Andrew GM was right earlier today, its pretty tragic when a simulation cannot be read properly. Correct me if i am wrong upper scope shows blue line V+ , Red line shows V+ at the transistor emitter. Lower scope shows Light blue trace as spikes out of the op amp without transistors, and Red Line shows a Sine wave.
Cheers / Chris
Cheers / Chris
The light blue trace is the differential between the two opamp outputs. If they were the same it should have been a straight line. It shows phase shift as there is a fundamental sinewave and there's crossover distortion introduced by the transistors and their biassing. That is shown because the THD meters show the opamp without transistors to have pretty much sub ppm distortion while the red trace has .013% THD.
The top scope you had correct. It shows the AC loading of a simulated supply with internal resistance/inductance, both at the V+ line and at the opamp power input. It nicely shows the positive half loading, though with an increased Vpp at the opamp terminal as opposed to be connected directly to the supply line.
The top scope you had correct. It shows the AC loading of a simulated supply with internal resistance/inductance, both at the V+ line and at the opamp power input. It nicely shows the positive half loading, though with an increased Vpp at the opamp terminal as opposed to be connected directly to the supply line.
I wasn't trying to be clever or get into technical arguments.
I don't have this type of knowledge to contribute amongst the serious engineers and hobbyists here.
I just think it's quite unfair and unjustifiable to just write something off without trying it and some of the ' slap downs ' didn't seem normal, even for this place 😕
So, read the traces - it's right there I guess😛
If Chris wants to sell it then why not - there's plenty of other members selling there wares and creations here, on websites and on E Bay.
We know who they are 😉
Hell, it's a recession and anyway look at his prices, he's hardly ripping anyone off and I don't imagine he's ordered his Porsche yet 😀
I don't have this type of knowledge to contribute amongst the serious engineers and hobbyists here.
I just think it's quite unfair and unjustifiable to just write something off without trying it and some of the ' slap downs ' didn't seem normal, even for this place 😕
So, read the traces - it's right there I guess😛
If Chris wants to sell it then why not - there's plenty of other members selling there wares and creations here, on websites and on E Bay.
We know who they are 😉
Hell, it's a recession and anyway look at his prices, he's hardly ripping anyone off and I don't imagine he's ordered his Porsche yet 😀
I'm not so sure where you got the 1KHz from.. if you mean the 1mS shown in the scopes, that's the simulation stop time, the time base division is 200nS/div. I just picked 1MHz to get the behaviour into view in a distinguishable manner, I haven't tried it at 1KHz or 20KHz 🙂
Edit: The scopes have independant ground inputs, hence it was easy to visualize the difference. The simulator used is Multisim.
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The light blue trace connects to the opamp without transistors, the inputs as I see it are equally shared , the light blue trace is the product of that device, not a product of summing or difference. If it is a product of difference why is there a Red scope wave at all ?
You assume both signals to share the same ground, but that's not the case. Channel A is grounded against 0V. Channel B, connected to the opamp without transistor, is grounded to the output of the opamp with trannies. That makes channel B show the difference between the two opamp outputs; it's at mV scale though.
My conclusion would be that it adversely affects an opamp's power supply rejection ratio, PSRR, at higher frequencies. At these frequencies the opamp sees a supply with an increased output impedance, making it harder for it to pack a punch (read speed/slew) and retain sufficient bandwidth to apply sufficient negative feedback to combat distortion. That's why decoupling caps are so important, to supply the immediate current opamp output stages demand to obtain their specs.
P.S. when you add a zener between the resistor/base node and ground, then it turns into an actual low impedance emitter follower. Then add a 47uF cap across the ompamp with a 100nF MKT/P in parallel on each rail and it should be happy, but that can take up some board space if you want to feed each opamp package that way.
P.S. when you add a zener between the resistor/base node and ground, then it turns into an actual low impedance emitter follower. Then add a 47uF cap across the ompamp with a 100nF MKT/P in parallel on each rail and it should be happy, but that can take up some board space if you want to feed each opamp package that way.
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Interesting, lets see some comments from people who have tried it, not simulated it.
