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Old 17-07-2020, 09:14 AM   #91
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Anyone here calculate how much power is lost/voltage drop through the speaker cables? So to size them appropriately?

For my work in real life, i often need to size power cables and calculate voltage drop and short circuit capacity for electrical installation (so to comply to code of practice).

But i am not sure what should be taken into account if i were to calculate for speaker and amplifier.

Im thinking whether the drop in voltage due to small cable size between amp and speaker will have an impact or not.

In the past, i estimate the power sent to my speaker by measuring the voltage at the speaker terminal, then square the value and divide by the nominal resistance. Then i set the limiter on my processor to limit power. But the impedance of speaker coil varies with frequency.
Maybe when im free i think about this.

Just some thinking.

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Here's how to calculate power loss in cable: Don't calculate power loss in cable.

In power transmission and etc, we care because the load is always changing. However speaker is a fixed load.

So all we need is to make sure the % loss in the cable is not significant, because that alters the sound because speaker impedance changes vs frequency.

Sound waves are recorded as voltage so just need to consider the accuracy of voltage.

Last edited by wwenze; 17-07-2020 at 09:16 AM..
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Old 17-07-2020, 09:26 AM   #92
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Careful with talking about phase shift in cables... Wouldn't want to go into the same thinking trap we did with skin effect i.e. it exists but not at the amount where you think it matters.

Phase shift vs frequency is measurable with impulse response. You can also calculate it since it is due to RC or R(whatever the speaker complex load is). I mean if we are too arsed to calculate like most engineers are we can just measure. Any mic will do, too.

BTW here's the kicker: Your speakers have phase shifts by themselves. That's why newer speakers are more and more anal about time alignment.

Also your tweeter usually has resistors in series, it's in the crossover.

You know what else actually matters more when we talk about delay? The distance between you and your speaker.

This distance is also what causes time alignment to screw up when the distance between tweeter and woofer is different i.e. small vertical sweet spot. Notice how some speakers purposely put the tweeter slightly behind the woofer to fix this.

That's why the often mentioned head-vice joke in diyaudio.

Sound is 343m/s, so 0.1ms it travels 3.4cm. 0.1ms is also one whole cycle at 10kHz. How easy is it to find 3.4cm worth of difference in real life?
Oh ok, thanks for pointing out.
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Old 17-07-2020, 10:18 AM   #93
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My Amazon cable 16 AWG vs WE cable 9AWG impulse response (timing difference)

I'll make it very simple. These are the graphs of before and after for just my Front Right and Left speakers Before referring to me using the Amazon 16 AWG cables and their distance from my listening seat being the same to the WE 9AWG which I refer to as After with my fronts.

Similarly, I had bought a WE RCA interconnect cable for my subwoofer. Surprisingly, there were a difference to the phase delay as well.

Even though yes, as wwenze has pointed out, seems really minor and trivial. But it does make the soundstage sound like a mess when you have all the speakers' sounds reaching your ear at different timing taking into consideration the room reflections which Dirac also takes into consideration. Similar with REW.
That is why time alignments of all your speakers matter to me at least. Cos I heard that difference and the impulse response charts reflects it.

And then, I have my side surround speakers which are the nearest to the main listening seat. And not surprisingly, in both Before and After where there's literally no change in the cables, they are using some horrible 18AWG cables, the timing remains constant by the time the impulse response reaches the listening seat where the mic is picking up the timing in regards to delay.

As a side note, the chart below it is what Dirac does to the timing of the audio. Where it shifts so that all sounds from all the speakers reach the listening position at that 16.7ms mark.

Both right and left FRONT Speakers (with short 1m 16awg Amazon cables)


Both right and left FRONT Speakers (with longer 2m 9awg WE cables)


Subwoofer Speaker (with 4.5m generic AmazonBasics Subwoofer RCA cable)


Subwoofer Speaker (with 3m WE subwoofer RCA cable)


For reference in regards to the before and after tests which are done on 2 separate occasions, the side surround cables were the only constant. So this is to make sure the 2 tests above were because of the change of cables and not because of a different room or position of mic.
So the sides in the impulse response measurement chart should remain unchanged with the Before and After test.

