LA-4 Modification, Upgrade and Parts Options
by Eddie Ciletti
Updated July 2014

If your LA-4 is unpleasant, grungy and noisy, this simple mod will make it a useable, more desirable piece of outboard gear. 

WILL IT SOUND BETTER?
YES! Replacing the stock opamps with an EC-4136 module will deliver a noticeable and pleasant improvement that allows the LA-4 to show off what it does best - smooth, optical dynamics processing - without the dark signal degradation of the original opamps.  The modified LA-4 will have more 'air,' and while it doesn't have the "color" of ithe LA-2a and the LA-3a, it is more versatile (by way of its five-position Ratio Control).  Both the Black-face and the Silver-face LA-4 have an output transformer, so there is some color to be had.

The earlier Silver LA-4 has IC sockets, making installation of the two EC-4136 upgrade modules as simple as Plug and Play.  There is an optional resistor change that reduces gain and noise by 6dB.  Later production runs of the Silver LA-4 have no sockets, so the ICs must first be removed - desoldering braid and IC sockets are provided free-of-charge.

For a Black-faced LA-4, the inputhalf of the upgrade is plug and play while the output half requires soldering skills.  For both versions, the noise is reduced while clarityand 'AIR' are improved - frequencies above 10kHz are better articulated and more delicate.  Gone is the upper-midrange grunge that gets worse when the signals are too hot.

DIY Amplifier Upgrade mods come with detailed instructions, images and operating tips.  There are optional Gain Structure Tweaks for both amplifier and sidechain, plus a simplified stereo calibration procedure.

Silver version or Black, the upgrade kit is $100, shipped in the continental USA, the stereo upgrade kit is $195 shipped.

IN-HOUSE MODS

Have you ever noticied the "Threshold jump" between 2:1 and 4:1?  All LA-4s shipped to our shop get the "dynamic threshold" modification that optimizes Threshold for each ratio.  Set the Threshold once for any Ratio and it's pretty much ball-parked for the other ratios.  This allows you to focus on LISTENING to determine the optimum ratio, then tweak as necessary.  (Low ratios are for compression, high ratios are for peak limiting.)  Price includes other "minor" mods, stereo matching and replacing optos, if necessary.  Minimum price is $300 per unit plus shipping.  Two LA-4s can be matched for stereo operation.

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DIY MOD PRICING
OPTION
DESCRIPTION
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QUESTIONS? 
Click here to e-mail for more info OR to request an upgrade kit 
or 
call 651-245-0153
USA
shipping
Black
 
BLACKFACE UPGRADE Part-1
A single EC-4136 upgrade retrofit board replaces IC-1 in the BLACK-FACE version.  High performance, high bandwidth National / Texas Instrument opamps are standard.  It's plug-and-play. 
 

BLACKFACE UPGRADE Part-2Blackface output amp upgrade includes socket, resistors and new output amp IC so that you can really hear the front-end improvement.  Includes Gain Structure mod.  Instructions included.

Requires soldering skills.
$100
shipped
Silver

LA-4

Upgrade

 
SILVER-FACE UPGRADE
Two EC-4136-TC retrofit boards replace IC-1 and IC-2 in the SILVER-FACE version.  High performance, high bandwidth National / Texas Instrument opamps are standard.  It's plug-and-play, Includes Gain Structure mod.  Instructions included.
Requires soldering skills.
 $100
shipped
OPTO-1
Matched Pair of Replacement Optos
( Please specifiy Stock or Upgrade )
Requires Test Equipment, 
mechanical & soldering skills.
$30
shipped

ALL IN-HOUSE MODS include: repairs, calibration and opto matching  the latter is especially important when LA-4s are linked for Stereo.  Each LA-4 has two optos one for metering, one for Gain Reduction. 

ABOUT THE OPTO

  • The stock Optos are not "slow," unless a large amount of gain reduction is applied.  For the LA-4 in particular, the 20:1 mode is a reasonably fast peak limiter, but it is not as fast as an 1176.  That said, for all VU meter equipped dybnamics processors, VU meters are slower than the Attack Time - what "looks" like 1dB of Gain Reduction, is actually much more. 
With the basic mods, the LA-4 like the LA-2A and the LA-3A is perfect for Bass and Vocals.  With all the options, the LA-4 can also work its magic on more delicate instruments like acoustic guitar and can process a drum kit without the dark grunge associated with the original opamps.  Best of all, the optical processing is very musical

An Operating Tip Sheet is also included with the upgrade package. 

     
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    ABOUT THE EC-4136

    The EC-4136 adapter was inspired by geek buddy Everett Carroll, who has created a dual-to-standard-quad adapter the EC-D2Q.  Both adapters allow any of the popular dual opamps to be retrofitted into EITHER a standard quad socket OR the rather unusual pin-out of the RC-4136 (used in the UREI LA-4 as well as many other pieces of gear including Carvin and Ashly).  Since high performance opamps are not available in all configurations (single, dual, quad) these adapters breathe new life into any device that uses generic quad opamps. 

    Click here to e-mail for more info OR to purchase an upgrade kit 
    or 
    call 651-245-0153