Master Thread: Are measurements Everything or Nothing?

[pkane]

Your icon indicates that you may be a little old fashioned

That's not a good likeness of me. But close.

 

[MatrixS2000]

It is the lowest, did you notice the minus in front of the figure??

My bad! My post should have read highest scoring. The absolute number is not what I was referring to.

 

[ArthurDK]

a - It’s the highest SINAD.
b - It is not about “sounding” (sorry about the quotes), SINAD points to accuracy, the higher the SINAD, the more accurate it is.
c - You may like a the sound of a DAC with a lower SINAD, no harm or foul there, but just realize that the cost of that is a loss of accuracy when compared to a DAC with a higher scoring SINAD.

SINAD points to low noise, not good sound.

 

[BDWoody]

I just tried to point in a direction of using for instance square waves and dual tone test and such new fashion things, to try to indicate why some devices sound
different than others. Because SINAD and THD+N does certainly not.

You are starting from the premise that they do in fact sound different, which has not yet been established. A mountain of anecdotal claims does not make for evidence of anything.

Provide actual evidence that supports your claims, then let's talk about what tests need to be added or changed.

Just continuing to be snarky and doubling down isn't going to lead to a long term stay.

 

[MatrixS2000]

SINAD points to low noise, not good sound.

And low distortion.

 

[danadam]

It is the lowest, did you notice the minus in front of the figure??

No. Where do you see it?

 

[Blumlein 88]

I just tried to point in a direction of using for instance square waves and dual tone test and such new fashion things, to try to indicate why some devices sound
different than others. Because SINAD and THD+N does certainly not.

Have read any reviews on ASR? They have IMD and Multitone tests. You are just being a troll posting in bad faith in your recents posts. The SINAD only idea is one of those trollish ideas. The reviews contain far more tests than that one test.

 

[Blumlein 88]

SINAD points to low noise, not good sound.

Actually SINAD is distortion and noise (I prefer they be listed separately myself). If both are low enough across the audible band, and frequency response is flat, yes you'll get accurate sound. If your definition of good is fidelity okay and if it is something else they you need to let us know what is good to you.

 

[ahofer]

OK, it seems here is no place for non-SINAD believers, so let us continue to measure unusable things like we always did - Things that does not show much difference between
different devices, and that does not contribute to anything. And let us keep believing that the best sounding device in the world is the device with the lowest SINAD.

Where did you see this SINAD monomania above? Or elsewhere in the site?

(and no, the presence of a graph does not imply that the metric in the graph is the ONLY thing).

 

[voodooless]

My bad! My post should have read highest scoring. The absolute number is not what I was referring to.

No! Not your bad! Don’t get distracted by the troll. You were absolutely right: the highest SINAD gives the highest objective fidelity (at least for the metric measured). SINAD already has the minus sign removed from THD+N.

 

[MaxwellsEq]

To me FFT analysis is a static analysis

You are missing something, and it's a common mistake. Consider a 1kHz sine wave: sometimes (at the zero crossing point) the voltage is exactly zero, but the rate of voltage change is high, so it sweeps towards the positive rail. It's now a high, positive voltage, but it's soon heading back towards zero. Then it moves quickly towards the negative rail, before diving back to zero. There's nothing static about a sine wave.

Now consider a very complicated piece such as a Beethoven orchestral recording. At any one instance, there is only a single value of voltage across the speaker terminals. So we need to understand how fast that single value of voltage needs to change to keep up with the music. And it's easy to show that a sine wave at 20kHz is more challenging for an amplifier than complex music. Sine waves are fully adequate tools to measure equipment with, and because of their purity, they make it easy to detect distortion.

 

[MatrixS2000]

No! Not your bad! Don’t get distracted by the troll. You were absolutely right: the highest SINAD gives the highest objective fidelity (at least for the metric measured). SINAD already has the minus sign removed from THD+N.

I know I was right, but I gave him the benefit of the doubt regarding how he interpreted my post. I read his reply to mean the actual measurement of noise for example, which would be a negative number. So I just cleaned up my post to make it clear, not that I think that would change his mind. Pretty sure he is stuck on it because he keeps talking about sound - which is subjective, while accuracy is objective.

 

[Rob_Gordon]

Hey,
Not trying to bring back an old debate but I was quite interested in the discussion in this thread on blind testing speakers vs sighted listening and I experienced something this week that made me think of it.

So, reading that Amir's advice to always EQ headphones, I looked for a preset. I apply the preset, listen to some music with it. I'm having a hard time knowing if I "like it" better (but kinda discard the question anyway). I generally have very little confidence in my ears–some pretend they have golden ears? I have stone ears lol. So, to me, the difference was noticeable but not spectacular.

After a 30 mins or so, I turn it off... and feel this time a BIG difference, I'm like "oh ok, it does change a lot!"... only to realize I actually hadn't turned it off!

I guess this isn't surprising at all, knowing all the biases involved... But it got me thinking: if seeing the speakers alters our perception of sound, applying an EQ (and thus, knowing precisely what frequencies are enhanced/mitigated) must definitely skew our perception too, right?

