BillFitzmaurice.info

Hi
From my understanding the low pass limit is relative to the spacing in between the sub. I might be wrong. In the post about sub placement there is not the information about the limit frequency for multiple t30 v-coupled side by side like in the picture.

The minimum frequency is 30Hz.

Sorry my question was not clear... i was thalking of the higher frequency. The limit for t48 is 100hz and 125hz for t39. So my thinking is it must be lower since the gap in between the sub is wider

joblow88 wrote: ↑Sun May 29, 2022 10:10 pm Sorry my question was not clear... i was thalking of the higher frequency. The limit for t48 is 100hz and 125hz for t39. So my thinking is it must be lower since the gap in between the sub is wider

It can be what you want it to be.

The decision isn't necessarily in the subs. It depends on the tops/mains you're using. For example, if you don't put ports in a DR250, then you would crossover more towards 125Hz, because that's what the Dr250's unported are capable of.
But if you put the ports in, then the DR250 tuning goes down to 80Hz, so you can make the subs low pass 100Hz, or lower.

The higher you set a low pass from 100Hz and up in subs, the more "locateable" they become. Below 100Hz, they are always omnidirectional.
Meaning they can be set up where they perform best, not based on what looks good/aesthetics. So wall and corner loading can become valid options for increased sub output.

So, what tops/mains are you using?
edit: not to worry, I see you building Jack15 lites?
Since J15's can do well below 80Hz by themselves, pick somewhere that sounds good to your ears, below 100Hz.

joblow88 wrote: ↑Sun May 29, 2022 9:00 pm Hi
From my understanding the low pass limit is relative to the spacing in between the sub. I might be wrong. In the post about sub placement there is not the information about the limit frequency for multiple t30 v-coupled side by side like in the picture.

Just to straighten you out on this, the lower high pass is about combined mouth area. A pair of any of Bill's sub designs will always have a higher low pass than 4 or more cabs together, as long as the mouths can couple. To further explain, if you have 4 subs, but they are in pairs either side of a stage that is less than 19 yards (for 40Hz) wide, it's arguable you should treat them as one pair in terms of high pass, as they can't mutually couple. It's only when they are all together you can lower the high pass limit, until you get to 4 subs per side more than 19 yards apart.

Hey thx for the reply Grant
My first top will be otop12 j-array in the end.
Im asking because i think i might be able to apply for a grant to build a lot of subs . I was thinking on something like 12 t30 would give us a prety nice sub wall to have 3 sets of 4 v plated side by side...

The value of V plating goes down as the number of cabs goes up. I'd say once you get past four cabs don't bother with it.

Bill Fitzmaurice wrote: ↑Tue May 31, 2022 4:45 pm The value of V plating goes down as the number of cabs goes up. I'd say once you get past four cabs don't bother with it.

That is super interesting... so i could just make a bunch t45 and the result would be the same but easier to carry around.

Yep.

joblow88 wrote: ↑Wed Jun 01, 2022 12:20 pm

Bill Fitzmaurice wrote: ↑Tue May 31, 2022 4:45 pm The value of V plating goes down as the number of cabs goes up. I'd say once you get past four cabs don't bother with it.

That is super interesting... so i could just make a bunch t45 and the result would be the same but easier to carry around.

And if you follow the sub placement sticky whenever you can, wall loading adds +6dB, corner loading +12dB.
Put that into perspective:
A doubling of cabs = +6dB.
So if you had 4 subs and wall loaded them, it would be the same output as 8 subs...