I'm working on trying to decipher performance based on specs/parameters. Taking this random 10" 4 ohm woofer for example, please help me understand what I can glean from these specifications. Can this be used to anchor a 3 way system up to say 300hz? Or is this better as a subwoofer? Why please ?
[/url]aa by Cullen Graham, on Flickr[/IMG]
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Oh, Zvuuuuu ? I'm going to make a believer of you, yet! 
[/url]20180111_210753 (2) by Cullen Graham, on Flickr[/IMG]
[/url]20180111_210711 by Cullen Graham, on Flickr[/IMG]
[/url]20180111_210725 (3) by Cullen Graham, on Flickr[/IMG]
[/url]20180111_210930 (2) by Cullen Graham, on Flickr[/IMG]
Now that's just beautiful.
Life's good sometimes. I'm whistling - Raindrops keep falling on my head 🙂
Life's good sometimes. I'm whistling - Raindrops keep falling on my head 🙂
I'm working on trying to decipher performance based on specs/parameters. Taking this random 10" 4 ohm woofer for example, please help me understand what I can glean from these specifications. Can this be used to anchor a 3 way system up to say 300hz? Or is this better as a subwoofer? Why please ?
[/URL]aa by Cullen Graham, on Flickr[/IMG]
This looks like a 10 inch 4 ohms car sub.
Low efficiency.
High xmax.
Mid/high Qts=sealed box (0.4-0.7).
Weak motor (BL).
Too bad Le is missing.
There is some info regarding TSP:
Understanding Loudspeaker Data | Eminence Speaker
Le is most likely high.
I wouldn't use this for mid duty, also because of high mms.
These Thiele/Small (T/S) parameters don't tell much about the usability of a driver as a mid. T/S parameters only give you information useful for working out the size of the enclosure that you will need to produce a given bass response, and the overall sensitivity and impedance of the driver.I'm working on trying to decipher performance based on specs/parameters. Taking this random 10" 4 ohm woofer for example, please help me understand what I can glean from these specifications. Can this be used to anchor a 3 way system up to say 300hz? Or is this better as a subwoofer? Why please ?
[/url]aa by Cullen Graham, on Flickr[/IMG]
As globalplayer pointed out, you can speculate that it looks to be a typical subwoofer (heavy cone, low-ish efficiency, high power handling), but it is just that - a speculation. None of those things specifically rule it out as being a good performer up the mid range. To determine the performance in the mid range would require a measurement of the frequency response and non-linear distortion through the mid frequencies. non-linear distortion is rarely published by the manufacturers however with careful inspection of the frequency response and knowing some of the T/S parameters you can speculate if it *may* be OK in the mids.
Knowing the Le would mean that you could work out where the response begins to roll off due to the voicecoil. Say that it was published as 1.95mH then you could work out the driver would have an electrical rolloff at Freq = Re/(2*pi*Le) = 3.28/(2*3.1415*0.00195) = 267.7Hz
Does this mean the driver is useful to 267.7Hz? Well no, because you would have to inspect a frequency response measurement of the driver to determine that it has no serious cone breakup peaks. If there was a big peak at say 400Hz you would have to deal with it in the crossover.
There is however one catch - if there is a big peak at any frequency, it is going to 'shape up'/'amplify' any non-linear distortion components which occur at it. So a peak at 400Hz is going to make 2nd order distortion worse at 200Hz, 3rd order worse at 167Hz, 4th order worse at 100Hz and 5th order worse at 67Hz. The exception to this would be if the speaker had a very linear motor system that produced very little non-linear distortion to begin with. The only way to know this is the measure the speaker driver to obtain a non-linear distortion graph like this harmonic distortion sweep here:
http://www.zaphaudio.com/8test/Dayton-SD215-88-HD.gif
Note the 3rd harmonic (blue trace) increasing at ~800Hz and the 5th harmonic increasing at ~480Hz, corresponding to cone breakup node at ~2.4kHz.
Contrast that measurement to this one of a Scanspeak driver which has a moderate cone breakup issues at ~1kHz and 3.2kHz, but no noticable increases in harmonic distortion because it has a very linear motor to begin with.
http://www.zaphaudio.com/8test/Scanspeak-22W8851T00-HD.gif
Note that if you calculate from Re and Le that the electrical rolloff is at 267Hz, and then you inspect the frequency response graph and see a response that is flat to 600Hz followed by a smooth rolloff, this indicates that there must be a broad cone breakup peak centered about ~400Hz that is pushing up the response from 267Hz to 600Hz. Although you wouldn't need to notch it out in the crossover, it will still 'shape up' the non-linear distortion as described above.
So, without actually having non-linear distortion measurement data for a driver and wanting to use it up to 300Hz you may want to avoid drivers which have significant breakup problems below about 1.5KHz (300*5 because it's uncommon for speakers to have major distortion above 5th order). This way even if the motor is not super-linear you can be reasonably confident you won't face major non linear distortion issues within the frequency range you want to use it.
Because subwoofers are rarely used above 100Hz very little design effort is put into the cone, so they often have massive cone breakup peaks. Fortunately the physical cone size means they can only occur above 800Hz or so for a 10" driver so it does not negatively impact it's performance when used as a sub. If you plan to use one higher up in the mid frequency range you need to tread more carefully.
Regarding the efficiency: The voltage efficiency is still usable at 88dB/2.83V which means you will be able to find mids/tweeters which can be integrated with it in a passive crossover. The power efficiency is not, which means you'll need a big amplifier for it to get loud. Most 10" hifi woofers are 90dB/W or better. As a rule of thumb, the woofer determines the sensitivity of the overall multi-way speaker. Give 4-6dB for baffle step compensation on the woofer and the rest of the drivers would need to be 82-84dB/2.83V or higher efficiency. Most 3-6" midrange drivers and dome tweeters are at least this. The mid/tweeter will be attenuated in the crossover to match the woofer. If using an active crossover or bi-wiring (separate amplifier for the woofer) then you no longer care about the efficiency and can use drivers of any efficiency together.
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