I mean, I get that you could say "at least you know the signal is better", but if I'm not sure that I hear it as it's supposed to sound...

So, can you apply an EQ and actually evaluate it/take advantage of it?

I also wonder how to ABX this...

 

[IEales]

This article is to look at the impact speaker cables may have on frequency response. For this study three amplifiers driving four speakers using no cables and 10’ (~3 m) of 18 AWG or 10 AWG cables are modeled and the frequency response at the speaker terminals simulated. The implicit assumption is that frequency deviations at the terminals can affect the acoustic output of the speakers given they are designed to be driven by an ideal voltage source (a perfect amplifier). In general, real amplifiers are used, so speakers may be designed using a particular amplifier (or set of amplifiers), but in practice these simulations will still show how frequency response can change with different cables.

The amplifiers are a wideband solid-state (SS) AVR amplifier with very low output impedance (and thus very high damping factor), another SS amplifier with more modest output impedance and bandwidth, and a relatively high-impedance (low damping factor) tube amplifier.

The speaker models are the Stereophile speaker load and three models based upon previously-measured speakers: a planar dynamic (e.g. Magnepan, a two-way model and not my MG-IIIa three-way speaker) model with mostly resistive impedance, a hybrid ESL speaker (e.g. Martin Logan), and an old hybrid speaker that I think is another ESL (I had thought it a ribbon, but the phase looks ESL’ish). The latter has a pretty severe impedance peak in the midrange and is one I have used for many years as a “heavy” load. Note that, due to the coupling transformer, the phase of ESLs is often inductive at high frequencies despite the panel itself being one big capacitor.

These are the same amplifier and speaker models I have used in previous articles.

The wires are 18 AWG and 10 AWG twin lead copper (not CCA) cables typical of speaker wire you buy at a store (or online). Resistance per conductor is 6.385 m-Ohms/ft for 18 AWG and 0.9989 m-Ohms/ft for 10 AWG, so the total resistance is doubled in the simulations since there are two wires in each pair (+ and -). I used a simple distributed model for capacitance and inductance, with 18 AWG having 15 pF/ft and 0.2 uH/ft, while the 10 AWG cable has 25 pF/ft and 0.1 uH/ft. These are typical numbers for standard “zip cord”. I choose two sizes that bound typical runs of speaker cable in my experience, though today most knowledgeable people are probably running 12 or 14 gauge cables.

Here are the output impedance and damping factor (into 8 ohms) of the three amplifiers. I have included phase since that question has been previously asked, though it is very small within the 10 Hz to 20 kHz audio band of interest. The plots go to 200 kHz so we can see the rising output impedance as feedback is reduced and output devices become more inductive (note the phase is trending positive). The models do not reflect the amplifier’s bandwidth past the audio band, it is a constant voltage, so the rising output impedance will not interact as much with the speakers as shown in simulations since the output will be much lower. The SS AVR has very wide bandwidth and output impedance changes little even to 200 kHz. The other SS amp has less bandwidth (though still well above the audio band) and thus higher impedance at higher frequencies, again still low within the audio band. The tube amplifier has high output impedance with bandwidth falling between the SS amplifiers.

View attachment 392334

Damping factor follows the output impedance as shown below. Ignore the units; they are an artifact of the simulation. You can see the SS AVR has very high damping factor, the second SS amp starts high but falls more quickly (though still 60 at 20 kHz, plenty for tweeters or most any speaker), and the tube has very low but fairly flat damping factor.

View attachment 392335

Next are the speaker impedances. The first (top) is the Stereophile test load as presented on their web site (and magazine; I originally pulled this long ago from the printed magazine). It is 8-ohm nominal with a low around 4 ohms. The planar-dynamic model is almost a purely resistive 4-ohm load. The hybrid ESL is not too bad until dropping over 10 kHz, though this particular model is still 3 ohms at 20 kHz (other ESLs drop to 1-2 ohms). You can see why the other hybrid (bottom) is such a hard load; it dips low in the bass and at high frequencies, with the aforementioned peak around 1.3 kHz. The phase in these plots is useful to show relative variation over frequency but ignore the absolute values (a consequence of phase unwrapping and the test probe).

View attachment 392336

For the first simulations, the speaker wire is modeled as purely resistive, with no capacitive or inductive components in the wire models. All the results show the frequency response at the speaker terminals with the amp connected directly to the speaker (“a_”), via 10’ of 10 AWG cable (“a_w1”), and 10’ of 18 AWG cable ("a_w2”). The speakers from top to bottom are the same as above: Stereophile model (a0), planar-dynamic (a1), hybrid ESL (a2), and second hybrid (a3, worst-case).

For the SS AVR, variation is less than 0.5 dB for all speakers, even with the 18 AWG wires. You can see, however, that 10 AWG wire is much closer to the amp without cables (directly driving the speakers), with just a fraction of dB loss and variation over frequency.

View attachment 392337

The second SS amp exhibits more variation as expected, though still <1 dB for all cases even with 18 AWG wires. Again we see that 10 AWG results in performance almost identical to that with no wires between amp and speaker.