Side surround speaker (with the same 18awg generic speaker cable) results received during the Amazon cable test


Side surround speaker (with the same 18awg generic speaker cable) results received during the WE cable test
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Old 17-07-2020, 10:34 AM   #94
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For an interesting tidbit, have a look at what these guys also think of using Umik-1 with REW. How you can do more than just EQ but also time alignment for all of your speakers as well. With Dirac, the only difference is they do it all automatically for me. I used REW before. But yup. There is some learning curve. But follow some guides on YT and you will be fine.

But for actual application for your REW to your speaker setup, you will need a miniDSP to apply those REW settings. Thus why I chose the Dirac route. It does the same thing as REW but does it all automatically. And definitely with more precision than Audyssey.

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Old 17-07-2020, 11:01 AM   #95
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Impulse response we're not just concerned with the timing, but the entire shape.

Because fourier series. If all frequencies reach at the same time, then u get the sharp square wave. If only high frequencies get delayed, then you get more curvey. Etc.
While most speakers IRL create a shape like... well stereophile has lots of examples. Well like your subwoofer also.
The impulse response can be FFT-ed to create the spectrum + phase plot in REW or similar. Then a FIR filter can be created.

Problem is to recreate a proper square shape, we need maybe at least 10x the bandwidth. So expect noisy data for signals at high frequencies. Notice a lot of the spikes probably don't last longer than one sample.

Subwoofer one is more conclusive. The duration of the differences last over a large enough samples to be a real result. Maybe the cable interacts with the line-level crossover. This should be measurable by measuring the signal on RCA at the load end.
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Last edited by wwenze; 17-07-2020 at 11:04 AM..
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Old 17-07-2020, 11:06 AM   #96
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Impulse response we're not just concerned with the timing, but the entire shape.

Because fourier series. If all frequencies reach at the same time, then u get the sharp square wave. If only high frequencies get delayed, then you get more curvey. Etc.
While most speakers IRL create a shape like... well stereophile has lots of examples. Well like your subwoofer also.
The impulse response can be FFT-ed to create the spectrum + phase plot in REW or similar. Then a FIR filter can be created.

Problem is to recreate a proper square shape, we need maybe at least 10x the bandwidth. So expect noisy data for signals at high frequencies. Notice a lot of the spikes probably don't last longer than one sample.

Subwoofer one is more conclusive. The duration of the differences last over a large enough samples to be a real result. Maybe the cable interacts with the line-level crossover. This should be measurable by measuring the signal on RCA at the load end.
Oh my goodness... I just derped. I forgot to zoom out since I had probably zoomed in last time and it kept the measurement chart in a zoomed in state. Guess I'll repost my measurements including the missing high frequency again soon. Am busy now.

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Old 17-07-2020, 11:08 AM   #97
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Your room reflection is around 3ms?

The differences in the subwoofer measurements are at 2ms and even longer. Probably way past phase delay from cables already and likely differences in reflections.
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Old 17-07-2020, 11:18 AM   #98
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So I just need to zoom in to the 1st 10ms of the speakers correct? Anyway, do you prefer me to leave both the right and left speakers combined in that 10ms zoomed in state too or change it to be separated?

Specifically which speakers do you have in mind? The fronts and subs or include the rear as well?


Your room reflection is around 3ms?

The differences in the subwoofer measurements are at 2ms and even longer. Probably way past phase delay from cables already and likely differences in reflections.
Here, I thought you were meant to look at the 9ms and the 8.3ms which means that the WE cables have a difference of 0.7ms and is therefore playing sound 0.7ms faster.

Now since Dirac was syncing all the audio to be playing at that 16ms mark, due to me using the old Dirac calibration profile where the delay Dirac applied to the subwoofer was 7ms, so that the 9ms will become 16ms.

When I use that same calibration profile meant for my old cable, it literally means that the subs will play at 15.3ms instead. Thus resulting in it being out of sync. Similarly, for the front speaker as well. with a difference of around 0.4ms. Meaning with the Dirac profile, audio is playing way faster than intended. I still have the centre and Atmos speakers that also has the new WE cables as well.

Together, all the speakers are playing at different times. And it resulted in my soundstage mess.

Last edited by LiLAsN; 17-07-2020 at 11:26 AM..
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Old 17-07-2020, 11:34 AM   #99
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I was speaking in relative terms, so the 10ms or 3ms after the main signal first appeared on the mic recording.

