Compact sub for mobile dj

tizlaney

Member
2020-08-12 1:19 pm
I just built two of Jbells SS15 using 3015LFs and am blown away. I first powered them with a Yamaha PX3 bridged at 4ohm mono and now a Behringer NX3000D limited. These are a little large (physical size, mostly height) for some of my small gigs

I now want to build a small compact single sub to supplement my smaller systems.

I am considering the Cubo 12 because I like the size of it. I could go for a premium woofer (Amp options above) to maximize the power I already have. Ideally 4 ohm.

Thoughts?
 
IMO, for DJ use, solid output at 40Hz is high up on the list of priorities, and a Cubo 12 won't manage that.

Recently, I've done a few smaller gigs* with a single ported 12". It's an OEM driver that I got cheap, with 600w continuous power handling, and around 10mm Xmax.

* Providing for a wedding DJ with 30-50 people on the dancefloor, and an 80-seat theatre with some hip-hop dance stuff thrown in.

It needs a good amount of voltage swing (it's 8ohm) to really do the job, but something like a Faital 12HP1060 in the 4ohm variant would also do well.

Chris
 

tizlaney

Member
2020-08-12 1:19 pm
The look of the enclosure is not important in this application but I do like the 18sound, design, but they dont have that woofer in 4ohm.

I just want max output from a single 12 using amplifiers I already have. Which means I need a 4 ohm woofer. Weight is not an issue either so Ferrite is fine. The Fatial 12HP1030 is available in 4ohm but as with many woofers right now availability in the US is hit and miss.

Previously I used EV ZXA-1Sub (1 or 2) for these small gigs but I sold them in a bundle about 2 years ago. I would like to achieve the same output as 2 of these ZXAs (coupled) in 1 cabinet with 1 12" of similar dimensions 20"x20"x20" max.

Here are the simple specs for the EV ZXA-1S
Freq range (-3) 53-93
Freq Resp (-10) 44-118
Max SPL 128
Crossed 100hz
Watts advertised 700w
 

tizlaney

Member
2020-08-12 1:19 pm
chris661 I am looking at this Teeny tiny PA 15" thread and am wondering 3 things:

1. Could this design be modified for the 12" Fatial 12HP1030 4ohm (I found one in stock in the US) - I am not that great at figuring out these dimensions, box designs, or any simulation stuff. Actually building them - i am good at.

2. If it cant easily be modified what would be a good design to use for the 12HP1030 mentioned in 1.

3. If 12" is still not a viable option what would be the ideal woofer for the "Teeny Tiny PA 15" in its current form the Beyma or Fatial?
 
Hey Tiz,

To answer your questions:

1 - You could try just reducing the width and driver cutout diameter, but I'd run it through Hornresp before putting saw to wood.

2 - A sensibly-designed reflex would be fine. Make sure there's plenty of port area to avoid compression, and you'll be good to go.

3 - Both drivers work well. A high-end 15" sub driver from any reputable manufacturer will work fine - they all converge on a set of T/S parameters which happen to fit this design quite well. In my experience, the Beyma 15P1200Nd overloads (goes past Xmax) a little more gracefully than the Faital 15HP1060, plus the extra 20% thermal power handling doesn't hurt. The Faitals are no slouch, though.


Some other notes to consider:
- For smaller venues, I do think a single 12" will do what you're looking for just fine.

- Either way, make sure you leave plenty of space between the front of the cone and the grille. Go for Xmech +20%, measuring from the front surface of the driver. The cones on the Beyma (which have a thicker mounting flange than the Faitals) can easily hit the grilles on mine, so I might rebuild them in the future. For now, I've added some spacers, but it doesn't look great.

- I really do think neodymium is worth the added cost. When it's a 3am load-out, you'll want everything as light as possible.

Chris

PS - That EV "sub" doesn't seem great. -3dB @53Hz doesn't count as a subwoofer in my opinion. Something reasonably meaty that's solid at 40Hz will be a serious upgrade.
 

kipman725

Member
Paid Member
2007-06-10 12:41 pm
Warrington
Nice compact 12" build here: Shaped Ports - Bass Projects - Data-Bass Forums

Can confirm Chris's compact 15's work well as well. Faitals look a bit better on paper than some other brands drivers as they use a different xmax calculation. I prefer the B&C way of stating the xmax from geometry and the actual limit of linear excursion from measurement of xvar. Sometimes xvar is more than xmax and sometimes less. Resale value on the NX3000D is pretty good so it might be worth getting an amp upgrade:
Luke's basic amplifier tests - Page 9 - Bass Gear - Data-Bass Forums
looks like the NX3000D will be around 500W per channel into 4ohm, wheras amps like the Admark K30 are >3kW per channel:
K30 Amplifier On The Bench - Speakerplans.com Forums - Page 1
so ~+8dB assuming the box can take the extra power, this is more than doubling up the number of subs (again assuming the subs are behaving linearly which is a big assumption at this power level).
 
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tizlaney

Member
2020-08-12 1:19 pm
Thanks Kipman - I am certainly not opposed to an amp upgrade.

