SLA DJ/Pro style

[bzb]

Regarding weight, I'm expecting the cabs to be right around 30 lbs finished. The 4-driver version which I will build should come in right at 24 lbs. While I would love to have 18 pounders like the EV ZX1-90s I just returned... I think I'll take the benefits for the slight increase in weight.

Alphalites will only save you 2 lbs per driver. 12 additional lbs is your make or break it point? (although if built with the Alphalites... it *would* bring it closer to the 18 lb point... HMMMM)

[guitarhiker]

In regard to the weight issue I just want to stay as light as possible as I usually work with a small ensemble that is mostly middle-school girls in the summer and I want them to be able to take ownership of their sound setup. As you were saying with the alphalites you gain a 2lb weight advantage per driver which with 6 drivers would be 12 lbs. Being a backpacker that counts ounces that is pretty significant. (I just can't carry the 60lb pack anymore like I could when I was twenty something!)

Any thoughts on the Aura neodymium closeouts on PE? Very good low end for a 6" driver and a respectable 91db spl and 50watt rms. Not a pro driver as such but they are under a pound each! Only $10 each in quantity of 4+.

http://www.parts-express.com/pe/pshowde ... er=299-030

[Benj Ross]

I would think that the aura would do fine. Bill will need to weigh in with the final word on that. Or just get the plans and see what the driver specs are, when they are available.

Cheers
Benj

[Bill Fitzmaurice]

I would think that the aura would do fine. Bill will need to weigh in with the final word on that. Or just get the plans and see what the driver specs are, when they are available.

Cheers
Benj

The recommended driver for the SLA Pro is the Eminence Alpha 6. Other drivers with similar T/S specs and SPL charts will work.

[guitarhiker]

Got the SLA pro plans today as well as the TLAH for comparison. I think what I need and intend to build is a bit in-between the two so I need a couple of clarifications. I want a cab that is floor standing as apposed to pole mounted, but 60" in the max height I can easily haul in my vehicle and I want to keep it light. There was mention in another post of adding another tweeter to the TLAH pro which Bill responded would actually reduce vertical dispersion. I'm thinking I will use 6 or 8 6in drivers in a 60" cab with the melded array. As I mentioned earlier my goal is max horizontal dispersion. I realize the other post was talking about tweeters not mid basses. What I am wondering is if adding a driver vertically reduces vertical dispersion does it increase horizontal dispersion? Will the TLAH have wider dispersion than the SLA?

I like the looks and idea of the melded piezo array which looks fairly easy to do. My question there is for a cabinet size in between the SLA pro and the TLAH pro would the melded 6 piezo or 8 piezo be better or will it make that much difference? Just wondering what kind of dispersion I will get with that setup as my goal is more toward the 120 degree mark.

Lastly, in building something in between the two I'm wondering about porting/tuning. The SLA's handle/ports seem pretty basic so I'm wondering if using more/different drivers what changes would be needed as I am still leaning toward the 6" Aura drivers for the sake of weight. The Qts and Vas is very close but the Fs is actually much lower than the alpha 8 -- the Vas on the Alpha 6 as speced for the SLA is much smaller. I guess I can use WinISD software to calculate a normal bass reflex style tuned port, although the specs of the Aura indicate I could even do a sealed cab and have an F3 of 70-75 depending on box size. Conversely, I don't quite grasp the bottom opening of the trapezoidal free standing TLAH as far as tuning. Is the TLAH shape and opening adaptable enough for changes in number and size of drivers? I remember seeing one post where using a different driver with different specs cause some negative effect on the bass output. My hunch is I would be better off building a variation of a short TLAH than an expanded SLA as the specs are closer except Fs but I don't want to loose bass by mismatching the aura drivers with that design as I better understand how to adapt the more normal SLA type box/ports.

[Bill Fitzmaurice]

Got the SLA pro plans today as well as the TLAH for comparison. I think what I need and intend to build is a bit in-between the two so I need a couple of clarifications. I want a cab that is floor standing as apposed to pole mounted, but 60" in the max height I can easily haul in my vehicle and I want to keep it light.

I see no reason for a cab that size for your application. If you really need a cab that high, which could drive stadiums without PA support, build two SLA Pro and stack them. You could then set them off-axis in a spiral configuration for the widest possible dispersion.

[guitarhiker]

The point of a cab that high is to only have one thing to carry -- no stand and only one speaker cabinet -- that will have the drivers at a height that will cover the audience. With a Dayton plate amp it literally could be all you carry. I don't quite understand the filling a stadium comment -- then what is the point of using TLAH pro's in small to midsize sanctuary spaces which seems to be the most common use in the posts? By the same logic isn't that overkill? Not meaning to be impertinent but it doesn't all seem to jive.

[Bill Fitzmaurice]

what is the point of using TLAH pro's in small to midsize sanctuary spaces which seems to be the most common use in the posts? By the same logic isn't that overkill? Not meaning to be impertinent but it doesn't all seem to jive.

That's for pushing an entire band, not one guitar and a mic or two.

[bzb]

Bill, since the piezos are sideways in the Pro, what type of horizontal dispersion are we looking at?

And is it correct to assume that the 6-piezo version just smooths the high frequency response?

[Bill Fitzmaurice]

Bill, since the piezos are sideways in the Pro, what type of horizontal dispersion are we looking at?

90 degrees. I've measured the 1016 and there's no significant difference with dispersion on either axis.

And is it correct to assume that the 6-piezo version just smooths the high frequency response?

Yes, by eliminating frames between the individual mouths.

[guitarhiker]

In regard to the piezo array -- if that gives 90 degree dispersion is there another option for increasing that other than the V array which wouldn't work in this type cab (and other than stacking two SLA's with a little rotation as mentioned previously)?

[Bill Fitzmaurice]

In regard to the piezo array -- if that gives 90 degree dispersion is there another option for increasing that other than the V array which wouldn't work in this type cab (and other than stacking two SLA's with a little rotation as mentioned previously)?

Not really, and the woofer dispersion angle won't be more than 90 degrees through most of their range anyway, so going wider than that with the tweeters won't be of any benefit.

[Tom Smit]

Does "most of their range" mean up to approx. 4k hz? If so, is this what differentiates them from OTops, Jacks, and O10? I think I have it figured out...in these cases the piezos run up from approx 2k Hz.

[guitarhiker]

Bill,
Okay . . . now I'm really confused. You state above that the mid bass drivers in the SLA/TLAH won't disperse wider than 90 degrees which matches the piezo array. I thought the purpose of a line array was to get wider dispersion and many standard pro audio cabinets are rated at 90 degrees. The Bose Panary MA12 according to their white paper has a dispersion approaching 160 degrees. Now I know Bose tends to overstate things, but I do know they are much wider than 90 degrees. I assume the smaller drivers with a cabinet front not much wider than the driver itself helps with that dispersion, which makes me wonder if I should follow that logic in what I am wanting to build for increased dispersion -- larger number of smaller full range drivers. I am also guessing from what has been stated earlier here as well as various white-papers from Bose that more drivers in the array helps widen the horizontal and decrease the vertical. Of course the MA12's roll off an octave higher than what I want, but maybe there is a middle ground somewhere.

[Bill Fitzmaurice]

I thought the purpose of a line array was to get wider dispersion .

It is not. In a line array the horizontal dispersion of the array is the same as the horizontal dispersion of one driver. The problem with traditional 'cluster array' PA is that when cabs are placed side by side the horizontal dispersion is lessened, and comb filtering is introduced. Line array cabs allow vertical stacking, eliminating those problems.
As for the Bose claims, look at their polar charts at 4kHz and higher. That's not 160 degree dispersion.