What are op amps?
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- Опубликовано: 22 июл 2024
- Whenever high-end designers talk about circuit improvements inevitably they discuss replacing op-amps or improving op amps. What is an op-amp and how does it work? Have a question for Paul? Go to www.psaudio.com/ask-paul/
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Love your eyesight, the same as mine,being 76 years old, the best bit is at this age is everything sounds great!!! stay safe young man!!!
you must be a lot of fun to be around !!! WOW !!! Designing something on a page ? it's got to be soooo good to understand all that you spoke about. You are the MAN !!! thank you !!!
I thoroughly appreciate your time and effort to share your depth of knowledge
The opamp in your hand was an AD706. I think you use it very often for low frequency low noise input stages with higher gain (phono). I like it very much because of its low noise and very low µV offset. In fact it is a bipolar opamp but with nA input currents comparable to FET opamps. Unfortunately it is a little bit too slowly for power amps.
its cool that you do this / I think you are the only CEO of a audio company that does this, shows your passion for Audio!
A little correction to your feedback resistor network: it is a voltage divider. When we consider the resistor between non-inverting input and ground as R1 and between output and non-inverting input as R2, the gain is (R1+R2)/R1 or R2/R1+1.
Hey Paul, thank you for your time and explanation, i hope you will get into more details and complicated stuff, i don't know why but i get the source of knowledge when things get more complicated. Cheers and respects...
You are my audio GURU.🙏 Thanks sir, for teaching us all this for free, love from India.
I can remember am article in Electronic World about building an operational amplifier with tubes, I think it used 4 dual triode tubes. I thought about building one but when I priced out the parts I just could not afford it, I was a junior in high school at the time. I think Philbrick used to sell a simplified unit that had two dual triodes on a phenolic base that would plug into a single socket..
When I got out of the army I worked for Analog Devices when they were on Binny St in Cambridge but most of my work there was on 4 quadrant multipliers. This was in 1970 and IC's were in very early days, they came into being because of the moon program with NASA and the military doing the heavy lifting for the R&D costs.
At this time high end op amps and multipliers cane in potted blocks that were about 1.5" sq and had pins coming out the bottom side. I still have some of those modules down my cellar and the sockets they plugged into. IC's were mostly used by government agencies and they were nothing like we saw later on as far as performance goes.
Your 1K and 10K resistors give a gain of 11, not 10. For a gain of 10 you need 1k and 9k.
Best explanation I have found. Thanks
Bob Widlar (Irish pronounced "wide-lar") was more like an artist than an engineer. He was a genius, a little bit crazy and paranoid and he was one of the first "drop outs" of Silicon Valley. He co-founded Linear Technology which belongs now to Analog Devices. Many linear circuits from the 1970ies and -80ies came out of his brain.
I wound up using a budget opamp preamp while my Hafler was on the fritz. Every bit the Hafler's equal.
Bob Pease commented a lot about Wildlar. Pease’s and Jim Williams’ books are required reading on analog design.
Can you use two different brands of op amps? Like a discrete version and IC.
Are you sure the Phono Preamp had a 709. After a year, there was a mod to change to a faster Motorola transistor which improved the sound. Though the passive eq. was soft and not dynamic for the bass. Good looking with the Wood side panels. Have to look through Audio mags. I think the unit sold for $40. And the mod was about $10. Made in your garage?
4:05 explanation starts here
I Ave heard reviewers say op amp swaping/rolling in a device such as the xduoo xd-05 hand held dacamp is all placebo and dosent change the sou d, what you have just told me is that changing to a burr browm/TI op amp]hich are regarded as providing g a warmer sou d is not placebo then but a valid exercise, or is the change miniscule?
Nice explanation,
That was superb Paul, thank you.
I dont mean to be so off topic but does any of you know of a tool to log back into an instagram account?
