trasfer function graph

[nestorberrios]

hi, im currently working on a the mid-bass component in a 3-way speaker system. im using a program called winISD. im having trouble chossing witch alinement to go with. im also having trouble reading the trasfer function graph. i dont realy know waht to look for.

Here are the specs of the driver (selenium 8W4P)
VCdia: 1.81" *Le: 0.79 mH *Nominal impedance: 8 ohms *Re: 5.2 ohms *Frequency response: 100-6,500 Hz *Magnet weight: 44 oz. *Fs: 107 Hz *SPL: 96 dB 1W/1m *Vas: 0.32 cu. ft. *Qms: 13.2 *Qes: 0.74 *Qts: 0.70

project one is QB3 Quasi-butterworth vented enclosure.Vol- 1.058 tunning freq-59.4
Project two is c4/sc4(sub)chebyshev vented enclosure Vol-1.737 tunnng freq-64.24Hz
project three is BB4/SBB4 (Super)boom box Vented enclosure Vol-0.756 tunning freq-107.04

which one looks like the best for this driver

<A HREF="http://www.putfile.com/nesgt500kr/images/">http://www.putfile.com/nesgt500kr/images/</A>

[JustinG]

> hi, im currently working on a the mid-bass
> component in a 3-way speaker system. im
> using a program called winISD. im having
> trouble chossing witch alinement to go with.
> im also having trouble reading the trasfer
> function graph. i dont realy know waht to
> look for.

> Here are the specs of the driver (selenium
> 8W4P)
> VCdia: 1.81" *Le: 0.79 mH *Nominal
> impedance: 8 ohms *Re: 5.2 ohms *Frequency
> response: 100-6,500 Hz *Magnet weight: 44
> oz. *Fs: 107 Hz *SPL: 96 dB 1W/1m *Vas: 0.32
> cu. ft. *Qms: 13.2 *Qes: 0.74 *Qts: 0.70

> project one is QB3 Quasi-butterworth vented
> enclosure.Vol- 1.058 tunning freq-59.4
> Project two is c4/sc4(sub)chebyshev vented
> enclosure Vol-1.737 tunnng freq-64.24Hz
> project three is BB4/SBB4 (Super)boom box
> Vented enclosure Vol-0.756 tunning
> freq-107.04

> which one looks like the best for this
> driver

> <A HREF="http://www.putfile.com/nesgt500kr/images/">http://www.putfile.com/nesgt500kr/images/</A>

None really look all that great, you don't really want any of those humps before the graph falls off. This will probably lead to some characteristics of "one note bass" where you get a spike in the response aroud the tuning frequency. Try a bigger volume on "Project 2" and see if that flattens things out.

What is the application you are using these for? You say "mid-bass" so is this going to be paired with a larger woofer for the actual lows, or are you using this as the low end in the speaker?

The driver you picked is more of a midrange driver (Fs of 100 Hz). It would probably work fine in a sealed enclosure if used as a midrange. But, if you are using this for the lows try my suggestion above.

[Chris Roemer]

> hi, im currently working on a the mid-bass
> component in a 3-way speaker system. im
> using a program called winISD. im having
> trouble chossing witch alinement to go with.
> im also having trouble reading the trasfer
> function graph. i dont realy know waht to
> look for.

> Here are the specs of the driver (selenium
> 8W4P)
> VCdia: 1.81" *Le: 0.79 mH *Nominal
> impedance: 8 ohms *Re: 5.2 ohms *Frequency
> response: 100-6,500 Hz *Magnet weight: 44
> oz. *Fs: 107 Hz *SPL: 96 dB 1W/1m *Vas: 0.32
> cu. ft. *Qms: 13.2 *Qes: 0.74 *Qts: 0.70

> project one is QB3 Quasi-butterworth vented
> enclosure.Vol- 1.058 tunning freq-59.4
> Project two is c4/sc4(sub)chebyshev vented
> enclosure Vol-1.737 tunnng freq-64.24Hz
> project three is BB4/SBB4 (Super)boom box
> Vented enclosure Vol-0.756 tunning
> freq-107.04

> which one looks like the best for this
> driver

> <A HREF="http://www.putfile.com/nesgt500kr/images/">http://www.putfile.com/nesgt500kr/images/</A>

Given its Qts value of 0.70, this driver is best suited for a closed box (which precludes its use as a woofer).

For vented alignments, look for drivers with Qts values in the range of 0.30 to 0.43 or so. They'll "roll off" without that characteristic hump you're getting. For bass, shoot for an F3 of around 50 Hz. For "deep" bass, I like to reach mid 30's (if not lower).

[dthomas]

> hi, im currently working on a the mid-bass
> component in a 3-way speaker system. im
> using a program called winISD. im having
> trouble chossing witch alinement to go with.
> im also having trouble reading the trasfer
> function graph. i dont realy know waht to
> look for.

> Here are the specs of the driver (selenium
> 8W4P)
> VCdia: 1.81" *Le: 0.79 mH *Nominal
> impedance: 8 ohms *Re: 5.2 ohms *Frequency
> response: 100-6,500 Hz *Magnet weight: 44
> oz. *Fs: 107 Hz *SPL: 96 dB 1W/1m *Vas: 0.32
> cu. ft. *Qms: 13.2 *Qes: 0.74 *Qts: 0.70

> project one is QB3 Quasi-butterworth vented
> enclosure.Vol- 1.058 tunning freq-59.4
> Project two is c4/sc4(sub)chebyshev vented
> enclosure Vol-1.737 tunnng freq-64.24Hz
> project three is BB4/SBB4 (Super)boom box
> Vented enclosure Vol-0.756 tunning
> freq-107.04

> which one looks like the best for this
> driver

> <A HREF="http://www.putfile.com/nesgt500kr/images/">http://www.putfile.com/nesgt500kr/images/</A>

Since you say a midwoofer in a 3 way I assume this driver will be in a bandpass filter. At what frequency do you intend to cross the mid woofer? If it is in 100Hz to 200 range you could choose the alignment with the higher tuning and get the results I think you are looking for. Personally I would tune at around fs for this situation. If it is a higher frequency in the 250 to 500Hz range you might want to look at doing a sealed alignment. Though tuning at around fs would not have any ill effects. The lower tunings would not offer any benefit.

Dave

[gordoncalder]

Hi,

I'm not all that familiar with winisid, but I think it's more for modelling woofers than mid-ranges, since the lower end of a midrange will be rolled-off electrically by the crossover. The driver you have there might be better in a sealed box. Have you tried the tools at the frd consortium? If you down-load unibox there, it might allow you to try more box-models with that driver (and it has easier to read graphs too). Give that a try and see what you get.

Gordon