However, the reason for wanting a single 4ohm sub is so I can run the NX3000D in bridged mono at 4ohm - it is advertised at 3000 @4 ohm mono. Now I understand that it will be less than that but if I can get half of that it would be ideal. Also noting this will be for a "small" rig so I would probably never double this up due to this being used a smaller venues where space is limited.

Here is where I am at in this quest. I have basically decided to go with a 15" driver. I am now debating on going with a traditional bass reflex or maybe going 6th order bandpass in the style of a Nexo LS600. There is also a chance I will build both.

Driver is Ciare 15.00SW-4
Impedance 4 ohms

AES Power Rating 1,000 Watts

Program Power 2,000 Watts
Frequency Response 20Hz - 200Hz
Sensitivity (1W/1m) 94dB
Voice Coil Diameter 4" / 100mm
Magnetic Gap Depth .4" / 10mm

THIELE-SMALL PARAMETERS
Resonant Frequency (fs) 29Hz
Impedance (Re) 3.6 ohms
Electrical Factor(Qes) .44
Mechanical Q (Qms) 5.4
Total Q (Qts) .41
Compliance Equiv. Vol. (Vas) 113 Liters/3.99cu. ft.
Voice Coil Overhang (Xmax) 14mm
BL Factor 25.0 T-M
Diaphragm Mass (Mms) 224 Grams
Mechanical Compliance (Cms) .97mm/N
Surface Area of Cone (Sd)m2 0.075m2
Reference Efficiency .62%
Coil Inductance (Le) 2.0mH
 
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tizlaney

Member
2020-08-12 1:19 pm
Here is the Ported "green" vs the 6th Order "blue" both tuned to 32hz.

I am a little new to this cabinet design quest. Just curious to those of you familiar with port tuning 6th orders (parallel) - I have the rear chamber tuned to 32hz...but what do I tune the front chamber to? The graph attached has it tuned to 120hz...which seemed to give be the best curve (I tried in 10hz increments)

view
 

kipman725

Member
Paid Member
2007-06-10 12:41 pm
Warrington
Ah yes this makes more sense then the NX3000D should output around 1500 - 2000W depending on frequency in this configuration (actually pretty decent).

The data I see for the Ciare 15.00SW-4 has a geometry defined xmax of 11.5mm. Looks like a good driver. 6th order bandpass will be larger than bass reflex. The advantage for me would be to avoid grills by having the driver inside the sub. You can also avoid grills in bass reflex by using a driver 'cover' as the required open area is small compared to the cone area. See the sub in my sig for an example of this.
 
6th order bandpass will be larger than bass reflex.

FWIW, haven't done a complete comparison, but not WRT net Vb based on a max flat alignment, so assume would be valid for any practical reflex alignment.

Hadn't given it any thought till you mentioned it, so while my sim is based on the driver chamber = the driver's calculated ~173 L max flat net Vb, I did one with the chambers totaling ~173 L and it simmed only a fraction less under damped, which we know from history WRT HR sims that it will be flatter or even slightly over damped in reality.
 
I have the rear chamber tuned to 32hz...but what do I tune the front chamber to?

The short answer is ~79-80 Hz the way I figure it.

Don't know the real math for calculating the low pass filter, just use some basic reflex math plus various ratio rules-of-thumb [ROT] for the rest, though assume it's the same as for calculating the front chamber of a compression horn.
 

tizlaney

Member
2020-08-12 1:19 pm
OK ---so here is a follow up

I built the reflex box (5.5 ft3) in the style of a Bass Boss SSP118 simply because I like the look. Box is tuned to 32hz using the above mentioned Ciare 15.00 SW-4

It worked out really well. I used it at a gig (Nov. 6th) along side a single Bose L1 Model 2 with B2 bass module. I used the "Sub out" of the Bose amplifier since it limits the B2 to act more like a traditional 2way top - it adjust the processing when it detects a connection from the port.

The event was around 150 guest and I had really good sound on the dance floor and across the venue.

Flash forward, this past weekend (Nov 13th) I used my 2 JBell SS15s along with my2 - NXL24 copies and was still blown away with the output. I had my amplifier limited pretty much about the same for the 2 SS15s as I did for the single reflex 15 the weekend before. Since the response of the SS15s was more pleasing to me it leads me to believe that the performance below 40hz is not as important (to me) as mentioned in the earlier post in this thread.

This left me still curious about building a smaller TH, Hybrid, or Paraflex using the Ciare 15.00 SW-4 to get more output.
So this morning I did some more reading.

Here is what i am considering trying:
-Cubo 15 Extra Extended (single sheet ply) (620x620x620)
-THAM 15 (single sheet ply) (500x680x550)
-Paraflex Alt-Con 1x15 (2 sheets ply) (446x915x765)

What are your thoughts?

Please keep in mind I am not great at planning out these horned boxes, but I am good at building them so I PREFER a box that already has readily available plans (as these 3 above do)

Also- excuse the mess in the SS picture, I cant help what the "host" workshop (100'x60') looks like.
 

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