Op-Amps Does anyone make their own?

[M23Bomber]

Hello ALL,


During the last 2 days I got interested Im OPAmp design. I browsed the web and found a few PCBs and schematics:


http://www.audio-gd.com/Pro/diy/OPA/OPAEN.htm - The Website has a well described and detailed replacement list. Also a couple of schematics.


- Did anyone try them already?

- If the OP Amps are designed by DIY community are they the ultimate tribute to DIY and Music?

Regards,
M.

[GibsonGM]

I *have heard* that some people have built discrete opamps, yup.  The designs sure are out there.   Would I?  No, too much time for too little reward....the ones you buy are already pretty much awesomely-designed, and are consistent from unit to unit.   What's to be gained?   The loss of a BIG chunk of space, for a device that has more limits than the one you buy pre-packaged?

Not sure about the "ultimate tribute", Bomber...an opamp is a known and 'already been done' kind of thing.   IMO, what you USE the opamp for has much more to do with creating something of lasting worth.   I mean - you COULD build your own clipping diodes, with a bunch of ingenuity...but, to what end?  They already exist...I've seen some 'ultimate tribute' things, but they tend to be something so far out there, which WORK, that everyone is amazed that someone actually thought it up   

[R.G.]

The web site says:

Generally the IC opamp application is designed for industrial usage. When the IC opamp is used for audio, the performance is less than satisfactory.

This is one of those advertising non-sequiturs that are GREAT for advertising. It is true that most IC applications are for industrial usage. However, that is unrelated to the next sentence. The first does not apply imply the second, and provides no proof of the second being true. Further there is no proof given of the standards of performance or who is satisfied by what measurement.

That is, it's technobabble.

This discrete opamp uses accurate matching of components and audiophile grade resistors

Accurate matching of components for discrete components is remarkably - remarkably!! - difficult. The gold standard for matched semiconductors is devices diffused and cooked on the same semiconductor substrate by the same processes at the same time. That is, monolithic integrated circuits. Even "matched pairs" in the same package are actually two-transistor integrated circuits using monolithic IC processes.

That statement immediately raises my "Advertising Detected!" alert flag. Going on to say "audiophile grade resistors" just raises the alert level higher.

It is true that certain things are more difficult on an IC, notably the generation of complementary N and P type devices, but there has been a lot of work on this in the last 50 years of semiconductor technology.

If you want to mess with discrete opamps - and I personally have, for fun - either mess about in general with the, or go read some things. I like Doug Self's power amp books. These produce a remarkably good insight into the design of discrete opamps, which is what modern power amps are. Or do both.

If you want to do opamp tributes to DIY and music, remember that a tribute is not necessarily accurate to the original. It's a reproduction in the same style that's reminiscent and pleasing in some way with being an exact replica.

[Edit: ca'tn tpye]

[Ice-9]

Take a look at the Boss BD2 schematic which is basically two op amps but using discrete components to make up the two stages.

[davent]

Here's a few commercial discrete opamps someone might like to try, or not, in their next clipping-diodes-in-the-loop opamp shootout.

http://www.partsconnexion.com/opamp_burson.html

[LightSoundGeometry]

I make them. Some people need buffers , especially guys who play worship because they use the volume pedals and typically have a large chain or loops of effects ..some even have up to 4 delay pedals going

also, some old vintage pedals will suck tone from you along with cheap cables and poor rig set ups .