Bill can you do this?? Sub design question D&B Audio B4

[smpzpirate]

Hi all,
Please watch this talk through of the design of the D&B Audio B4 which I think is a real innovation regarding subs and certainly for the kind of setup I am very much interested in:

http://www.youtube.com/watch?v=OxPz0_dF ... ata_player
http://www.youtube.com/watch?v=Tg788_9m ... ure=relmfu

I heard and used (played through with the band) a DB Audio rig which included a pair of these in the traditional top hat / mid high on pole from sub this week and as a small system it was just incredible with chest thumping bass throughout the room which was essentially a large square venue with capacity for 400 plus I'd say space wise.

The floor was not a hollow and the subs were not wall / boundary loaded just a simple 2 top boxes and 2 subs either side of the stage and the subs were maybe a similar size to a QSC K-Sub.

Simply, the sound was awesome and full with that chest thump without being over powering. It wasn't intrusive to the neighbourhood outside or anything and these were 2 subs placed like you are not supposed to place them in the room.

Incidentally, D&B usually uses heavy processing on their cabs to deal with some issues but on this one they claim that they used 'PSP' rather than 'DSP' that is; Plywood signal processing! In other words the box is the key with another speaker in there carefully designed to deal with the usual problems with subs. They claim (and it does) that the box will run off a single amp channel too so if you needed more the footprint and power consumption remains low.

I know that the main reason I have not committed to a build despite owning the plans for quite some time is that for most of my gigs it is impractical and unsightly for us to wall / boundary load subs no doubt disturbing neighbours and for instance hotel guests or likewise V-coupling in front of the band would also be intrusive visually unless we had a stage in most venues which we do not.

Also, a pair of these subs will go in your average estate car / station wagon.

So I was hoping Bill might investigate this and analyse the design perhaps with a view to making an addition to the line?

My warmest regards and congratulations on your website in any case and I read other people's experiences with great interest. Please understand that I have the highest respect for the designs available already but this video and my experience this week has knocked me out with those B4 speakers!

.....The only problem possibly is that it looks like they are custom drivers according to the 2nd video.

[Bill Fitzmaurice]

It's a cardioid sub. Typically cardioid subs use separate boxes rather than all in one, otherwise the technology is well known, a google search will find many examples. It's beneficial when the sub cannot be placed close to the rear wall, especially outdoors, where there is no rear wall and you want to keep radiation directional in the lows. Any subs can be used, you just need twice as many of them, and the amps to drive them.

[smpzpirate]

Thanks very for your reply Bill. Actually this one is a new (ish) model and is supposed to fix the issues like the amount of amps and subs etc.

The guy addresses this in the video compared to the misgivings of a normal cardioid sub showing diagrams of potential deployment against a standard cardioid sub as the B4 will run off a single amp channel and needs only a crossover to get it to do it's job due to their 'PSP' rather than digital time aligning etc. i.e. maybe equal number of subs needed but half as many amps.

Interestingly though, this type of sub would work so well in many situations like you say for example; outdoors. To my mind that makes a lot of sense rather than having to think about putting them against walls etc and keeps everything neat and tidy whilst getting optimal results... I couldn't believe the chest thump coming from these 2 boxes and a speaker each on top - I went in thinking, 'how is that gonna work'? I was a big powerful sound from a 4 box setup and although you might get a better result outdoors with another 2 subs, you could easily do most events we would need to do for example as a 5 piece cover band with minimal fuss and with just 2 amps with the 4 box rig.

What I would like to do is do my build of the omni tops or perhaps one of the DR series and have equally manageable boxes like the B4 below. I know you are the man for the job though so I much appreciate your comments and perhaps you'll consider a design like this but I understand that this could be an issue if it is a specialist driver to achieve it! I would be quite happy though if I needed an amp (both channels) to power each box considering the performance you get from your other designs. For me though there are practicality issues with building the T39 or T48s and also the convenience of being able to set up in a hurry - no coupling needed etc.

Much appreciate your thoughts

[Bill Fitzmaurice]

Much appreciate your thoughts

I'll consider it, but doubt it, as it doesn't lend itself to a horn loaded cab.

[Gregory East]

The custom drivers required to do away with processing throw a spanner in the DIY model.

