the H3 is greater than H2 as soon as 300 hz and in many other drivers as well ? Asking myself if it's not a pattern of the reccording environment ? Notice the H3 becomes lower than H2 at 11 volts .
How to understand the - db of the HD curves scale: is the H1 always is zero dB on the graphs ? See also the 8" Usher... high H3 as well from few hundred of hz, for illustration !
How to understand the - db of the HD curves scale: is the H1 always is zero dB on the graphs ? See also the 8" Usher... high H3 as well from few hundred of hz, for illustration !
No, it is not a pattern of the recording environment.
The curves show you the ratio 20lg(Hx/H1) at every frequency.
Please, give a link to the true distortion pattern of Usher 8955a as you see it. Maybe it is just how you would like to see it?
I would like nothing, I just ask because I do no understand !
Not the usher, I mistaked (see too much datasheets as I' searching a 8" for a good -40 hz -f3 with not too much h3 till 800 hz and flatest as possible or good against a bafle step behavior till 200 hz to +F3 at 800 hz. it could be a 6" or a 10", I don't look at the too much expensive for my pocket like the revelators for instance.
it was those ones : SB Acoustics SB20PFC30-8 | HiFiCompass
SB Acoustics SB29SWNRX-S75-6 | HiFiCompass
SB Acoustics SB17MFC35-4 | HiFiCompass
SB Acoustics SB17NBAC35-8 | HiFiCompass
Dayton Audio RS225P-8A | HiFiCompass
https://hificompass.com/en/speakers/measurements/peerless/peerless-830869
https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb23nacs45-8
often too much high h3 and often above h2 very early in the fhz range of the upper bass and low mid i'm looking for. Sometimes very near at -5db from the H2 if below.
How i shoud read it ? And I do not understand the 20lg. Could you please give an illustration : if I see the first Hx at - 40 db, does it means the fundamental is normalized at zero dB in the screen captures ?
It's very informative but maybe a question of budget where I look at ? For instance I had great expectation about the SB NAC or a peerless, but seeing the h3 so high I could fear in the harmonics polluting the upper registers... so my doubt about how to read it or if it was a measurement behavior.
Could you please advise a method to calculate the max spl possible when reading the T&S of a driver ?
Not the usher, I mistaked (see too much datasheets as I' searching a 8" for a good -40 hz -f3 with not too much h3 till 800 hz and flatest as possible or good against a bafle step behavior till 200 hz to +F3 at 800 hz. it could be a 6" or a 10", I don't look at the too much expensive for my pocket like the revelators for instance.
it was those ones : SB Acoustics SB20PFC30-8 | HiFiCompass
SB Acoustics SB29SWNRX-S75-6 | HiFiCompass
SB Acoustics SB17MFC35-4 | HiFiCompass
SB Acoustics SB17NBAC35-8 | HiFiCompass
Dayton Audio RS225P-8A | HiFiCompass
https://hificompass.com/en/speakers/measurements/peerless/peerless-830869
https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb23nacs45-8
often too much high h3 and often above h2 very early in the fhz range of the upper bass and low mid i'm looking for. Sometimes very near at -5db from the H2 if below.
How i shoud read it ? And I do not understand the 20lg. Could you please give an illustration : if I see the first Hx at - 40 db, does it means the fundamental is normalized at zero dB in the screen captures ?
It's very informative but maybe a question of budget where I look at ? For instance I had great expectation about the SB NAC or a peerless, but seeing the h3 so high I could fear in the harmonics polluting the upper registers... so my doubt about how to read it or if it was a measurement behavior.
Could you please advise a method to calculate the max spl possible when reading the T&S of a driver ?
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Yes, it is reality. A majority of speakers have such a THD behavior.
Yes, you are correct in your understanding
I think you should not be afraid. Those speakers are very good. Unfortunately, there are no any low budget speakers with very low THD in that frequency range. You can try a pair of SB17xxxx speakers instead of alone of 8" one.
Such a correlation simply doesn't exist. You can just evaluate the max SPL based on Pin, Xmax and Seff data from a datasheet. But different speakers having same parameters may have very different THD at their SPLmax, it depends on their construction.
Regarding multiple woofers vs single. Typically multi, like 2 woofers, will perform better since in part, you have the same SPL output as one large but half the excursion with the 2 drivers.
Less excursion retain more motor control, the total distortion will therefor be lower with 2 (or more) drivers compared to 1 large.
On top of that you have less moving mass with 2 smaller woofers and hence better transients since the smaller cone with its better motor control, will settle faster.
All in all, unless we are talking heaps of visceral sensation, using multiple drivers are beneficial. Ofc, it also depend on the type of music you listen to. Classic can certainly benefit from large woofers for impactfull performance while multi drivers work very well with more modern music.
2x10" can typically produce enough low-end and visceral connection to the music, so not really any reason to go larger in domestic use.
