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Simplified
LA-4 Modification, Upgrade
and Parts Options
by Eddie Ciletti
Updated November 2008
EC-4136 modules
are back in stock!!!
There was a rush on LA-4
upgrades over the summer and early fall 2007 that completely depleted my
stock of EC-4136 modules. The parts and circuit boards just arrived
the first week of November - so, I expect to have inventory to ship before
Thanksgiving.
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. The LA-4
may not have all the "color" of it's older vacuum tube and discrete solid-state
siblings, but it is more versatile - and yet, still simple to use - by
way of its five-position Ratio Control. Both the Black-face and the
Silver-face LA-4 have a discrete transistor output stage followed by a
transformer, so there is still color to be had in addition to the optical
magic.
Installing two EC-4136
upgrade modules into a Silver-faced LA-4 is as simple as Plug and Play.
For a Black-faced LA-4, half
of the upgrade is plug and play while
the other half requires soldering skills - that's why the upgrade is separated
into Black-1 and Black-2. (.)
For both versions, the improvements are Clarity and AIR - the upper-midrange
grunge is gone; frequencies above 10kHz are better articulated and more
delicate.
If your LA-4 is unpleasant,
grungy and noisy, this simple mod will make it a useable, more desirable
piece of outboard gear.
All DIY Amplifier Upgrade
mods come with optional Gain Structure Tweaks for both amplifier and sidechain,plus
a simplified stereo calibration procedure and operating tips.
SILVER-1
A mono upgrade kit is $100,
shipped, the stereo upgrade kit is $195 shipped (paypal this address).
BLACK-1 & 2
The full Blackface upgrade
is the same price as the Silverface upgrade - mono is $100 shipped, stereo
is $195 shipped (paypal this address) - which includes one EC-4136 module
for the input amps - PLUS part-2 - the output amp retrofit
requires soldering, for which detailed plans are included. Again,
with basic soldering skills, you can do this. For those without solderign
skills, the upgrades are available separately.
BLACK GOLD (2008)
This "new" blackface mod
starts out with one EC-4136 module - but now there is a discrete class-A
FET output module that is sweeter than the original LA-3 amplifier - very
tube like. However, the mods are a bit more intense and not DIY.
I am also considering the possibility of swapping an input transformer
for the EC-4136 so it would essentially be an LA-3 with a ratio control.
No prices set yet (see below), but the minimum would be $350 plus shipping.
TEXAS TEA
All LA-4s that Eddie upgrades
get "dynamic threshold," a modification that optimizes the Threshold
setting for each ratio. Low ratios are for compression, high ratios
are for peak limiting. You set the Threshold once and it's pretty
much ball-parked for the other ratios so you can focus on LISTENING to
determine the optimum ratio, then tweak as necessary. Price includes
other "minor" mods, stereo matching and replacing optos, if necessary.
Minimum price is $300 per unit. Two LA-4s can be matched for stereo
operation.
How
to Pay
DIY MOD PRICING
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OPTION
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DESCRIPTION
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PRICE
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Black-1
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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 Burr-Brown 2604 opamps are standard. It's plug-and-play.
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$50
shipped
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Black-2
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BLACKFACE UPGRADE Part-2
Blackface 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
mechanical and soldering skills.
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$50
shipped
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Silver-1
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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 Burr-Brown 2604 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
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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
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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 and effective peak limiter.
Applying 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 651-554-0304
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