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LA-2A hot rod
Old 21st July 2005
  #1
Gear Maniac
 
cornboy7x's Avatar
LA-2A hot rod

hello all,

i was wondering if anyone has any info on what people do to hot rod LA2A's? im not asking for any secrets or anything, just a vague description at least. do they change tubes, component value changes, transformer changes? i am thinking about building a couple of bloo technolgies LA-2A clones but instead of trying to make them sound like excatly like an LA2A (which will never happen, so why bother trying) i want to make LA2A based compressors. i dont think i am going to use UTC's. i have some old RCA transformers that sound amazing for the output (assuming theyll work, or ill try to make them work), but im not sure yet what im gonna use for the inputs. anyways, thats my plan. any advice would be greatly appreciated.

Thanks
Old 22nd July 2005
  #2
Lives for gear
 

jensen

My fav la2a was at right track in nyc, I think it was hired in though.
It had a sharpied tag on the back that said, "replaced utc trannies with Jensen in and out".

It was really nice, but not as gritty as a standard la2. I liked it better for tracking vocals.

I think the circuit drawing is on the jensen site somewhere.
Old 22nd July 2005
  #3
Lives for gear
 
brianroth's Avatar
 

H,mmmm..I never realized there was anything wrong with the sound of an LA-2, for a gven purpose!



Bri
Old 22nd July 2005
  #4
Replace C1 with a .022 uf MIT PPFX. Replace C2 and C3 with a .1 uf MIT PPMF 600 v. Replace C5 with a Panasonic 22 uf 400 v EB series. Bypass with a MIT .1 uf PPMF 600 volt.
Replace the UTC A-10 with a Jensen JT-11P-1.
Replace the UTC A-24 with a Jensen JT-10K61-1M
Replace the TB-4 opto cell with a fast release version from UREI.
Sell the UTC transformers on EBAY for several hundred dollars. Use the money to pay for these new parts. Be happy.

Jim Williams
Audio Upgrades
Old 22nd July 2005
  #5
Lives for gear
 
blackcatdigi's Avatar
Hhmm...

The way I read it, the threadstarter was looking for mods to a 'clone' design. That is understandable.

But Jim; You're advocating a lot of changes on a very collectible vintage piece. And selling off (what some consider to be) some of the 'mojo' components! You surely must be aware this will kill the value of this gear...

If you want an LA2A get one. If you want something similar, there are many LA2A inspired pieces of gear available. Hell, UA makes one you could do Jim's mods on.

But, I sure as hell wouldn't advocate bastardizing a vintage LA2A...

YMMV I guess.
Old 24th July 2005
  #6
Information supplied is for entertainment purposes only.

Whether the reader wants better resale value or better sonics I will leave to the forum.

I go with better sonics. If I bought/used gear only on it's percieved resale value, I would never take the unit out of the box but would preserve it for future sale.

If I had to smash an LA-2 to pieces to get the desired result could anyone fault me? Reminds me of the action directors in Hollywood that think nothing of smashing a $200,000 camera into a car windshield just to get "the shot". An aspiring director might shudder at the thought, but it does make for great camera work that is easily justified with the budgets they operate on.

Jim Williams
Audio Upgrades
Old 24th July 2005
  #7
Lives for gear
 
blackcatdigi's Avatar
Touche' !!!

Your 'parts list' just freaked me out!

Old 8th August 2005
  #8
Kev
Gear Nut
 
Kev's Avatar
 

I'm not convinced a fast T4B is sonically better ....
now you will need two units

... a fast one and a slow one

I'll have the UTC trafos if you can't be bothered selling them on E-bay.
Old 8th August 2005
  #9
It is if you want the gain reduction meter to return to 0 anytime soon. Run a pop kick drum through one. You will see the gain reduction meter needs 4 seconds to return to 0. By the time it does, the kick has hit again and the meter is always in gain reduction. The faster release version overcomes much of this. Heck, they come on a socket, just plug in the slow one's for drippy ballads.

Jim Williams
Audio Upgrades
Old 8th August 2005
  #10
Kev
Gear Nut
 
Kev's Avatar
 

I don't use the LA2 for Kick
simple

I like it just the way it is on vocal and bass guitar

as I said
... if you must have one of the fast ones ...then you may want to have an additional unit for one of the classic slow ones.
I like the UTC transformers and the difference between the UTC and Jensen output may not be so marked when into a bridging input like on a typical DAW Interface.
yes,
get the caps you mentioned and make sure the rest of the unit is working up to spec.

I should also point out I have opto compressors made with my own and freinds opto devices and we think they are the best for the job we apply them to.

I also like the RC4136 in the side chain of the LA4.
Yes,
upgrade the signal path to better opamps but I like the sluggish nature of the 4136 in the detector.
Old 10th August 2005
  #11
Gear Maniac
 
music friend's Avatar
 

I've heard that the Mastering Lab has modified LA2As that they use across the bus. This is all second hand info, but I also heard that this is among the few compressors Sax has ever used for this purpose. I'd love to know how they were modded.
Old 10th August 2005
  #12
When I used to get laquers cut there in the 80's they didn't use them. Must be a later developement. Once the dynamics of cd's were destroyed, they may have come in vogue.

Jim Williams
Audio Upgrades
Old 1st November 2006
  #13
Gear Maniac
 

la2a

If your looking to get rid of those UTC tranformers I would be interested.

Very scary mod replacing UTC transformers but if your use to calling a chip replacment a mod you get the picture dfegad
Old 1st November 2006
  #14
Quote:
Originally Posted by Kev View Post
I don't use the LA2 for Kick
simple

I like it just the way it is on vocal and bass guitar

as I said
... if you must have one of the fast ones ...then you may want to have an additional unit for one of the classic slow ones.
I like the UTC transformers and the difference between the UTC and Jensen output may not be so marked when into a bridging input like on a typical DAW Interface.
yes,
get the caps you mentioned and make sure the rest of the unit is working up to spec.

I should also point out I have opto compressors made with my own and freinds opto devices and we think they are the best for the job we apply them to.

I also like the RC4136 in the side chain of the LA4.
Yes,
upgrade the signal path to better opamps but I like the sluggish nature of the 4136 in the detector.
BTW, from my request, Brown Dog has made a 4136 to 2 surface mount duals adaptor for only around $3. Sure beats the $30 pcb's I was getting from Eddie Chiletti and Dan Kennedy. I also use slower side chain opamps when I replace these in LA-4's. You have the choice when split into 2 dual opamps.

Jim Williams
Audio Upgrades
Old 1st November 2006
  #15
Lives for gear
 
gsharp's Avatar
 

Quote:
Originally Posted by music friend View Post
I've heard that the Mastering Lab has modified LA2As that they use across the bus. This is all second hand info, but I also heard that this is among the few compressors Sax has ever used for this purpose. I'd love to know how they were modded.
It is true. I have no idea what the hell is still left inside though.
Old 1st November 2006
  #16
Kev
Gear Nut
 
Kev's Avatar
 

Quote:
Originally Posted by Jim Williams View Post
... 4136 to 2 surface mount duals adaptor for only around $3. Sure beats the $30
not as cheap but JLM has an option too

http://www.jlmaudio.com/4136%20to%202%20x%20NE5532.htm
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