I can probably do a quick and dirty comparison in a minute. My lounge room looks a bit different to normal, have been speaker testing all day (freq response measurements, and testing zobels, stuffing etc.....)
I'll just do it on the floor, when I checked the difference before between sitting on the floor and properly clamped in free air their was very lillte difference (at the moment with the furniture rearangement I can't get out the door to the garage to get the other stuff
Tony.
I'll just do it on the floor, when I checked the difference before between sitting on the floor and properly clamped in free air their was very lillte difference (at the moment with the furniture rearangement I can't get out the door to the garage to get the other stuff
Tony.
looks like there is no real difference
Hi Kelticwizard,
Just pulled one of the drivers out of the box, and ran two tests (just sitting on the floor). One with the speaker being driven by the amp, and the other with the speaker being driven by the sounc card direct. There is virtually no difference, any there is I would say would be normal variabillty I would encounter if I ran multiple tests.
So I'm kind of relieved.... I don't have to test everything all over again, and the other thing is it is a lot easier for me testing straight off the sc, as I don't need to bring the puta downstairs or the amp upstairs
Tony.
Hi Kelticwizard,
Just pulled one of the drivers out of the box, and ran two tests (just sitting on the floor). One with the speaker being driven by the amp, and the other with the speaker being driven by the sounc card direct. There is virtually no difference, any there is I would say would be normal variabillty I would encounter if I ran multiple tests.
So I'm kind of relieved.... I don't have to test everything all over again
, and the other thing is it is a lot easier for me testing straight off the sc, as I don't need to bring the puta downstairs or the amp upstairs Tony.
Attachments
Tony:
Thanks for doing the measurement and posted.
The measurements are identical, even though the output impedances of the soundcard and the amp are vastly different.
I am almost tempted to start a new thread asking why.
One thing that bothers me, though.
Your Morel woofer is supposed to have an Fs of 45, and a Vas of 12 liters.
You have a Vas of 12 liters, but an Fs 53. And a Qts that is higher-0.414 instead of the published spec of 0.36.
Very often, with good woofer brands, which the Morel certainly is, if Fs is higher, it is counterbalanced by Vas being lower, so that when the speaker is placed in the box, it balances out.
Here, 53 Hz is a quarter octave higher than the listed 45 Hz, yet you have no lower Vas to balance that out.
Basically, it looks, overall, like you are getting 3 dB less output out of this woofer than published.
Not necessarily 3 dB in lost midband efficiency. I mean that if two woofers are in the same box, with the same midband efficiency and the same impedance, if Speaker A has a cutoff a quarter of an octave lower than Speaker B, then Speaker A is 3 dB more efficient than speaker B.
I might run both specs through a program which calculates midband efficiency later. If things are right, your speaker should have more midband efficiency than the listed specs, to compensate for the higher Fs and equal Vas.
Thanks for doing the measurement and posted.
The measurements are identical, even though the output impedances of the soundcard and the amp are vastly different.
I am almost tempted to start a new thread asking why.
One thing that bothers me, though.
Your Morel woofer is supposed to have an Fs of 45, and a Vas of 12 liters.
You have a Vas of 12 liters, but an Fs 53. And a Qts that is higher-0.414 instead of the published spec of 0.36.
Very often, with good woofer brands, which the Morel certainly is, if Fs is higher, it is counterbalanced by Vas being lower, so that when the speaker is placed in the box, it balances out.
Here, 53 Hz is a quarter octave higher than the listed 45 Hz, yet you have no lower Vas to balance that out.
Basically, it looks, overall, like you are getting 3 dB less output out of this woofer than published.
Not necessarily 3 dB in lost midband efficiency. I mean that if two woofers are in the same box, with the same midband efficiency and the same impedance, if Speaker A has a cutoff a quarter of an octave lower than Speaker B, then Speaker A is 3 dB more efficient than speaker B.
I might run both specs through a program which calculates midband efficiency later. If things are right, your speaker should have more midband efficiency than the listed specs, to compensate for the higher Fs and equal Vas.
Basically, output impedance of the amp has no effect on resonant frequency. Measuring a woofer with the constant voltage (ammeter) method rather than the constant current (big series resistor) method will sometimes give a lower Fs, not directly because of the measurement method, but rather because the constant voltage method will have a higher drive level. Resonant frequency is a nonlinear parameter, and at higher drive levels it goes down, interestingly enough......
Before using speaker workshop, I preferred measuring with a small series resistor and doing more calculations - you can actually measure total impedance (amplitude and phase) this way. I did an uncertainty analysis and it seems that teh small series resistor method is a bit more accurate as well.
Remember that the accuracy of your T/S measurements is really only on the order of 5-10%.
Before using speaker workshop, I preferred measuring with a small series resistor and doing more calculations - you can actually measure total impedance (amplitude and phase) this way. I did an uncertainty analysis and it seems that teh small series resistor method is a bit more accurate as well.
Remember that the accuracy of your T/S measurements is really only on the order of 5-10%.
Hi kelticwizard,
I just shoved in VAS of 12L manually (as SW puts in 1000L by default), didn't do the calcs as I use the added mass method, and just wanted to get a quick and dirty comparison of the T/S specs (I was also too lazy to go back and check my previous measurements). The VAS of that woofer is actually 9.8L (now that I looked at my original measurements)
The original measurements had an FS of 52Hz on this particular woofer (though considering this time around it was sitting on the floor, I'm not too concerned about the difference).
I was quite disapointed with the large variance of these woofers specs initially (not so much varying from manufacturers specs, but variability between the four) but after mounting a couple in a box and listening I'm not so worried any more
I did some freq response testing of two of the other woofers in their boxes yesterday, and must say that it was a worthwhile excercise, found some problems, and some unexpected things too. One thing that I though was odd, was the F3 was about 61Hz but the sims showed it at about 80Hz......
Tony.
__________________
Any intelligence I may appear to have is purely artificial
I just shoved in VAS of 12L manually (as SW puts in 1000L by default), didn't do the calcs as I use the added mass method, and just wanted to get a quick and dirty comparison of the T/S specs (I was also too lazy to go back and check my previous measurements). The VAS of that woofer is actually 9.8L (now that I looked at my original measurements)
The original measurements had an FS of 52Hz on this particular woofer (though considering this time around it was sitting on the floor, I'm not too concerned about the difference).
I was quite disapointed with the large variance of these woofers specs initially (not so much varying from manufacturers specs, but variability between the four) but after mounting a couple in a box and listening I'm not so worried any more
I did some freq response testing of two of the other woofers in their boxes yesterday, and must say that it was a worthwhile excercise, found some problems, and some unexpected things too. One thing that I though was odd, was the F3 was about 61Hz but the sims showed it at about 80Hz......
Tony.
__________________
Any intelligence I may appear to have is purely artificial
Before stuffing, bracing some lining and taking into account the displacement from the woofer, 6.6L.
The response curve is somewhat different to what I would have expected. It could be that I'm not reading it right
Since we are getting off topic here I've created a new thread http://www.diyaudio.com/forums/showthread.php?s=&threadid=50579
so if you want to continue there that would be great
Tony.
The response curve is somewhat different to what I would have expected. It could be that I'm not reading it right
Since we are getting off topic here I've created a new thread http://www.diyaudio.com/forums/showthread.php?s=&threadid=50579
so if you want to continue there that would be great
Tony.
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