Ro808, thank you for your suggestion.
To clarify, I previously had a rough test box with not so suitable dimensions for forecoming room placement . I won't be using it anymore, but am currently preparing two pairs of test and maybe final enclosures for a reproduction range of about 30-600Hz. One set for 12" choices is easy: theyre based on enclosures made for a previous project, repurposed. They were designed to be wall-mounted and were heavily stuffed with wadding. They were for Sonido oval FR and I sealed holes and made an new opening for a 12" woofer on the opposite side.
First I mounted Axiom 401. It could be interesting alternative for 12PR320 if crossed at approx 500Hz to J.Crowes H.1931.
Box volume is about 87 liters and has two vents from time they housed Sonidos (2pcs of diam. 60mm, length 70mm). Attached is a Dats measurement with Axiom 401.
The enclosure had almost none damping material (wanted to see difference it makes and possible problems) and it appears that resonances are well observable. The comparably flat and tall form is cause of this. Reflex tuning might be challenging; the Peerless SLS12 might work best here if plugging the ports and stuffing full . I could also fit a 12PR320 with the tuning you suggested, but is the shape of the enclosure such that the cabinet resonances will require such strong damping that the reflex tuning's effectiveness is impaired?
To clarify, I previously had a rough test box with not so suitable dimensions for forecoming room placement . I won't be using it anymore, but am currently preparing two pairs of test and maybe final enclosures for a reproduction range of about 30-600Hz. One set for 12" choices is easy: theyre based on enclosures made for a previous project, repurposed. They were designed to be wall-mounted and were heavily stuffed with wadding. They were for Sonido oval FR and I sealed holes and made an new opening for a 12" woofer on the opposite side.
First I mounted Axiom 401. It could be interesting alternative for 12PR320 if crossed at approx 500Hz to J.Crowes H.1931.
Box volume is about 87 liters and has two vents from time they housed Sonidos (2pcs of diam. 60mm, length 70mm). Attached is a Dats measurement with Axiom 401.
Wow. Been playing with this co center in NY head as the best approach with 12inch midbass and a low crossover horn. Seems best to enable a better listening window. But what of these diffraction concerns? Would that necessitate a more rounded horn shape to mitigate such concerns?
I would not attempt to guess what sound pressure level you "require".
A 1.4" diaphragm is on the small size, but could do ~100dB at 800 Hz with only 4dB of horn gain.
The diaphragm Sd, not the throat exit diameter determine SPL capability at lower frequencies.
But what would you really recommend, not as brand, that one should really be thinking if trying to do things like 600-750 levels, with minimal distortion in a domestic setting? I think there's an advantage to reaching as close as possible to a concentric horn presentation. And I'm beginning to slowly accept that going lower requires more than a 12 also? I have a Cp755nd. It can go low
Not per se. It's about pipe (horn), (driver) end correction, which in 4 pi (free) space is 0.61r, so convert the horn's terminus at its vertical polar angle to round to get the correct distance or just play with gapping it till the horn sounds right in free space.
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Some types want the free space around them and some are happy to be constrained.
You're unlikely to find much for sale at these frequencies. Hifi pushes you into DIY territory.
You're unlikely to find much for sale at these frequencies. Hifi pushes you into DIY territory.
Good question. Ok, exponential has a finite size and shape which can be defined for a given cutoff, so it doesn't have an extended fit.
Hyperbolic has good properties but when you try to analyse it as a waveguide it's a bit of a mess so it isn't clear.. but it tends to half space.
Tractrix is good because it resembles LeCleach, and LeCleach is best freestanding.
Conical is best as an infinite horn but can be released to a nominal space constraint by radiusing. Conical is sometimes also blended to LeCleach for termination.
Parabolic.. is that used other than as an approximation for straight sided sections?
Hyperbolic has good properties but when you try to analyse it as a waveguide it's a bit of a mess so it isn't clear.. but it tends to half space.
Tractrix is good because it resembles LeCleach, and LeCleach is best freestanding.
Conical is best as an infinite horn but can be released to a nominal space constraint by radiusing. Conical is sometimes also blended to LeCleach for termination.
Parabolic.. is that used other than as an approximation for straight sided sections?
600-750 is a frequency range in Hz.
SPL (sound pressure level) is measured in dB.
Distortion is measured in %, which relates to the harmonics dB level below the fundamental (f1) frequency.
"Minimal" is a subjective term.
You have not presented an answerable question.
Dispersion is related to cone size and design, but in general larger cones have more narrow dispersion, if that's what you are slowly accepting.
A 12" cone driver's -6dB dispersion generally will exceed 90 degrees below 1000 Hz, at 600Hz ~110 degrees.
A 15" cone driver's -6dB dispersion will be slightly more narrow, at 600Hz ~90 degrees.
A round 90 "waveguide" (mostly conical expansion) type horn with -6dB dispersion at 600Hz will generally be wider than a 15" basket.
As can any driver..
The Cp755nd's 2.85" (72.4mm) diaphragm will allow it to do ~+7dB more SPL compared to a 1.75" (44mm) diaphragm more typical for a 1" exit driver.
That said, a 12" will easily outrun the Cp755nd SPL capability at 600Hz in terms of "minimal distortion" on a "waveguide".
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I think you have been purposefully evasive of my basic question, while still educating. Listening to music in a domestic setting means something not deafening. You expressed concern that seemed to suggest that going low may require more than a 1.4cd. My question remains the same: what would you suggest, from your knowledge and experience, as a suitable sized driver for doing such and why?
Hmm, hadn't thought of it from this POV; but technically, yes.
Attached is a Tom Danley measurement of an Altec 511 sectoral horn with/without a baffle added; note the slight gain BW from ~700 - 1200 Hz, then a 6 dB eigenmode dip in the response of the baffled one as the trade-off.
Not many 'free lunches' in audio design.
Attached is a Tom Danley measurement of an Altec 511 sectoral horn with/without a baffle added; note the slight gain BW from ~700 - 1200 Hz, then a 6 dB eigenmode dip in the response of the baffled one as the trade-off.
Not many 'free lunches' in audio design.
![0Altec 511 [old] Tom Danley measurement.PNG](/community/data/attachments/1295/1295981-fb7608cbdd635ecca87d1070f8d69e07.jpg?hash=IWnjvVugB3)