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Should I buy some Bullet Tweeters???

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reessi View Drop Down
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    Posted: 28 March 2015 at 4:06pm
Hi all,

I have built the MT122's which sound great. But I've seen alot of rigs with Bullet Tweeters as well as the Compression Drivers. So I have the P-Audio BMD750 2" CD.

So I'm wondering if my system would sound alot better with some bullets. The CD range drops off a little after 5k and then dramatically above 10k. So I see that the bullets usually run from 3.5k - 20k, so on paper this seams a no brainer for getting right up to max human hearing.

But I have none to test with so prior to parting with any money can I have some advice from people on how much difference they make please from your listening experiances.

Also instead of buying Bullets can I just boost the 10k - 20k on an equalizer to get the same affect or near enough to not warrant buying extra, although I am itching to just buy some anyway to hear first hand.

So If I bought some which ones would be recommended to go with what I have?

My CD is 100w so what wattage bullets do I need and how many, from this chart below, it would appear that the range 1.5k - 10k is approx 15% power used and 10k upwards is 5%, if I was to cross as 10k.

So if cds are 100w being 15% then would I need a min 33w bullet as it only requires a third of the power 5%. Chart link:

http://sound.westhost.com/lrp-f71.gif


Also where do people normally cross them, 10k seams a good point to me as the cd drops off at that point. Also do I then need to have a LPF for the CD at 10k so no overlap with the bullet or is this not required?

Another point is the crossover unit I have has no output for adding a bullet. Could I just build a passive third order filter. I managed to build some passive crossovers for my X15's successfully (After much help from people on here, thanks). And if overlap was no problem and I used a third order filter then I could run them off same channel/amp parralled with the CD's.

Cheers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote reessi Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2015 at 4:08pm
Oh yeah, also what application are Piezo's used for? They seam cheap as chips and have a good range? Is quality of the sound an issue, not seen people using them.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 28 March 2015 at 11:52pm
  In my limited experience I've always found a system sounds better with something 'above' a 2" horn, be it a bullet, super tweeter or 1" horn, you could boost the 2" from 10k up but it will never sound as good or as detailed as using something that will actually go that high IMO.  I wouldn't get too caught up on the power handling side of things but try and match the sensitivity of the bullets to your comp driver. 2x bullets per 2" comp driver is usually ample but you can sometimes get away with one.
  
  As an example (or two) my last system had some ancient Cerwin Vega 2" on top running from 1.5k and up and whilst very, very loud (mc's would take your head off if not careful!) rolled off rapidly above about 8k so I had some Fane cd130s passively crossed (with an off the shelf hpf wired in parallel with the 2") above from 6k and up, overlapping wasn't an issue although I did have to put a nice big shelf eq on from 10k up to compensate for the difference in sensitivity between the 1 and 2" and the constant directivity horn the 1" was on.
   
  For my yet to be built new system I've been toying with a single bullet running from 7k and up (from a passive off the shelf hpf again) in each mid top cab and I seem to be getting far better results, with a bit of experimenting they seem to do the job more than well enough and add a lot of nice detailed sparkly top end.  
 
 I'm using these bullets by the way; http://www.ebay.co.uk/itm/33358-Professional-Heavy-Duty-Titanium-Bullet-Tweeter-Speaker-300-W-8-ohm-18-Oz-/271040890310?pt=LH_DefaultDomain_3&hash=item3f1b4bc5c6, they may be cheap but are very effective and very well received on this forum.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:02am
  Regarding Piezos, they are cheap as chips and will do top end very nicely but they still have to be crossed over properly and you have to use a lot of them to get enough output so you may as well get a half comp driver or bullet.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Conanski Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:12am
By all means try adding a high freq boost via DSP.. if you got the driver on a CD horn it should have CD correction anyway. Super tweeters can be good but a properly processed system shouldn't need much help. I did the piezo thing for a while back in the '90s when they were new, thought they were great until I tried a proper bullet, now I don't care if I can get half decent response up to about 15khz from the comp drivers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote reessi Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:19am
Thats good to know that the idea of passivly crossing them works then without worrying about overlap. Just wondering njw why you say if you use piezos you need alot, its just the cheapest piezos on blue aran at £1.50 are 150w and 100w ones. Or is this an inflated wattage by the manufacturer and not RMS? Also just noticed the piezos go way above human hearing to 30k, do you think this is of any help. Presumably we might be able to hear something above 20k its not just instant cutoff?

Cheers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mini-mad Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:34am
the 100w "rating" is more just to point out it has a voltage glass ceiling before you just burn them up.

i would say if you want to do piezos do boxes of 4-8 per side and learn how to build super simple high passes and the basics of L-pads.
If it sounds like a gorilla is trying to escape, turn it down.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote njw Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:35am
   The problem with piezos is that the cheap ones tend to be very inefficient, typically only achieving a sensitivity of 93db ish, therefore you would need two piezos to achieve 96db, four to achieve 99db, eight to achieve 102db, 16 to achieve 105db and 32 to achieve 108db which is where most decent comp drivers are.
 And with regards to human hearing, if you can hear 18khz you're doing well I reckon!Smile   
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Post Options Post Options   Thanks (0) Thanks(0)   Quote reessi Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:40am
Hi cool, I know how to build some high passes and an l-pad but I keep hearing stuff about Piezos not needing a hp as they act like a capacitor so in affect are a hp themselves as they're not a coil, or is this utter rubbish that some inexperianced people have written on the web?

Can you offer any pros and cons between bullets and piezos to help me decide? But if I decide to go bullets then I'll buy some piezos any ways as so cheap for testing, just need to decide if its worth getting the bullets.

Cheers.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote reessi Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:43am
Ah, I see, my CD's are 112db sensitive so the piezos would have a hard time keeping up! Especially if I want to parralell some new tweeters with the cd's then it would help with levels if I got something around the same sensitivity.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mini-mad Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:48am
...go bullet.

If it sounds like a gorilla is trying to escape, turn it down.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote reessi Quote  Post ReplyReply Direct Link To This Post Posted: 29 March 2015 at 12:50am
In fact there is a dual piezo on blue aran that states it only needs a series resistor. Is this true for all? It only states it on that one, also noticed only one had the sensitivity labeled. It was low like you said.
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