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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How
to Pay and Communicate
DIY MOD PRICING
|
OPTION
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DESCRIPTION
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PRICE
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QUESTIONS?
Click
here to e-mail for more info OR to request an upgrade kit
or
call 651-245-0153
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USA
shipping
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Black
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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.
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$100
shipped
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Silver
LA-4
Upgrade
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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.
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$100
shipped
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OPTO-1
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Matched Pair of Replacement
Optos
( Please specifiy Stock
or Upgrade )
Requires Test
Equipment,
mechanical & soldering
skills.
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$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.
E-mail,
Policy and Payment Options
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
|