Stereo reproduction is its best feature,
From my listening with every CD thus far I am enjoying every one like never before.
Cheers / Chris
Stereo reproduction is its best feature,
From my listening with every CD thus far I am enjoying every one like never before.
Cheers / Chris
Clarence Zener was certainly very clever but released an idea with plenty of noise particularly around 8.2v. As we know a IR diode when biased at about 20ma is virtually noiseless but 15v would involve 5 or more. So I don't agree with zeners, they would couple too much noise. The ideas behind cascodes appeal as there is bandwidth extension. David Blackmer of DBX fame was right on the target exploring not only companding but also bandwidth and extension of frequency, even if it challenged Nyquist sampling. He if I recall was most frustrated with CD having brickwall filters at 22Khz.
Cheers / Chris
Thanks Magic Box but how do you solve the lack of a ground pin on an op amp DIP ? on some inverters Pin 3 is ground but not every op amp is an inverter , or is it a case of providing a Pin with instruction to connect your ground here ? 🙄 simulating an onboard ground is that possible ?
An opamp itself doesn't have a ground, just two supply terminals, + and -. The choice of supplpy determines whether you get a real ground or have to create a virtual ground. Opamps work best when the signal being processed is biassed halfway its supply, which naturally is the ground with a symmetrical supply.
Extra pins usually are for offset compensation.
Extra pins usually are for offset compensation.
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MagicBox,
Since you have the model going, could you plot the voltage across Q1 and the emitter current (or voltage / current ) to show the change in impedance ?
Thanks
-Antonio
Since you have the model going, could you plot the voltage across Q1 and the emitter current (or voltage / current ) to show the change in impedance ?
Thanks
-Antonio
Urge you to stop simulating, and start trying it in reality. Its not a difficult circuit to breadboard or connect up. I am currently listening to John Lee Hooker swapping between a non transistor op amp just to check differences, in every case the transistor based op amp sounds much much better.. and it is not hard to hear. It is sad if simulation becomes stimulation ... when ears ( a great source of reality ) and a soldering iron are also available.
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Chris
Sorry if my request seemed for dismissal of the technique it was not intended that way.
If you find it sounds better then you should certainly use it and enjoy.
However everyone on this forum has different goals and brings different perspectives, for me this is what makes audio so fun and satisfying.
Thanks
-Antonio
Sorry if my request seemed for dismissal of the technique it was not intended that way.
If you find it sounds better then you should certainly use it and enjoy.
However everyone on this forum has different goals and brings different perspectives, for me this is what makes audio so fun and satisfying.
Thanks
-Antonio
I know where you're coming from and don't doubt what you hear is an improvement. I think I and others are just interested in what's going on in there. I mean, I love the sound of ancient 301 i.c's forced into class A for heaven's sake.
Op amp use massive amounts of negative feedback to obtain the ostensibly low distortion with steady state signals. The assumption is infinite open loop BW. Real world op-amp have finite BW. Music is not steady state with high transient multi-frequency components. Op-amps would be great if the open loop BW were infinite and could actually reproduce the transient multi-frequency components of music. In my experience op-amp look great when analyzed with steady state sources but just sound like crap when listening to music. In fact I have a preamp that was built in the 70’s using LM301 op-amps. This pre-amp has extremely low distortion when analyzed with the typical steady state techniques but when listening to music through it sucks to my ears anyhow. Give me an inherently linear amplifier with extremely large open loop BW and the very minimum of negative feedback any day over an inherently non-linear op-amp with low open loop BW using massive amounts of negative feedback.
Don
Don
"who is the fool ?" You are for blindly following the blind. "I just have ears and want to make some gains from learning." you are learning nothing because you only use your ears, try using your mind.
The simulation is very inconclusive, when listening is quite and I would say 100% conclusive that this is a huge leap forward in the way we use op amps . How is that explained ?
My test set up for listening is at the moment is a Marantz CD 80 and Sennheiser headphones.
Cheers / Chris
My test set up for listening is at the moment is a Marantz CD 80 and Sennheiser headphones.
Cheers / Chris
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Great, now try an OpAmp from this millenium, instead of that piece of garbage...
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