BillFitzmaurice.info

This is a discussion I’m having with a guy on Facebook,he insists that the V plate allows for lowering of the hi pass,I’m telling him it only adds 3 dB of sensitivity and extension is not affected and “stacking” the subs is what allows us to lower the hi pass,I even copied and pasted Bills description of the V plate yet this guy insists he knows Bills designs better than Bill.

Here's how to find out. Run an impedance sweep of the stack before and after placement of the v-plate. If his statement holds water, one would see a shift of the impedance peak to the left, just as with the addition of cabs. I haven't done this myself, but with the designs where the baffle + v plate contributes to a decent percentage of path length (ie. Titans), it's a possibility.

Nowhere in any of the plans does it say that AFAIK.
The High pass is dependant on cab count. 4 or less is one value, more than 4 another, lower value.
Adding a V plate doesn't make 2 cabs become 4.
You're correct in saying using a V plate can add up to 3 dB in the lower part of output passband as far as everything I have seen in the forum.

My answer to the larger mouth area being a defining limit to both HP and an increase in sensitivity is this: It has a finite point, where it makes no significant difference to either output, sensitivity and never HP, to build a cab with a certain diameter driver beyond X value. eg 10" driver in a T39 maximum of 20" wide.

There have been varying discussions over time, but, generally, anyone who is looking for a lowering of high pass by using a V plate is looking for a free lunch, instead of building the right cab in the first place. eg They built a pair of T39's when they could have had a lower high pass with a pair of T48's.

Do they think that 2 pairs of cabs (+/- V plate), more than 2 wavelengths apart, is still 4 cabs for HP purposes?
That's not how I read it.
The lower HP for 4 or more cabs is also dependant upon coupling.

Don't argue with the person. Don't feel pressured to agree if the discussion is beyond your understanding. Just let them blow their gear up.

djtrumptight wrote: ↑Sun Jan 03, 2021 11:10 pm This is a discussion I’m having with a guy on Facebook,he insists that the V plate allows for lowering of the hi pass,I’m telling him it only adds 3 dB of sensitivity and extension is not affected and “stacking” the subs is what allows us to lower the hi pass,I even copied and pasted Bills description of the V plate yet this guy insists he knows Bills designs better than Bill.

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Happy New Year DJ Trumptight . Good to see you around.

As far as what's been written by Bill in the plans, the placement thread, and the SPL Charts section... I think you're right. He has said over the years that each doubling of cabs extends the response shoulder lower and flattens response. No mention, that I can recall, about the addition of a v-plate also gleaming the same benefits.

However, I think horn theory goes much deeper than what's discussed on this particular site. It seems Bill has chosen to keep his plans and information around them as simple to understand as possible.

It could be that there's more to it. Makes sense to me that adding a v-plate extends the horn length and would therefore play lower than without. But, I have no idea whether that pans out into anything real in actual practice or not. I'm curious about what little tidbits of information this discussion will turn up.

Grant,I think we are on the same page lol

Radian wrote: ↑Sun Jan 03, 2021 11:37 pm Here's how to find out. Run an impedance sweep of the stack before and after placement of the v-plate. If his statement holds water, one would see a shift of the impedance peak to the left, just as with the addition of cabs. I haven't done this myself, but with the designs where the baffle + v plate contributes to a decent percentage of path length (ie. Titans), it's a possibility.

This guy doesn’t have any Titans,he’s speaking on basic horn theory that may not apply to Titans

Arrr goodo,
You might like to check they understand that extension and a lowering of high pass are not the same thing...

The V Plate does reduce driver excursion and increase sensitivity at the lower end of the pass band, so it also allows lowering the high pass filter, but only by maybe 3Hz, which isn't worth doing.

So Bill,are u saying a stack of 4 v plated T-48’s can safely be hi passed at 32hz instead of 35hz but the difference gained wouldn’t be much ?

Yes and yes. You would not be able to hear it.