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.
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.
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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.
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.
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.
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.
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.
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.
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.
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.
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.
You probably could get a decent 34Hz low end albeit not very loud 96dB half-space with 70W per driver, if you apply the proper filters as suggested by Linkwitz.
your baffle size will create a -6dB/oktave slope below 100Hz and also a peak at 125Hz.
So 3 filters are needed to get a useful bandwidth up to 150Hz, because later there will be a dip in the frequency response.
1. low 6dB shelf with +12dB at 30Hz
2. 2nd order high-pass at 34Hz with Q=0.9 this serves as subsonic filter to prevent the voice coil bumping on the pole-plate. The Q=0.9 together with the driver Q=0.55 will result in a nice -3dB at 34Hz.
3. a bell with -3dB at 125Hz Q=2-3 to compensate the peak
at maximum power the drivers will move 8.3mm at the lowest frequency and have maybe 10% diustortion
Be aware that these values are more-less in the ballpark and have to be verified by proper measurements of impedance and frequency response.
your baffle size will create a -6dB/oktave slope below 100Hz and also a peak at 125Hz.
So 3 filters are needed to get a useful bandwidth up to 150Hz, because later there will be a dip in the frequency response.
1. low 6dB shelf with +12dB at 30Hz
2. 2nd order high-pass at 34Hz with Q=0.9 this serves as subsonic filter to prevent the voice coil bumping on the pole-plate. The Q=0.9 together with the driver Q=0.55 will result in a nice -3dB at 34Hz.
3. a bell with -3dB at 125Hz Q=2-3 to compensate the peak
at maximum power the drivers will move 8.3mm at the lowest frequency and have maybe 10% diustortion
Be aware that these values are more-less in the ballpark and have to be verified by proper measurements of impedance and frequency response.
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Any bass horn would be as large as Klipschorn... and it would sound really great with OBs filling the room with clean (if not terribly low) bass. But otherwise, as egellings says, pretty nutty idea.
On the other hand, textbook notions of OB bass are no better than any other abstract notion. Best to measure what you have now or what "low hanging fruit" is possible with DSP (I always say folks should buy or borrow a DSP for experimentation). Might be easy to create functional OBs bass by creative shaping to reduce short-circuits and add long-circuits.
BTW, the subjective impressions of the first post are really imaginative, in a bad sense. Square boxes do not make square sound. Other than my liking for Klipschorn bass, can't say as subs have much character other than their frequency response and distortion.
B.
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