One of the challenges is interpreting the distortion from a -dB graph.
The tweeter appears to rise below about 2.5K according to Yevgeniy’s measurements… but it is rising from a very low -60dB.
One must take into account the absolute SPL. As @IamJF has demonstrated, the twin woofers have more THD than the tweeters or mids, which is not unusual.
I’ve often wondered whether this is why ribbon tweeters can still sound “good” despite having higher THD; they are high only when compared to their some cousins, but not when compared to their midrange or woofers they make friends with in a complete speaker.
And, as I have recently discovered, although ribbons have relatively high directivity in the vertical plane, they have a low, constant directivity-like projection in the horizontal plane:
From:
Fountek NeoCD3.0 in Statements II speaker- 11.5" wide cabinet
The tweeter appears to rise below about 2.5K according to Yevgeniy’s measurements… but it is rising from a very low -60dB.
One must take into account the absolute SPL. As @IamJF has demonstrated, the twin woofers have more THD than the tweeters or mids, which is not unusual.
I’ve often wondered whether this is why ribbon tweeters can still sound “good” despite having higher THD; they are high only when compared to their some cousins, but not when compared to their midrange or woofers they make friends with in a complete speaker.
And, as I have recently discovered, although ribbons have relatively high directivity in the vertical plane, they have a low, constant directivity-like projection in the horizontal plane:
From:
Fountek NeoCD3.0 in Statements II speaker- 11.5" wide cabinet
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Thanks!
Seems a 24dB 400hz crossover is not a problem for any sane playback level in a home. 🙂
Noise is masking most homemade tweeter measurements. With alu-tweeter peaking around 20kHz make peak for H2 10kHz, H3 at 6800Hz etc.
Magnetostat ribbons should not be forgotten!
Magnetostat ribbons should not be forgotten!
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Given the scale, that’s one the most even HF horizontal dispersion drivers ever.
No, didn't try. Looks promising! But my last projects where very little cost restricted, so I went for T25B ;-)
It reminds me to ScanSpeak D2904/980000 which I liked.
The problem is the uneven directivity in the vertical plane! It's a "long" line and directivity totally changes in the 2kHz to 20kHz range.
@hifijim
Have you checked the relatively new Volt RV2501 and RV2550 drivers? These are like since two years or so on the market and Volt increased a lot their distribution lately. These are 10 inch, first one is typical woofer the second subwoofer. On a Volt page there is also translated review with measurements from german Hobby HIFI magazine.
Have you checked the relatively new Volt RV2501 and RV2550 drivers? These are like since two years or so on the market and Volt increased a lot their distribution lately. These are 10 inch, first one is typical woofer the second subwoofer. On a Volt page there is also translated review with measurements from german Hobby HIFI magazine.
BMS 12N630 is a good driver, but has double stiff compliance than SB34NRXL - so in CB you will need to EQ more heavy in the low bass and need more power for it. BMS is PA driver, SB is Hifi driver, so compliance might be also more progressive with the BMS. In CB you want to linearize compliance with air suspension, so soft compliance is preffered. SB has more xmax and a bit lower mechanical losses. Cheapest price in Europe i could find is 300 for the BMS and 250 for the SB. So SB34NRXL wins the tradeoff for me. Serious competitor is RSS315HFA-8. If maximum SPL is desired I would take Faital 12RS430 in vented enclosure or TML.
Since this topic has been raised again…
I've been searching for similar 12” woofers. Assuming the same size sealed enclosure, it's a small range of options.
The loudspeaker database has been very useful in this search. Specify all brands, subwoofer & woofer, 11~13” diameter, Xmax ≥11mm (that of the SB34NRX75-6), impedance of ≥4 ohms or higher. A slew of drivers come up. But not that many with parameters that work well in a sealed box.
