Double 15” and Horn Drum Fill

Peter Morris

Senior
May 8, 2011
991
90
28
Australia
I decided I needed a decent cost-effective loud drum fill. This is what I came up with and I though some others on this forum may be interested.

1 x Box 1220mm high x 550mm wide x 500mm deep

2 x ports – 100mm dia 80mm long plastic pipe

1 x BMS 4592nd + BMS HF crossover 16 ohms
http://www.bmsspeakers.com/index.php?id=bms_4592nd

2 x Faital Pro 15hp1060
https://faitalpro.com/products/files/15HP1060/8/15HP1060_datasheet_8.pdf

1 x EV HP940 ( had to cut a little of the side off to get it to fit}
https://www.electrovoice.com/binary/HP940_Horn_EDS.pdf

1 x Behringer iNuke 6000 DSP

The design

In my opinion the traditional double 15” + horn speakers don’t really work. The two 15” drivers don’t play well together above 500Hz and their directivity and the phase cancellation between the two 15's becomes problematic. The trick with this design was to find a horn and compression driver that can cross happily that low and still produce serious SPL. In this case I have selected 600Hz crossover as a bit of a compromise - not perfect, but it seems to work well enough.

Being intended for use as a drum fill I could not afford the latency associated with FIR filters and a cheap solution was to use a Behringer iNuke 6000 DSP to provide amplification, crossover, PEQ and limiting … I know, not the best solution but cost effective and simple.

Here are the results. I actually managed to get a slightly better frequency response (40Hz to 20KHz +/- 1.5 dB at the drummer ear :)) but did not save the screen shoot.
 

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David Morison

Freshman
Aug 21, 2012
147
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18
Aberdeen, Scotland
Hi Peter,
Great looking project well executed as always, thanks for sharing it.
Can I ask, do you find that the 2 100mm ports are enough for the 2 15" drivers when it's cranked up?
I've not used those drivers but a quick play in WinISD suggests they might be happier with a bit more vent area.
Many thanks,
David.
 

Peter Morris

Senior
May 8, 2011
991
90
28
Australia
Yep ... the vent area is a bit small. I would suggest unacceptable for a sub application but in this case the 15's are operating up to 600Hz so its unlikely they will be getting full power at 40Hz. I was also hoping that it may provide a bit of Xmax limiting should the engineer do some crazy EQ-ing on the drum monitor ... which does happen.

I was also expecting the box could be on top of a double 18 for FOH or side fill applications. Crossed at 80Hz there are no issues with port velocity.

If you want more of a general purpose box or a sub I think you should use 4 or more vents and they should be flared, in fact I would use a different port design all together. In this case I wanted to get the two 15's and horn as close as possible to minimise the problems between 2/3 different acoustic sources.

The big issue for me was getting the directivity correct and having it sound really nice with great impact - which it does. The box is a little large for this driver and there is a small bump in the frequency response - accordingly there is a -3 dB filter Q2 at 40Hz to get things to perform correctly in the time domain.

Edit - Just to add a bit more – by crossing over at 600Hz allowed the use of LF drivers more optimised for sub applications than mid-range performance, and hence more LF output.

Often a drum monitor is a 15”+2" horn on top of an 18” sub, however by not crossing over to a sub at 80 – 100 Hz you can save about 5ms of group delay and hopefully give the drummer more impact and have a box that performs very well for this application. I don't think a drum monitor requires extended LF performance.

What was also critical for me was ensuring that the driver remained in its linear Xmax range during its intended operation – in this case about +/- 8.5mm (Hvc – Hgap)/2 although the driver is rated +/-12.5mm.

By keeping the VC in the magnetic gap you have a better chance of maintain mid-range clarity.

The 15hp1060 has a long VC (28.9mm) and is quite efficiency. It also has an FS of 40Hz which is very high for a driver with a rated Xmax of 12.5mm and suited the alignment I wanted – solid performance to 40Hz, but I didn’t want to go lower.

Here is the Xmax at 2000 watts with the applied filters -



Hi Peter,
Great looking project well executed as always, thanks for sharing it.
Can I ask, do you find that the 2 100mm ports are enough for the 2 15" drivers when it's cranked up?
I've not used those drivers but a quick play in WinISD suggests they might be happier with a bit more vent area.
Many thanks,
David.
 

