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Joined 2003
I think to answer that question there are 30+ examples at Hificompass to compare against the datasheets.
I re read the on axis on hificompass.com Revelator drivers. Seem near enough to 1 db according the unit datasheet curve.
https://www.scan-speak.dk/product/18m-8631t00/ looks good.
https://www.scan-speak.dk/product/18m-8631t00/ looks good.
Just found the 4 ohms version test 
. Should be helpfull to find the sensivity of the 8 ohms big brother : https://audioxpress.com/article/tes...eak-18m-6431t00-revelator-6-5-midrange-driver , here the difference with the datasheet is around 1.5 dB.
Anyway, if a fellow had listened to it already, a feedback is appreciated.
. Should be helpfull to find the sensivity of the 8 ohms big brother : https://audioxpress.com/article/tes...eak-18m-6431t00-revelator-6-5-midrange-driver , here the difference with the datasheet is around 1.5 dB.Anyway, if a fellow had listened to it already, a feedback is appreciated.
Troels used the 8ohm version in the MUN17, he seemed to like it
http://www.troelsgravesen.dk/ScanSpeak-MUN-17-3W.htm
http://www.troelsgravesen.dk/ScanSpeak-MUN-17-3W.htm
@HiFiCompass
Are you accepting any drivers for testing at this present time? If so, would you please start a conversation with me?
I sent a message earlier...
Are you accepting any drivers for testing at this present time? If so, would you please start a conversation with me?
I sent a message earlier...
Yes, I continue doing speaker testing but not so active at present time due russian agression. Nevertheless, I do🙂.
I just have answered on your earlier message.
Hey guys, I've been enjoying reading you for months now and I have a question on how to measure drivers, and let's take TB Speaker 75-1558SH as an example.
Review by Voice Coil can be found here
FR/THD measurements :
I'm not an expert, but THD is very low...cool!
But, when I compare the measurements TB sent me by mail :
Hmmm not as good.
So I asked why, why such a difference between the two :
So different way to measure lead to different results. But where is the truth? Anyone already has this mid-dome?
Cheers!
J.
Review by Voice Coil can be found here
FR/THD measurements :
I'm not an expert, but THD is very low...cool!
But, when I compare the measurements TB sent me by mail :
Hmmm not as good.
So I asked why, why such a difference between the two :
So different way to measure lead to different results. But where is the truth? Anyone already has this mid-dome?
Cheers!
J.
The truth is at hificompass.com
.Measurements from different sources can never be the same due to different hardware, software and measurement conditions.
Sound pressure levels are very important here as well.
Go have a look at hificompass website and see the difference at different voltage levels and how the different distortion harmonics shift from each other.
This is why just one THD graph at one SPL doesn't say much at all.
But yeah, in general, measurement conditions say a lot, especially when done @ 1 meter
Nearfield measurements would at least give a very similar shape.
Never trust a linear THD scale (log makes way more sense)
Voice coil measures at 2,83V as far as I remember? TB probably a little more - but 2% is a lot for such a driver. The old ones where better and they should be very similar. TB only measured from 500hz on, so the interesting part is missing. I don't trust their measurements at all, tested a few drivers and never got close to what their datasheet sayed. Maybe better now with a Klippel system?
But the Voice Coil measurement shows to less K2 in my opinion. These "weak" domes always produce some K2 - so the truth will be somewhere in the middle.
Over all this is a good driver, built a custom studio speaker with it some years ago and owner is very happy. But when cost is no problem ... take a Bliesma 3".
(log makes way more sense)Voice coil measures at 2,83V as far as I remember? TB probably a little more - but 2% is a lot for such a driver. The old ones where better and they should be very similar. TB only measured from 500hz on, so the interesting part is missing. I don't trust their measurements at all, tested a few drivers and never got close to what their datasheet sayed. Maybe better now with a Klippel system?
But the Voice Coil measurement shows to less K2 in my opinion. These "weak" domes always produce some K2 - so the truth will be somewhere in the middle.
Over all this is a good driver, built a custom studio speaker with it some years ago and owner is very happy. But when cost is no problem ... take a Bliesma 3".
