I recently acquired a vintage Carver C-4000 Preamp. I love this unit but I want to improve its performance by upgrading some of its 14-pin DIP quad opamps - in particular the RC-4136 and the TL074. For the RC-4136, I will be using the Brown Dog RC4136 Upgrade Adapter and for the TL074 a 2X Dual-to-Quad Op-Amp Adapter. These adapters accept two SO8's and adapts them to 14-pin DIP. According to the C-4000 schematic, both opamps have 12+/12- running to their rails. I am thinking that my best bet would be the BB OPA2134/2132. Any other suggestions?

Please don't use OPA2134/32... very limited soundstage
try the AD8066

You might like the sound signature of an opa404.

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If you'll go from 4136, anything will be an upgrade!

OPA2134 is quite nice if it is allowed to work properly.

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You can say that again.

peranders, I agree, the opa2134 is not bad. It's just that it is not good
(it has low noise, low distortion, works well even in quirky circuits). but it has NO soundstage.... AD823 is much better and 0.80$ more expensive. the ad8066 is double the price of an opa2134, but 5$ isn't really that expensive.


another question: are there high quality quad opamps? I only know of the opa4134, and you all know what I just said about that chip family

You have to be careful about substituting opamps into the circuit. The AD8066, for example, has a max voltage rating of only +-12V, and the circuit may have more than that. Also, the board layout is probably not done with high-speed, wideband opamps in mind, and using a Browndog adapter only makes matters worse.

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I share your concern and that is the reason why I am looking for constructive criticism. Nevertheless after perusing the WWW, it seems like others who have replaced these vintage Opamps with the no longer made 14-pin DIP version of the OPA4134 (quad version of OPA2134) experienced success. It should be safe as the voltage swing is fairly wide for the OPA2134, ±2.5V to ±18V.