Help needed with Unibox

[infinia]

Somethings to ponder

1) If you are using a passive lowpass filter between the amp and your sub woofer don't forget to add the Rdc of the inductor to unibox. It changes Qts and thus your optimum box calc's.

2) Think about using a highpass filter to limit LF levels where the port/PR unloads the driver (just before Fb). Depending on your sources and content can it be problem.

 

[FSHZ42]

Hi
Tried it with a Dayton 10" PR with added mass of 30 grams. Looks like the optimum design, everything looks much better!

F-3dB is 36 Hz.

Hi infinia, I was looking at the Peak Cone Excursion graph and noticed that you have entered 30 watts for the power. Shouldn't that be 80watts as that subwoofer's nominal power is 80watts?

 

[infinia]

No, they lied.

 

[FSHZ42]

No, they lied.

Could you please explain how they lied?

 

[infinia]

Most woofers run out of Xmax well before they hit the thermal limit.
Take a few from PE catalog and see for yourself. Just one of those things in real life.

 

[FSHZ42]

Most woofers run out of Xmax well before they hit the thermal limit.
Take a few from PE catalog and see for yourself. Just one of those things in real life.

Can you explain how you came up with using 30 watts for calculating in unibox? Or in otherwords, How do I figure out how to do this? That way I will have a better outcome when using unibox.

 

[infinia]

Experience or really just cut and try.

 

[FSHZ42]

Experience or really just cut and try.

It seems that there should be some type of a formula for doing this!

 

[infinia]

see "Hoffman's Iron Law"

"You can have low end extension, high efficiency, or small enclosure size. Pick two."

You picked a small 8 " and low freq. extension so for now you gave up SPL.

edit > Build 4 of them and get some SPL back (figure about increase of 3dB/sub.)

 

[djarchow]

You can put in 80 watts for the power but you will see that the lowest frequency before you exceed excursion of the driver and PR moves up a lot. Setting the power level really just tells you how loud and low you can play the speaker.

Regards,

Dennis

 

[FSHZ42]

Thanks Dennis, Just trying to figure out why and how infinia came up with the 30 watts for nominal power, when the manufacturer's specs say 80 watts?

Emile

 

[djarchow]

Emile,

I am sure he chose a power level that gave a reasonable level of low end extension and output without exceeding excursion.

Again, the power level is completely up to you as the thermal limits(power rating) have nothing at all to do with the sub's mechanical limits in a given enclosure at a given frequency.

You could run 80 watts all day long at 100 Hz through that driver and never hurt it. Try to push 80 watts through at 25 Hz and it would certainly sound bad and probably damage the woofer and or pr.

Dennis

 

[FSHZ42]

So in other words I would have to play around with the wattage for a specific woofer to see what the maximum power would be before the woofer would get damaged? As in excessive excursion for lower frequencies?

 

[djarchow]

Yes.

 

[infinia]

So in other words I would have to play around with the wattage for a specific woofer to see what the maximum power would be before the woofer would get damaged? As in excessive excursion for lower frequencies?

Hi Emile
How is Unibox working for you now? Can you repeat what I did above? Post your result (charts) and I'll even help you if you need it.

PS There are some plate amps in the Market Place Forum you might look at for your subs. From one of the speaker designers at NHT named J. Hindley.

 

[FSHZ42]

Hi Emile
How is Unibox working for you now? Can you repeat what I did above? Post your result (charts) and I'll even help you if you need it.

PS There are some plate amps in the Market Place Forum you might look at for your subs. From one of the speaker designers at NHT named J. Hindley.

Hi Infinia, Still tinkering with it a little. I have been a little busy with other things at the moment, but I will post something if I need some more help. Once again, Thanks to all for the additional help!

Emile