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biovizier 20th May 2005 08:25 AM

discrete opamp modules

Has anybody come accross discrete opamp implementations for sale online (such as the Welborne labs or Johnhardyco units) as replacements for monolithic units and has anyone used them or compared them with monolithic opamps?



JensRasmussen 20th May 2005 08:59 AM

Try this link


Sigurd Ruschkow 21st May 2005 09:01 AM

Forssell Technologies
Some of the best discrete OPamps out there are the ones made
by Forssell Technologies!

I have both the DLR-1 and the JFET-993 and they sound great! The 993 can be used with 600 Ohms, and the DLR-1 is made
for higher resistance loads (>1k). The DLR-1 sounds a bit better. It is almost as good as Borbely's Superbuffer1!!!

They are all pure class A, and made up out of JFETs and some very good SMD resistors (Tantalum nitride).

Prices are really low for such quality!

Highly recommended.


Sigurd Ruschkow 21st May 2005 09:11 AM

Some photos I made:


Sigurd Ruschkow 21st May 2005 09:21 AM

This is how I have evaluated the 993 and the DLR-1 (I have used sockets for the pins so I can interchange between the DLR-1 and the 993 - I just pull them straight up like pulling out an DIP OPamp from an IC socket).

Caddock MK132 resistors, MICA cap for the feedback resistor, ELNA Cerafine 47u cap and WIMA FKP-3 0.1u.
Silver wire for the signal path.


biovizier 21st May 2005 09:48 AM

discrete opamps
Thanks - which monolithic opamps have you compared these units with and what would you say the sonic benefits were?


steenoe 21st May 2005 09:59 AM

This might be of interest. It is possible to make your own opamps, both Jfet's and bipolar transistor versions.


Sigurd Ruschkow 22nd May 2005 06:20 PM

I have not tested against any OPamps in my new preamp. I do have the space reserved for a pair of OPamps but not had the time to do the testing yet.

I do have written a review of the Superbuffer1 vs the S&B volume attenuator transformers. See this forum.


biovizier 22nd May 2005 06:52 PM

thanks - I saw that. Very interesting. I had looked at a custom built preamp using the S&B from MFAUDIO (S&B in disguise) but they messed me around so I gave up.

Sigurd Ruschkow 23rd May 2005 06:09 AM

At 40 USD each for the Forssell DLR-1 discrete JFET Class A modules, you cannot go wrong.

Why not buy two and try them out? With good components around them (they deserve the best), I do not think you will be disappointed.


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