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Front loaded horn sub as OB helper sub?
Front loaded horn sub as OB helper sub?
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Old 8th June 2021, 12:51 AM   #1
lasercut is offline lasercut  Ireland
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Front loaded horn sub as OB helper sub?
Default Front loaded horn sub as OB helper sub?

After some playing around with hornresp a front loaded horn sub looks like it might have potential as an OB helper sub.

I have a pair of 10'' SLS-P830668

I tried sealed for the helper sub but didnt like it, it did not integrate well with the OB. Too closed in and restrained sounding compared to the OB, too much undesirable room interaction.
OB subs are ideal but it means a huge baffle and this has too many problems.

I have often heard BLHs being described as dynamic and open sounding,
but a FLH, like sealed and OB, will not have phase issues of the rear ported designs and that seems more appropiate.

The results from hornresp are the surprising part, when aiming for only modest ~50Hz extension the required front horn sizes are a lot smaller than expected, only around 1m.
Im modelling an untapered horn, as you can probably find some sort of piping in the appropiate diameter for this.

I havent found much discussion on FLH subs here (or at least anything explicitly described as a FLH) only on pro sound forums, is there some downsides I'm missing here?
Bandwidth too limited? Still feel like people would work around that if performance was good, like they work around OB limitations.

Last edited by lasercut; 8th June 2021 at 01:11 AM.
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Old 9th June 2021, 06:23 AM   #2
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With the advent of relatively inexpensive DSP to EQ/TD/XO stepped pipe, multiple entry BP alignments, etc., there's no need for huge [downside] compression [build complexity] horns in prosound or the home.

FWIW, I 'chased' ever higher SQ/'you are there' systems, winding up with corner loaded dual 15" 70 Hz truncated expo horns that could be XO'd up to 800 Hz, though used 500 Hz and later 300-350 Hz, but never felt the need SQ-wise to compression load lower, just used high SQ dual 15" vented pipe horns [aka ML-TQWT, ML-Voigt in more recent times]/20 ft^3 subs XO'd at 120 Hz that could keep up WRT pace, rhythm and timing.

Still a big system, though flush fitted in the corners didn't take up an excessive amount of floor space and with [8] Altec 515B plus the huge dual Altec 1" driver mids/HF DIY horns perched on top, not for 'penny pinchers'.

Long gone now and as much as I enjoyed it, have had zero desire to go down that 'road' ever again once I auditioned a multiple driver entry horn [Unity/Synergy concept] that could do it all in a relatively compact bulk plus the one thing mine couldn't and that was replicate a lightning strike good enough to make me feel/jump like I've been hit or standing next to one on several occasions.

If it can do that, it for sure can accurately replicate a recording of any musical instrument; or explosions in an action movie for that matter.

Anyway, the TLs you're simming are plenty good enough for a fairly narrow BW and by offsetting the driver down a 1/3 allows a wider usable BW.
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Old 9th June 2021, 12:06 PM   #3
lasercut is offline lasercut  Ireland
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Front loaded horn sub as OB helper sub?
Thanks for the input, it is idea that horns will have their own 'special' quality that draws me to it, probably a lot of it colouration.
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Old 9th June 2021, 03:13 PM   #4
tommus is offline tommus  United States
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You could put 2x15 or 2x18 dual-opposed subs in a dipole W-frame and it would be a relatively compact cabinet, and get you reasonable SPL @ 40hz.
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Old 9th June 2021, 03:44 PM   #5
lasercut is offline lasercut  Ireland
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Front loaded horn sub as OB helper sub?
I did find a reasonable solution for the subs using stereo pair of 10'' woofer on single large 1.5x0.75M open baffle.
Still a decent output down to 40Hz in a sine sweep without EQ, it rolls off quite fast below that.
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Old 9th June 2021, 05:47 PM   #6
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Quote:
Originally Posted by lasercut View Post
Thanks for the input, it is idea that horns will have their own 'special' quality that draws me to it, probably a lot of it colouration.
Traditional compression horns definitely euphonically 'color' the sound to a greater or lesser extent depending on its flare factor, which down low is ideally pure hyperbolic with OB being its 'mirror' flare.
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Old 9th June 2021, 09:00 PM   #7
lasercut is offline lasercut  Ireland
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Front loaded horn sub as OB helper sub?
Right, that was the result of simple straight horn, a lot of ripple in respons.

I see some have constructed FLHs from paper mache, if the considerations for FLH constructions are different to the typical cab housing a driver (e.g mechanical vs acoustic energy) even at low frequencies then a low-tuned paper FLH with good flare design for my alpair 7p would make an interesting project.
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Old 10th June 2021, 02:29 AM   #8
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Normally, paper mache is limited to a few hundred Hz, so as you go lower, the throat, mouth needs to be more dense.

Regardless, pretty sure none of the Alpair drivers can withstand any real compression loading, only minor WG loading at best.
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Old 10th June 2021, 10:38 PM   #9
lasercut is offline lasercut  Ireland
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Front loaded horn sub as OB helper sub?
With a conical horn it would be easier to make, with a wider range of options for materials.
Maybe thin ply or mdf sheets would work... common, cheap and should be a step up from paper.
The cutout could be calculated and any flat sheet of relatively strong and flexible material could be cut and formed into the cone, although there would sonic sacrifices with the cone I gather.

And the hornresp results for 7p were once again surprising, most of the schematics that achieve desirable results, while not exactly compact, are within realms of practicality.

As for compression loading, I assume this applies to a sealed FLH since there are many BLH alpair designs already?
Or to achieving extreme SPL, which would not be the goal (the goal being reduced distortion at normal SPL)?

Sorry, I'm getting off topic in my own thread, I need to do more reading and might make new thread to ask or discuss some stuff about this.
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Old Today, 04:22 AM   #10
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Conical horn sonic sacrifices?

Just because the driver's specs sim a nice FLH, it assumes a rigid piston, which I gather that the current MA driver's diaphragms are anything but.

BLHs are compression loaded in that its rear chamber is typically too small by design for optimal loading by itself plus the terminus [mouth] pressure waves modulate it, so fundamentally the same as a FLH, just not to the same degree of loading. After all, remove the rear chamber cover of a FLH and what do you have? A BLH.

As probably been stated in every HIFI/HT BLH design thread, the goal is normally to only load out to the room baffle step frequency, which is in the 3 - 6 dB boost range depending on the room's acoustics, BLH location, so this sets the horn's design gain BW.
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