Hi everyone
What would you recommend as a 15 inch bass driver for strong deep LF output in a sealed 50-75 litre cabinet?
Upper crossover will be around 200 Hz, as front main Hifi speakers, secondary use as front HT speakers.
There will be subs, but I want these to run as extra subs, and hand over at the lowest frequency they can. DSP will be available, so that might factor in to your thoughts.
Sadly, money is a factor, so premium and affordable alternatives are sought. I don’t have a hard dollar limit, but cost-no-object suggestions will be fun to read but won’t be the answer.
Thanks
What would you recommend as a 15 inch bass driver for strong deep LF output in a sealed 50-75 litre cabinet?
Upper crossover will be around 200 Hz, as front main Hifi speakers, secondary use as front HT speakers.
There will be subs, but I want these to run as extra subs, and hand over at the lowest frequency they can. DSP will be available, so that might factor in to your thoughts.
Sadly, money is a factor, so premium and affordable alternatives are sought. I don’t have a hard dollar limit, but cost-no-object suggestions will be fun to read but won’t be the answer.
Thanks
Extra-deep extension with a sealed fifteen, and only some 75 Liters worth is almost a contradiction in terms.
Might I suggest the Dayton eighteen, four ohm, 8.25mm X ...the DCS450.
As the EBP is split between both sealed or ported at 54.6 ...sealed getting the same old slow roll-off, the ported variation reaches to -3.05 Db @ 22.59 hertz...with the caveat that it needs 330.3 liters worth to get that far down.
And this is before any DSP "magic" you may apply.
--------------------------------------------------------------------------------Rick...
Might I suggest the Dayton eighteen, four ohm, 8.25mm X ...the DCS450.
As the EBP is split between both sealed or ported at 54.6 ...sealed getting the same old slow roll-off, the ported variation reaches to -3.05 Db @ 22.59 hertz...with the caveat that it needs 330.3 liters worth to get that far down.
And this is before any DSP "magic" you may apply.
--------------------------------------------------------------------------------Rick...
70 liter sealed enclosure -3dB point vs. dB/w/m
20 hz - 82.5 dB
25 hz - 85.4 dB
30 hz - 87.8 dB
35 hz - 89.8 dB
40 hz - 91.5 dB
If you are relatively lucky with a somewhat small farily well sealed room, you may achieve good results with a sealed box that approximates the transfer function of the room, the room gain will be more or less complimentary to the sealed box roll off.
Do you already have an amplifier on hand? What is your budget, and how many cabinets are you planning on building?
Importing drivers would be expensive, but there may be local car audio drivers that will be more appropriate in terms of budget and typically have more xmax than other budget designs, and some have attention paid to reducing motor and suspension non-linearities.
20 hz - 82.5 dB
25 hz - 85.4 dB
30 hz - 87.8 dB
35 hz - 89.8 dB
40 hz - 91.5 dB
If you are relatively lucky with a somewhat small farily well sealed room, you may achieve good results with a sealed box that approximates the transfer function of the room, the room gain will be more or less complimentary to the sealed box roll off.
Do you already have an amplifier on hand? What is your budget, and how many cabinets are you planning on building?
Importing drivers would be expensive, but there may be local car audio drivers that will be more appropriate in terms of budget and typically have more xmax than other budget designs, and some have attention paid to reducing motor and suspension non-linearities.
Thanks Rick. Yes, I typed “it’s a hard ask” into the OP then deleted it — I do understand your point about it contradiction in terms.
But I’m after the names of the drivers that get closest. I mentioned DSP in case that helps narrow down the best drivers.
I forgot to mention corner placement. I should get some sealed cabinet roll off room gain happening.
Cheers
But I’m after the names of the drivers that get closest. I mentioned DSP in case that helps narrow down the best drivers.
I forgot to mention corner placement. I should get some sealed cabinet roll off room gain happening.
Cheers
You didn't mention target Qtc... and I'm a bit rusty knowing whether DSP can save you from boom from a too small enclosure....
a Dayton RSS390HF-4 will get you a Qtc=0.837 and Fs 34Hz in a 75L sealed. It will take 400watts before hitting Xmax (15mm) from 0Hz up.
a Dayton RSS390HF-4 will get you a Qtc=0.837 and Fs 34Hz in a 75L sealed. It will take 400watts before hitting Xmax (15mm) from 0Hz up.
