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Author Topic: Upper bass-range cabinets?  (Read 11849 times)

Craig Hauber

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Upper bass-range cabinets?
« on: October 15, 2009, 07:10:58 pm »

Looking for something to go between a sub like the LAB and my mid-high boxes that struggle to go as low as 130Hz (but would rather cross them over higher)

The mid/highs are a very large dual EV DL12x loaded on a 25" long horn with a custom phase-plug slot type throat.  They get wicked-loud with very minimal power.
I can put 1 on top of 2 JBL SRX dual-18's and still run out of low end with plenty of headroom left on the tops.  -I do not have sensitivity numbers on the top boxes as we are still getting them all up and running.  
Right now I'm looking for quick-and-dirty if need be, but would like to build a matching LF box in size. (Trap, 42"high X 30" deep X 24" wide front, 18" wide back)

here's a pic of the box.
index.php/fa/25521/0/
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Craig Hauber
CSA Productions Inc.
Ventura-Santa Barbara CA
www.csaproductionsinc.com

Art Welter

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Re: Upper bass-range cabinets?
« Reply #1 on: October 15, 2009, 08:34:12 pm »

Craig,

I used to have low mid horns similar to yours with EVM 12". A pair per side kicked down to the 60-80 HZ range, on some country gigs I actually ran them without any subs.

How are the low mid horns damped?
What is the compression chamber size?
Have you tried flipping half the cabinets over (coupling the HF) to reduce the width of the stack and reduce comb filtering problems that may be causing a lack of lower low mid?

Art Welter
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Ivan Beaver

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Re: Upper bass-range cabinets?
« Reply #2 on: October 16, 2009, 09:14:34 pm »

Is it me or does the HF horn look to have a much wider pattern than the low freq side?
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Tim McCulloch

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Re: Upper bass-range cabinets?
« Reply #3 on: October 16, 2009, 10:10:24 pm »

Ivan Beaver wrote on Fri, 16 October 2009 20:14

Is it me or does the HF horn look to have a much wider pattern than the low freq side?

You beat me to it.  With that much depth to work with, a narrower horizontal coverage HF horn would be doable, I think.

A tight pack of these would be a physics lesson. Wink

Have fun, good luck.

Tim Mc
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Craig Hauber

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Re: Upper bass-range cabinets?
« Reply #4 on: October 16, 2009, 10:51:08 pm »

Art Welter wrote on Thu, 15 October 2009 17:34

Craig,

I used to have low mid horns similar to yours with EVM 12". A pair per side kicked down to the 60-80 HZ range, on some country gigs I actually ran them without any subs.

How are the low mid horns damped?
What is the compression chamber size?
Have you tried flipping half the cabinets over (coupling the HF) to reduce the width of the stack and reduce comb filtering problems that may be causing a lack of lower low mid?

Art Welter


We only have six working and mostly use 2 per side, but flipping and stacking was what I was thinking If I got up to 4 per side.

The 12" driver chamber is sealed and not very large.  It is the width of the box and the driver magnets end up an inch-or-so from the back panel.  I stuffed them with fiberglass insulation and it seemed to smooth out some  of the low-mids.

The cones are sort of "phase-plugged" with a slot type opening where you can see the dustcap and cone surface immediately above and below it.  The cone hits it if you try to get loud LF out of them.  The tightness of the cones and the sealed chamber make it difficult to accidentally do it though.
The thickness of the drivers flange gasket and the at-rest position of the cone effect how much distance between cone surface and phase-plug.  (And I've found alot of variation in what are supposedly identical drivers.)  I do not know what that spec should be and how variations in it effect the audio.

The HF horn and MF seemed fairly well matched in overall width -Quite narrow.  The sidewalls of the HF stay narrow then flair out near the end.  All 4 surfaces are curved unlike older radial type horns with 2 straight sides.