[john]

db audio is a smart company thay ware yousing bbe drivers i ran a db audio sistem in tampa florida it was 1 of the best i have run to date so i do beleve what thay say... tom danley has some cool stuff over at danley sound labs i got to run sound on some td1s one time its a gr8 speakers he is one of the best on speaker bilding also . i had 6 lab horns at one time thay sound varry nice but its a big box 250pounds uuuuu moveing thim is no fun . i would love to hear some tuba some time

[john]

bbs driveers sorry

[Grant Bunter]

smpzpirate:
I'm sure they sound great, but what do 2 subs and 2 tops cost?
I can't find much info on the B4 series price wise, but other d&b series cabs seem pretty expensive.
So much so that I built all my BFM FOH and monitors and everything else I purchased for the entire rig for (a lot) less than the local retail price of 2 D6 cabs.
Having done that, I maintain that, bang for buck, Bill's designs are unbeatable in both price and performance.

If you have money to burn, go for it!


John:
Same deal. Bang for buck, look here:
http://billfitzmaurice.info/forum/viewt ... f=12&t=440

About 3/4 of the way down the page you can see 2 x T48's giving a lab sub more than a tussle. The T48 can be handled by one person, costs heaps less.

Or Lab sub V T60:
http://billfitzmaurice.info/forum/viewt ... 12&t=11124

T60 is as loud but lower, price is way down...

[john]

i have the plans i got off bill for the t60 but its just to big after i started thanking about it i bet it 1 of the best .i have 8 new cabs i just made my self i would post a picher but dont no how 4 new tops and for new mon if some one could tell me how to put up picher i would post thim so you could see how i made thim i have a 12 inch round wave gide and a 15 delta pro with a bNc de 250 comp driver in thim my wege are 12 inch delta pro with bNc de250 with a round 8inch wave gide so im just trying to figer out subs at this time john and yes the dNb stuff is a lot of $$$$$$$$$$ the cabs your looking at just a gess 4000 to 5000 each i could be off but not by much

[john]

im thanking about the t48s lol

[smpzpirate]

Hi,
Thanks for your comments.

With regards to system costs - yes, D&B stuff is pretty expensive but what they're effectively saying is that with the B4 they have taken away the need for DSP to control the 2 drivers in that particular cab. What struck me though was the authority of the system including the bottom end extended throughout the room without the need for placing the subs on boundary walls and the like or coupling them and of course the size.

For me, the size of the Titan cabs causes a few problems both in transport and in presentation in the kind of typical gigs I do. To me it seems less than ideal to have to wall load or couple them in the middle of the performance area particularly due to the size. For us it is important that the performance area remains just that - a performance area. We have quite enough separating us from the audience as it is without a pair of subs laying in the middle of the floor in front of us - we already have a pedalboard, couple of wedge monitors and mic stands etc. These are all things that stop you being able to connect with your audience or at least get in the way.

Many times we have very little time to get in and set up at a venue and either you can't place near boundaries due to restricted room or just we haven't the time to get things in an ideal situation and it's just easier to plonk the gear - tops on subs either side of the band. I just want to get in, do the job and get out again richer than I went in.

My point is that this B4 has some serious plus points but again, if it can't be done without custom drivers then I guess it's either get the b4 subs or go back to juggling less than ideal set ups.

As for the cost, yes they're probably silly money but then I refer you to the title of the thread.

[Charles Warwick]

Haha, PSP, plywood signal processing. Pretty good talk.

[smpzpirate]

...I think that's great.

[Charles Warwick]

My point is that this B4 has some serious plus points but again, if it can't be done without custom drivers then I guess it's either get the b4 subs or go back to juggling less than ideal set ups.

That seems about right, in the talk he did seem to imply that the driver used in the rear facing portion was especially odd, likely designed to change phase where the designer at D&B couldn't tune the ports' response out of phase to the front radiating driver. I'm not terribly familiar with the cardioid designs, but in the diagram that was put up it looked like a 6th order bandpass at the back of a regular vented woofer...It does make you want to go experiment with it, but it'd be hard to make good progress without fully understanding the theory.

If the T39's size is an issue consider the T24. Depending on your output needs, it's still a nice sub.

[Charles Warwick]

Here's decent article: http://www.prosoundweb.com/article/real ... ubwoofers/
http://www.prosoundweb.com/article/tech ... er_arrays/

Good quote from it:

While most cardioid subs are slightly larger than conventional subs, due to their rear-firing transducers, they often take less space and effort than building cardioid arrays.

The B4 is ~ 19 x 23 x 32 (8.1 cubic feet) which is bigger than a T24, and while I'm sure the directivity is better than the T24 but for many smaller gigs, you don't need the extra output and control the cardioid sub offers as long as you're within a 1/4 wavelength of a wall.