SB Acoustics SB34NRXL75-8 vs SB29NRX75-6 vs SB29NRX75-8

Bigger Vas driver better sound for bass enclosure ?

I wonder if the vooce coil inductance has an effect at those low frequencies, say in a 3 ways for < 200 hz/300 hz ?

IIRC @hifijim is very happy with his SB34 plateamped.

sligthy off topic :Talking about 10", had anyone the luck to compare L26Roy, the fiber glass Discovery from ScanSpeak, or.... vs PA driver with higher Fs (tipycally around highish 40 hz) for sealed bass enclosures ? Is it doable in a living room to have a high F3 between 70 to 80 hz and enough bass thanks to room placement and room gain ? Can be moved for a new thread if IamJF thinks is too much OT.

Thanks
 
You can have a look at HiFi Compass. Measurements are not 100% compareable but show the same picture. And they measured the 12" Scanspeak with great results!
I only use 8" ScanSpeak drivers (which are also fabulous!) and a LAB 12 which surprised me with also pretty good quality and low THD - but this one is now built inside my kitchen with no way to remove ... so no measurements in my lab room possible ;-)
I could test my 18" PA Woofers ... 🤓
 
In @IamJF 's other thread, I mentioned that I wanted to test my SB34NRX75-6 drivers for distortion, to compare to these measurements. This seems like a logical place to put that information.

The SB34NRX75-6 is similar in many ways to the woofer that @IamJF tested (SB34NRXL75-8). But one crucial difference is that the NRXL driver has a superior motor with Faraday shorting rings.

I tested my woofer at two different levels, 91 dB SPL and 100 dB SPL, measured at 1 meter at 200 Hz. I used an Audix TM1 mic, a Motu M2 interface, and the ARTA STEPS software. I ran sweeps from 30 Hz to 1000 Hz. I could not go below 30 Hz because the excessive buzzing and rattling of the windows and other stuff in the house corrupted the measurements.

Here are the results:

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I have not fully digested this data, but one thing that I noticed is that above 100 Hz, H3 H4 H5 do not change much from 91 dB to 100 dB. Only the benign H2 rises with total SPL.

I will have more to say about this data later.

j.
 
Can you let us know the cabinet volume where your SB34NRX7-6 in placed?
70 liter sealed.

My personal guidelines regarding harmonic distortion are this:

At normal "peak" listening levels, I want H2 to be less than 1% from 100 Hz up. For my main system, this is 95 dB SPL.

At normal "peak" listening levels, I want H3 to be less than 0.5% from 75 Hz up.

I want H4 and H5 to be less than or equal to H3.

So from my standpoint, this woofer meets my requirements.... but I am curious about the SB34NRXL, so I may have to get a pair...
 
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any opinion on the SB34SWPL76-4 I haven't seen it mentioned in this thread . I worked out that it would do f3 of 40hz in 22 litres sealed . have I miss calculated or missed something I thought this was the 12inch to get from sb acoustics . understand it is less sensitive than the others
 
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I have not fully digested this data, but one thing that I noticed is that above 100 Hz, H3 H4 H5 do not change much from 91 dB to 100 dB. Only the benign H2 rises with total SPL.
Thanks for contributing!
That's about the behaviour of the 10" drivers - they have some H3 which doesn't change a lot over level. This is no problem for low frequencies but I would not use them with higer rossovers in a 3-way. NRXL version doesn't show that behaviour and has lower over all THD and higer sensitivity at higher frequencies (= strong enough motor).
So for a 3-way ... you may have to get a pair 😉