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Effect Of Break In
Slightly off topic, but I started doing some measurements of Thiele Small Parameters for SEAS FA22 with various levels of break in. Each measurement was repeated 3 times. I did not measure Vas. I will later though.
I will let it continue to break in over night and do another measurement in the morning then I will start to measure the AN drivers.
It is interesting to note that the mesasurements are quite a bit different to the published specs of Seas. See if they get closer with further break in.
See the attachment for the results
Edit: The break in procedure used was 10Vpk at 35Hz to 45Hz sweep
Slightly off topic, but I started doing some measurements of Thiele Small Parameters for SEAS FA22 with various levels of break in. Each measurement was repeated 3 times. I did not measure Vas. I will later though.
I will let it continue to break in over night and do another measurement in the morning then I will start to measure the AN drivers.
It is interesting to note that the mesasurements are quite a bit different to the published specs of Seas. See if they get closer with further break in.
See the attachment for the results
Edit: The break in procedure used was 10Vpk at 35Hz to 45Hz sweep
Attachments
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T/S also vary with the voltage used, environmental conditions and measurement system employed. While we are often suspicious of manufacturer specs., & they are usually averages with x production tolerance, it doesn't necessarily follow that home measurements are automatically more representative of the general production run. Sometimes they are, sometimes not, and of course certain manufacturers tend to be more reliable than others on this score. 
Manufacturers also usually have (much!) better gear & facilities than we do. It then becomes a question of how the balance in is struck in the company between marketing & engineering. Too much of the former in many cases, sadly. 
With that all said, if the facility is available, I'd always measure my own units whenever possible, irrespective of the manufacturer, even if only for the sake of interest.
Manufacturers also usually have (much!) better gear & facilities than we do. It then becomes a question of how the balance in is struck in the company between marketing & engineering. Too much of the former in many cases, sadly. With that all said, if the facility is available, I'd always measure my own units whenever possible, irrespective of the manufacturer, even if only for the sake of interest.
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But the NFL rule (No Free Lunch) suggests that there must be a tradeoff with building a box smaller than Vas that pushes the response up by raising the Q. Afterall, it's making use of a resonance so there will be some phase shift somewhere. I'm not sure what it looks like, but I do agree that the attraction of a full-range is no network between amplifier and driver, BSC or otherwise.
Yes I agree with all of that.T/S also vary with the voltage used, environmental conditions and measurement system employed. While we are often suspicious of manufacturer specs., & they are usually averages with x production tolerance, it doesn't necessarily follow that home measurements are automatically more representative of the general production run. Sometimes they are, sometimes not, and of course certain manufacturers tend to be more reliable than others on this score.
With that all said, if the facility is available, I'd always measure my own units whenever possible, irrespective of the manufacturer, even if only for the sake of interest.
In addition to that, T/S Parameters change with break in.
I don't have much faith in T/S parameters given that they change with signal strength, etc etc.
Are there standards for measuring TS parameters? Are they even relevant to how we listen to music?
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I hate the idea of BSC circuits or EQ circuits on full range drivers, if you have to use them then you may as well be using traditional multiway speakers.
I don't mind using 1.5 way though because you are at least maintaining efficiency and you only need an inductor to achieve it.
I also like the idea of a woofer on top and woofer in front like the Ambience enclosure. Probably going to build it for the Seas to see how it sounds.
"A typical 110 mm diameter full-range driver with an Fs of 95 Hz at 0.5 V signal level, might drop to 64 Hz when fed a 5 V input. A driver with a measured Vas of 7 L at 0.5 V, may show a Vas increase to 13 L when tested at 4 V. Qms is typically stable within a few percent, regardless of drive level. Qes and Qts decrease <13% as the drive level rises from 0.5 V to 4 V, due to the changes in Bl. Because Vas can rise significantly and Fs can drop considerably, with a trivial change in measured Mms, the calculated sensitivity value (η0) can appear to drop by >30% as the level changes from 0.5 V to 4 V."
Bloody Hell
Bloody Hell
Do not use this on the Audio Nirvana speakers as Xmax is much smaller.
For AN I used around 2.5Vpk
Indeed they can, I didn't bother referring to that for obvious reasons given the discussion.
I do, but like anything else, it depends how you use them. They are a tool, imperfect, like most tools, but useful.
Yes & no. Measurement criteria can vary, but most manufacturers tend to follow similar paths; typically 1w or 2.83v. What is more likely to vary are production tolerances, and the presentation of data in general, of which T/S are only a part.
Indirectly yes, since for e.g., Q is a useful way of describing the elecromechanical damping of the drive unit. Granted, this can change to an extent on drive level, atmospheric conditions, & particularly the output impedance of the amplifier, but these can be factored in to a reasonable extent, & it can help you avoid, say, ending up with a speaker possessing +6dB peaking at Fb.
here you go
sweep_35Hz_45Hz.flac - 635.5 KB
a -3 dB, 32 bit, 96 KHz, flac file with a sweep from 35 Hz to 45 Hz with a 20 s period. play it somewhere, hit repeat, measure the voltage at the speakers according to melonhead's suggestion
um i hope what i did is a good idea
sweep_35Hz_45Hz.flac - 635.5 KB
a -3 dB, 32 bit, 96 KHz, flac file with a sweep from 35 Hz to 45 Hz with a 20 s period. play it somewhere, hit repeat, measure the voltage at the speakers according to melonhead's suggestion
um i hope what i did is a good idea
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