 'go to' 2-bus units, there are still some folk out there mixing without any 2-bus compression and frankly, a lot of their stuff sounds fabulous. In the seemingly never ending struggle to have the least dynamic range, to be the loudest thing that ever came out of the stereo in "Jimmy's bitchin' Camaro"...perhaps your stuff might stand out better if you bucked the trend? seems to have worked for Lenny Kravitz...made a whole new generation conscious of the old techniques and hardware.

coldsnow Wed, 05/30/2001 - 07:20

Yea but would the FMR work when the Manley EL OP does not. I guess what I'm asking, would this be a good combination to have? Also if I think I'm getting the M.E. 737, would the Manley EL Op be about the same thing as the 737 op compressor? Again I'm in a market that does not have a place to try things so I need to go with what I read so please excuse all the question. Thanks again Mike.

anonymous Wed, 05/30/2001 - 08:22

I'm afraid the answer to that is 'Yes, No, Maybe'. Sometimes the RNC will work better than the Manley, sometimes vice-versa. The only thing that's ever constant is that there are no 'absolutes'.

As for the Manley El-Op being even remotely similar to an Avalon Design compression device that employs an 'opto attenuator' more than Corvette is similar to a Pickup truck even though they both have "Big Block V-8" motors.

They work on the same principle, but in different ways, with different circuitry around the actual gain reduction cell.

Everything has a sound, sometimes it complements the music, sometimes it interferes with the music...the hardest part is knowing whether any particular box is "helping" or "hindering" in any specific application.

Jon Atack Wed, 05/30/2001 - 16:02

I have a Tubetech SMC2B (the 3-band stereo tube comp) and concur that it sounds good for mastering, the mix bus, subgroups. But I never throw it on the mix bus.

If the mix isn't rocking, my thing is working on it until it does -- with nothing on the mix bus. Getting the mix to stand out and sound good on its own. If the mix has problems, fixing it before it hits the 2-bus.

Why not just put a great mix butt-naked down to 1/2" and leave all the 2-bus shit, SMC2B or no, for the mastering step.


atlasproaudio Wed, 05/30/2001 - 18:22

My whole take on the LIMITER El-Op for two bus is that is doesn't work for anything that I have personally tried. You need something that reacts more consistantly, what elop have you met that does? Its supposed to be non linear, thats the magic. I would rather use the SSL before those. My advice, get one of the following....1969 Drawmer, Pair of Trakkers, haven't heard the new API 2-bus, but API rocks and it is supposed to be super versatile.

Nathan Eldred
Atlas Pro Audio, Inc.

MadMoose Tue, 06/05/2001 - 18:35

Originally posted by hollywood_steve:
, what does everybody think of the AMEK 9098 compressor? Is this a "contenduh" in the 2-bus compressor rankings? I've yet to actually see one in person (or hear it), so I'm looking for opinions from anyone who has. Thanks.


I've used it a few times on individual tracks and instruments, never on the 2-mix. It definatly has a "sound" to it. I hate to compare it to a 32264a but it sounded like a modern version of that to my ears. Maybe a little cleaner and less gritty but sort of effecty. I wouldn't go out of my way for one but if it fell into my hands at the right price I would pick it up.

Fletcher, have you tried the new API stereo comp yet?