Does Op-amp Rolling Work?

[Mnyb]

AI assisted gish galloping ?

The very knowledgeable people who answered this with real technical competence ( not me ) will not find the time refute all that . Don't we have a forum rule against posting AI slop ?

Point is a friendly exchange about audio between people is ok and fun , be happy

 

[antcollinet]

I can argue about that with technical facts about how opamps work

In order to do that, you'd have to actually know how they work.

A multitone test shows us the 'average' behavior of the op-amp when it's already 'warmed up' and stable.

Have you seen multi tone in the time domain? Much more complex than "real music"

I would argue that for human hearing (specifically our 10 microsecond ITD resolution), the accuracy of the transient flank is more critical for a convincing soundstage than an extra 5dB of SNR that sits well below the room's ambient noise floor anyway

You might argue that - but that which is asserted or argued without evidence can be dismissed without evidence.



Gonna stop now - never should have wasted my time in the first place.

 

[oleg87]

never should have wasted my time in the first place.

Generally the wise policy with walls of barely-coherent LLM spew.

Looking forward to him carrying out what will surely be a very rigorously controlled "test"

 

[amirm]

A multitone test shows us the 'average' behavior of the op-amp when it's already 'warmed up' and stable.

How do you know it is warmed up? For all you know it could be dressed in t-shirts in the middle of a snow storm!

 

[RexrothPigeon]

I come from the era of cassette decks and dbx noise reduction (copying vinyl 1:1 on cromo tapes). Back then

Then you, like me, are old and have degraded hearing. You probably can't hear a single peep over, say, 14kHz. You might even have "deaf spots" lower down. At a minimum, you can't hear as well as you could back in those tapedeck days

More importantly, unless you conspire to defeat sighted biases, you are not "hearing" at all. We know very well that blind, controlled tests are the only way to defeat those ineradicable biases.

 

[KSTR]

I did that, with a rather complex procedure, measuring down to 150...160dB residual, some 40dB down in the noise floor: Nothing. The only thing I found was 1/f noise and DC drift of the reference voltages in the DAC and ADC used. Will link to thread later...

Making very small distortions/errors audible with music signals. Some examples.

Hi, Over the course of the last weeks I managed to set up and stabilize a procedure that allows to expose the error residual of Null-Tests á la DeltaWave. Actually I'm using DeltaWave for the final stage of display and analysis but it does only level matching fine-tining here, the rest is done...

www.audiosciencereview.com

Mind you, tests at this level of resolution are extremely complicated and basically take one day per measurement. I tested a number of simple opamp circuits, all with modern opamps (OPA1602, OPA1612, OPA2143, LM4562 etc). Other than bog-standard harmonic distortion no ill-effects could be identified and, honestly, I lost interest in continuing. I could arrive at a personally relevant result and learned a lot in the process, so now let's move on.

Like with any test, there were limitations. As the extreme resolution is achieved by true time-domain averaging over many takes (up to 1000) of the same signal, things that are not strictly correlated with the signal mostly average out, like mains hum/buzz, supply fluctuations etc. The other relevant thing that was nicely exposed by the tests is that the independent reference voltages for the DAC and ADC have their own independent life, showing individual 1/f noise and DC drift, which means that the infinite null cannot be achieved by this fact alone because the gains of DAC and ADC are not stable. This issue can be mitigated by using one single reference supply for both the ADC and DAC, and for all channels. This way, any fluctuations are the same for DAC and ADC and thus will cancel to a very high degree to afford another ~20dB of null depth increase for the self-test.

Thermal Tail (Thermal Memory): Transistors on the silicon die change temperature with every current spike, modifying bias and gain-factors in real-time. An Audio Precision sweep is too slow to capture this; by the time the sweep registers, the chip has reached thermal equilibrium. This results in signal-dependent modulation perceived as a lack of micro-dynamics—a dynamic non-linearity that static THD measurements simply mask.

Chip makers have found a way dealing with this already decades ago, using a cross-quad arrangement of the input cells. No matter from which direction a termal gradient is attacking the DC-offset and other parameters this arrangement nullifies it, cancelling out the errors. Also, not to forget, you need significant output load on the opamp to actually induce any thermal change. Only opamp driving headphones have such a load that might have been relevant without the cancelling scheme.