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Max Warasila

Graduate
Feb 20, 2013
1,150
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48
Richmond, VA
I've started using the new NX[x]000DSP amps for my latest 12" 2-way build. They're killer little amps, and have a slightly better sound than the iNukes.
 

Peter Morris

Senior
May 8, 2011
991
90
28
Australia
Hi Max,

The initial concept was to build a simple cost effective drum fill using some parts I already had. I was going to build a passive crossover but I found a secondhand iNuke for about the same price as it would have cost me to build the crossover, so it became an active 2-way with a passive crossover on the BMS 4592ND.

The box seems to have turned out much better than I expected ....and the iNuke performs very well for the price. I think 3 of the new NX series with a passive crossover on the HF driver would be a cost effective way of powering the PM60 / PM90 or my double 10".
 

Peter Morris

Senior
May 8, 2011
991
90
28
Australia
Tested the drum fill on Friday and Saturday on a couple of small shows (not the one in the video) with the LOUD Australian rock band Rose Tattoo

The limiters were on all night but the drummer thought it was "awesome" :)

The idea of a large horn and a BMS4592ND crossed over quite low to a couple of state of the art 15's seems to work.

FWIW I ended up crossing at 550Hz, a bit lower than my inital settings, it adds a bit more clarity.
 

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Joris Achternaam

New member
Nov 29, 2019
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Belgium
Thank you for sharing this Peter.

I actually have been looking at ways to cross an efficient 12" with my BMS 4592 over some 15" kickbins; but reading this thread I'm wondering whether it wouldn't be an option to just take the more straightforward route and just use double 15's, ditching the kickbins.

The drivers I have are Eminence Kappa Pro LF2's, and I would like to couple the 4592ND with the official BMS 2236 horn (60x40°) in trap cabinets so if needed I can splay them horizontally in pairs. These cabinets would be used in stacks, on top of tapped horns which run up to 90Hz.

The processing available is an XTA DP446 with powersoft k-series amps.

I realize that these drivers aren't top of the line, but since I already have a whole bunch of them it would be nice if they could be used. If not, do you think getting a different driver (like the FaitalPro, suggestions welcome) would still be a better option than going the 15" kick + 12" mid route? It would definitely make for a simpler build and setup.

Any advice?
 
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Peter Morris

Senior
May 8, 2011
991
90
28
Australia
Hi Joris,

I’m not sure how low you can use the BMS2236 horn, its cut off frequency is 400Hz so you maybe able to use it to around 600Hz with good results.

If you can do this then 2 x 15” speakers will work quite well below it. The Eminence Kappa Pro LF2's have about half the Xmax of the Faital Pro 15hp1060’s I used … but if you are crossing over to a sub at 90Hz there should not be an issue with Xmax.

You will however need to use a different box volume and tuning frequency to suit these speakers.

With this combination I don’t see any advantage with a kick bin. If you were to use 12” drivers under the BMS horn then you could cross over to the horn a little higher and get a bit more SPL out of the 4592 but you would have less low mid capability.

If you use this combination for EDM then I suspect there would be an advantage using a kick bin between the 12's and the sub.
 

Peter Morris

Senior
May 8, 2011
991
90
28
Australia
What's the internal volume for the 15" drivers?
No sure, I did calculate it from the box dimensions at the time ... it was a little large and I suspect if I reduce the volume a little I could have got slightly better results, but I more or less had some spare cabinets that were a perfect match with my double 18's for truck packing ....and the drivers and horn I had fitted perfectly.

The basic concept was a double 15 and horn that crossed over low enough (600Hz or less) to work properly and still produce high SPL's.
 

Joris Achternaam

New member
Nov 29, 2019
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Time for a quick follow up.

I recently built a cabinet to try out this setup with some pretty good results. The BMS horn loads low enough and both on- and off axis response were good throughout the xo region (crossed at 600Hz). I compared this to a cabinet with 10" drivers and a dedicated bass section, and actually prefer having less x-over points.

Now I'm thinking about going down this route, and since the investment is pretty big I might as well do it the right way. I decided I'll sell the 15" Eminence woofers and look for a better option since I'll be needing more than 4 pieces anyway. I had a look at the Faitalpro 1060 you are using but don't have any experience with this brand.

