discrete opamp modules

[12796]

Has anyone here used discrete opamp modules in place of monolithic opamps?

DIY or off the shelf? Either way I would be greatful for more info

Thanks!

Nick

 

[peranders]

http://www.diyaudio.com/forums/showt...602&highlight=

Sigurd Ruschkowski from Sweden can tell you more about the subject.

 

[rickcr42]

Quote:

Has anyone here used discrete opamp modules in place of monolithic opamps?

I never ever use a monolithic opamp in a home arena,just portables where small size and battery operation are more important than absolute performance.And even that i shorten down to a single device over a full blown discrete opamp unless it offers superior perfromance for that particular use.

JE-990 and Great River are two complex discrete O.A.s,the Borbely,the Forsell and the N.Pass simple and the Leach somewhere in between but in some ways can be made better because of the jfet input and SE Class-a bipolar output stage.Both types of devices are used to their strengths-jfets for voltage gain,bipolars for current gain.

a lot of times I see a full blown discrete opamp used in a unity gain situation where a simple jfet,maybe with a CCS and cascoded could be used as the input buffer to isolate R/C stages such as filters/tone controls/X-Over networks and a compound jfet/bipolar amp to isolate the output of these networks and drive the next stage or a cable.

Simple is usually better than complex IMHO but choices are just that and an individual thing.Some like the little "black box" with a complex circuit and the many transistors of the opamp because they have no idea what is inside but the beauty of all the above discrete examples is the "no more than what is needed" philosophy

 

[12796]

Thanks - are any of those suggestions an off the shelf drop in replacement for an 8 pin opamp as thatI can try out the concept?

Regards,

Nick.

 

[rickcr42]

I think they all may need an adapter but the closest to 'ready to go" is the more than reasonably priced Forsell opamp module.
$65 may seem like a lot but this is an entire discrete circuit optimised for Class-A and better considered as you would a preamp module.

http://www.forsselltech.com/JFET990-2.htm

the DIY option would be to use the first generation opamp module schematic

http://www.forsselltech.com/schemati...et%20Opamp.PDF

http://www.forsselltech.com/JFET%20Opamp.PDF

The Jensen JT-990 you have to request from Jensen Transformers but is a great read to see how they got there and for a simplistic though totally workable design look at the N.Pass opamp ;

http://www.passdiy.com/pdf/diyopamp.pdf

This is a step by step blow by blow to designing a discrete opamp stage and really the way to go if DIY is your goal.Better to design your own and understand it than toi just copy another design and have no clue