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LA-4 Mods Anyone DIY?
Old 22nd June 2009
Gear Nut
Jeff S's Avatar
LA-4 Mods Anyone DIY?

I have a pair of black face LA-4s and want to try the upgrades that seem to make them more usable. I've searched the GS and PSW forum as well as Google but would like some GeekSlutz input. The 4136 swap out for the input seems easy enough but what about the output mods and gain structure mods? I was reading the Eddie C description and that sounded fairly straightforward and somewhat affordable. Also some A+ reviews on the Alactronics mods but very pricey ($500!) - way out of my financial reach. I guess my question is for those who have done the mods.... would you care to shed a little light on the process and/or results? What about the opto matching/replacement? Thanks for the input
Old 22nd June 2009
Gear Addict
buschfsu's Avatar
i used 2 of these in my siverface and loved the results
Two Pre-Mounted OPA2134UA on RC4136 Upgrade Adapter (p/n OPA2134UA-060601)
Old 22nd June 2009
They are done here, but I don't charge $500! I use a Brown Dog adaptor as Eddies's are way too expensive and poorly made. Brown Dog now makes a gold pinned 4136 to 2 S0-8 dual opamp adaptors after my request. They are about $5 compared to $30 for Ed's.

Unlike the rest I use very fast high current opamps, not necessarily audio grade parts, I don't use common parts like OPA2134, much better are available. Phase compensation and psu bypass caps are added to maintain stability. The power supply is rebuilt with very large low impedance caps, resistors are changed to Dale and the coupling caps are bypassed with polyprop film caps. Gain staging is reset to lower noise further. All mods are then tested on the Audio Precision.

Jim Williams
Audio Upgrades
Old 25th June 2009
Here for the gear

vintage gear query

Where would be a good place to sell a couple of pieces of vintage gear? ...
A Urei Teletronix LA-3A and Lexicon PCM-70 reverb. I'm located in NYC.
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