I have been looking at the B&C 15nbx100 (226 euro) and the Precision Devices pd158 (218 euro). Both look like they'll pack quite the punch and the FR looks good up to the xo point, however I'm a bit worried about the midrange clarity. Any advice on what to keep in mind when looking for a suitable driver? Any other suggestions (RCF mb15n351 or B&C 15nw76 for example)? I don't have experience with using a heavier driver like that for (lower) midrange.

An important piece of info is that I'm planning to use these with subs, so 90hz and up, but since we play mostly EDM it's important that the upper bass isn't lacking.
 
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Steve White

New member
Jul 6, 2018
20
4
3
Fort Worth, Texas
Dual 15's and a horn, a basic workhorse for PA use and suitable for just about any application.

I remember doing a showcase in a club in LA back in the day for Cheryl Dilcher (RIP). We were the second act on. When getting ready to setup for the sound check, the house engineer talked me into only using only two drum mics, one inside the kick and one about 18" over the kick, parallel to the stage facing straight back and just behind the front of the kick. Both were SM57's. The guy was cool and insisted it worked well in the room with the PA they had - so I gave it a try. House PA was a pair of JBL 4508's with 2205's in them and a pair of JBL 2390 horn/lens on top with JBL 2441's on them - system was bi-amped.

It sounded great.
 

Joris Achternaam

New member
Nov 29, 2019
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So I decided to go for B&C DCX464 drivers instead of the BMS because when building 4+ of these the difference in price started to become substantial. Today I did some tests in my prototype cabinet.

Cabinet volume 260L including drivers, basic wadding applied but it needs more; reflex tubes still need to be mounted. In my test I highpassed the cabinet at 90Hz.

First impressions:
I expected the DCX to sound very similar to the BMS but was surprised by the difference in sound. The BMS sounds a bit more 'gentle' to the ears and seems to have better imaging. The DCX does have less sibilance and is more 'forward sounding'. When switching back and forth between the two at similar volume the BMS - even though it sounds more open - sounds a bit muffled. Overall it immediately gave me the impression that the DCX'll do great as a CD for electronic music.

Just to test if I could get away with using them I mounted my Eminence Kappa Pro LF2 drivers. Even crossed at 500Hz they were lacking midrange clarity and transient response just wasn't good which was disappointing. At this point I'm very tempted to go for the Precision Devices PD158 woofers instead. Any tips or alternatives are very welcome.

89050908_249925646006364_5430669129960914944_n.jpg
 

Steve White

New member
Jul 6, 2018
20
4
3
Fort Worth, Texas
Joris, you should start another thread brother. Your input could get lost over time and your sharing the trials and tribulations of component/system design is interesting for those of us that are experienced with it and should prove to be invaluable to newer engineers just starting down this path. The thought process and testing is an interesting read. No charts or graphs - they have their place - but in the end it all about "how it sounds" and that can't be determined by Transfer Function testing - only listening. After the laboratory testing, come the listening tests.

Let me try and properly articulate a few thoughts - hopefully this comes across and I can organize it well enough to do so.

Something I find interesting is the degree of expertise we use when choosing drivers, driver combinations, waveguides, etc. I customize many many things - working on some baffles for shop alarm system motion sensors so they well detect bad guys and not my dogs. Did a relocation of sensors about a month ago, worked fine until Thursday, then I got a call from alarm company, notified police and hauled ass back to my house to review video from security cameras and saw one of my dogs set it off. Did a nozzle/jet change on 20" surface cleaner on 13hp pressure washer to optimize working pressure. Been tuning engines for 50+ years starting with a 3hp flathead on a mini-bike and cox control line model airplane engines. Dirt bike, racing go-karts and even assisted uncle tuning blown alcohol 540' drag boat. Also, audio gear - started building home stereo speakers when I was about 15. Built amps, tube and solid state and preamps from both kits and scratch from schematics.

Many items in shop are custom - air manifold system, and so on - you guys get my drift. I'm a gearhead and tuner by nature.

I just did a full rebuild on the small studio system which is the monitor setup for this PC and also studio for the DJ business music library. Pictures attached. It just didn't sound good - ended up most of the problem was the on-board sound in the computer - D/A conversion sounded crappy. I changed the DSC from a eBay special to a dbx Driverack PA2 and also pulled the JBL 2426 out of the sub and installed a Dayton 15" I had laying around - much better suited for studio application subwoofer. System sounds good now, real good - good enough to serve as a studio reference standard for my needs.

