fsp small combo

ive done a few virtual test on drivers the box volume used was 31lt, with 2 ports 80mm by 120mm. input volume 700watts. Driver in the test are......

2 x 10MD26 B&C

2 x 10NDA610 18Sound

2 x 10NDL64 B&C

2 x 10NMB4200 18Sound

Test results below.......

Another question is there a formula to work out the perfect volume needed in lt for the box and what port size best......

Formulas do exist to calculate theoretical ideal values but in reality there is a wide range which will actually work and you are governed by what is an actual sensible sized box. For a mid-top such as this, the tuning is in some ways not as critical as for a bass cab because the tuning will be below the crossover point.

I would maintain that the first two drivers on your list are designed primarily for horn loaded midrange sections from 200-250Hz upwards and would not integrate well into the system. If we are aiming for a crossover point at say 120Hz, I would want the mid top to be useable (not necessarily maintain full efficiency) down to a bit below 100Hz in order to get a nice crossover between it and the bass cab.

Is that BassBox Pro? I don't know the software but is there an option for an actual SPL graph rather than Normalised Amplitude because the normalising means you can't compare the relative efficiency different drivers on that graph. Also note that the SPL for the 10NMB420 will appear lower because the T/S parameters given are for the 16Ohm version, not the 8Ohm.

Yes bassbox pro illhave a look and print that page off i agree in not using the the first two on the list.

chris this is all the plots so far....

You could probably have omitted a few of those and made them a big bigger! The custom amplitude response is the main one we're interested in at the moment.

I am really liking the look of the 10NMB420. I haven't used that one but I built some cabs for a mate using the 8NMB420 which is a really nice driver. The 10" looks just to be a scaled up version.

im liking the plots too ive started to adjust the box and port settings on each driver and the 420 is coming out on top so far it has the flattest reponse. ill post new plots...

updated virtual test settings.....

You may be aware of this but simulations such as this are only valid up to a few hundred Hz. Therefore you can ignore the fact that the other three drivers seem to have a a much higher SPL in the 500Hz+ region. I should do some simulations myself really. Btw, you should be tuning the boxes at or above the driver resonant frequency. For this type of mid-top I would imagine a tuning in the 70Hz region.

ok ive reset the box to 70hz and ignored the 1st 2 drivers that way we can consontrate on the two relevant ones.....