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

[IamJF]

I never used them but normally the mms is the minimum weight. Maybe ask your seller if that's also the case here?

 

[Krab007]

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.
View attachment 1206784
View attachment 1206785
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.
View attachment 1206787
View attachment 1206788
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".
View attachment 1206790
View attachment 1206791
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.

Hello, what is better, sb34nrxl or volt rv3143? Thanks in advance for your answer

 

[IamJF]

I never measured the Volt driver. The measurements here show pretty high THD and H3 peak at 210Hz which corresponds with a peak at 600Hz:
https://audioxpress.com/article/test-bench-volt-rv3143-studio-monitor-woofer
Audio Express measurements are a little "special" but when true it would not be ideal. Also Xmax is lower. But I really like the construction of these Volt drivers!

Without additional information I would stick with the SB34NRXL, esp. for the price.

 

[diyiggy]

What if a little mass was added to the 34RNX-L cone, please ? Will it lowish the F3 and F6 in a sealed design ? (to use a standalone one in spite of two with low end EQ)

 

[neutrino_th]

@diyiggy
Add a resistor to lower the fs.
This can be simulated with Winisd for e.g.

L

Post in thread 'Exploring Purifi Woofer Speaker Builds'

2024-08-15 2:52 pm

by increasing Qts the tuning can be shifted to a bigger box and lower tuning frequency. Qts is increased adding a little bit of series resistance with the woofer, eg using less copper in the xover coils). See the spk16 blog post.

• lrisbo

• 

 

[diyiggy]

Thank you, I will sim that. I have found how adding the mass in Vituix.

 

[IamJF]

Loading the cone with mass reduces more or less higher frequencies. When you have an EQ or DSP in your sub amp I would not do that.
WinISD can simulate both things, also combined with some filters.