Question, when put in a box, say a closed box (sealed box), was the difference stil there?
Reason asking: my experience is that damping material alone can easily cause a greater shift in fs.
Second question: that same driver(just the driver) when playing some vocal music softly whilst holding it close to your ear, how did it sound?
Yes, totally useless, because it's not representative for any cabinet design at all.
Those little things are only kind of useful for very crude filter design.
One can get an amp, audio interface as well as a resistor for the same amount of money.
Software can be found for free to do the same thing.
Just crank it up?
I think you're totally missing the point of having proper predictions how certain things are gonna behave beforehand?
Unless you're one of the lucky ones that can keep on buying stuff and just get there with trial and error.
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Joined 2003
Oh I don't know, I've mostly lost interest in this topic a few posts back, but the president of the debate club keeps powering on with full steam. It sounds like a 3" fullrange paper cone TB driver at all volumes.
I've no interest in building a box for this driver just to entertain this thread, so I will change gears and test with the worst speaker I have that is complete in a box. It's a Dayton DA135. The box is ported, for this basic measurement I plugged the port to rule out any notion of port compression etc as the cause for change.
"quick and dirty" PN Noise, yes I did observe a change in impedance once the cone started to move a bit, at which point we are clearly out of the range that I would define for T/S use.
Change in stuffing has a similar effect. There is not much stuffing in this low end speaker, but with it removed the peak is larger and shifted slightly up in frequency.
Any other investigations you would like to make from here, simply get out your test jig and have at it.
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Joined 2003
Which cabinet model here is useless? The one designed using low level signal, or the one with high level signal? By your logic, most DIY speakers must be junk.
By my logic, the low level signal is more correct as far as the definition for T/S goes, and cabinet models lack accuracy beyond low level signals because they don't have knowledge of Kms(x), Le(x) and Bl(x).
Hello,
I have a question about Arta.
I wanted to create a new thread but I guess this one is perfect!
If this has previously been pointed out here I'm sorry for asking again but I don't have the courage to read it all.
This afternoon I wanted to measure an old sig generator THD and I got huge amounts of distorsion (too much, like 90%, mistakes were made).
Until now I was using Arta in loopback configurations only, with the generator being Arta.
With this external signal generator Arta was obviously not the source anymore and I figured out that by tuning the internal Arta sine generator (which was turned off) frequency to the exact frequency of the external generator, my measurements were back to normal (almost in the range of the ext gen datasheet).
I am aware that there's a big big notch filter on the fundamental f when it comes to THD measurements but I was hoping that Arta would detect and track the fundamental. My external generator is an old piece of equipment and the output frequency can drift a little bit +-1% which is actually quite stable considering the age of this generator. The Arta filter seems to be a very high Q and highly selective filter (to the hertz and under) so I had to constantly enter new values in the gen box.
My THD+N levels were stable, independantly of the Arta's gen frequ, which is quite strange because when I took a look at the equations in the help file I found out that 'FoundamentalPower' was of course filtered out in both THD and THD+N measurements.
Is there a way to automatically track the fundamental in Arta SPA? A built in feature that I'm not aware of or an alternative way to do this or another Spectrum analyzer that does this?
Thank you, I really like Arta and I'm quite familiar with a bunch of measurements now so I would love to hear that there's a simple box to check and that I'm an Idiot
I have a question about Arta.
I wanted to create a new thread but I guess this one is perfect!
If this has previously been pointed out here I'm sorry for asking again but I don't have the courage to read it all.
This afternoon I wanted to measure an old sig generator THD and I got huge amounts of distorsion (too much, like 90%, mistakes were made).
Until now I was using Arta in loopback configurations only, with the generator being Arta.
With this external signal generator Arta was obviously not the source anymore and I figured out that by tuning the internal Arta sine generator (which was turned off) frequency to the exact frequency of the external generator, my measurements were back to normal (almost in the range of the ext gen datasheet).
I am aware that there's a big big notch filter on the fundamental f when it comes to THD measurements but I was hoping that Arta would detect and track the fundamental. My external generator is an old piece of equipment and the output frequency can drift a little bit +-1% which is actually quite stable considering the age of this generator. The Arta filter seems to be a very high Q and highly selective filter (to the hertz and under) so I had to constantly enter new values in the gen box.
My THD+N levels were stable, independantly of the Arta's gen frequ, which is quite strange because when I took a look at the equations in the help file I found out that 'FoundamentalPower' was of course filtered out in both THD and THD+N measurements.
Is there a way to automatically track the fundamental in Arta SPA? A built in feature that I'm not aware of or an alternative way to do this or another Spectrum analyzer that does this?
