LA4 op amps

Yep Rob used opa2134 according to invoice. I am yet to use it as the VU bezel mounting broke in freight so waiting for replacement part to arrive.
Probably a good question to shoot to Rob why he chooses that one over the other one.

I put Fairchild 4136CP in mine if I recall correctly. They are fine. Don't get too dark.

I use ADA 4898-2 for the expensive seats and OPA1602's for the cheaper seats. Many other things are also done like the power supply, loop gain staging, power transistors, passive resistors, feedback bandwidth, etc. I use one high quality film cap, the rest is direct coupled.

The OPA's are essentially LME49720's with the BurrBrown rail to rail output section. Those will lower the self noise and add extra headroom on top for an increased dynamic range.

thanks, mine already has those in it... 

cheers

Wiz

thanks I will look into those

Cheers

Wiz

So much knowledge in our community: impressive !!

Once you wet your toes you will jump in with both feet and enjoy the ride. The LA4 taught a lot of people some very important cruel lessons & Mods by Eddie, Jim and others taught some important wonderful lessons. The original LA 4 was a shock and dissipointment to many after the linage of 176, 1176, LA2 &3, I mean what real studio didn't have 2 of those who would book a room without them? It was also the box that many of told me started the "all Chips are bad " fad, some had a hard time adjusting to the LA3 but the stock LA4 took the reputation of Urei down !
The First time I played with one of Eddies modded LA4's my jaw dropped! I had learned the lesson years earlier that a stock LA4 was just another blah comp, so it took some convincing but this thing while not a LA2 or 3 had some personality of its own and because the Opto was a Faster Anthony Demaria did its own very useful thing that worked on some voices like nothing else!
Over the years I have heard many of Eddies, JW's and others mods of these and all brought something a little different to the table all very useful. LA4's are not the bargain they were 15-20 years back but still can be had and modded without breaking the bank and less than its more famous brethren, so go have some fun!
Side not always wondered what a CAPI take on SS Opto would sound like with that old API flavor Iron and gain could be a ton of fun with the right Opto!

Or alternately, you could just rock the LA4A as it is, because the sound of the LA4A is a sum of the parts.. Change a part and you no longer have an LA4A..  A lot of these older designs owe a lot of their distinctiveness to their design (read: flaws).