Replace resistor by low-inductance resistor - Is it audible?

[SIY]

Correct, but both representations give different viewpoints from the other, otherwise we would only have one representation if they were the same.

They give the same inductance. I'm not sure why this is hard to understand.

 

[Selah Audio]

You might also test two resistors of similar wattage to compare the effects of the temperature coefficient.

 

[ctrl]

Good work, but I'd suggest doing some time domain tests as well, as you've only covered frequency domain.

Can the measurement of a single chassis not be considered a minimum phase system. In this case, the phase corresponds to the minimum phase and can therefore be derived directly from the frequency response. Will therefore not show any deviations.

However, since the tweeter measurements were made in dual channel mode, the complete phase information is available.
I don't know which representation you expect, so here are two representations.

The measured step response of the two resistors serial to the tweeter in near field (sand cast the green curve, MOX the yellow curve):

Same as above, but as group delay plot:

 

[ctrl]

You might also test two resistors of similar wattage to compare the effects of the temperature coefficient.

Sure, I could do that. But I also want to give others a chance to get involved
I think I'm much more diplomatic than Amir

 

[Shazb0t]

Don't tell @maty

 

[Francis Vaughan]

Yes I am, a square wave and an impulse test on both would've shown more of a difference in inductance rather than solely frequency domain.

I don't think you are as familiar as you hope.

A theoretical square wave or impulse has energy at infinite frequencies. We are in the real world, and any test signal is bandwidth limited. Sure, if you extend the bandwidth of the test out further the response change due to the inductor will be greater with increasing frequency. But at any given frequency, the response will be identical no matter what the stimulus waveform is. Using a square wave or impulse versus a swept sine will have exactly no effect on the change in response at any given frequency. The inductance value will not change depending upon the stimulus waveform.

The time domain and frequency domain anaylsies are duals of one another. Ignoring normalisation, the FT of a FT is the original signal. Changing domains is useful to make different aspects of the problem easier to manage with the tools at hand (be they mathematical or representational). but they do not affect the actual results.

 

[typericey]

If no difference in sound, any difference in other aspects? i.e. longevity, reliability, operating temperature

 

[617]

If you cannot see the difference in the measurements....you are making the wrong measurements!

In all seriousness, the speaker designers use the big resistors is for power dissapation and not wanting to start fires. I never worried about the audio quality.

 

[617]

I don't think you are as familiar as you hope.

A theoretical square wave or impulse has energy at infinite frequencies. We are in the real world, and any test signal is bandwidth limited. Sure, if you extend the bandwidth of the test out further the response change due to the inductor will be greater with increasing frequency. But at any given frequency, the response will be identical no matter what the stimulus waveform is. Using a square wave or impulse versus a swept sine will have exactly no effect on the change in response at any given frequency. The inductance value will not change depending upon the stimulus waveform.

The time domain and frequency domain anaylsies are duals of one another. Ignoring normalisation, the FT of a FT is the original signal. Changing domains is useful to make different aspects of the problem easier to manage with the tools at hand (be they mathematical or representational). but they do not affect the actual results.

Believing that the time and frequency domains are somehow distinct is one of those misconceptions which will probably never go away.

 

[Francis Vaughan]

If no difference in sound, any difference in other aspects? i.e. longevity, reliability, operating temperature

So long as the device is rated for the use case, there will probably never be any issue. Carbon composition resistors are hardly ever seen, but they can have problems long term. Running resistors close to their operating voltage at power is an issue, and requires derating. As will lack of air movement. For domestic speakers this is not going to be that much of an issue as speakers usually are not run a huge power. Professional sound reinforcement is another matter, but they moved away from passive crossovers in any system delivering real power decades ago. But there is a reason you see 20 watt sand cast resistors. You can't replace a 20 watt with a 1 watt and expect things to be happy.
Electrolytic capacitors are (as usual) the component that can cause problems. Even then, they are not usually sitting in a hot environment like in an amplifier. I have measured electrolytic crossover capacitors from the 70's that were perfectly fine, and dead on value.

 

[Wombat]

So long as the device is rated for the use case, there will probably never be any issue. Carbon composition resistors are hardly ever seen, but they can have problems long term. Running resistors close to their operating voltage at power is an issue, and requires derating. As will lack of air movement. For domestic speakers this is not going to be that much of an issue as speakers usually are not run a huge power. Professional sound reinforcement is another matter, but they moved away from passive crossovers in any system delivering real power decades ago. But there is a reason you see 20 watt sand cast resistors. You can't replace a 20 watt with a 1 watt and expect things to be happy.
Electrolytic capacitors are (as usual) the component that can cause problems. Even then, they are not usually sitting in a hot environment like in an amplifier. I have measured electrolytic crossover capacitors from the 70's that were perfectly fine, and dead on value.

