I'm waiting on a pair of B&C 18NW100s for a high power sub build. We'll see how they are out of the box and whether the specs are close.
That being said, I can attest that a pair of SB34NRXL per channel will go down past 25 hz and have 22mm xmax for plenty of output while easily managing to play very cleanly past 400 hz. They have a 75mm VC and other fancy high power stuff. These are one of those unicorn drivers which can do hifi and studio. Even their cheaper 12" stuff has massive motors and VCs.
That being said, I can attest that a pair of SB34NRXL per channel will go down past 25 hz and have 22mm xmax for plenty of output while easily managing to play very cleanly past 400 hz. They have a 75mm VC and other fancy high power stuff. These are one of those unicorn drivers which can do hifi and studio. Even their cheaper 12" stuff has massive motors and VCs.
Since this thread is about high powered subs that have a very low rolloff, I thought its ok to share my planned project.
My subwoofer buuld will be a rather large DCR with 2 B&C 18NW100-4, fed by either IcePower modules or QSC PLXD. I've previously used the 8 ohm version of this speaker before with great results, so I thought I'd give the 4 ohm model a try. I wanted something with a stiff cone and larger dual spider for best linearity at higher excursion. This is more important with a larger, lower tuned enclosure with less compliance support by the enclosure itself.
Most B&Cs usually run on the higher side of Qts in the real world, so that will only help LF extension at the same given Fs. Since B&C isn't very forthcoming on the actual specs of the 4 ohm 18NW100, it will depend on how it measures out of the box. The BL is very high on these newer NEO motor subs while the motor linearity is considerably better than most comparable priced subs with similar TSPs. No, its not BMS driver, but its also considerably cheaper.
The sweet spot of Qts is about 0.35 to 0.40 for a QB3 reflex enclosure and slightly higher for a 4th order bandpass. With a dual chamber reflex, it will perform exceptionally if chamber and port geometries are able to be optimized for the best possible transient response. Usually the driver will tell you what environment it likes, but the measured 8 ohm TSPs are favorable to be hopeful for the 4 ohm version to work well for my planned uses.
My subwoofer buuld will be a rather large DCR with 2 B&C 18NW100-4, fed by either IcePower modules or QSC PLXD. I've previously used the 8 ohm version of this speaker before with great results, so I thought I'd give the 4 ohm model a try. I wanted something with a stiff cone and larger dual spider for best linearity at higher excursion. This is more important with a larger, lower tuned enclosure with less compliance support by the enclosure itself.
Most B&Cs usually run on the higher side of Qts in the real world, so that will only help LF extension at the same given Fs. Since B&C isn't very forthcoming on the actual specs of the 4 ohm 18NW100, it will depend on how it measures out of the box. The BL is very high on these newer NEO motor subs while the motor linearity is considerably better than most comparable priced subs with similar TSPs. No, its not BMS driver, but its also considerably cheaper.
The sweet spot of Qts is about 0.35 to 0.40 for a QB3 reflex enclosure and slightly higher for a 4th order bandpass. With a dual chamber reflex, it will perform exceptionally if chamber and port geometries are able to be optimized for the best possible transient response. Usually the driver will tell you what environment it likes, but the measured 8 ohm TSPs are favorable to be hopeful for the 4 ohm version to work well for my planned uses.
For those searching for a higher end performing LF driver at a great price, you can get the SB34NRXL on Black Friday sale for $219 at Madisound, which is a killer deal for a 12" driver. Its the Revelator of the east, as I dubbed it. Most of you guys know I'm very fond of this driver.
How bad of an idea would this be. This is a side view of a what would be two sets of ppsl woofers. This pic is 26" tall, with a set of 15" and 18" woofers. I am currently sketching something at 31" to see what could be. Can't bend lines in HR but I sim'd the two sources best I could and they play together.
If your idea is for "High Output Subs that play 20Hz to ≥200Hz", something with response that takes a nose dive below 100Hz and above 200 Hz does not fit the idea.