With audio we strive to attain a combination of elements, in most cases intended for a specific application or set of conditions. i.e. drum fill and general purpose PA use monitor. Take 50 different designs, all in this class and they will each sound different, unique nuances separate them - but to trained ears, musicians engineers audiophiles - there will be noticeable differences. Some will "sound good" and some "not so good" when compared to the rest.

Glad I found this place to exchange ideas with like minded people. It's really interesting to watch someone else practicing the art of design, watching the progress, the decision making along the path and in the end, the results.

The design process for DIY as noted here, is exactly what manufacturers do, they have better toys in the lab, but also face constraints that we don't. They have to work around business case and marketing and we don't. I think many times those that don't DIY loose sight of this. Not taking a shot at anyone here. But, a pre-packaged design isn't always the best solution nor does it always offer the best performance.

Take a JBL 2226, like the one I pulled out of the sub. It's a good general purpose workhorse 15" driver and can be successfully used for just about any application. I will be using them in two-way stage monitors and two-way some traps. It worked as a sub, but not as well as the Dayton that replaced it. That being said, the Dayton wouldn't be worth a schitt in the two-way stage monitor. Decisions and choices is the name of the game.

I'm making a re-entry into regional sound, anything from a single mic at a neighborhood association or school PTA meeting to a 2000 seat rock show to include a custom DJ system. The gear has to be scaleable and flexible. For the speakers, DJ, mains, monitors, nothing in the inventory will be stock out of the box commercially available gear - all is or will be custom built/modified for specific purpose. I don't think regional sound is high on the list for manufacturers due simply to where the market lies. We're in a unique place, and optimal solutions are many times unavailable in commercial packages IMO. Maybe just change the wiring format on the Neutrik's to Male/Female and associated speaker input/output panels - but, there's always something I want to change to best suit my needs.

The "Point Source" -vs- "Array" battles are amusing at the very least. Many times reminiscent of Ford -vs- Chevy -vs- MOPAR. I have a mix of both. Array elements can be used any way ya want and scale real well - in pairs on tripods to full-on hangs. Due to the overall versatility, packaging and light weight, they make a good choice for a small regional operator.

Maybe I'm just a tweaker - I'm ok with that too - as it's the curse of being an engineer.

Being a lifelong designer/builder it's a good fit to work in a field that has is wide open to innovation and creativity.

Rock on ladies and gents. Appreciate you sharing your adventures.
 

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Max Warasila

Graduate
Feb 20, 2013
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Regional sound companies form a very large part of every manufacturer's market, Steve. Maybe you should start that discussion in another thread, though. :cool:
 

Joris Achternaam

New member
Nov 29, 2019
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So I went ahead and ordered myself 8 PD.158 woofers and oh my do they sound lovely. The respone and clarity in the midrange is really good for a 15, and they need little to no EQ to match the DCX (only some taming around 300-350Hz). The lower end of their band (90-120Hz) sounds clean and punchy.

I also ordered me some passive crossovers designed specifically for the DCX464 by Convair Electronics (through Blue Aran) and I was very pleasantly surprised. The FR with the passive XO is a great starting point (had to reduce some of the 1-2kHz midrange with a low Q filter and flip the polarity of the Hi membrane) and saves me an extra amp channel.

One quick side note: the dimensions of the cabinet were originally meant for the BMS 2236 horn. I think I could still lower the height a couple cm and reduce the width by ~2cm; however I don't think I will at this point as this means I would have to redo the baffles. I hope I won't regret this once I try splaying them horizontally.

If anyone's interested I can post some measurements without EQ, just to give an idea of the actual performance.

89608813_2501199806761088_6430125255443873792_o.jpg
 

Frank Jansen

New member
Sep 6, 2018
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2
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Netherlands
Joris,
Great to see how quickly you have put these together. You indicate that you havent used the BMS2236. From the foto i can see that you used the xt1464. Is that right? In adation i would like to ask where yo got the dcx464. BlueAran is soldout as is TLHP
The passive crossover they offer looks great. The reason i'm asking is that i am building a pair of pm60/90 and also want to use this driver horn combination. I could use a little help. I 'm using xilica xd processing an if you had a startingpoint for setting that would help.
Greeting Frank