Overall they work really well and I love the efficiency.  Very hard to find a large enough space to set up and thoroughly test on my current budget.  Many of the shows we have used them on have been toss-up-and-go events.  The sound is very pleasing for live use and the customers are so amazed at how much sound comes out of such relatively small and few boxes.  -And they are absolutely dead from behind -tough to even tell they are working.

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Craig Hauber
CSA Productions Inc.
Ventura-Santa Barbara CA
www.csaproductionsinc.com

Art Welter

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Re: Upper bass-range cabinets?
« Reply #5 on: October 17, 2009, 12:29:32 pm »

Craig,

When I asked how are the low mid horns damped, I was wondering about the actual horn, not the compression chamber.

On the fiberglass horns I made, we laminated Built-rite, a kind of wood fiber insulation material to the horn, then filled the chambers with expandable foam.

That treatment increased both the level and quality of the low end.

The DL12X is about 5 dB hotter at 400 HZ than at 100, it takes a fair amount of EQ to get them flat even in a front loaded cabinet. You may be mistaking the usual slanted horn response for a lack of 100-130 HZ.

Xmax is 4.1 MM, even without an additional "donut" if you are hitting the cone and have about 1/4" clearance you are over Xmax.
You should experiment with the rear chamber size, you may find that a smaller compression chamber will work better.

Loading styrofoam "bricks" into the compression chamber is an easy way to test, keep loading more until the LF/excursion does not improve.

Have fun!


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Craig Hauber

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Re: Upper bass-range cabinets?
« Reply #6 on: October 19, 2009, 04:14:23 pm »

Art Welter wrote on Sat, 17 October 2009 09:29

Craig,

When I asked how are the low mid horns damped, I was wondering about the actual horn, not the compression chamber.

Sorry, didn't get the terminology -was thinking driver damping.  The horn walls are exceptionally rigid -like slapping the side of a 45' sailboat -they sound at around 1k (and up) when struck.
Quote:

On the fiberglass horns I made, we laminated Built-rite, a kind of wood fiber insulation material to the horn, then filled the chambers with expandable foam.

That treatment increased both the level and quality of the low end.

I can't get into the space between horn and cabinet side -it doesn't open into the driver chamber.  I can holesaw into it from the driver chamber but think it is already filled with something -box side is very dead sounding when pounded on.
Quote:

The DL12X is about 5 dB hotter at 400 HZ than at 100, it takes a fair amount of EQ to get them flat even in a front loaded cabinet. You may be mistaking the usual slanted horn response for a lack of 100-130 HZ.

I love the shear loudness of that range, would rather add to the 100Hz range instead of subtracting the 400-and-up.  Right now I can get useable show volume with a 100W amp if I had to.  (Great for "green" events running off solar panels or car battery amps.
I'll pull some impedance plots and measured frequency responses for you to look at.  How do I do a 1w/1m test? (don't "watts" vary by impedance? -what voltage do I use for a 4-ohm load)
Quote:

Xmax is 4.1 MM, even without an additional "donut" if you are hitting the cone and have about 1/4" clearance you are over Xmax.

How does varying the distance effect the system?  If I'm farther back away from the plug vs being almost on it.  Been wondering what the ideal spacing is as I got all these boxes used and unloaded.  Don't know what they originally came with but tried many drivers (including vintage ones) and the EV 12" ones seem to work the best -in clarity and SPL
Quote:

You should experiment with the rear chamber size, you may find that a smaller compression chamber will work better.

Loading styrofoam "bricks" into the compression chamber is an easy way to test, keep loading more until the LF/excursion does not improve.

It's really hard to measure or even see the cones, is there a procedure for this?  (They are way up a narrow horn and you just see dustcap) -Stobelight?  Laser?  High-Speed photography?
At the levels it takes to get them moving it hurts my head getting up in there for a look -even with plugs!
Quote:

Have fun!

I fully intend to!