If the 15" and 18" woofers share a common back chamber, it is a bad idea.
Is it really an issue that these drivers have high sensitivity, in that area, is it a consequence EQ cannot fix? Either there is enough efficiency or there isn't, is how I look at it. Considering everything we are looking at involves, 2mm at 30hz, with 110-115db predicted in room frequency response, of a single channel.
When I remove the room sim it looks like this. I EQ'd the response of the 15"s a little. Both sections are low passed of course. The rear chambers are able to be separated.
The efficiency of this design is similar to the same woofers separated by MTM so its hard to warrant it.
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As I continue operation fit as much Sd in one box as I can, I thought this a unique situation
Exhibit A
vs
Exhibit B
A vs B
I've likened myself to group delay situations that were low. I think I have found a Unique way to deal with this while using a vented Enclosure. Not only does this Put group delay in a low position as it should be, it lowers excursion and raises efficiency. I see some interesting things going on, I see the Q of the excursion null being lowered, and in turn the Q of the roll off is lowered as well. Lowering Q in many aspects is favorable. With the addition of damping material the results might be impressive.
Exhibit A
vs
Exhibit B
I've likened myself to group delay situations that were low. I think I have found a Unique way to deal with this while using a vented Enclosure. Not only does this Put group delay in a low position as it should be, it lowers excursion and raises efficiency. I see some interesting things going on, I see the Q of the excursion null being lowered, and in turn the Q of the roll off is lowered as well. Lowering Q in many aspects is favorable. With the addition of damping material the results might be impressive.
I have a couple of ‘big’ low tuned tapered pipes and a paraflex thing that all have ‘group delay’ in them.
The only one that sounds weird (other than having a very strong Fb resonace ) is the paraflex where the parallel resonators don’t quite ‘align’ right above 3 * Fb . It’s got a huge decay issue they’re that’s nothing like the ‘normal’ ringing in my other pipes or series high order qw.
I still don’t know how to ‘describe’ the sound in a way that I feel is technically accurate ? It happens to ring AND howl in that area uniquely however ?
The only one that sounds weird (other than having a very strong Fb resonace ) is the paraflex where the parallel resonators don’t quite ‘align’ right above 3 * Fb . It’s got a huge decay issue they’re that’s nothing like the ‘normal’ ringing in my other pipes or series high order qw.
I still don’t know how to ‘describe’ the sound in a way that I feel is technically accurate ? It happens to ring AND howl in that area uniquely however ?
What you seem to have come upon is the difference between a C4 vented box alignment and a QB3/B4 vented box alignment. These have been discussed by Small back in 1973. The C4 alignment offers a more extended bass response but with more ringing being present when looking at the step response of the system. See the following post in another thread for some further details.
@GM I was hoping to get your attention. I am playing around with the tapered Line you shared with me.
The below Frequency response is of a sealed enclosure.
Raw on the left and Filtering on the right. The Red represents the forward facing woofer and the Green is the woofers facing each other.
This is the Response as dealt with like a single channel though the amplitude on the side woofers need to be corrected. Optimizing the front firing woofer separate from the opposing woofers would allow more fine tuning but also another Amp/DSP must be used. I think as is, this would make it to a 300hz XO point. Damping material in the slot could solve some issues.
single triple
Whats the deal with 3 anyway? Might it be related to the 3 in three quarter? @Booger weldz I have done some experimenting and thinking about group delay. Speaking from a strictly technical standpoint, excess group delay is a distortion. There's less sensitivity to GD in the lower notes and after being placed in a room, GD does all sorts of things. I think this can be compensated for with EQ, matter fact or at least to some effect. I still like designing towards it being low. I personally believe there's some desirable traits of a system that doesn't have spikes in the GD. I have a hard time defending my position lol. It's just bad house keeping I feel.
20hz cycle time is 50ms, sending a test tone, as long as peak energy is reached soon enough, perception doesn't suffer. Bench racing it just seems like a metric to flaunt. Like oh it takes you 36ms to reach peak energy at 30hz? Mine only takes 12ms lol.
