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Old 7th August 2010, 09:18 AM   #1
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Default PA Speaker Project [Newbie alert]

Hey everyone, I've been lurking these boards for a while now and learning quite a bit, and when this popped up I thought I'd seek out some knowledge from here.

Long story short, our band has a very DIY mentality, and since we're making 2x12 guitar cabs, we figured we'd make a pair of PA Speakers for vocals to run through. We'd be using these speakers at Basement shows, small venues, and so on.

I'm looking at these woofers:
New 15" Pro Replacement Raw Woofers Subs DJ PA PP15N on eBay.ca (item 250668291074 end time 16-Aug-10 19:46:33 EDT)

Plenty of watts and a high SPL so it should be good.

Question is, what type of tweeters should I be looking at? I don't know much about them, and I just want a simple 2-Way speaker that'll sound decent and loud.

Also, crossovers seem to be the bane of many peoples existence; would I be needing one? I don't know much about them either, apart from splitting the High and Low frequencies.

Help is much appreciated!
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Old 7th August 2010, 01:43 PM   #2
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I do not see the TS parameters for those woofers, you may get lucky with a box but unless you can test them it will be a crapshoot with the tuning.

What amp are you using?
How many people do you normally play for?

Commercial Pro sound boxes are hard for the DIY'ers to compete with when you add up the cost of X-overs, (you will need), grills, horn flares, etc. You may want to visit the Pro sound web forums and look at Bill Fitzmaurice designs before you start.
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Old 7th August 2010, 01:52 PM   #3
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Hi,

If you want good clarity in vocal range, forget 15" two way (unless you're willing to pair it with $$$ compression driver and cut around or below 1 kHz). If it's for vocals only, you don't need to worry about anything below 100 Hz anyway, and two 8" or 10" drivers sound so much better in the midrange and you can cross around 2,5...3 kHz and 2...2,5 kHz accordingly and therefore use much cheaper and smaller compression driver and horn. If you later plan to put drums and bass through PA just add some 15" or 18" subs and you've got a loud and good sounding rig. As for compression drivers, BMS 4538 or 4524 on 18sound XT1086 horn would be good. For 8-inchers I can recommend Eminence Beta-8 - cheap but really good in the midrange and handles a ton of power. Two of these should get you in the 124 dB area, just like one 15" would. About good 10" I am not so knowledgeable though (my favourite sizes for midrange are 6,5" and 8"), but 18sound 10W400 for example looks very good.
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Old 7th August 2010, 02:20 PM   #4
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Quote:
Originally Posted by mr. doom View Post
I do not see the TS parameters for those woofers, you may get lucky with a box but unless you can test them it will be a crapshoot with the tuning.
That.

Quote:
Commercial Pro sound boxes are hard for the DIY'ers to compete with when you add up the cost of X-overs, (you will need), grills, horn flares, etc. You may want to visit the Pro sound web forums and look at Bill Fitzmaurice designs before you start.
I disagree - decent commercial speakers are all around and above 1000$ per box - cheap stuff like JBL JRX or Mackie are not that good. Loud, yes, but nasty, especially in the treble. You can do so much better yourself with 1000$.

I also don't like Bill Fitzmaurice's designs, advanced woodwork with cheap drivers (and piezos! dozens of them!) is not my cup of tea (although I like cheap Eminence 6,5" and 8" drivers very much, I'm not a fan of most of their bigger models).

As for crossover, simple 2. order and L-pad for the horn would do it, I'm sure we can help you with that if you have chosen the drivers. Also there are a lot of x-over calculators on the net.
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Old 7th August 2010, 02:22 PM   #5
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Oops, I should have specified the power amp.

It's a friends' QSC; it runs 300W X 2 @ 4 ohms and 200W X 2 @ 8 ohms.

We play to around 50-100 in a really small basement. There aren't any TS Parameters, but the dealer is quite respectable, and if they don't sound good they take returns within the 30 days. I know there are audio geniuses on the forum, and I don't mean any offense, but we really don't need a super professional sounding thing. We're in a hardcore band, and the vocals are "dirty" and yelled out...there's no real singing.

@Technofreak: Yeah I figured 15" wouldn't be ideal, but I should've mentioned that we would like to run some guitars/drums through the speakers as well, not too much, just a little, and I've heard whole bands go through Yorkville NX750p's, which have a 15" woofer, and they sound great.

I've been looking into compression drivers, but what about Piezo drivers?

Tyler from the website recommended these HF drivers:
1 Pr. Replacement for Motorola KSN1188A Tweeter Drivers on eBay.ca (item 330450105616 end time 08-Aug-10 20:04:37 EDT)

They seem pretty decent, and with a lower SPL rating and Watts, my limited knowledge tells me they wouldn't be too overpowering?

Also, for crossovers, are there places I can buy them? Cause I don't know how to/if I have the ability to properly make one..
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Old 7th August 2010, 02:30 PM   #6
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Quote:
Originally Posted by mr. doom View Post
I do not see the TS parameters for those woofers, you may get lucky with a box but unless you can test them it will be a crapshoot with the tuning.
Do you mean get lucky with the woofer, or get lucky with building the cab?
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Old 7th August 2010, 03:49 PM   #7
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Well after a lot of looking into, I found the TS Parameters:




Parameter
Value
Unit/Notes
Effective piston area (Sd)
872.9
cm2
Free air resonance (Fs)
46.7
Hz
DC resistance (Re)
5.5
Ω
Mechanical Q factor (Qms)
11.25
Electrical Q factor (Qes)
.37
Total Q factor (Qts)
.36
Voice coil inductance (Le)
141.2
mH/milli-Henrys
Equivalent air volume (Vas)
141.2
Liters
Moving mass (Mms)
88.2
Grams/Mmd + air load mass
Suspension compliance (Cms)
131.92
M/N/micro-Meters per Newton
Force factor (Bl)
19.49
Tm/Tesla-Meters
Sensitivity (SPLref)
99.4
dB/reference 8Ω/2.83Vrms
I don't know much about them/understand them at all but maybe it'll help with something?
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Old 7th August 2010, 04:40 PM   #8
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The parameters look OK, should work OK in this cab: Speakerplans.com.

Forget piezos if you want the rig sounding any good. They also tend to burn easily. As mentioned above, go for BMS - 4554 is reasonably priced and mated to 18sound XT1464 horn can be crossed low enough to mate with 15". BMS 4524/4538 are cheaper but need to be crossed a bit higher, around 2 kHz.

As for crossovers, there are some ready-made ones available - get the ones that are rated to more than 200 W and have the x-over frequency at around 2 kHz (or 1,5 khz if you choose BMS 4554). But the easiest and best solution (though more expensive) is to get another amp around 100...150 watts per channel at 8 ohms one (or a bigger, 500...1000 /ch at 8 ohms for woofers and keep the current one to highs) and an active crossover - behringer CX2310 should to the trick. You can use a patch panel with NL4 Speakon connectors and 4-core speaker cable with the same connectors for easy, safe and quick setup - wire low amp/woofer to +1/-1 and high amp/comp.driver to +2/-2 poles, and that's it.
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Old 7th August 2010, 05:31 PM   #9
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10 EconoWave designs linked from the first post here:

Flex Your PCD Mettle: - Techtalk at Parts-Express.com

[So far.... ]

Last edited by ZilchLab; 7th August 2010 at 05:33 PM.
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