I was dumb forgot my password. I would love any help you can offer me
@Axl Parker instablaster =)
@Roland Carlos thanks so much for your reply. I got to the site through google and Im trying it out atm.
I see it takes a while so I will get back to you later with my results.
@Roland Carlos It did the trick and I finally got access to my account again. I am so happy!
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@Axl Parker No problem :)
Great video
is it possible perraling two or more op-amps together (input and output)? for better stability?
You mean like an instrumentation amplifier?
en.m.wikipedia.org/wiki/Instrumentation_amplifier
I would guess that you biased the 709 into Class-A to make it sound better in your phone stage?
I think it is X11? (1V in, 11V out)
Yes, in this configuration gain is 1+ Rf/Rin (until you encounter the amp's gain-bandwidth product, and then it rolls off).
The calculation that Paul did, is valid for the inverting configuration, with signal applied to the input resistor (instead of it being grounded), and the non-inverting input grounded.
The modification that Paul mentioned which they used for the 709 op amps, was probably to bias the output stage to class A by connecting a current source to it. This is a common method for low-distortion applications, although many modern op amps have such low distortion that they don't need it.
so its a crossover essentially.
Schiit Magni 3+ amp vs Magni Heresy ??
(Paired matched transistors) VS (op-amps used: OPA1662 for gain, OPA1688 for output-eight (8) OPA1688 stages per channel) what is the best guys thx!
How your opinion about JRC4558 opamp that everyone hate?
4:00 AD706J
AD706
J 027
G30175
decent
www.analog.com/media/en/technical-documentation/data-sheets/AD706.pdf
Excellent :-D
Paul,I think the gain is 11x
Nice “Bob Ross” of the audio design world!
That Bob Widlar reference. Wow! Such guys aren’t made any more. Read as deep into Wikipedia as I could grasp 😬👍
your diagram was confusing
miss all these type of vids paul.its all gone towards the money side now.
Hey Paul thanks for all your efforts. I've learned so much. BUT... we're not all engineers! Way too deep. Keep It Simple!!!
He did answer it simply. An operational amplifier is a differential amplifier followed by a gain stage. If you aren't interested in the circuit stuff, that is about as much as you really need to know.
Using an IC op amp makes designing small amplifier circuits trivially easy (as well as things like mixers, differentiators, integrators, comparitors, etc.); but, most of them were not designed for high end audio purposes.
@@timharig Yeah, that doesn't help us non-engineers either. I mean, what the heck is a differential amplifier? And a gain stage for that matter?
In my opinion, a really smart person should be able to give both a really simple and a really complex answer so that all people can gain something and learn from what is being said. I mean, circuit diagrams mean absolutely nothing to the average person, none of it makes sense to them because they don't understand any of it, and it just turns them off, some puns intended.
I believe it could be been better explained by using simpler, more basic terminology first, basically defining what things are and what they are for, before going into detail about how they work.
@@mydogskips2 I guess that really begs the question, if you are not interested in learning about circuit diagrams, then why are you watching a video about what is ultimately a circuit component? It's a little bit like somebody who is afraid of math asking a question about calculus and getting mad because the answer involves math.
Nevertheless, I will give you a grade school math definition of what an operational amplifier does without terminology.
An operational amplifier takes two input voltages (we will refer to them as A and B). It subtracts one from the other to get the difference (this is what the differential amplifier does). Then it multiplies the result by a very large number (typically on the order of a millions -- this is the gain stage) and output's the result:
output = (A-B)×1000000
That's it. Do you feel satisfied?
I doubt it since that simple definition, while completely accurate, doesn't really give you any real sense of how to actually use an operational amplifier to do anything useful. Most of an operational amplifier's purpose comes from the circuits that they are contained in.
So engineers are not taught to think of them that way. We taught that they are a black boxes and given some rules to use when analyzing them in circuits. Many junior engineers would not even know the content of this video. They don't care what an operational amplifier does or how it works. They are just interested in how to use them to do necessary operations in their circuits.