Using the curves provided in the loudspeaker database, I checked the Max SPL at 30Hz: Your current SB34NRX75-6 does 102.2 dB. https://loudspeakerdatabase.com/SB/SB34NRX75-6
Parameters of promising drivers were downloaded from the loudspeaker database and the predicted closed box 0.7 Qts checked in WinISD.
Here’s a short list of hifi & car audio brand offerings that clearly exceed 102 dB Max SPL & have T/S parameters suitable for a sealed box. It is not an exhaustive or definitive list:
Acoustic Elegance IB12AU-8 - 107 dB
Scan-Speak Revelator 32W/4878T00 - 104.9 dB
Dayton RSS315HFA-8 - 104.6 dB
FaitalPRO 12RS430 - 105 dB
Peerless XXLS-P830845 - 105 dB
Eminence LAB12 - 103.8 dB
Some of these drivers in 0.7 Qts enclosures need significant EQ to achieve flat response to 30Hz, but the predicted Max SPL should still hold. The AE driver needs a huge 182l volume for 0.7Qts.
Among other 12” SBA options only the SB34SWPL76-4 does better: 104.2 dB. It's a much heavier cone at 266g, vs 99g for SB34NRX75-6, so response higher up is not great. I would not go higher than 150Hz.
JL Audio 12W6v3-D4 is a dual VC car sub with 19mm Xmax. Only sold via car audio dealers. Its 106.5 dB is one of the highest Max SPL @ 30Hz among the 61 12” drivers in the loudspeakerdatabase I examined & needs only a 42 liter box for 0.7Q.
The Parts Express page on the Peerless XXLS-P830845 suggests it can be bought in small qty & will be in stock 5/2/2025. For the $$, I'm tempted to grab a few. (Assuming the silly threatened tariff wars don't ensue.)
Prices vary tremendously from <$200 to ~$700.
I've been searching for similar 12” woofers. Assuming the same size sealed enclosure, it's a small range of options.
The loudspeaker database has been very useful in this search. Specify all brands, subwoofer & woofer, 11~13” diameter, Xmax ≥11mm (that of the SB34NRX75-6), impedance of ≥4 ohms or higher. A slew of drivers come up. But not that many with parameters that work well in a sealed box.
Using the curves provided in the loudspeaker database, I checked the Max SPL at 30Hz: Your current SB34NRX75-6 does 102.2 dB. https://loudspeakerdatabase.com/SB/SB34NRX75-6
Parameters of promising drivers were downloaded from the loudspeaker database and the predicted closed box 0.7 Qts checked in WinISD.
Here’s a short list of hifi & car audio brand offerings that clearly exceed 102 dB Max SPL & have T/S parameters suitable for a sealed box. It is not an exhaustive or definitive list:
Acoustic Elegance IB12AU-8 - 107 dB
Scan-Speak Revelator 32W/4878T00 - 104.9 dB
Dayton RSS315HFA-8 - 104.6 dB
FaitalPRO 12RS430 - 105 dB
Peerless XXLS-P830845 - 105 dB
Eminence LAB12 - 103.8 dB
Some of these drivers in 0.7 Qts enclosures need significant EQ to achieve flat response to 30Hz, but the predicted Max SPL should still hold. The AE driver needs a huge 182l volume for 0.7Qts.
Among other 12” SBA options only the SB34SWPL76-4 does better: 104.2 dB. It's a much heavier cone at 266g, vs 99g for SB34NRX75-6, so response higher up is not great. I would not go higher than 150Hz.
JL Audio 12W6v3-D4 is a dual VC car sub with 19mm Xmax. Only sold via car audio dealers. Its 106.5 dB is one of the highest Max SPL @ 30Hz among the 61 12” drivers in the loudspeakerdatabase I examined & needs only a 42 liter box for 0.7Q.
The Parts Express page on the Peerless XXLS-P830845 suggests it can be bought in small qty & will be in stock 5/2/2025. For the $$, I'm tempted to grab a few. (Assuming the silly threatened tariff wars don't ensue.)