Thanks for the advice!
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Craig Hauber
CSA Productions Inc.
Ventura-Santa Barbara CA
www.csaproductionsinc.com

Art Welter

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Re: Upper bass-range cabinets?
« Reply #7 on: October 19, 2009, 05:14:29 pm »

Craig,

Sounds like the builder of your cabinets used a lot more fiberglass then I could afford in 1979, or did something similar to what  I did.

A 45 foot sailboat generally would have nearly an inch thickness of fiberglass below the waterline, which would make a horn like yours weigh about 150 pounds without an enclosure.

If your cabinets are relatively recent, they could use siped foam core and epoxy (like current surfboards), which was not around in the bad old days. It is very expensive to use those products.

Who is the designer / builder?

Amps delivers more power into a lower impedance, but for a nominal 4 ohm load just set the amp at 2 volts sine wave at 60 HZ, then sweep up. Most meters will be accurate at 60 HZ AC, not so much at other frequencies, so calibrate at 60 HZ.

Lay the cabinet on the side, prop it up paralell to the ground, put the mic on the ground one meter away from the center of the two cones, subtract 6dB for a equivalant LF  free space reading.

20 volts at 10 meters would be more accurate, but loud as hell.

As far as excursion, a dot on the cone is pretty easy to see move, but the depth of the horn will make it hard to get off axis enough to measure.
You could gaffer tape a Popsicle stick 4.1 mm from the cone, then slowly advance power and see what voltage is required to make it hit.

The tapping noise should be easy to hear. Start loading the styrofoam “bricks” in the compression chamber and and see what happens.

Without seeing the phase plug design I can’t say what moving the cone away from the plug will do, but for sure the plug should be farther than Xmax from the cone or you are limiting the output.

Don’t expect the cabinets to be flat, there is nothing wrong with EQ.

Art Welter
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Duane Massey

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Re: Upper bass-range cabinets?
« Reply #8 on: October 19, 2009, 11:57:36 pm »

It is not particularly difficult to build a mid-bass horn using a 15" driver, but there are very few people actually doing it. I would certainly think this would be appropriate for your situation, but such a box will not be small.
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Duane Massey
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Craig Hauber

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Re: Upper bass-range cabinets?
« Reply #9 on: October 25, 2009, 05:38:24 pm »

Art Welter wrote on Mon, 19 October 2009 14:14


Who is the designer / builder?


Not sure, the only label on them is "harbinger" and I don't know if thats a builder, owner (or both) but searching that name brings up nothing related except for a cheap chinese speaker brand.

Here's the compression chamber showing the "phase plug"  The opening above is just a tilt-handle and access into the upper portion of the box which contains the 2" and horn only.
index.php/fa/25727/0/
It is roughly 2.4 cu ft (not including driver volume) and I put a batt of 3" fiberglass in there.
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Craig Hauber
CSA Productions Inc.
Ventura-Santa Barbara CA
www.csaproductionsinc.com

Art Welter

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Re: Upper bass-range cabinets?
« Reply #10 on: October 25, 2009, 06:21:48 pm »

That type of phase plug would be very specific to the cone curve.

You might need a "donut" to space the cone further away.

Harbinger as a name has been used by many over the years.

I have heard guys describing Harbingers used in the 70's in England, but never saw them myself.
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Elliot Thompson

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Re: Upper bass-range cabinets?
« Reply #11 on: October 26, 2009, 02:21:21 am »

Craig Hauber wrote on Sun, 25 October 2009 21:38

Art Welter wrote on Mon, 19 October 2009 14:14


Who is the designer / builder?


Not sure, the only label on them is "harbinger" and I don't know if thats a builder, owner (or both) but searching that name brings up nothing related except for a cheap chinese speaker brand.

Here's the compression chamber showing the "phase plug"  The opening above is just a tilt-handle and access into the upper portion of the box which contains the 2" and horn only.
index.php/fa/25727/0/
It is roughly 2.4 cu ft (not including driver volume) and I put a batt of 3" fiberglass in there.



