I did some measurements today of these 3 drivers in closed volumes. In my measurement room, 0,5m distance groundplane - so there is a little rrom influence left, but good enough for a comparison. Level is corrected for 1m freefield.
First SB34NRXL75-8. One of the best drivers I know, especially for that money. Very good use for a 3-way but could also be a subwoofer.
THD is incredible low - 1% at 105-110dBSpl! I use 2 of them in my new speakers ... that's enough for most rooms ;-)
Also 0,05% THD ... not often I measure that with a speaker!
Now SB29NRX75-6. My goto chassis for closed subwoofers, put 6 of them in my homecinema as SBA. Not expensive, doesn't need a big volume, not to heavy membrane, huge venting hole, 75mm coil, not to heavy membrane, noise free Xmax.
Frequency response already shows us this is no midrange chassis. THD is good at low frequencies but doesn't scale as it should at low levels! I know this behaviour from PA chassis, didn't expect it here. No problem for a woofer - but I would not use it up to a few hundred Hz.
And now the SB29NRX75-8. I expected something in the middle between these 2 according the datasheet - a smaller and cheaper alternative to the 12".
Nope - that's not what I need for a low mid driver. The same THD behaviour - it looks like about the same driver just with higer impedance coil.
All of these drivers had no problem at all with 25V -> 80W/8R sine power, you need a bigger amp as an AHB-2 to bring them to their limits.
SB Acoustics has some gems in their programm but their "normal" driver range can't compete with the best from ScanSpeak. They are half of the price - it's probably ok ;-)
I still recommend the SB29NRX75-6 for subwoofers - huge coil and perfect venting, these drivers can take power!
But their SB34NRXL75-8 ... is one of these gems. One of the best 12" available.
First SB34NRXL75-8. One of the best drivers I know, especially for that money. Very good use for a 3-way but could also be a subwoofer.
THD is incredible low - 1% at 105-110dBSpl! I use 2 of them in my new speakers ... that's enough for most rooms ;-)
Also 0,05% THD ... not often I measure that with a speaker!
Now SB29NRX75-6. My goto chassis for closed subwoofers, put 6 of them in my homecinema as SBA. Not expensive, doesn't need a big volume, not to heavy membrane, huge venting hole, 75mm coil, not to heavy membrane, noise free Xmax.
Frequency response already shows us this is no midrange chassis. THD is good at low frequencies but doesn't scale as it should at low levels! I know this behaviour from PA chassis, didn't expect it here. No problem for a woofer - but I would not use it up to a few hundred Hz.
And now the SB29NRX75-8. I expected something in the middle between these 2 according the datasheet - a smaller and cheaper alternative to the 12".
Nope - that's not what I need for a low mid driver. The same THD behaviour - it looks like about the same driver just with higer impedance coil.
All of these drivers had no problem at all with 25V -> 80W/8R sine power, you need a bigger amp as an AHB-2 to bring them to their limits.
SB Acoustics has some gems in their programm but their "normal" driver range can't compete with the best from ScanSpeak. They are half of the price - it's probably ok ;-)
I still recommend the SB29NRX75-6 for subwoofers - huge coil and perfect venting, these drivers can take power!
But their SB34NRXL75-8 ... is one of these gems. One of the best 12" available.
Of course I don't stop with measurement results like these ... 
Here H2 and H3 from the SB29NRX75-8 (good I whish for an easier name for these drivers after typing it 30 times today)
H2: looks good and normal.
H3: Opps. Only starts raising at very high levels and causes the higher THD at low levels.
It's still not horrible - that's about 0,5% THD. But some part in this driver produces "symmetrical" limitation. (like soft clipping, peaks of the positive and negative wave seem not perfect)
SB Acoustics - are you reading here? What's going on?
Here H2 and H3 from the SB29NRX75-8 (good I whish for an easier name for these drivers after typing it 30 times today)
H2: looks good and normal.
H3: Opps. Only starts raising at very high levels and causes the higher THD at low levels.
It's still not horrible - that's about 0,5% THD. But some part in this driver produces "symmetrical" limitation. (like soft clipping, peaks of the positive and negative wave seem not perfect)
SB Acoustics - are you reading here? What's going on?
