After attempting to get a good in-room response using Beyma 18p80nd (in 180l) actively up to 200hz I have come to the conclusion that I will get a better response (that sonically matches the B&C8ndl51 and Beyma TPL150 (without waveguide) using the Faital 15PR400 (all system to be driven actively). Although at present my funds are limited my intention long-term is to use 2 15" woofers per side. Room is 9mx5m and I listen to quite a lot of modern music that contains a lot of bass information (eg Lorde, Katy Perry - system is used by whole family). I have struggled to find information relating to using 2 bass drivers and few of the on-line calculators allow these calculations. I think I'll be happy with an F3 of 30Hz and probably an enclosure volume of around 360 litres. Can any of the experts on here guide me to enclosure design (?1 compartment per bass driver or both units sharing the same space) and whether I should be using 1 port or 2. When I have performed the calculations using a sealed box of 360 litres and a single driver I get an F3 of 80hz - which obviously means I need a ported enclosure.
Thankyou.
Thankyou.
No expert, but:
You can simply calculate F3 for a single driver in a 180 litre box. It won't change much when you double up.
Pro and high power applications often use 1 compartment per bass driver so that a failure of one component doesn't cause any knock-on effects.
For home use, I doubt that's likely; I use dual 15s in a common compartment.
*Shrug* I don't think it matters much - I'd go by looks / price / availability. The only (sound quality) reason I can think of for using >1 port is symmetry. With a single port, the stiffness of the airload the driver 'sees' will be different on one side than the other.
Again: no expert, so sorry if I have phrased this incorrectly. I also dunno whether this asymmetry has ever been demonstrated as making an audible difference.
Something else to consider (sorry if you're way ahead of me on this):
Having 2 sources will have different room interaction depending on how they are oriented e.g. a pair of large woofers stacked vertically will have different floor bounce to a single woofer. That's something else to model, if you want to get the model 'perfect'.
Personally, for the range 30-200Hz, unless the application dictated otherwise, I'd be tempted to:
-use a single compartment
-use opposed (vibration cancelling) mounting
-run the drivers 1.5 way (eg front driver 30-200Hz, rear driver 30-100Hz)
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Have you experimented with sealing the Beyma 18P80Nd 180l box and using active equalization with a higher power amplifier? A Linkwitz transform is one simple equalization filter. More extensive DSP_box or multi-band equalizator can also smooth some room effects. A sealed box woofer will have superior transients over a ported box, but requires much higher power to achieve low frequency bass.
You might want to review what Tony Gee did with the 15PR400 in his design of Calpamos.
I have heard those in his listening room. I was very impressed with the dynamics and extension. I absolutely loved what he did with the crossover and the mid/highs with the Faital HF201 (somewhat off topic)
I have heard those in his listening room. I was very impressed with the dynamics and extension. I absolutely loved what he did with the crossover and the mid/highs with the Faital HF201 (somewhat off topic)
Then it would have sounded even better with a decent, ie non diffraction slot flare.
Thanks all.
Saw Tony Gees design rationale with the woofer and his words seemed to resonate with my findings of the Beyma woofer - great at high volume but kind of indistinct and one note at lower volumes. I think some of the harmonics also played havoc with the midrange.
The Beyma was sealed and driven with 500 watts via a Marchand XM9.
I think the room probably does need work and its got a suspended floor.
Think I’ll try 200L ported, single driver and go from there. If I need to double up I’ll add a second driver at the back - I am presuming the tuning remains the same even with a second driver?
Saw Tony Gees design rationale with the woofer and his words seemed to resonate with my findings of the Beyma woofer - great at high volume but kind of indistinct and one note at lower volumes. I think some of the harmonics also played havoc with the midrange.
The Beyma was sealed and driven with 500 watts via a Marchand XM9.
I think the room probably does need work and its got a suspended floor.
Think I’ll try 200L ported, single driver and go from there. If I need to double up I’ll add a second driver at the back - I am presuming the tuning remains the same even with a second driver?
Speaking for myself, I like the critically damped alignment. The woofer reaches a bit lower. The larger baffle moves the baffle step down and the diffraction effects as well. I'm boosting the low end a bit w/DSP EQ (faux Linkwitz transform) and the bass extension is good enough for me without subs (rolls off 18db). Lower mid range isn't muddy at all. Nice woofer for a two way design crossing around 1khz.
Can take a measurement if you'd like .... but not tonight
Can take a measurement if you'd like .... but not tonight
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I'd already got the 180l box from my previous trials with the 18p80nd. I originally had made it ported but much prefer the taughtness of the sealed enclosure - like puppet I think the midrange extension (harmonically) is excellent. I've now settled with an 8pe21 and DE250 with the XT 1086. I have a pair of stacked esl57's in the same room and rarely think it worth swapping them over. This is a special collection of drivers......if only I could afford a TAD compression driver!