An op-amp with a narrow Phase Margin or a sub-optimal feedback loop exhibits "ringing" and overshoot following a steep transient.
[...]
In a Null Test, need these op-amps reveal a distinct spike in the residual signal at every transient, affecting timing precision and soundstage focus

This is not what I found, you'll probably need a really mediocre opamp or a completely screwed-up circuit to see something here.

I'm not saying absolutely all circuits will sound/measure the same when swapping opamps. But when using competent opamps in reasonable circuits the only major difference I ever found was subtle changes in harmonic distortion profile which are typically way below what has been shown to be audible. No other nasty stuff, nada.

 

[solderdude]

I'd love to see someone with an AP-analyzer run anull test with actual music instead of just sine waves to see if these temporal differences manifest as a measurable residual. There are arguments that the better SNR or a lower noise floor (where bipolar chips often win) are the ultimate goal. But a lower noise floor on a static chart doesn't compensate for temporal smearing.

So you want someone else to do the work for you and prove your 'theory'?

My interest isn't in 'rolling' for the sake of it, but in seeing if the inherent lack of input bias current in a JFET-input stage provides a cleaner transient response than the bipolar LM4562, which are prone to thermal drift under dynamic loads.

What dynamic load does the op-amp see in the buffer stage of those class D amps ?
The resistive load is not high and constant (somewhere around 1k so 3mA max we are talking 9mW of 'heat' in load and around 30mW in dissipated heat in the output stage of the op-amp at max. output voltage) and the capacitive load after that resistor also is not high and simply forms a high pass.
The real issue in these amps is not the huge bandwidth of the opamps in the low gain op-amp stage (which will be >> 100kHz unless it has a Miller cap lowering the BW) but the 'speed and timing' issues are all caused by the class-D stage and their low pass filters.


In digital systems the max. bandwidth is limited.
Only directly after the AC stage the inputs of op-amps and how they react (often determined by the capacitors in the feedback path) is of importance.
This is an entirely different application than a few times gain stage in a buffer stage.

 

[VientoB]

I would argue that for human hearing (specifically our 10 microsecond ITD resolution), the accuracy of the transient flank is more critical for a convincing soundstage than an extra 5dB of SNR that sits well below the room's ambient noise floor anyway.

Do you measure the exact distance from your speakers to each ear, and always keep your head in that exact position when listening?

 

[Ropeburn]

Do you measure the exact distance from your speakers to each ear, and always keep your head in that exact position when listening?

Quick calculation says sound travels about 3cm in 10 microseconds, that would be your margin of error for head and ear position then... Outside of that tiny spot (with head angle straight within 1-3° of course) you're in deep shit regarding timing of your precious listening session, according to our new member.

 

[wwenze]

How do you know it is warmed up? For all you know it could be dressed in t-shirts in the middle of a snow storm!

KH 80 review...

Just for the record, is the AP in the same room as the Klippel

 

[voodooless]

Do you measure the exact distance from your speakers to each ear, and always keep your head in that exact position when listening?

Never mind that the whole proposition does not hold because if we can measure ps jitter we can certainly measure microsecond jitter, and it would most certainly show up in “static” measurements. And secondly, he does not understand what the 10 microsomes metric actually means…

 

[jareinertson]

The opamp song... to the tune of Rawhide;

Rollin', rollin', rollin'
Rollin', rollin', rollin'
Rollin', rollin', rollin'
Rollin', rollin', rollin'
Op-amps

Keep rollin', rollin', rollin'
Though the circuits are swollen
Keep those opamps rollin'
Op-amps

Through noise, distortion together
Hell-bent for better
Wishing my sound was clean and wide
All the things I’m changin’, good gain, smooth and flowin'
Are waitin' at the end of my ride

Move 'em on, swap 'em out, swap 'em out, move 'em on
Move 'em on, swap 'em out, opamps
Cut 'em out, roll 'em in, roll 'em in, cut 'em out
Cut 'em out, roll 'em in, opamps