And a quick comparison of SB29NRX75-6 and SB34NRXL75-8. About 2,8Vrms at the drivers.
The 12" has the magnet strenght to be a proper midbass driver. But don't use it over 5-600 Hz! I use them with the Bliesma 3", works fine so far.
At low frequencies you don't gain sensitivity over the 6R chassis. So for a passive design all of this sensitivity in the mids doesn't help a lot - but would be perfect for a 3.5 system.
THD ... that's the difference between a state of the art driver and a normal, solid driver.
The 12" has the magnet strenght to be a proper midbass driver. But don't use it over 5-600 Hz! I use them with the Bliesma 3", works fine so far.
At low frequencies you don't gain sensitivity over the 6R chassis. So for a passive design all of this sensitivity in the mids doesn't help a lot - but would be perfect for a 3.5 system.
THD ... that's the difference between a state of the art driver and a normal, solid driver.
The 10" in about 40L minus bracing and speaker + dampening.
12" in about 55L but just in a prototyp housing.
@IamJF
Do you have any comparisons of the SB models with the original Peerless models from the past, XLS 830500, XLS 830452? They used to be the go-to recommendations for low distortion subwoofers back in the day. I don't know if the quality changed after Tymphany took over the brand. I used them in a few projects. I am just curious if there has been real progress in thd.
Since the Peerless use 2" voice coils and the SB use 3", I expect the SB to have superior power handling, but does this translate to lower thd at moderate spl?
Do you have any comparisons of the SB models with the original Peerless models from the past, XLS 830500, XLS 830452? They used to be the go-to recommendations for low distortion subwoofers back in the day. I don't know if the quality changed after Tymphany took over the brand. I used them in a few projects. I am just curious if there has been real progress in thd.
Since the Peerless use 2" voice coils and the SB use 3", I expect the SB to have superior power handling, but does this translate to lower thd at moderate spl?
The SB34NRXL75-8 is my favorite 12" driver for ported enclosures running higher xover points. It still sounds great crossed at 400 hz. Something most 12s can't do. Only a handful of pro audio 12s can pull this off without getting wonky in the lower mids. Two of the SBs will do about 94 - 95 dB @ 2.83V, which is pro driver territory. The power handling is superb for a rubber surround 12 and SB's spec of 200W continuous is very conservative.
I never used the Peerless XLS - I always try(ed) to use chassis with lighter membranes. (But a listening comparison I did once didn't hint any problems with heavier membranes - it's probably a "feel good" thing ;-))
AS @profiguy says - these 3" coils can take a lot of power. PA companies would probably rate them with 600W
@Draki - the 8R 10" is already out of the box but I can do the others later/tomorrow.
@Bon
SBA The SB34NRXL75-8 has been well characterized by @HiFiCompass
https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb34nrxl75-8
It's a good driver. The only fly in the ointment for me is the over-sized driver frame. It's a whole 38mm (1.5") larger than the 12" XXLS.
But that's being extremely critical...
SBA The SB34NRXL75-8 has been well characterized by @HiFiCompass
https://hificompass.com/en/speakers/measurements/sbacoustics/sb-acoustics-sb34nrxl75-8
It's a good driver. The only fly in the ointment for me is the over-sized driver frame. It's a whole 38mm (1.5") larger than the 12" XXLS.
But that's being extremely critical...
The larger frame is an advantage in terms of mechanical integrity. This provides better VC alignment precision and allows for a tighter VC gap. You'd be surprised how much a flimsy driver frame distorts when bolted down onto a less than optimally flat baffle. The older larger Scan Speak frames are notorious for this.
@IamJF The almost tenfold reduction in THD according to your measurements is quite impressive with the NRXL version. It does have some of the cleanest lower mids of any hifi 12" driver I've ever heard and it costs much less than comparable performing drivers.
The only negative thing about it is the 700 hz spike in HD and a kink in FR, but that can be easily avoided.
The only negative thing about it is the 700 hz spike in HD and a kink in FR, but that can be easily avoided.