Prices vary tremendously from <$200 to ~$700.
It seems that these woofers SPLmax comparison is based on manufacters data sheet. Several reviews proves that depending on the brand, these data are not always reliable. My feeling based on Erin, audioexpress, ... reviews is that xmax from scanspeak or purifi are consistent while SBA or faital are sometimes overestimated. You cannot beat Purifi datasheet 🙂.
This SB34SWPL76-4, long throw brother of SB34NRXL is even cheaper, it is 200 EUR/piece in THLP shop in Europe if you buy 4 of them. It is probably Champ of the World in price per volume displacement with xmax of 30 mm...and smaller Vas means smaller box.
However, it doesn't have shorting rings and inductance rises quickly toward higher frequencies. I don't know if this is even important since it's a true sub unit....I know that I like advanced motors, they are clipping soft when driven to mechanical limits, but can't imagine to force four of these to limits in normal sized room....If distortion would be similar to NRXL then this would be real deal.
I wish if somebody would measure them.
However, it doesn't have shorting rings and inductance rises quickly toward higher frequencies. I don't know if this is even important since it's a true sub unit....I know that I like advanced motors, they are clipping soft when driven to mechanical limits, but can't imagine to force four of these to limits in normal sized room....If distortion would be similar to NRXL then this would be real deal.
I wish if somebody would measure them.
I'm going to use 4 for a pair of W-frame OB bass boxes. I have 3 of the 4 drivers needed; Solen said they won't have any more stock till April! 😕
I will measure them some time soon. Maybe compare with the SB34SWNRX-S75-6 I also have.
IS that really true?
AFAIK, Xmax is a pretty simple measurement of how much the voice coil can move within the magnet gap. It is not the true maximum excursion of the cone, which is described as Xmech or Xlim. This takes into account all the other limitations on cone excursion which Xmax does not.
Perhaps what the 3rd party reviews report has more to do with Xmech. There is the question of how well or smoothly the driver responds to being over-driven -- beyond Xmax.
I don't like the H2 spike in the 400Hz area, this is not good for this project. Otherwise an interesting speaker!
Yes. There are a number of accepted methods for physical meqasurement of xmax and they don't give the same value. Faital use the optimistic version.
What none of these physical measurements do is tell how much distrortion will be produced at those excursions.
Klippel measurements of BL and Suspension compliance non linearity give a much better idea of whether the driver can be used up to it's rated excursion or whether the BL or compliance will limit it's useful output before then. The SB17 motor hits 10% distortion due to a compliance limitation a long way before it's rated xmax, but it is unfair to extrapolate that all their drivers will do the same.
B&C use a figure called XVar which is meant to be a figure that shows how much useful output the driver has. On most of their drivers it is more than the Xmax.
SB Acoustics driver motors are not all at the same level. SB34NRXL does very well and is on par with ScanSpeak. SB17 and the Alu 20cm chassis is not bad but not in the same league. WO24 also seems very good, the smaller ones have higher THD at low frequencies but are great at higher ones.
The 10" SB chassis I measured are all good at low frequencies and give A LOT of clean Xmax but not all of them perform well at higher frequencies like the NRXL.
With Faital ... I'm more cautious. There are drivers which often measure even better as the spec sheet (ScanSpeak) and some which often don't meet the spec sheet (TB speakers). I only believe Faital specs after I measured them myself 😏
So far my experience and measurement results of the bunch of drivers of these 2 companies I had on my table.
The 10" SB chassis I measured are all good at low frequencies and give A LOT of clean Xmax but not all of them perform well at higher frequencies like the NRXL.
With Faital ... I'm more cautious. There are drivers which often measure even better as the spec sheet (ScanSpeak) and some which often don't meet the spec sheet (TB speakers). I only believe Faital specs after I measured them myself 😏
So far my experience and measurement results of the bunch of drivers of these 2 companies I had on my table.