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WinISD is giving crazy high SPL

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ClayR

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Nov 26, 2023
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Greetings!I have an old school Blaupunks sub IPCwg100.I want to build a box for. It's from when Blaupunkt was a division of Bosch and made good stuff. They went out of business now and someone now uses that name on china junk. WinISD gives the speaker SPL of 112db! It's actually 93db. Even if I correct the parameters in the software it still graphs it at 112db with 0db gain in the transfer function. Is this effecting my cone excursion graph? If so, can I use a static filter to fix it? I'm also concerned that this might be caused by a typo in the published Thiele Small specs that could cause other issues, but with Blaupunkt out of business, there is no tech support.
Thanks for the help.
POWER HANDLING 180 Watts rms
540 Watts peak
SENSITIVITY 92 dB (2.83V/1m)
89 dB (1W/1m)
FREQ. RESPONSE 20 - 2kHz
NOMINAL IMPEDANCE 4 ohms
MAGNET WEIGHT 40 oz
MOUNTING CUTOUT DIMENSIONS 9.2 inches (234mm)
MOUNTING DEPTH 5.0 inches (127mm)
AIR VOLUME DISPLACEMENT 0.17 cu.ft.
VOICE COIL DIAMETER 2.0 inches
THIELE-SMALL PARAMETERS
Resonance frequency 30 Hz
Total Q factor (Qts) 0.35
Electrical Q factor (Qes) 0.36
Mechanical Q factor (Qms) 7.02
Volume equivalent compliance (Vas) 2.75 cu.ft.
Linear excursion (Xmax) 0.20 in. (1 direction)
DC resistance (Re) 3.56 (ohms)
Force factor (BL) 10.2 (Tm)
Effective cone area (Sd) 320 (sq.cm.)
Compliance (Cms) 540 (uM/N)
Moving mass (Mms) 61 g
 
I can't diagnose your issue with the information given.

I have some advice though:
If you want decent speaker simulations, then you need to measure your woofer's actual T/S parameters with something like the Dayton Audio Test System (DATS for short).

Manufacturer provided numbers don't cut it in many cases, especially if the woofer was manufactured a while ago and/or is well used.
 
Are you looking at the SPL graph or the transfer function graph? The SPL graph will change to match the wattage you set in the simulation settings, that isn't a bug.

Your cone excursion graph will also scale off the wattage, if you are exceeding xmax then you should implement a high-pass filter. This is especially important for bass reflex aka ported builds.
 
The sensitivity numbers winISD gives are way higher than Man specs. Also, box SPL at 1w are way higher than Man specs for the identical box in there manu
al. 18 db higher. No way that speaker has a 112dm 1w/1m efficiency.
 
staticV3 said:
I can't diagnose your issue with the information given.

I have some advice though:
If you want decent speaker simulations, then you need to measure your woofer's actual T/S parameters with something like the Dayton Audio Test System (DATS for short).

Manufacturer provided numbers don't cut it in many cases, especially if the woofer was manufactured a while ago and/or is well used.
Click to expand...
It is older, but never used.
 
Hi, best to measure TS parameters. This is recommended for any driver, not just for obsolete ones. Can spot defects like stiff suspension. PA woofers I have measure cold very different params than on the datasheet. Small print on the datasheet says the values are from warm driver. So, design box for cold or warm driver? For both! need to sound fine on both.

If measuring is problematic, then try another program like VituixCAD. Haven't been using WinISD in long time, VCAD enclosure tool is way more usable. Have fun!:)
 
You must have put 180 W in the System input power to get 112 dB. That is the thermal limit and shouldn't be used. Try putting in 1 W and see what you get.
 
ClayR said:
The sensitivity numbers winISD gives are way higher than Man specs. Also, box SPL at 1w are way higher than Man specs for the identical box in there manu
al. 18 db higher. No way that speaker has a 112dm 1w/1m efficiency.
Click to expand...

Check that the T/S parameters got entered correctly, if the units are wrong that will cause compounding issues because values are auto-calculated from what you already entered.

Also worth trying VituixCAD, it can do the same job but has a more modern UI and can model crossover impact. A large capacitor or inductor can change your woofer behaviour.
 
alex-z said:
Check that the T/S parameters got entered correctly, if the units are wrong that will cause compounding issues because values are auto-calculated from what you already entered.

Also worth trying VituixCAD, it can do the same job but has a more modern UI and can model crossover impact. A large capacitor or inductor can change your woofer behaviour.
Click to expand...
Definitely make sure that your TS measurements are entered into WinISD correctly, I noticed early that your VAS measure is in Cu Ft. Make sure you translate all the measurements correctly in WinISD. As other stated also make sure that just because your Max and Nominal wattage may be one figure its your AMP and your personal listening choice that will determine your driver travel.
 
Are you looking at the SPL view? If so - check your signal power isn't set to something crazy as the SPL view will model with the given input power (whereas the Maximum SPL view will take into account max possible SPL based on Vd, thermal and excursion limit, regardless of signal power entered):
1716244520904.png
 
Last edited:
Check your environment settings, I have had this change from 1 atmosphere to something weird once in the past. Also its worth the effort to learn Virtuix Cad, it is a great free tool.

winisd.jpg
 
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