WSR subwoofer comparison

• all frequency columns are in dB
• some subs are passive and the amplifer is not included in the cost
• ~ = a fuzzy or slightly distorted signal was measured at this Hz and dB
• < = a value slightly less than this dB was measured
• Exactly how Mr. Hardesty accounted for room modes and room gain is unknown. Bass traps, tuned positioning, absorbative material, equalization??? I don't know. Mr. Hardesty's listening room is 24'x13'x8' with his listening position being about the middle of the room. If you run the dimensions thru the Room Mode Calculator you will see some nice strong bass modes at 24Hz and 44Hz. My question is how does the response of Mr. Hardesty's room change the reported max SPL numbers? Maybe we will find out in a future article by him but rest assured these numbers will vary dramaticaly in your room!
• volume was calculated using external dimensions and assuming 3/4" MDF
• Xmax excursion numbers were calculated using dB at Hz numbers and a sealed box formula. It was assumed all dB SPL values were displacement and NOT wattage limited. This assumption is wrong I admit but it is a good starting point. Vented alignments, should be off roughly by 50% since doubling Xmax excursion gives +6dB.
  • For a description of the sealed box formula used to estimate Xmax check out the piston excursion calculator page.
  • Isobariks were calculated with half the number of drivers, what we are interested here is the radiating surface, how much air can it move.
  • even though the Xmax calcs are not valid for vented enclosures, port tuning frequencies, and vented F3's can be determined from this data.
  • at the higher frequencies (>35Hz+ ?) the amplifier wattage becomes the limiting factor, this also can be determined from looking at the Xmax numbers.
  • an assumption is the max dB values at the onset of distortion are Xmax limited. Not amplifier clipping, and not port vent noise.
  • another assumption is that all room gain / standing waves have somehow been "absorbed out."
  • For a better understanding of the displacement limited and power limited output, check out some of my plots on my search for the ultimate sealed woofer page.
  • after accounting for alignment types, the measured Xmax data shows a non linearity for most subs, especially at 20Hz. Since at this frequency subs are basically excursion limited and not power limited, this can mean a lot of different things. Measurement error, bad driver construction, or breakdown of Theile/Small theory at large excursions.
  • some manufacturer excursion specs:
    • BagEnd driver Xmax = 9mm
    • HSU ASW_1201 Xmax = 14mm (believed to be in the TN1225HO)
    • NHT1259 Xmax = 13mm
    • Sunfire TrueSub driver Xmax = 22.2mm (WSR numbers)
    • Earthqauke Supernova driver Xmax = 18.7mm (WSR numbers)
    • M & K MX-700 driver 12.7mm (WSR numbers)
    • Velodyne HGS-12 driver Xmax = 16mm (WSR numbers)
    • Energy ES-18XL driver Xmax = 14.3mm (WSR numbers)
    • ServoDrive ContraBass Xmax = 9.5mm
    • Dynaudio 30W100XL Xmax = 9mm

Sorted by max SPL

The bargin sub, cheapest route to 115dB at 25Hz

Notes:

• All combos under $5000 are listed.
• number of subs * cost each = total cost
• Sorted by total cost.
• Remember every doubling of drivers and wattage gives +6dB gain. See my table of dB laws etc.
• This list is the cheapest combinations of sub inorder to get 115dB or more at 25Hz. This might not yield the best sounding setup. And there is no guarantee that this setup will be the loudest at 20Hz.
• The reason I choose 115dB @ 25Hz was that 115dB SPL is the maximum bass volume with the AC3 or DTS LFE (low frequency effects) channel when played back at the 0dB THX reference level. Most movie bass is in the 40Hz region, but some films do go lower. So the 25Hz level will usually be overkill. On the other hand 20Hz is accepted by many to be the lowest frequency humans can hear, so that would of been a good frequency to choose. 25Hz seemed like a good compromise and all subs in the survey had 25Hz SPL numbers while only a few had 20Hz and below numbers. Personally I believe 115dB at 10Hz is a good subwoofer goal to strive for but this would be one outrageous box. Try fitting that in your room! Great goal but not really practical.

Check out my quest for bass page.

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