Keep movin’, movin’, movin’
Though they’re disapprovin'
Keep those opamps movin’
Op-amps

Don’t try to understand ‘em
Just swap and tweak and brand ‘em
Soon we’ll be soundin’ high and wide
My heart’s recalculatin', my true sound is waitin'
Be waitin' at the end of my ride

Move 'em on, swap 'em out, swap 'em out, move 'em on
Move 'em on, swap 'em out, opamps
Cut 'em out, roll 'em in, roll 'em in, cut 'em out
Cut 'em out, roll 'em in, opamps

Rollin', rollin', rollin'
Rollin', rollin', rollin' (yeah)
Rollin', rollin', rollin' (yeah)
Rollin', rollin', rollin' (yeah)
Op-amps (yeah, yeah, yeah)
Op-amps!


©
JSmith

Well done!

 

[PMB]

If you have couple of ne5532's in your class D amp it is not bad choice. Changing makes difference to the sound. But not all can hear it. There are better than ne5532's and also worse. You can for example go cheap jrc4558 that can sound very very good with certain music. Maybe opa1612 considered higher end compared to ne5532.

In the end it is about research of power if it is compatible with your amp and second can your ears actually hear the difference. Halve the people can't can't hear the difference while the other halve can and maybe quarter of that can claim there is a significant difference. First figure out how good is your hearing if it is even worth the trouble. This is the argument because halve claim there is no difference because they can't hear it.

 

[Buckeye Amps]

Changing makes difference to the sound. But not all can hear it.

Why?

 

[Jiraya369]

Why?

ur ears arent golden enough my guy

 

[amirm]

Just for the record, is the AP in the same room as the Klippel

No. Thankfully AP is in my lab/office indoor so not impacted by seaons.

 

[amirm]

Halve the people can't can't hear the difference while the other halve can and maybe quarter of that can claim there is a significant difference.

Yeh, the problem is that word: "claim." Instead of screwing around with op-amps, your first step needs to be to learn how to perform unbiased and proper listening tests. Otherwise, you will be chasing your tail.

 

[oleg87]

First he would need to be here in good faith, and so far I haven't seen the faintest sign that he's here in any other capacity than troll.

 

[BeeKay]

If you have couple of ne5532's in your class D amp it is not bad choice. Changing makes difference to the sound. But not all can hear it. There are better than ne5532's and also worse. You can for example go cheap jrc4558 that can sound very very good with certain music. Maybe opa1612 considered higher end compared to ne5532.

In the end it is about research of power if it is compatible with your amp and second can your ears actually hear the difference. Halve the people can't can't hear the difference while the other halve can and maybe quarter of that can claim there is a significant difference. First figure out how good is your hearing if it is even worth the trouble. This is the argument because halve claim there is no difference because they can't hear it.

 

[antcollinet]

If you have couple of ne5532's in your class D amp it is not bad choice. Changing makes difference to the sound. But not all can hear it. There are better than ne5532's and also worse. You can for example go cheap jrc4558 that can sound very very good with certain music. Maybe opa1612 considered higher end compared to ne5532.

In the end it is about research of power if it is compatible with your amp and second can your ears actually hear the difference. Halve the people can't can't hear the difference while the other halve can and maybe quarter of that can claim there is a significant difference. First figure out how good is your hearing if it is even worth the trouble. This is the argument because halve claim there is no difference because they can't hear it.

Watch and understand the following. Changing opamps in an already competent design can only degrade the sound. Most of the time in any case it will do nothing audible for any human.
Remember that there is nothing we can hear that can't be measured, and there is only noise, distortion and frequency response that can impact the sound.

Does Op-amp Rolling Work? [Video]

In this video I "upgrade" the 57 cent op-amp in the Douk A5 stereo amplifier with a $49 one. Does it make a measured difference? Watch to find out: Test review at: https://www.audiosciencereview.com/forum/index.php?threads/does-op-amp-rolling-work.61518/ Please subscribe to the channel. It...

www.audiosciencereview.com

Amplifier Op-amp Rolling Part 2 [Video]

Follow up video I did on op-amp rolling, covering the latest two tests: [And subscribe to the channel :) ]

www.audiosciencereview.com