Jeff Baby had good results crossing the SB29RNX at 200Hz for a Kairos 3 way.
https://meniscus.lightningbasehoste...he-Kairos-and-Continuum-Three-Way-Writeup.pdf
(Download this before it disappears)
How did you go in your design?
https://meniscus.lightningbasehoste...he-Kairos-and-Continuum-Three-Way-Writeup.pdf
(Download this before it disappears)
How did you go in your design?
I have a concept for a HighEnd/HighPower speaker with 4 of them in closed volumes. Strategical positioned in the housing to chancel out vibrations and some room modes. Of course bliesma 3" and 34mm tweeter ;-) (or PHL midrange if someone really wants). 3.5 way with 4 ways DSP.
That would be an "end game" speaker when you can't do a bass array ;-)
I also used the NRX up to between 80-200Hz during development and listening to my 8"/1" home cinema speakers. Was ok in that range. Sounded more "tight" as my ScanSpeak 8" in comparison (but different position in the room -> would not put to muh into that).
K3 at low frequencies produces "tight, clear" sound (compare to transformer THD in preamps) ... hmmmm...
Used as sub THD is low, it rises at 100Hz and higher. So your experience seems legit (even when "horrible" sounds a little dramatic ... can you write a few words about your project?)
the reason I’m not enamoured by overly large frames is because I feel there’s missed opportunity for increasing Sd; which can help in the sub-bass.
To put it into context, the SB34NRXL has a Vd is about 5% more than the SEAS L26ROY (2 layer VC) (or ROY3- 2 layer VC with black cone)
So one takes up a minimum of 346mm (just over 13.5”) and the other is 280 (just under 11”).
So it really is 2.5” bigger than the SEAS.
But not better sub-bass performance.
Now someone is going to say the price is lower. But the price should be a lot lower too-If you’ve ever been to Indonesia, average wages there are a third of that in China.
The SEAS are made in Norway. Don’t even ask how much a ordinary beer or pizza costs in Norway…
To put it into context, the SB34NRXL has a Vd is about 5% more than the SEAS L26ROY (2 layer VC) (or ROY3- 2 layer VC with black cone)
So one takes up a minimum of 346mm (just over 13.5”) and the other is 280 (just under 11”).
So it really is 2.5” bigger than the SEAS.
But not better sub-bass performance.
Now someone is going to say the price is lower. But the price should be a lot lower too-If you’ve ever been to Indonesia, average wages there are a third of that in China.
The SEAS are made in Norway. Don’t even ask how much a ordinary beer or pizza costs in Norway…
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I tried to get it sounding decent by tweaking the crossovers and cabinets but it always sounded slow and fat and boomy.I gave up.
I ended up using cheap ten inch woofers isobaric loaded which sounded much better .The Kairos two way as it is [sealed box] is excellent.
I did try it as a subwoofer and it was OK for that.
In box impedance measurements. Both speakers didn't run very long but should have enough for break in.
SB34NRXL75-8:
You see the impednace hump at about 650Hz - keep away from this area. I would say that's a surround resonance or something similar caused from the low loss surround (Qms is very high for such a driver). That's the price you have to pay for low losses. These dips are way less critical as membrane resonances but of course still to avoid. Qts is stable compared 1W vs. small signal.
SB29NRX75-6:
Impedance is clean, little hickup at 860Hz. Qts is a little higer - wanted to stay with the small volume. It goes down btw with higher excursion - I normally measure these speakers with a realistic wattage for real listening, but these numbers then don't line up with manufacturers.
Hope I find time today to add SB23MFCL45-8!
SB34NRXL75-8:
You see the impednace hump at about 650Hz - keep away from this area. I would say that's a surround resonance or something similar caused from the low loss surround (Qms is very high for such a driver). That's the price you have to pay for low losses. These dips are way less critical as membrane resonances but of course still to avoid. Qts is stable compared 1W vs. small signal.
SB29NRX75-6:
Impedance is clean, little hickup at 860Hz. Qts is a little higer - wanted to stay with the small volume. It goes down btw with higher excursion - I normally measure these speakers with a realistic wattage for real listening, but these numbers then don't line up with manufacturers.
Hope I find time today to add SB23MFCL45-8!