The Lavoce ferrite models are well priced. 12mm xmax for this model.
LaVoce WAF154.00 15" Subwoofer 8 Ohm
LaVoce WAF154.00 15" Subwoofer 8 Ohm
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JBL2256G could be a possible solution, with its 25Hz fs and 20mm Xmax. Besides, in a sealed enclosure, you could also cheat some volume without serious problems. This model is also known as / JBL W15GTi in the car audio world.
MODEL FS QTS QMS QES VAS EFF PE XMAX RE LE SD BI MMS FLUX
2256G 24.2 0.47 7.79 0.5 138.5 600 20.3 3.1 0.7 0.078 15.7 284 0.657
We should pay attention to Xmax numbers because they differ from manufacturer to manufacturer.
LaVoce states 12mm Xmax but defines it by next equation:
(Xmax)=(Hvc - Hg)/2+ Hg/4
Hvc - height of the voice coil
Hg - height of the magnetic gap
They obviously presume that magnetic field will uniformly extend for 1/4 of the gap height - that is +/-3.25mm beyond the gap itself. While i'm not saying it is impossible, i think that only Klippel measurements would tell us what is the real Xmax.
LaVoce is not the only one. FaitalPro defines it as: Xmax= [(winding depth - magnetic gap depth)/2] + (magnetic gap depth/3) - as you can see, the calculation of Xmax by manufacturers is quite arbitrary.
Erin, from erinsaudiocorner.com shows the data like this:
"There are one of two sets of thresholds which can be used to define linear excursion:
Non-Subwoofer Drivers: The thresholds Blmin= 82 %, Cmin=75 %, Zmax=10 % and d2=10% generate for a two-tone-signal (f1=fs, f2=8.5fs) 10 % total harmonic distortion and 10 % intermodulation distortion.
Subwoofer Drivers: The thresholds Blmin= 70 %, Cmin=50 %, Zmax=17 % create 20 % total harmonic distortion which is becoming the standard for acceptable subwoofer distortion thresholds."
In that conditions SB17CAC35-4 has Xmax of +/-2.8mm which makes it a good midrange, not woofer.
I think that datasheets should look very different.
LaVoce states 12mm Xmax but defines it by next equation:
(Xmax)=(Hvc - Hg)/2+ Hg/4
Hvc - height of the voice coil
Hg - height of the magnetic gap
They obviously presume that magnetic field will uniformly extend for 1/4 of the gap height - that is +/-3.25mm beyond the gap itself. While i'm not saying it is impossible, i think that only Klippel measurements would tell us what is the real Xmax.
LaVoce is not the only one. FaitalPro defines it as: Xmax= [(winding depth - magnetic gap depth)/2] + (magnetic gap depth/3) - as you can see, the calculation of Xmax by manufacturers is quite arbitrary.
Erin, from erinsaudiocorner.com shows the data like this:
"There are one of two sets of thresholds which can be used to define linear excursion:
Non-Subwoofer Drivers: The thresholds Blmin= 82 %, Cmin=75 %, Zmax=10 % and d2=10% generate for a two-tone-signal (f1=fs, f2=8.5fs) 10 % total harmonic distortion and 10 % intermodulation distortion.
Subwoofer Drivers: The thresholds Blmin= 70 %, Cmin=50 %, Zmax=17 % create 20 % total harmonic distortion which is becoming the standard for acceptable subwoofer distortion thresholds."
In that conditions SB17CAC35-4 has Xmax of +/-2.8mm which makes it a good midrange, not woofer.
I think that datasheets should look very different.
Hmm, per the attached, ~20 Hz/70 L = ~0.01%/100 = ~0.0001
112 + 10 log[~0.0001] = ~72 dB, so ~40 Hz/0.1% = ~82 dB
Attachments
real high fs and a low q. Without a lot of DSP, this won't ever be a subwoofer. In a sealed enclosure, it's barely a woofer. With DSP, you're going to run out of whatever it's actual xmax is pretty fast.
Agreed.
I was assuming these would be used as helper woofers since they'll be run up to 200hz.
Power is cheap and 12'ish mm xmax should be good for decent levels from 40hz up.