With a depth of 30-inches, they are probably 180-200 Hz horns and, lose their efficiency rapidly under 200 Hertz. Since the cabinet is sealed any means of bass extension is eliminated.

You also have Electrovoice DL 12X that cannot deliver a lot of mid bass without excessive cone movement. The EV DL 12X is actually the old EVM 12L (Lead Guitar) designed to handle more wattage.

Those are two major obstacles that will prevent you from achieving anything under 200 Hertz with high efficiency. You would need to redesign the cabinets and replace those EV drivers with woofers (The EV DL 12X are Lead Speakers) for a lot of mid-bass ranging from 180 – 90 Hertz. Two EV DL 12X sitting in a 2.4 sealed cubic box will give you a –3 dB @ 174.3 Hz.

If you want to stick some cabinets in between, you can go to www.speakerplans.com and, build a few HD 15s. I am not sure if you are looking to create such a configuration in terms of cabinets. However, the harsh reality is those cabinets are midrange cabinets despite looking as if they can deliver a lot of low-midrange/mid-bass.

Best Regards,
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Elliot

Craig Hauber

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Re: Upper bass-range cabinets?
« Reply #12 on: October 26, 2009, 08:57:27 pm »

Elliot Thompson wrote on Sun, 25 October 2009 23:21




With a depth of 30-inches, they are probably 180-200 Hz horns and, lose their efficiency rapidly under 200 Hertz. Since the cabinet is sealed any means of bass extension is eliminated.

You also have Electrovoice DL 12X that cannot deliver a lot of mid bass without excessive cone movement. The EV DL 12X is actually the old EVM 12L (Lead Guitar) designed to handle more wattage.

Those are two major obstacles that will prevent you from achieving anything under 200 Hertz with high efficiency. You would need to redesign the cabinets and replace those EV drivers with woofers (The EV DL 12X are Lead Speakers) for a lot of mid-bass ranging from 180 – 90 Hertz. Two EV DL 12X sitting in a 2.4 sealed cubic box will give you a –3 dB @ 174.3 Hz.

If you want to stick some cabinets in between, you can go to www.speakerplans.com and, build a few HD 15s. I am not sure if you are looking to create such a configuration in terms of cabinets. However, the harsh reality is those cabinets are midrange cabinets despite looking as if they can deliver a lot of low-midrange/mid-bass.

Best Regards,



I'm fine with the midrange, more than fine actually -they get very loud, stay very clean at high volumes and carry for a very long distance!  I don't want to give that up so my original post was about building a quasi-matching low-mid box to get me down to at least 80 or below to cross over to a more true subwoofer like the LAB.
I think it's the Lead Guitar capability of the EV that works so well.  The DL-12's we have in a couple of them are out of SX-300's and are the same as in some of EV's single-12 install series cabinets.  We have no issues with them.

From some rough calculations I could put 2 of those HD-15's on their sides and stacked and the frontal size would be roughly the size of the front of my mid/highs.
My only questions would be how do you build that curve and what model of currently available 15 would give you the best results?
-Also could you trapezoid the cabinet to physically match the tops? ...like this:
index.php/fa/25754/0/
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Craig Hauber
CSA Productions Inc.
Ventura-Santa Barbara CA
www.csaproductionsinc.com

Elliot Thompson

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Re: Upper bass-range cabinets?
« Reply #13 on: October 27, 2009, 10:44:33 am »

Why not pose your question on the HD 15 forum?

When I was 13, I remember watching a carpenter use water to bend a sheet of wood to create a flare. I believe the wood was 5/16 of an inch.

With the amount of users of the HD-15 on Speakerplans, I'm quite sure all your questions will be answered. There is also a dual HD-15 version running about in addition, to another design called I believe "The Wicked One" that was designed specifically to work over the Lab Subs.

Best Regards,


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Elliot

Art Welter

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Re: Upper bass-range cabinets?
« Reply #14 on: October 27, 2009, 11:27:33 am »

Straight approximations of curves work fine, a curve as you show would only require two parts.

