I've been playing on box simulation softwares: WinISD and BassBox 6 Pro.
Driver used in the simulations is a Scan-Speak 26W/4558T00. The enclosure selected was simply a closed box with Qtc of 0.5. Nonetheless, they gave different results.
BassBox 6 Pro suggested a box volume of 1.0 cu.ft for the target Qtc (Qtc = 0.5), whereas WinISD suggested a 2.7 cu.ft box for the same Qtc.
So, which one can be trusted?
Driver used in the simulations is a Scan-Speak 26W/4558T00. The enclosure selected was simply a closed box with Qtc of 0.5. Nonetheless, they gave different results.
BassBox 6 Pro suggested a box volume of 1.0 cu.ft for the target Qtc (Qtc = 0.5), whereas WinISD suggested a 2.7 cu.ft box for the same Qtc.
So, which one can be trusted?
Attachments
The most reliable way is to perform the simulation oneself. Should be less than 10 lines in a loop plus a few lines above collecting data and a few lines below plotting it. The radiation impedance may need a bit of pondering but the rest is simple RLC. The equivalent circuit is straightforward to solve by inspection.
A spice input file will have 10 components plus a few to setup and plot. I'm sure there are many examples on the web. A pretty reliable way to go about this type of thing.
Alternatively you could use a current and likely more reliable "black box" program like vituixcad and see which one agrees with it (assuming one does). It probably won't help with understanding what happened since it's unlikely either program is "wrong" given how long they have been around and used.
A spice input file will have 10 components plus a few to setup and plot. I'm sure there are many examples on the web. A pretty reliable way to go about this type of thing.
Alternatively you could use a current and likely more reliable "black box" program like vituixcad and see which one agrees with it (assuming one does). It probably won't help with understanding what happened since it's unlikely either program is "wrong" given how long they have been around and used.
I had tried online calculators as @andy19191 suggested. The result is neither WinISD nor BassBox Pro 6 match them.
Most of the online calculators suggested box volume of 2.0 cu.ft, for producing Qtc of 0.5.
I also tried hand calculation from Vance Dickason's textbook, it affirmed the 2.0 cu.ft volume.
So, I think maybe the online calculators are the most reliable. Lol
What do you all think about it?
Most of the online calculators suggested box volume of 2.0 cu.ft, for producing Qtc of 0.5.
I also tried hand calculation from Vance Dickason's textbook, it affirmed the 2.0 cu.ft volume.
So, I think maybe the online calculators are the most reliable. Lol
What do you all think about it?
BassBox considers the box to be "heavily filled" which gives an apparent enclosure volume increase. I just doubt it would double the apparent volume ...
For winISD i suppose there is either a unit mismatch (litres/cu.ft or cm/inches) or a wrong parameter input, as the box resonance seems to be 37 Hz which is too high AND the volume is also very high.
Edit:
I like this online calculator for cross checking:
http://www.mh-audio.nl/Calculators/CCC.html
I suggested vituixcad not online calculators. Some of the latter may give "correct" answers (subject to the set of modelling assumptions which are possibly not given) but they cannot be considered reliable. Vituixcad is likely to be the most widely used blackbox speaker design program at the moment and hence the one most widely tested by usage with an active author making fixes and improvements.
Personally, I briefly used winisd a few years ago but it had issues with locking up, some parameter adjustments leading to what appeared to be internal inconsistency, needing to use wine to run it, interest and support from the authors disappearing decades ago, inability to include it in scripted workflow, etc... It gave me the expected results when the parameter sets were consistent (i.e. plots matched the mathematical models given in the manual) but it could sometimes give obviously wrong values usually shortly before locking up or crashing. Never used bassbox, online calculators or vituixcad.
I now tend to use my own software. Sometimes a python script and sometimes a network solver depending on what I am doing. If one is comfortable with programming it is likely to be the most reliable and flexible approach. If not then the most widely used current speaker design software is likely to be the way to go. I believe that is currently vituixcad but it used to be other programs in the past and no doubt will be other programs in the future. The vituixcad website suggests later versions of wine might work but with issues. Can anyone confirm or deny this?
Most Hand Calcs don't account for stuffing.
There are some that do. Margolis-Small presented some hand calculator methods back in the 80's that sorta work
They predict around 50 liters lined and 37 liters if stuffed for this woofer.
A sanity check for any "calculator" is always the old Qtc/Qts=sqrt(Vas/Vb+1) I would never trust a program (Bassbox) that told me stuffing could reduce the volume by half.
My sim shows a Q very near 0.5 with 45 liters Qa=Qb=20 Changing these values a fair amount doesn't change things much except for impedance.
FWIW, This woofer is very much a ported woofer, in 50 liters tuned to 25, it digs pretty deep and handles a lot more power down to 20Hz, but needs a long port, or a PR.
Question: does this output actual absolute SPLs? Or everything normalized to "0 dB"? I'm looking for something to compare different woofers in the same box, or even multiple woofers in a box versus one different woofer in that same box. To be meaningful the simulator needs to generate actual SPL. I used to use LEAP but that's pretty gone (RIP Chris Strahm you genius).