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Discrete Op-amp module

Started by mckayprod, May 29, 2017, 11:42:39 PM

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mckayprod

OK, who wants to start the discussion on this baby?

https://orangeamps.com/shop/components/op-amp/

I guess there are other similar modules out there.  This one sure is expensive, compared to the chips it replaces.  Besides bragging rights, what do we get for our money?

J M Fahey

Quote from: mckayprod on May 29, 2017, 11:42:39 PM
OK, who wants to start the discussion on this baby?

https://orangeamps.com/shop/components/op-amp/

I guess there are other similar modules out there.  This one sure is expensive, compared to the chips it replaces.  Besides bragging rights, what do we get for our money?
In practical terms:

mckayprod

 :lmao:
My impression of Orange was that they didn't much care about their solid state offerings, anyway, compared to their tube amps.  I seem to remember a previous post about their under-designed heat sinking, etc.  A module like this takes some r&d.  Must be some money to be made somewhere.

g1

 "can be used in any CD player, DAC, or preamplifier that currently runs DIP 8 based IC dual op-amp types."

Sounds like they have realized there is money to be made in the hi-fi audiophool market.
Didn't Marshall have some kind of ipod speaker or something?

J M Fahey

Surething.
Mind you, I´m quite certain that discrete Op Amp is killer, with very high specs ... just that it´s a waste in a humble rough **guitar**  amplifier, where Lo Fi is preferred  :duh

teemuk

I fail to comprehend what particularly makes it superior to other opamps. Just being discrete isn't exactly a merit by itseli.

DrGonz78

Could be the first opamp on the market that the component itself is actually repairable? That was the only benefit I could think of for this thing. Repairing that thing would be a pain in the butt too. Still easier to just grab another opamp and just replace it.
"A person who never made a mistake never tried anything new." -Albert Einstein

galaxiex

Some guys on Madbean pedals forum were talking about these.

Still not sure they would be any better? than a regular op-amp in a distortion or other pedal?

Ya, I'm thinking these are aimed at the audiophools.

Oh, I got a bunch of original short leg carbon comp resistors that I removed from my "vintage" Fender amp.
I'll sell them to you lucky guys for a mere $5.00 each.  ;)   :duh  :loco :lmao:
If it ain't broke I'll fix it until it is.

Loudthud

Several designs like this are floating around.

This is a single that needs a heatsink:

http://www.diyaudio.com/forums/pass-labs/120445-pass-discrete-opamp-dip-8-package.html


J M Fahey

#9
Sometimes they are justified.
One big unavoidable problem with standard Op Amps is that all are "designed as Operational Amplifiers" .... even if we do NOT use them to perform any (Mathematical) operation at all, but as "Audio Amplifiers" which is NOT the main design goal.

Original use was in Analog Computers.
But ...but .... that must certainly be a typo ...... computers are *digital* ..... even the humble 4 function calculator !!! 
Or those must have been just a freakish Lab Toy !!!!

Not really, Analog Computers were so important that , among other things, USA airspace safety (specially Washington airspace) in case of Nuclear War :o depended on Analog Computers, which were used to control these:


Notice the computer here:

QuoteThe RCDC Director's Console with 4 cabinets included the electro-mechanical Servo Computer Cabinet with the analog ballistics computer[6] ("Intercept Computer")[7] which calculated the relative location of a launched Nike missile

To accomplish Math operations: addition - substraction - multiplication - division but specially Calculus: Integration - Differentiation plus assorted others such as Log extraction, exponents, etc. Op Amps (even early Tube ones ) relied on having a flat, *starting from DC* VERY high gain stage,think 40000/60000X for Tube ones, usually 1000000X for transistor ones, but with an unavoidable built in "stability" capacitor dropping gain at 6dB/oct .... starting from 1 Hz up, so even if you add no other external component gain is dropping 6dB/oct throughout the whole Audio range !!!!!
Clearly Op Amps were NOT designed for Audio use!!!!

That said, they are so cheap, abbundant and easy to use that they were shoved into Audio circuits.
I for one am an early user ... since 1969 when I used primitive external compensation 709 Op Amps .... until an Engineer running ENEKA, "the"  advanced Electronics shop in Buenos Aires, told me: "hey kid, try these newfangled ones, they are called 741 and need no external compensation".
It was love at first sight.

That said, they were not meant for Audio, main problem being hisssssssssssssssssssssss and plain running out of gain at high frequencies (3dB down at 10kHz if used at 100X gain).
Having very poor slew rate was also a consequence of that internal compensation cap, it was noticed not only by high frequency loss, which was tolerable, but by ugly slurring whenever the "S" letter was pronounced, we could detect by ear whether a 741 (only poker game in town by the way) input stage was used.

So barely usable in many places but very poor as balanced microphone inputs, which I needed, so I had to design my own discrete Op amps :o
Very simple because they had to perform just one job; a simple differential pair input, a single transistor gain stage with 4k7 load resistor, and only had to supply 10X or 20X gain , with low hiss and enough open loop gain at high frequencies so response was shaped by the NFB loop and not by circuit limitations.
Basically this, with current sources replaced by plain resistors: 22k for the differential pair, 1k BE at the voltage gain stage, 4k7 as load resistor.
Oh, and used PNP inputs and NPN output: PNPs hiss less.

Worked like a charm.

Given that, I find it very logical that early high quality Recording/PA mixer designers (think Neve and such) had to cook their own Op Amps, specifically for Audio use.
Discrete of course, for the very basic reason that any Semiconductor Manufacturer would have asked for a minimum 1 Million unit order just to consider making them.

Of course, Technology advances all the time, and modern Op Amps are so good that they are excellent even for Audio use .... specially since Analog Computers lost favour some .... 50 years ago or more .

teemuk

#10
If low noise, precision, etc. is indeed required then why not just use the circuit architecture of countless mic preamps, which is discrete differential stage amplified by any generic opamp. Naturally matched, low noise, etc. transistors need to be handpicked for the duty, but that is really no different than what one would do when building an entire discrete opamp for the purpose.

I'm quite sure that the simple discrete design (which they can house on those tiny boards) is no match for a much more complex integrated circuit.

mckayprod

Great history lesson.  I always get suspicious when someone says their device sounds more "musical".  What electrical parameter defines musicality, exactly?  I'll give this thing it's cool factor, however.  It would look pretty good on my Elliot P27 board, but Rod would have me shot for using it.