Hi,
I picked up two pairs of SB17CRC35-8 "Rohacell/Carbon fibre" mid-woofers and a pair of Satori TW29R-B tweeters today.
It will be interesting to see how it measures compared to the aluminium cone version.
The carbon fiber cone looks a bit sexy.
The sandwich cone is rather thick, an estimate is about 4-5mm.
The tweeter also looks nice, but the dome is a bit sticky and it's collecting dust as soon as it's unpacked.
Hopefully I will have some measurements after this weekend.
Regards
/Göran
I picked up two pairs of SB17CRC35-8 "Rohacell/Carbon fibre" mid-woofers and a pair of Satori TW29R-B tweeters today.
It will be interesting to see how it measures compared to the aluminium cone version.
The carbon fiber cone looks a bit sexy.
The sandwich cone is rather thick, an estimate is about 4-5mm. The tweeter also looks nice, but the dome is a bit sticky and it's collecting dust as soon as it's unpacked.
Hopefully I will have some measurements after this weekend.
Regards
/Göran
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Hi everyone,
I have now finished my measurements on the SB17CRC35-8 mid-woofer. You can read about the details here: SB Acoustics SB17CRC35-8
A short summary:
Generally it measures nicely, but unfortunately it doesn't have the same clean distortion profile as the aluminium cone mid-woofer SB17NAC35-4 has.
The Carbon/Rohacell driver has some sort of resonance issue at 1.6-1.7kHz, which can be seen in both the impedance plot and frequency plots. This is probably due to the thick sandwich cone and its attachement to the surrond, creating a cone edge resonance.
It also has somewhat elevated odd-order distortion around 1.6-1.7kHz, even though not dramatic.
I haven't done any listening comparison between the two different drivers (CRC vs NAC) yet, so I can't give any subjective sound judgement between the two.
Regards
/Göran
I have now finished my measurements on the SB17CRC35-8 mid-woofer. You can read about the details here: SB Acoustics SB17CRC35-8
A short summary:
Generally it measures nicely, but unfortunately it doesn't have the same clean distortion profile as the aluminium cone mid-woofer SB17NAC35-4 has.
The Carbon/Rohacell driver has some sort of resonance issue at 1.6-1.7kHz, which can be seen in both the impedance plot and frequency plots. This is probably due to the thick sandwich cone and its attachement to the surrond, creating a cone edge resonance.
It also has somewhat elevated odd-order distortion around 1.6-1.7kHz, even though not dramatic.
I haven't done any listening comparison between the two different drivers (CRC vs NAC) yet, so I can't give any subjective sound judgement between the two.
Regards
/Göran
Thanks for the nice measurements.
Datas seems to make possible a sealed cabinet as well !
The distors of the fundamental seems relativly high in the low (around 200/300 Hz) ? but the data is not easy to read for me on your graphic... what would you advise ? 120 to 1000 Hz second order or too smooth because the around 1700 distorsion peak ?
Something with a SS 10F or a Vifa TG9 above at 800 Hz (like T. Gravsen.... but no tweeter above)
Below a Peerless SLS bass driver 10" or 12" sealed too: around 35 HZ to around 120 Hz?
Seal Vou play too !
Datas seems to make possible a sealed cabinet as well !
The distors of the fundamental seems relativly high in the low (around 200/300 Hz) ? but the data is not easy to read for me on your graphic... what would you advise ? 120 to 1000 Hz second order or too smooth because the around 1700 distorsion peak ?
Something with a SS 10F or a Vifa TG9 above at 800 Hz (like T. Gravsen.... but no tweeter above)
Below a Peerless SLS bass driver 10" or 12" sealed too: around 35 HZ to around 120 Hz?
Seal Vou play too !
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Actually, the results shown are after burn-in. Completely new the four samples had a Fs of about 41-42Hz. I don't expect much lower Fs than this over time, at most 1-2Hz in my experience.
This is the T/S parameters measured after 10min massage and with one minute rest before measurement.
Regards
/Göran
Thanks for the nice measurements.
Datas seems to make possible a sealed cabinet as well !
The distors of the fundamental seems relativly high in the low (around 200/300 Hz) ? but the data is not easy to read for me on your graphic... what would you advise ? 120 to 1000 Hz second order or too smooth because the around 1700 distorsion peak ?
Something with a SS 10F or a Vifa TG9 above at 800 Hz (like T. Gravsen.... but no tweeter above)
Below a Peerless SLS bass driver 10" or 12" sealed too: around 35 HZ to around 120 Hz?
Seal Vou play too !
Disregard the measurements below 300Hz because of room and measurement setup influence.
Even though it has a narrow spike in the distortion plot, the overall distortion profile is low. In fact the spike is lower than many drivers in this price range have all over their usable frequency range.
This driver can most likely be used as a normal mid-woofer in this size up to 1.5-2kHz.
Regards
/Göran
It's also worth paying attention to the fact that T/S parameters change vs drive level so unless one knows the factory level you cannot replicate this yourself.
From a usage point of view though you have to pay attention to how the parameters work together. The ones Gornir measured have a significantly higher Qts and fs, but this is somewhat offset by the fact that they also have a much lower VAS. You'd need to simulate with them to see exactly how different they are.
From a usage point of view though you have to pay attention to how the parameters work together. The ones Gornir measured have a significantly higher Qts and fs, but this is somewhat offset by the fact that they also have a much lower VAS. You'd need to simulate with them to see exactly how different they are.
thanks for your inputs gentlemen,
I have actually a lot of pleasure with a 5" aluminium 125 to 2000 Hz, but lack a little of headroom for my tastes while being enough in a flat !
I know focal made a sandwich too with rohacell foam with the W line if i'm not mistaking while it's not woden carbon on the surface ...
If the data are not moving, a sealed mid could be maybe good...I'm looking forward to your listening test between the both previous drivers if you can play it on a same frequencies range.... VS the Satori !
I have actually a lot of pleasure with a 5" aluminium 125 to 2000 Hz, but lack a little of headroom for my tastes while being enough in a flat !
I know focal made a sandwich too with rohacell foam with the W line if i'm not mistaking while it's not woden carbon on the surface ...
If the data are not moving, a sealed mid could be maybe good...I'm looking forward to your listening test between the both previous drivers if you can play it on a same frequencies range.... VS the Satori !
My apologies! Goran
No problems! You can call me by my nickname or real name.
Rgds
/Göran
Yes, that's absolutely correct.
Usually SB acoustics are fairly correct in their official specifications compared to many other manufacturers. Personally I think many people focus to much on box size calculation theories compared to the rest of the loudspeaker design process.
Most drivers are pretty flexible regarding box volume and port tuning frequencies. In this regard the loudspeaker can be tuned to fit personal taste and room placement etc. With that said, you can't go wild up or down in box volume or port tuning, but +/- 10% or more from e.g. a theoretic QB3 alignment isn't a problem in my experience. Also, many forget to add the series resistance from the x-over in the box calculations, which has an impact on the T/S parameters.
Here's some quick box simulations and as everyone can see, in real world such T/S parameters difference on paper doesn't really matter much.
SBA = SB Acoustics official specification.
WT2 = T/S measurements done by Smith & Larson Audio WT2 woofer tester.
WT3 = T/S measurements done by Dayton Audio WT3 woofer tester.
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