RC causes HF to shift more than LF i.e. you will see the shape change first before the entire thing shift.

The entire thing shifting without a shape change is more due to other factors. Example, your computer. It can lag.

Heck, I think when I tried measuring the latency on the S3000Pro my variation was in the order of a few ms.

If you think your Dirac measurements are wonky, just re measure it again a few times. Take whatever result that suits you better.
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Last edited by wwenze; 17-07-2020 at 11:42 AM..
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Old 17-07-2020, 12:13 PM   #100
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now petetherock may have to come in and split the thread again, haha.....

But thanks for the links and sharing LiLAsN!
Haiz, now need to figure out the cheapest way to get Dirac into my PC again so that it is system wide rather than just specific apps.

I'm a bit confused by your experience though now. Are you saying with the Amazon cables installed, you have timing issues btw speakers? While with WE cables, you don't have timing issues?

Also curious, could the timing differences be a result of small changes in speaker positions when you switch cables earlier?

Last edited by lxXXxl; 17-07-2020 at 12:32 PM..
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Old 17-07-2020, 12:32 PM   #101
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Anyone here calculate how much power is lost/voltage drop through the speaker cables? So to size them appropriately?

For my work in real life, i often need to size power cables and calculate voltage drop and short circuit capacity for electrical installation (so to comply to code of practice).

But i am not sure what should be taken into account if i were to calculate for speaker and amplifier.

Im thinking whether the drop in voltage due to small cable size between amp and speaker will have an impact or not.

In the past, i estimate the power sent to my speaker by measuring the voltage at the speaker terminal, then square the value and divide by the nominal resistance. Then i set the limiter on my processor to limit power. But the impedance of speaker coil varies with frequency.
Maybe when im free i think about this.

Just some thinking.

Sent from Your Favourite Non-Biting Talking Pillow using GAGT

Isn't that what the guy did in the video you shared? So you want to recreate this testing platform? That would be interesting.

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Old 17-07-2020, 01:03 PM   #102
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This is a good, simple to understand video on how someone edits the frequencies to remove harsh 'Ssss' in vocals when producing a song. He shows 2 methods, with an automatic plugin (can see the reduction in dB in realtime) and manually reducing volume/gain.

Now imagine that instead of editing the frequency, the producer switches headphone cables instead to try to achieve the same aim....

It is definitely understandable that for a consumer without a simple way to include an equalizer into their audio system, they will resort to 'physical' methods and products to equalize their songs. If they have the cash, that's definitely fine. But hopefully more people understand, what they are really trying to achieve....


Last edited by lxXXxl; 17-07-2020 at 01:10 PM..
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Old 17-07-2020, 01:44 PM   #103
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This is a good, simple to understand video on how someone edits the frequencies to remove harsh 'Ssss' in vocals when producing a song. He shows 2 methods, with an automatic plugin (can see the reduction in dB in realtime) and manually reducing volume/gain.

Now imagine that instead of editing the frequency, the producer switches headphone cables instead to try to achieve the same aim....

It is definitely understandable that for a consumer without a simple way to include an equalizer into their audio system, they will resort to 'physical' methods and products to equalize their songs. If they have the cash, that's definitely fine. But hopefully more people understand, what they are really trying to achieve....

This one is not new. In the old days, there were mini hifi by various companies like Sony, Aiwa, Pioneer etc...., can adjust using equalizer. Some old sony walkman also have equalizer.

Many AVR also allow you to adjust type of sound. Mimic effects of surround etc....can adjust bass/treble.
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Old 17-07-2020, 01:58 PM   #104
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This one is not new. In the old days, there were mini hifi by various companies like Sony, Aiwa, Pioneer etc...., can adjust using equalizer. Some old sony walkman also have equalizer.

Many AVR also allow you to adjust type of sound. Mimic effects of surround etc....can adjust bass/treble.
Yup, didn't say it's new technology. Other than tone control, in the absence of actual equalizers, people are essentially using their cables to function as equalizers (and now the harshness is gone! etc).
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Old 17-07-2020, 07:08 PM   #105
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If cable does not make a difference, then all those cable manufacturers can closed shop liao.

Measurement is one thing but can u really hear the difference is another thing.

Cables come with different characteristics which must match your audio system and it's subjective to individual listening taste.
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