Thank you, I really like Arta and I'm quite familiar with a bunch of measurements now so I would love to hear that there's a simple box to check and that I'm an Idiot
Member
Joined 2003
Thank's for reply,
I have another questions, i have buy a ecm8000 mic and if i want measure a frequency response with m-audio duo, do i need a measuring box? If I want measure a loudspeaker impedance with power amp and LIMP, can i use the input 1 and 2 of m-audio duo and the measuring box? thank's again Maxpou
I have another questions, i have buy a ecm8000 mic and if i want measure a frequency response with m-audio duo, do i need a measuring box? If I want measure a loudspeaker impedance with power amp and LIMP, can i use the input 1 and 2 of m-audio duo and the measuring box? thank's again Maxpou
Last edited:
Member
Joined 2003
For dual channel frequency response as simple as possible, no special jig is required, just a TRS patch cord to loop back the audio interface output to input for timing reference. This is detailed as "semi-dual" method in the ARTA manual.
For impedance, you will require some resistors. All detailed in the manuals. If you build the measurement jig, best to built it for "full dual channel" measurement instead of the semi-dual suggestion above.
For frequency response, like this:
For impedance in LIMP like this:
Have you used "external" gen source in arta menu instead of "sine" (see the pic)?Hello,
I have a question about Arta.
I wanted to create a new thread but I guess this one is perfect!
If this has previously been pointed out here I'm sorry for asking again but I don't have the courage to read it all.
This afternoon I wanted to measure an old sig generator THD and I got huge amounts of distorsion (too much, like 90%, mistakes were made).
Until now I was using Arta in loopback configurations only, with the generator being Arta.
With this external signal generator Arta was obviously not the source anymore and I figured out that by tuning the internal Arta sine generator (which was turned off) frequency to the exact frequency of the external generator, my measurements were back to normal (almost in the range of the ext gen datasheet).
I am aware that there's a big big notch filter on the fundamental f when it comes to THD measurements but I was hoping that Arta would detect and track the fundamental. My external generator is an old piece of equipment and the output frequency can drift a little bit +-1% which is actually quite stable considering the age of this generator. The Arta filter seems to be a very high Q and highly selective filter (to the hertz and under) so I had to constantly enter new values in the gen box.
My THD+N levels were stable, independantly of the Arta's gen frequ, which is quite strange because when I took a look at the equations in the help file I found out that 'FoundamentalPower' was of course filtered out in both THD and THD+N measurements.
Is there a way to automatically track the fundamental in Arta SPA? A built in feature that I'm not aware of or an alternative way to do this or another Spectrum analyzer that does this?
Thank you, I really like Arta and I'm quite familiar with a bunch of measurements now so I would love to hear that there's a simple box to check and that I'm an Idiot
Martin
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Ooooh that must be it!!! Thank you very much, will test again with these settings.
Member
Joined 2003
Member
Joined 2003
Not to beat a dead horse on the impedance measurement methods. I was recently speaking with someone who was comparing a simulated box model to his real measurements and wondering why they were so different. It turned out that the box model was using the driver datasheet, not real measured T/S for the driver. The comparison below shows quite a difference.
Dashed lines are the simulation, solid is the real measurements.
So the next step was obvious - comparison must be made with real measured data for the driver. This was completed using a voltage divider method, and with the "totally useless" DATS. As expected, simulation of the box model with real measured parameters is much closer to reality.
End result - real measured data is always better than manufacturer data, even with simple low voltage divider method used in DATS and the wiring arrangement detailed in the ARTA manual.
Dashed lines are the simulation, solid is the real measurements.
So the next step was obvious - comparison must be made with real measured data for the driver. This was completed using a voltage divider method, and with the "totally useless" DATS. As expected, simulation of the box model with real measured parameters is much closer to reality.
End result - real measured data is always better than manufacturer data, even with simple low voltage divider method used in DATS and the wiring arrangement detailed in the ARTA manual.
That's a very strange statement to make for multiple reasons;
1 - Define "better"?
2 - low level signal from DATS is not representative for normal music levels at all and can only be used for passive filters.
3 - There are plenty of manufactures that provide data that can be perfectly reproduced and is very representative for normal use. So just claiming that (therefor) data from manufactures is wrong be default is a subjective claim not based on statistical numbers or research.
I appreciate the critical approach, but when one tries to stay objective and un-biased, one also has to face the other side of the story. Otherwise you're just spreading more myths in this world.
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Joined 2003
1. “Better” for match of computer model vs reality, shown above clear as day. Speaker tested above is not junk, it’s a half decent driver from a popular manufacturer.
