Need help with Modeling Software

[Wright]

Hey Guys,

I have been trying to model up a subwoofer for my friend using the Tangband 8" W8-740c. The parameters for this woofer can be found here and here. We decided to use the plate amp from Partsexpress
here. We are looking to do a vented design with a long port to save money over pr's. I have tried to model the sub in "subwoofer simulater" and "winisd" but I'm not having much luck. I think I have all of the parameters entered in correctly but I wasn't sure about the "PE", "Z", or "dia". Is that the diameter of the voice coil or of the cone? Also for Le does the software want it at 1khz or 20 khz?
My goal in using these programs was to determine necessary box size and port length, and hopefully get an idea about how low it will go and how flat it will be. I was also confused with winisd about the power tab. I entered in 100 watts as opposed to 1 watt and the spl graph went off the chart, is that supposed to happen?
I appreciate the help, hopefully I can get up to speed with these programs.

George

[Ron E]

Probably not a good idea to use that sub without a PR.

LE won't matter much so it doesn't matter what you enter.

To get a response shape that works OK with that bass amp - it has ~6dB boost at 30Hz - I tried a 12 liter box tuned to 28Hz with a 2" diameter by 24" long port. Port velocity reaches 40+m/s, which is high and you will likely have noise, even if flared. Using a 3" port 55" long, your port velocity goes down to 17m/s, which is better, but the port is ridiculously long...

Tuning small boxes to low frequencies is a job for a passive radiator.

[tg3]

No experience with above programs.

But have you tried UniBox from the FRD Consortium? Very easy to use.

And I'm always amazed at the number of Seattlites on the audio forums...

[Ap]

The only parametes you need to model sub volume
are qts, fs, vas.

For tuning & vent velocity you will need power (pe) & Qes.

I get 10litres tuned to 40hz using winisd with a port 2 x 13"yields flattest response

This driver is very inefficient at 84db & low Re so will require high power & stable amp.

The parts express one looks up to the taks but hard to comment unless tested.

[kelticwizard]

Originally posted by Wright
Hey Guys,

I have tried to model the sub in "subwoofer simulater" and "winisd" but I'm not having much luck. I think I have all of the parameters entered in correctly but I wasn't sure about the "PE", "Z", or "dia". Is that the diameter of the voice coil or of the cone? Also for Le does the software want it at 1khz or 20 khz?

George

Since I haven't modeled the TangBand, I cannot comment on the advisability of using a port or Drone Cone, (the original term for Passive Radiator, coined by it's inventor, Harry Olson), but I can give you the terms.

Pe = Max Continuous Power, (not instant peak power).

Z = Nominal impedance. Generally either 4 ohms, 8 ohms, or nowadays, even 6 ohms. Never 4.7 ohms or 6.8 ohms or whatever. It is the ohmage the manufacturer gives to fit into the 4 ohm/8ohm mold.

dia = The diameter of the circular frame around the cone. A speaker with a 10 inch circular frame and a 8½" cone will be called a 10 incher. It corresponds to the popular 15", 12", 10", 8", and 6½" that everyone uses anyway.

The actual cone itself is generally given as "Sd", and that is the area of the cone surface itself. It is a different number entirely from "dia".

Le is generally given as the Le at 1,000 Hz.

[Ron E]

Applying boost below the tuning frequency is a no-no Tuning to 40 Hz, no matter how flat it might appear in a simulator that doesn't account for amplifier response, is likely to cause overexcursion below resonance. A 2" port in a 10L box would have a velocity of ~47m/s when tuned to 40Hz, with ~35V input. Pretty cool if you want port noise and be able to blow out candles at 30 paces.

Without a PR, I'd probably use a small ~5-7L sealed box.

It'd make a nice (small) car woofer. There are better choices for use with a plate amp in a home.

[Wright]

Wow thanks for all the helpful replies! It is good to know what those t/s parameters mean. I wasn't having much luck with the other two programs, but I did try unibox, and found it to be more user friendly. I enjoyed entering some values and seeing it calculate the rest of them right on the money! (I am easily amused). The only thing I'm not fond of is that I can't figure out how to enter my own port length; seems the program does that for me?
Anyway about the subwoofer: I was talking to Al (RAW) before and he also encouraged me to use a passive radiator/drone clone, but since they run $50 for the high excursion version it is over our budget. He made it sound like I could go ported if I was desperate but perhaps it's a bad idea. Considering our target price range of $30-$50 for the driver, do you guys have any other driver suggestions that I could run in a ported box? The application is computer system/HT use to be coupled with a pair of SuperElf's and a pair of Elf1.0's in the rear. I would love to try and get down into the lower 30's (frequency, not price) if possible, but that might be asking to much of a small driver. Amp is as stated above, unless you have other suggestions at or below that price point. I really appreciate your suggestions, and I'm sure my buddy does too.

George

[kelticwizard]

How about a Peerless CC 260, or 831727 in a 28 liter, (1 cu ft) box, tuned to 30 Hz?

The box is only a little bigger than your planned box, the 10 inch has a pretty long throw. I will explain later, but it has a symmetrical magnetic system that in a ported box, will give much less distortion than a non-symmetrical system-and the TangBand does not mention a symmetrical system, which means it probably does not have one.

The Peerless is more efficient.

The simulation is by Subwoofer Simulator, written by our own F4ier.

The lower line is the response not counting the room, like most modeling programs do it.

The upper line includes standard room response-actual room response may vary.

The room response was an option added by our own member, Serow.

As you can see, at 30 Hz, even without room response, you are down to around 80 dB.

With room response, you are up to around 86 dB-more efficient than your TangBand even in the midband!

Price isn't much more than the TangBand.
http://www.partsexpress.com/pe/pshow...=297-616&DID=7

You can always make the box bigger if you want, for even better response.

To tune it so low, you might get some port noise, but not too outrageous. This is a computer system, right? And a slight increase in box size leads to less port noise, if you want to get bigger.

Nice deal, I think.

[f4ier]

The room response was an option added by our own member, Serow.

Hi kelticwizard, once again thanks for the vote of confidence on SubSim, but what did you mean by this? Room response plotting has always been a feature of Subwoofer Simulator from day one


Wright, with which part of SubSim did you have trouble while designing your sub? It would help me improve the user interface of SubSim if you could be more specific. I know a number of SubSim users find the interface to be odd at first. While they email me for feature suggestions, no one really comments on the user-interface


Cheers,

Isaac

[mikee12345]

f4ier=

i think that, that member,,just submitted a room gain graph for people to use,thats all\

the user interface is alternative

i like 3db scales with lines going across,it ran slowly on my old stuffed 133mhz so i stayed with winisd.