My 2 cents
Less excursion retain more motor control, the total distortion will therefor be lower with 2 (or more) drivers compared to 1 large.
On top of that you have less moving mass with 2 smaller woofers and hence better transients since the smaller cone with its better motor control, will settle faster.
All in all, unless we are talking heaps of visceral sensation, using multiple drivers are beneficial. Ofc, it also depend on the type of music you listen to. Classic can certainly benefit from large woofers for impactfull performance while multi drivers work very well with more modern music.
2x10" can typically produce enough low-end and visceral connection to the music, so not really any reason to go larger in domestic use.
My 2 cents
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The PuriBliss-BeWg project is finished! Read it for your inspiration.
In Russian for a while. The English version is coming...
PuriBliss-BeWg
In Russian for a while. The English version is coming...
PuriBliss-BeWg
Half the excursion but same SPL - as a thumb rule. In reality it also depend on motor strength (Tesla's) and various construction technics.
Typically you will see a 3dB difference as well.
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Look at it this way. Two drivers share the same work that one driver does. Sharing the work or load, halves the required energy input.
I can show you the effects in some graphs. Give me a few minutes
Ok, but they need the same output level and transfer function to really be comparable?
Not really. There is a difference between driver performance, matching etc vs comparing the output of 1 vs 2, 3 etc drivers.
If you use 2 x 12" you will see similar "doubling" of the SPL like we see here. Its a common rule that doubling the Sd halves the excursion or at the same excursion but +4-6dB.
Another point is box tuning or the Qtc which also affect the overall output, sealed vs ported and so on.
My response was to show what happens when you use two smaller vs one large woofer with similar motor structure, relatively similar sensitivity.
12" (6 ohm nominal) = Sensitivity (2.83V/1m) 88.5 dB
8" (8 ohm nominal) = Sensitivity (2.83V/1m) 90 dB
The 4 ohm version of the 8" = Sensitivity (2.83V/1m) 92 dB but would not do well in parallel connection (Zmin 1.7 Ohm @ 386.1 Hz) so when used in series the resistance clime to Zmin: 6.6 Ohm @ 386.1 Hz and output drop to 91dB with a cone excursion of 1.1mm @20Hz.
The 12" compared to the 4 ohm version has the 2.1mm at 91dB output, so in the 2 x 4 ohm scenario (series connected), the SPL = same but excursion = half.
There, I hope that helps
If you use 2 x 12" you will see similar "doubling" of the SPL like we see here. Its a common rule that doubling the Sd halves the excursion or at the same excursion but +4-6dB.
Another point is box tuning or the Qtc which also affect the overall output, sealed vs ported and so on.
My response was to show what happens when you use two smaller vs one large woofer with similar motor structure, relatively similar sensitivity.
12" (6 ohm nominal) = Sensitivity (2.83V/1m) 88.5 dB
8" (8 ohm nominal) = Sensitivity (2.83V/1m) 90 dB
The 4 ohm version of the 8" = Sensitivity (2.83V/1m) 92 dB but would not do well in parallel connection (Zmin 1.7 Ohm @ 386.1 Hz) so when used in series the resistance clime to Zmin: 6.6 Ohm @ 386.1 Hz and output drop to 91dB with a cone excursion of 1.1mm @20Hz.
The 12" compared to the 4 ohm version has the 2.1mm at 91dB output, so in the 2 x 4 ohm scenario (series connected), the SPL = same but excursion = half.
There, I hope that helps
Thank you. Very usefull inputs for my understanding in order to make a choice.
Could we at least,avoiding HD in mind, to calculate a max spl with the X-Max and given T&S to stay in the linearity of the spl curve and know what the spl outputt at max X-Max... and stay 10% spl below this X-Max as an approximation ?
Any formula ?
Could we at least,avoiding HD in mind, to calculate a max spl with the X-Max and given T&S to stay in the linearity of the spl curve and know what the spl outputt at max X-Max... and stay 10% spl below this X-Max as an approximation ?
Any formula ?
He's talking about electrical input, you're talking about acoustic output.
The answer is yes. At the same frequency, same baffle shape, the drivers are acoustically close-coupled, etc., if you have the same volume displacement (swept volume of the diaphragm/cone), the SPL is the same. The sensitivity of the pair depends on other factors such as wiring.
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The T-S parameters are only to help you design the enclosure for a specific transfer function (frequency response) in the bass region. They will not tell you what SPL a driver can reach.
To calculate maximum SPL, all you need is the volume displacement and at what frequency of output. This is easily calculated with a sheet such as this:
http://www.linkwitzlab.com/spl_max1.xls
Note that the calculations on that sheet do not factor in power compression, which is a phenomenon where as you add increasing power (voltage), the actual SPL gain is less than expected due to thermal-related electrical losses. You can do additional research on that regard on your own.
As to what is the true Xmax of a driver, it depends on what your design will allow. Many times, the Xmax on a spec sheet is at a higher distortion level than what you would like to tolerate.
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