I'm not very impressed by Bliesma 3"Never trust a linear THD scale
Voice coil measures at 2,83V as far as I remember? TB probably a little more - but 2% is a lot for such a driver. The old ones where better and they should be very similar. TB only measured from 500hz on, so the interesting part is missing. I don't trust their measurements at all, tested a few drivers and never got close to what their datasheet sayed. Maybe better now with a Klippel system?
But the Voice Coil measurement shows to less K2 in my opinion. These "weak" domes always produce some K2 - so the truth will be somewhere in the middle.
Over all this is a good driver, built a custom studio speaker with it some years ago and owner is very happy. But when cost is no problem ... take a Bliesma 3".
Ahah! nice way to compare!
About Bliesma, it's just the THD under 1Kh, not very low by judging Hifi Compass measurements.
OK I just saw your posts here : https://www.diyaudio.com/community/...es-3-dome-midrange-lineup.380200/post-7140555
Will re-consider it then!
About Bliesma, it's just the THD under 1Kh, not very low by judging Hifi Compass measurements.
OK I just saw your posts here : https://www.diyaudio.com/community/...es-3-dome-midrange-lineup.380200/post-7140555
Will re-consider it then!
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The new audio strobe from Dayton could probably detect rocking modes in large domes with only a single suspension! (and no ferrofluid for stabilisation)
Ferrofluid can introduce its own set of problems if not very carefully accounted for by the manufacturer! I would avoid it also because it is not long-time stable ..
Greetings from Remulak
Ferrofluid can introduce its own set of problems if not very carefully accounted for by the manufacturer! I would avoid it also because it is not long-time stable ..
Greetings from Remulak
Lol, that's 80 bucks for just a standard stroboscope?The new audio strobe from Dayton could probably detect rocking modes in large domes with only a single suspension! (and no ferrofluid for stabilisation)
Ferrofluid can introduce its own set of problems if not very carefully accounted for by the manufacturer! I would avoid it also because it is not long-time stable ..
Greetings from Remulak
Interesting.... I would rather advice a fast FPS camera.
although that would probably be over this budget (maybe 2nd hand one?)
Ferrofluid is kinda difficult in the sense that it works extremely well to stabilize any driver around the Fs significantly.
But the downside that it can dry up after a couple of years (depending on climate etc)
This is THD at 94dBSpl at 0,5m with 2 alu Bliesmas in MTM + TT configuration. And up to 114dBSpl - but remember it's 0,5m distance. Crossover at 450Hz when I remember right.
While there IS higher THD it's still very low compared to normal drivers. It's just insane low at 1kHz!
And it's mainly K2 what you can see at my other measurements, K3 sticks 10-15dB lower, even at low frequencies. (last measurement is from 1 ALU 3")
While there IS higher THD it's still very low compared to normal drivers. It's just insane low at 1kHz!
And it's mainly K2 what you can see at my other measurements, K3 sticks 10-15dB lower, even at low frequencies. (last measurement is from 1 ALU 3")
Depending on FF formulation , colloid stability can be a problem in high Tesla spaces! And FF creeps into any tight spaces by cappilaric action! Also it is a solvent for some glues!
Furthermore , it distributes not evenly around the air gap! (gravity related .. and magnetic field distribution which is always off to some degree)
FF should be used only on the (smooth) inside of the VC , but with sandwich coils it no work ...
Mechanical losses on the coil outside due to FF rub - also no good!
FF has fallen totally out of favour in the audio biz , guess why!
Furthermore , it distributes not evenly around the air gap! (gravity related .. and magnetic field distribution which is always off to some degree)
FF should be used only on the (smooth) inside of the VC , but with sandwich coils it no work ...
Mechanical losses on the coil outside due to FF rub - also no good!
FF has fallen totally out of favour in the audio biz , guess why!
Fair points, although I have never seen it so bad in practice.
Probably because most decent companies use the right stuff and amounts.
I have seen an overall much better behavior of having a much more stable Fs with FF
For that last point, well mostly because of the total myth of "sounding slower" as well as the drying out part.
Which is really annoying (read: expensive!) in production and after sales customer service and warranty.
Unless you mean speakers in general (so also woofers), yes I totally see your points there.