I am not that good yet, to defend it but its just one less distortion to worry about. Distortions tend have other side effects or come in multiples so it just seems proper. Either way, this is definitely a Unique way of addressing it. The output at 2mm is very close to a desirable about of max headroom, so the GD issue is icing on the cake for me.
The below Frequency response is of a sealed enclosure.
Raw on the left and Filtering on the right. The Red represents the forward facing woofer and the Green is the woofers facing each other.
This is the Response as dealt with like a single channel though the amplitude on the side woofers need to be corrected. Optimizing the front firing woofer separate from the opposing woofers would allow more fine tuning but also another Amp/DSP must be used. I think as is, this would make it to a 300hz XO point. Damping material in the slot could solve some issues.
Whats the deal with 3 anyway? Might it be related to the 3 in three quarter? @Booger weldz I have done some experimenting and thinking about group delay. Speaking from a strictly technical standpoint, excess group delay is a distortion. There's less sensitivity to GD in the lower notes and after being placed in a room, GD does all sorts of things. I think this can be compensated for with EQ, matter fact or at least to some effect. I still like designing towards it being low. I personally believe there's some desirable traits of a system that doesn't have spikes in the GD. I have a hard time defending my position lol. It's just bad house keeping I feel.
20hz cycle time is 50ms, sending a test tone, as long as peak energy is reached soon enough, perception doesn't suffer. Bench racing it just seems like a metric to flaunt. Like oh it takes you 36ms to reach peak energy at 30hz? Mine only takes 12ms lol.
I am not that good yet, to defend it but its just one less distortion to worry about. Distortions tend have other side effects or come in multiples so it just seems proper. Either way, this is definitely a Unique way of addressing it. The output at 2mm is very close to a desirable about of max headroom, so the GD issue is icing on the cake for me.
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I dunno wtf I’m Doing but if I try and mess with the area of the high tuned resonator (with dsp eq or ‘peaking filters’) that also creates that strange phase/group delay/decay ringing anomaly it only gets ‘worse’?
‘Paraflex ‘ is unique as all of this seems to be uniquely ‘worse’ in those designs and present more intersting challenges to resolve and LEARN about sound (exciting!) instead of try and observe small changes in simulations …
If we could share what we hear/measure/exoeriemce with some of these more obvious types of designs I think it would be a huge advancement in our collective ‘knowledge’ .. too bad they’re a huge waste of wood and expensive drivers 😝🙈
Any ideas?
‘Paraflex ‘ is unique as all of this seems to be uniquely ‘worse’ in those designs and present more intersting challenges to resolve and LEARN about sound (exciting!) instead of try and observe small changes in simulations …
If we could share what we hear/measure/exoeriemce with some of these more obvious types of designs I think it would be a huge advancement in our collective ‘knowledge’ .. too bad they’re a huge waste of wood and expensive drivers 😝🙈
Any ideas?
I went back,. created a more accurate representation of the FR situation and it is more dire then I'd like, and basically begs to be addressed by low passing the side woofers to avoid the null.... I am really curious to the effect of placing damping material at 50% of the depth of the slot.
As Ive seen modeled in the past the reflections can be cured. but with another woofer behind the damping material what have we?
I'd like all 3 woofers to share an enclosure space. @weltersys can you run 3 identical woofers in the same space while low passing some of the woofers? What are the limits of using multiple woofers or different woofers in the same enclosure space if they are all playing the signal redundantly?
As Ive seen modeled in the past the reflections can be cured. but with another woofer behind the damping material what have we?
I'd like all 3 woofers to share an enclosure space. @weltersys can you run 3 identical woofers in the same space while low passing some of the woofers? What are the limits of using multiple woofers or different woofers in the same enclosure space if they are all playing the signal redundantly?
You can.
I would not advise using woofers with different parameters in the same enclosure space.
Placement of the woofers within no more than 1/4 wavelength of each other at the highest frequency of operation could be considered a limitation.
Another woofer with damped high frequency.