View attachment 392338

Finally, this is the response using the tube amplifier. Because its output impedance is high, speaker cables have little impact on the response, since the cables are in series with the amplifier’s output impedance. I could zoom in to show the effect, but it is essentially buried by the output impedance, so the curves practically overlie. This is an example of why people might choose particular amp and speaker combinations to meet their preferences.

View attachment 392339

Here are the results with distributed RLC models of the speaker cables. The main change is a slight peaking in high-frequency response of the SS amplifiers, especially with the ESL speakers; there is essentially no change with the tube amp.

SS AVR amp:

View attachment 392340

SS Amp:

View attachment 392341

Tube amp:

View attachment 392342

Finally, here are the results for the second SS amplifier comparing the purely-resistive 10 AWG model (w1) to the RLC models (w2). This makes it easy to see how reactive elements change the response, and how it interacts with the amp and speaker impedances. In all cases, the resistive and RLC models essentially overlie until 1 kHz or above. The Stereophile model causes slightly higher response, though negligible at less than 0.05 dB. The planar-dynamic has very little change. The two ESL hybrids exhibit about 0.2~0.3 dB change at 20 kHz from the purely resistive wire to the RLC models.

View attachment 392343

These simulations indicate that ten feet of cable can have some impact, though likely inaudible unless the cable is small, and if the amplifier has sufficiently low output impedance so that the cable’s added impedance is significant. The results also show the effect of cables is primarily due to their resistance, although adding capacitance and inductance can influence the higher-frequency response significantly (not sure if audibly, leave that to you).

HTH - Don

Edit: For actual speaker measurements, Pavel @pma has this excellent thread: https://www.audiosciencereview.com/...er-cables-in-frequency-and-time-domain.22894/

Addendum: The plot below shows the second SS amplifier driving the same four speaker loads but now using 12 AWG cables that are 3’ (top), 10’ (middle), and 20’ (bottom) long. This allows us to assess how length affects the response.

View attachment 392517

Addendum 2: I attached a zip file with the LTSpice schematics and plot files. Consider them "as-is", though the filenames are somewhat descriptive, but hopefully looking at the schematics will tell you what they do. I also included the older speaker impedance files for reference.

See attachment 20240916_Amp_plus_wires.zip

LTSpice: https://www.analog.com/en/resources/design-tools-and-calculators/ltspice-simulator.html

Wow! Excellent!
Takes a lot of work to do all those simulations.

I've been a 'cable believer' for over 50 years since we began experimenting with cables in the 70's.

However, no one should believe ANYTHING most manufacturers claim.
The only way you can evaluate any component is in your system!

A few years back, I made a similar effort throwing in a bit on Mains Wiring and Bi-Wiring for good measure: Cable Snake Oil

 

[Keith_W]

The only way you can evaluate any component is in your system with a double blind test!

Fixed it for you.

 

[JSmith]

I've been a 'cable believer' for over 50 years since we began experimenting with cables in the 70's.

JSmith

 

[IEales]

Fixed it for you.

"The only way you can evaluate any component is in your system with a double-blind test!" <- Fixed "double blind"

That's not necessarily true.

Just as a 'tin ear' can't hear any change, astute listeners intimately familiar with their systems can immediately pick up differences if they exist.

My missus had perfect pitch, played piano and clarinet. About 20 years ago, I was evaluating some line cables. When I put in yet another after rejecting a few, she looked up from her knitting and said "Those are the only wires where the clarinet sounds like a clarinet." and went back to her knitting. No back and forth, no knowledge of technology and very little interest. No need to swap back.

 

[IEales]

JSmith

Is this meant to indicate that you can't hear don't believe cables make a difference?

 

[Soria Moria]

Just as a 'tin ear' can't hear any change, astute listeners intimately familiar with their systems can immediately pick up differences if they exist.

Which a double-blind test will reveal.

My missus had perfect pitch, played piano and clarinet. About 20 years ago, I was evaluating some line cables. When I put in yet another after rejecting a few, she looked up from her knitting and said "Those are the only wires where the clarinet sounds like a clarinet." and went back to her knitting.

Turns out your missus is just as suspectible to brain tricks as everyone else.

 

[Bruce Morgen]

My missus had perfect pitch, played piano and clarinet. About 20 years ago, I was evaluating some line cables. When I put in yet another after rejecting a few, she looked up from her knitting and said "Those are the only wires where the clarinet sounds like a clarinet." and went back to her knitting. No back and forth, no knowledge of technology and very little interest. No need to swap back.

As a now-retired/lapsed musician who spent eight years running a five-technician audio repair shop, I can testify that musicians' subjective impressions are no more credible than anyone else's. One of my customers was Laszlo Halasz, a conductor of some note who brought in his personal Uher R-R tape recorder for service -- and every time, the heads were loaded with oxide. The thing is, the resulting dull playback was never the maestro's complaint -- it was always some mechanical issue. IOW, even highly accomplished musicians are not necessarily good judges of audio quality. Enough said.