Unibox Help

[todd95008]

I'm using Unibox to tune a ported/vented design and want to get more info/detailed descriptions on exactly what to enter for the following:
Physical Vb
Aborption Qa

The design is with a 38 a Liter box with with 3/4" Sonic barrier on 90% of the walls and additional Acoustistuff both behind the woofers and at the the top and bottom of the (38 inch tall) exclosure.

The note for Physical Vb states: "Add volume displaced by driver, port and bracing to get real construction volume".
I would think they mean subtract driver, port & bracing ??
What about volume dispaced by dampening material ??

I have had Qa entered @ 35 but don't know how close to real world this is ??

Can someone who has a good understanding of these parameters please respond....

Thanks Todd

[augerpro]

That's a good question. I've yet to find good answer about this. For example Unibox has defaults of Ql=15 and Qp=140 while Soundeasy uses Qb (I think the same variable as Ql in unibox) =10 and Qp=30.

Little guidance is given in unibox about the values but not much. All SE says is Ql of 10 is typical of small enclosures and larger ones should use lower values. Implying 10 is low leakage. Unibox portrays this value as the worst case, "minor leaks". Having done some small enclosures and comparing the measured Z to the calculated Z leads me to think 10 is probably close, maybe 15 with a really tight box. Big boxes probably would be fairly low in the real world.

Qp seems to have a small effect from one extreme to the other in unibox. I'll have to look at the SE manual again but I don't remember seeing much guidance about Qp. From this I wouldn't think you need to be to concerned, although people seem to think this makes a big difference in the real world, so who knows.

Qa seems to have a large effect on response. Wall coverings seem to dominate the effect for all but the heaviest fill so I think in your case just using the Qa for "walls covered" is probably close enough.

[norcad]

The note for Physical Vb states: "Add volume displaced by driver, port and bracing to get real construction volume".
I would think they mean subtract driver, port & bracing ??
What about volume dispaced by dampening material ??

Thanks Todd

Hello Todd
Vb is the Volume_box, and this is the volume "seen" by the driver. So its correct that you should ADD the volume displaced by driver, port and bracing when you construct the box. After you have the driver, port and bracing in the box, the volume should be = Vb. OK?

The dampening material dont displace any volume, it adds volume, when we talk about volume that the driver "sees" or "feel". But you dont have to think about that, because this is the "Absorption, Qa" parameter, that you choose with "Damping"

Norcad

[todd95008]

Hello Todd
Vb is the Volume_box, and this is the volume "seen" by the driver. So its correct that you should ADD the volume displaced by driver, port and bracing when you construct the box. After you have the driver, port and bracing in the box, the volume should be = Vb. OK?

The dampening material dont displace any volume, it adds volume, when we talk about volume that the driver "sees" or "feel". But you dont have to think about that, because this is the "Absorption, Qa" parameter, that you choose with "Damping"

Norcad

O.K. but in my case I have a 38 liter box already built so the real volume has the drivers, port & bracing subtracted for "Physical VB" entry. Correct ??

Yes, I now understand the Qa parameter and will keep it between 20-40. Someone sugested that I measure the impeadance curve and change Qa until Unibox matches the real worrd and then I can get a real number for the Sonic barrier & stuffing I used.

Thanks For the reply !!
Todd

[Paul H]

O.K. but in my case I have a 38 liter box already built so the real volume has the drivers, port & bracing subtracted for "Physical VB" entry. Correct ??


Thanks For the reply !!
Todd

Correct