Need more info tnargs.
I was assuming these would be used as helper woofers since they'll be run up to 200hz.
Power is cheap and 12'ish mm xmax should be good for decent levels from 40hz up.
Need more info tnargs.
Hi, I’m not sure what info?
Some woofers are more suited to sealed box usage than others. Which ones are these? Preferably 15-inch, but change that if you must.
I’m not after a predicted response and max SPL solution to some target spec. I’m just asking for some help in identifying the most suitable woofers for the usage as outlined.
Cheers
Some woofers are more suited to sealed box usage than others. Which ones are these? Preferably 15-inch, but change that if you must.
I’m not after a predicted response and max SPL solution to some target spec. I’m just asking for some help in identifying the most suitable woofers for the usage as outlined.
Cheers
Hi tnargs,
Just look at the value of fs/Qes. If this value turns out to be below 100, the driver is more suitable for sealed enclosures than for vented ones. However, this is not a rule, but just an easy way to identify such woofers quickly. Also, people specify different thresholds for sealed and vented choices, many agree on fs/Qes< 50 => sealed and fs/Qes>100=> vented, and in between these two, it's just discretion.
EDIT: My recommendation eariler (JBL2256G) was also based on the value for fs/Qes (=50).
Regards.
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Assuming the DSP can do it (i.e. if a biquad filter can be applied), a Linkwitz Transform filter can change the Qt and Fs to meet whatever is required, with the tradeoff being the power needed at low frequencies and the driver excursion limit at those low frequencies.
Remember that applying a filter does not change the actual output capability of the driver, just the shape of the response.
I use an LT in with RSS315HF-4's in a slightly too-small sealed box, and in my experience it works as predicted.
Bill
Exactly.
The 15" I linked above will put out 110db @ 40hz in a half space environment when driven to 12mm. 116db for two. A lot of HT guys have been using prosound 21" in recent years with good success.
The 15" I linked above will put out 110db @ 40hz in a half space environment when driven to 12mm. 116db for two. A lot of HT guys have been using prosound 21" in recent years with good success.
good point. I completely missed that this sub has a 1500w power handling capacity, and amazingly, doesn't reach xmax at that level. Because of that... yeah, over 110dB SPL at 40hz. It drops all the way to 100dB at 20hz, so it's still not what I'd consider the ideal home theater sub, but it'll to a hell of a lot of damage down to 40hz.
OK, then based solely on an HT's definition of 'deep' bass, this equates to the THX LFE channel's 115 dB/20 Hz/LP assuming your mains meet the THX LCR mains, surrounds channel's = 105 dB/80-120 dB/LP, so they must be higher at +6 dB for every doubling of distance if > 1.0 m away from the LP.
Worse, if you set the mains, surrounds channel's in 'small' mode, then the LFE channel must have a much higher dB SPL capability to compensate.
LP = listening position
TTBOMK it's highly unlikely such a 'beast' of a subwoofer exists and any that can come close will at least need a very large box or a large array of $$$ true subwoofer horn drivers $$$ and even then, such drivers tend to be design limited to the THX LFE channel's 120 Hz max XO upper limit, so you're still in the 'if wishes were horsepower, bagels would fly' scenario.
In short, scope out drivers with a combination of the lowest Fs, Qes, Vas to get a small enough box with a low tuning [Fc] 200+ Hz XO point and the highest Xmax to get as much dB SPL as practical.
I'm not even remotely current on what's available, so limited to posting some math to juggle these variables to see what, if any, comes 'close enough' once some room acoustics are factored in.
Assumed: 20 Hz Fs/200+ Hz in a 70 L net/1.0 Qtc sealed cab alignment [FWIW have personally used up to a 2.0 Qtc to create compression horn drivers], then:
Qes = < 2*Fs/200 = ~0.20 [$$ horn driver spec $$]
EBP = 20/0.2 = 100 [on the cusp of sealed/vented]
a = [1.0/0.20]^2 - 1 = 24
Vas = 70 L/24 = ~82.6 L/2.917 ft^3 ['unobtanium' construction in a > 15" subwoofer?]
Good luck! Looking forward to seeing what's most viable and its compromises.
In Aus, Wagner has a couple of the SB Audience 15 inchers available at reasonable prices that might be worth considering