When I was building tube guitar amps, finding voltage ratings for readily available resistors required some sleuthing. I shudder to think how many DIY projects may have under-rated resistors - possibly even commercial ones.

 

[ROOSKIE]

Excellent work AND. I think we need to try some blind tests somehow. The GR Research guy (along with some others in history) already showed the frequency response doesn't change much if at all. He also claimed the difference was very audible despite the measurements matching.
He made a set-up where one speaker has two crossovers inside. You can switch between them. If anyone has the gumption to try this, then that would be an excellent thing.
The main thing is that there are people saying measurements do not tell the whole story, so you therefore can not use them in this debate. It must ultimately be a listening test to determine if there are things happening that can not be measured (or measured as of yet)

 

[typericey]

This is what I have in my car:

Those are sand cast amirite? I'm not an engineer but I do know that those speakers are expected to run loud (given the "nature" of car audio) and those xovers are expected to be exposed to high in-car temps (parked outdoors in summer). Maybe sand cast does a better job in that environment?

 

[kevon27]

Danny Richie from GR-Research will disagree with this review.

 

[amirm]

Danny Richie from GR-Research will disagree with this review.

He will if he ever performs a blind test. I can put a sticker on a speaker and say it has better parts and everyone will think it sounds better even though nothing is changed inside.

 

[SIY]

The main thing is that there are people saying measurements do not tell the whole story, so you therefore can not use them in this debate. It must ultimately be a listening test to determine if there are things happening that can not be measured (or measured as of yet)

Then they can run those tests and publish the details. They have the burden of proof. The fact that they haven't, even after decades of claims like this, is pretty presumptive- they got nothin'.

 

[Francis Vaughan]

When I was building tube guitar amps, finding voltage ratings for readily available resistors required some sleuthing. I shudder to think how many DIY projects may have under-rated resistors - possibly even commercial ones.

Of course when it comes to tube guitar amps there is a whole new world of component mystique. Carbon resistors become preferred because of their non-linearity. Then there is whole thing about vintage capacitors, let alone tubes themselves. $10 for a single NOS 0.1uF Mullard mustard cap. Nuts. I guess compared to hi-fi it is still minor beans.
I have a Stax amplifier for a pair of Lamdas I bought a zillion years ago. It failed when a couple of resistors that saw most of the supply rail died. They were running idiotically close to their absolute maximum ratings. Easy fix, but not inspiring engineering.

 

[Spocko]

But what about the Pace, Rhythm and Timing!

Did wifey come out of the kitchen demanding you keep the low inductance resistor?

 

[ROOSKIE]

Then they can run those tests and publish the details. They have the burden of proof. The fact that they haven't, even after decades of claims like this, is pretty presumptive- they got nothin'.

Yes but neither have the measurement folks. Measurement oriented people (and I am one) have the very same burden of proof. Yes we have proved that they measure the same but no one has proved that they sound the same.
Listening tests are the only way to prove that they sound the same, there is no other way.
Despite the fact that these measurements show no real change they can't prove you can not hear some difference for some reason yet to be understood or measured. Along the years of audio study many new measurement techniques have been added. Prior to them people were hearing this or that aspect of sound that at that time there was no way to measure and now there is. There may still be plenty more to understand. (And it is possible that there are aspects that can not be measured yet are real. The fact that this is always a real possibility IS what makes science a useful tool. Ultimately it IS open minded or it is not science but dogma)

 

[SIY]

Yes but neither have the measurement folks. Measurement oriented people (and I am one) have the very same burden of proof. Yes we have proved that they measure the same but no one has proved that they sound the same.
Listening tests are the only way to prove that they sound the same, there is no other way.
Despite the fact that these measurements show no real change they can't prove you can not hear some difference for some reason yet to be understood or measured. Along the years of audio study many new measurement techniques have been added. Prior to them people were hearing this or that aspect of sound that at that time there was no way to measure and now there is. There may still be plenty more to understand. (And it is possible that there are aspects that can not be measured yet are real. The fact that this is always a real possibility IS what makes science a useful tool. Ultimately it IS open minded or it is not science but dogma)

OK, so burden of proof isn't on people making the sonic claims that aren't borne out by measurement; no new measurements or actual listening tests by the folks who claim differences. Zero evidence for the claims, which contradict basic principles. And negatives must be proved.

My goodness. Classic Russell's Teapot.