Speaking for myself, I like the critically damped alignment. The woofer reaches a bit lower. The larger baffle moves the baffle step down and the diffraction effects as well. I'm boosting the low end a bit w/DSP EQ (faux Linkwitz transform) and the bass extension is good enough for me without subs (rolls off 18db). Lower mid range isn't muddy at all. Nice woofer for a two way design crossing around 1khz.
Can take a measurement if you'd like .... but not tonight
Hi, no intention to nitpick since these are valid things to defend bigger baffle in certain circumstances. Lets say here is another point of view
The room dominates the bass. Little more extension doesn't really matter if the room introduces huge peak there anyway, or conversely has severe dip. There would be audible difference if response went to 80Hz instead of 30Hz, but between 35Hz or 40Hz I suspect no difference at all unless you have room that doesn't affect at those frequencies.
Bigger baffle does in a way push the diffraction effects down but the upper limit for diffraction stays the same since it is related to the driver size. In a sense making baffle bigger you worsen the diffraction because the diffraction now occurs on wider bandwidth, between the bafflestep and driver beaming. More over, bigger enclosure drops all the resonances inside the box lower in frequency and harder to be dealt with.
For these reasons my opinion is to use as small enclosure as possible. One sacrifices some bass by doing this but improves the mids. Bass can be good by adding more bass sources. I see no valid reason to use big bass box other than reaching required SPL, anything bigger and there is no advantages only disadvantages. Although, there is an argument to get some directivity to the schroeder frequency, but thats about it. On the other hand 20cm deep box against wall is infinite baffle territory below 200Hz (< 1/8wl from the wall).
Big boxes look cool, so anything goes since the aesthetics is a big part of home audio.
Jolly weekend!
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Does this apply to the 15" PA drivers or do you mean in the absolute, the littlier the same at the end ? Seas 10" LROY ? If one has to ad bass sources, is it not better then to go with a lower PA that is mor subtile for the medium area as the Faital 12PR320 for instance to keep a high enough efficienty and Sd, working with it till 60 hz aith bass sub of the said not PA drivers à la Seas that are made for small sealed box and can be EQ due to their long Xmax ?
Of course people use also such 15 PA like theyused the old Altec.. Not sure it makes sense when higher than 600 hz cause off axis response ? Also in case of EQ, it also means more break-ups and not sure the midrange (100 to 600 hz) stays as good.
@ deank : there are today some good less expensive drivers with subjective close results if we read the litterature at Faital, 18THSound, BMS... problem is more the horn for home uses !
Of course people use also such 15 PA like theyused the old Altec.. Not sure it makes sense when higher than 600 hz cause off axis response ? Also in case of EQ, it also means more break-ups and not sure the midrange (100 to 600 hz) stays as good.
@ deank : there are today some good less expensive drivers with subjective close results if we read the litterature at Faital, 18THSound, BMS... problem is more the horn for home uses !
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In a sense that sound has size (wavelength) and transducer and enclosure has size, it is universal. But, if the box is for low frequencies only, much longer wavelengths than a 10" subwoofer box, it doesn't matter. Small box is pretty much invisible acoustically when the wavelengths are room size. Problem arises when the wavelengths become small enough, similar size to the box and smaller. While 200Hz is ~170cm long 800Hz is only ~42cm. Problems arise with multiway speaker bass, not with subs.
Of course anyone can do what ever they want and need. My ramblings are just thoughts what compromises would be worth it and what would not. Minimal box has minimal influense on the sound on the upper end of the bandwidth the transducer and box is responsible for. However low end of the bandwidth can almost always be substituted with another bigger transducer and box because the longer wavelengths allow so. Reasoning from this the upper end of the bandwidth should get most of the attention of any way of multiway speaker because that defines the quality of that part of the system. Until at the room sized wavelengths anything that fits in the room is fine.
Of course anyone can do what ever they want and need. My ramblings are just thoughts what compromises would be worth it and what would not. Minimal box has minimal influense on the sound on the upper end of the bandwidth the transducer and box is responsible for. However low end of the bandwidth can almost always be substituted with another bigger transducer and box because the longer wavelengths allow so. Reasoning from this the upper end of the bandwidth should get most of the attention of any way of multiway speaker because that defines the quality of that part of the system. Until at the room sized wavelengths anything that fits in the room is fine.
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So if I made an 80 litre enclosure this would improve midrange intelligibility? How would it impact on max spl? My room is 8x6m listening seat is ~ 3m away from speakers the loudest I listen is 105db peaks (rarely) most of the time 80-86db. I am assuming a smaller box at these low volumes will make no difference and I will only get benefit??