If, for aesthetics, you want curves, laminating 2 or three pieces of 1/4" fir plywood bends easy with no special treatment required.

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David Russell

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Re: Upper bass-range cabinets?
« Reply #15 on: January 25, 2010, 03:24:42 pm »

I used four of these Harbinger cabinets in the mid 80's and they were fantastic.  Mine were loaded with JBL drivers and they worked fine for everything from jazz, blues, rock and Reggae, lots of low end, great mid-range and highs.  Two a side were plenty loud in volume with great response.  Two coupled together side by side was the original intention of the company.  I wish I still had them.  Mine used JBL 15" on the bottom.
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Tim Padrick

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Re: Upper bass-range cabinets?
« Reply #16 on: January 31, 2010, 02:51:32 am »

When I was in high school, I did not have any trouble building A-7s until it came to the horn.  My dad suggested (and help with) installing battens the shape of the curve, then bending (and gluing & screwing) 1/8" tempered Masonite as the horn material.  Installation went without a hitch, and it made for a very stiff horn.

Duane Massey

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Re: Upper bass-range cabinets?
« Reply #17 on: February 01, 2010, 01:20:18 am »

To make the curves on my bass horns (and mid-horns) I use a single piece of 3/4" plywood and cut "lines" in the backside every 2-3" that are approx 1/2" deep. Depending upon the plywood this depth can be adjusted a bit to make a decent bend. For the bass horns I do a layer of 3" wide strips of 3/4" plywood and laminate the finished layer on top (lots of glue!).

For years I just laminated sheets of 3/8" plywood (4 layers), and this was structurally great, but I just didn't like the final appearance, as 3/8" is hard to find in a finished grade.

As far as the curve, send me a PM and I'll be glad to give you some suggestions based on my experiences.
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Robert Harker

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Re: Upper bass-range cabinets?
« Reply #18 on: June 30, 2010, 12:58:05 pm »

They are indeed Harbinger speakers.  The phase plug is unique to the Harbinger design.

Harbinger was a San Francisco Bay Area company located in Menlo Park in the same building as The Music Annex recording studios.  Mark Wayne and Gil Deliso were the principals.  Mark was the designer and Gil managed the shop.  Mark's designs competed with John Meyer (Meyer Sound) and John DeLoren (Apogee Sound) designs.  They were very popular in the bay area and used by Bill Graham Productions for a long time.  Unfortunately they hit the market at the wrong time.  Most sound companies were building their own speakers and were not willing to pay for high quality designed and manufactured cabinets.  I gather that they ran out of money and the company failed.  They were in business from 1982 to 1985 or so.

The horn flare employed was an oddball shape.  They were referred to as "cat's eyes".   Your speakers were the model 228 mid-high cabinets in their array-able model 828 mains.  Each of your cabinets would sit on top of a single 18" model 805 "cat's eye" bass bin.  Harbinger may have also made a double 18" cat's eye" bass bin but I can not find any record of them.  The original designs used all pro JBL components so the EV drivers are wrong.  They would have used JBL 2020 12" drivers and a a 2440 or 2441 2" driver.  I think the high frequency horn is the same design as their 1208 standalone horn.

One of the hallmarks of Harbinger designs was to physically time alline all the speakers in the system.  This was true of their horn loaded fronts and their JBL k130 / 2410 floor monitors.  Harbinger also balanced the efficiency of the components in a cabinet so you could use a passive crossover without an L-pad.  At the time Harbinger was state of the art in speaker design.

As to what to do with these?  I would replace the drivers with the original JBL drivers.  I would then try an find six 805 18" bass bins to put under them.  If you can find them, I suspect they would be cheap.  The 18" bass bins would fit right in between the mid-high boxes and a bunch of LAB subs.  These speakers really need to be used in arrays.  They are a long throw design and don't really start to sound good until you are at least 50 feet front hem.  But then they really rock.

RLH
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