2. Purpose of low level signal test is to gather T/S parameters which are defined as low level. Shown above, it produces “good enough” data for a cabinet model that matches reality.
3. How do you know ? Suppose you could set up some sort of jig with software to verify…and just because your drivers match manufacturer spec doesn’t mean everyone’s will. Parts vary batch to batch, often suppliers and parts change in production without data sheet updates, manufacturers test speakers using different methods, skew results for more marketable specs, etc. There’s many reasons to throw away the data sheet once you have the driver in your hands. Trust your own data was my point. You don’t have to trust my data, after all you’re not the one listening to my crap speakers.
FWIW I have drivers that measure perfectly on spec using low level voltage divider test method.
What is the myth?
If the myth is that manufacturer data often doesn’t match the speaker you purchased for many reasons, I’m happy to continue perpetuating that myth.
If the myth is that you can’t design a cabinet that reliably matches the computer model using information gathered by a simple series resistor, I’ve yet to find evidence of that in any of my own data.
2. Purpose of low level signal test is to gather T/S parameters which are defined as low level. Shown above, it produces “good enough” data for a cabinet model that matches reality.
3. How do you know ? Suppose you could set up some sort of jig with software to verify…and just because your drivers match manufacturer spec doesn’t mean everyone’s will. Parts vary batch to batch, often suppliers and parts change in production without data sheet updates, manufacturers test speakers using different methods, skew results for more marketable specs, etc. There’s many reasons to throw away the data sheet once you have the driver in your hands. Trust your own data was my point. You don’t have to trust my data, after all you’re not the one listening to my crap speakers.
FWIW I have drivers that measure perfectly on spec using low level voltage divider test method.
What is the myth?
If the myth is that manufacturer data often doesn’t match the speaker you purchased for many reasons, I’m happy to continue perpetuating that myth.
If the myth is that you can’t design a cabinet that reliably matches the computer model using information gathered by a simple series resistor, I’ve yet to find evidence of that in any of my own data.
@DcibeL
I don't care how you use your own data for your own speakers.
If you're happy with it, I am happy with it.
Do only thing I DO care about, is writing it down as a standard and correct approach.
In fact, praising the wrong products that are just not made for this job, seen from a general point of view.
The measurements you're doing do not represent any models that are useful for practical use/in reality.
Unless you would like to listen to speakers that use less than 0.1-0.5Vrms (ballpark figures).
Depending on the usage, that is very far from "good enough".
The only right thing to do, is to verify datasheets from manufactures and cross correlate.
How do I know? Because that's exactly what I have done for the last 10-15 years!
Again, if you're happy to this approach, feel free.
But it's not recommended to use this as a rule of thumb or default approach for other people.
The advice I can give, is to dive into some papers about loudspeaker non-linearities.
If you understand those, you understand why this approach will never objectively give satisfied results.
This wouldn't even be a discussion.
I don't care how you use your own data for your own speakers.
If you're happy with it, I am happy with it.
Do only thing I DO care about, is writing it down as a standard and correct approach.
In fact, praising the wrong products that are just not made for this job, seen from a general point of view.
The measurements you're doing do not represent any models that are useful for practical use/in reality.
Unless you would like to listen to speakers that use less than 0.1-0.5Vrms (ballpark figures).
Depending on the usage, that is very far from "good enough".
The only right thing to do, is to verify datasheets from manufactures and cross correlate.
How do I know? Because that's exactly what I have done for the last 10-15 years!
Again, if you're happy to this approach, feel free.
But it's not recommended to use this as a rule of thumb or default approach for other people.
The advice I can give, is to dive into some papers about loudspeaker non-linearities.
If you understand those, you understand why this approach will never objectively give satisfied results.
This wouldn't even be a discussion.
Member
Joined 2003
Please don't make assumptions about the measurement amplitude. Just for you, I grabbed the speaker in front of me and tested it.
First, I tested at low volume level nearfield like I usually do. I could be 0.1v, don't know don't care, its about "talking volume". Then I checked again at elevated volume. Here I used PN Noise in ARTA, we have a about 2mm of excursion of the woofer, measured 2.25VRMS with my multimeter at the driver terminal. You may think this is still fairly low voltage, however the volume of the noise is what I would call above normal listening level, rather loud in fact. Made sure my mic didn't make contact with the driver, lowered mic preamp gain to avoid clipping. This is much higher than I would normally measure nearfield for cabinet model verification, or for driver impedance & T/S.
Compared measurements as overlays, driver output and port output. Make your own conclusions, I've already made mine.
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Joined 2003