BillFitzmaurice.info

Hi all,

I need to build a small pa speaker array using Goldwood GT-1005 Tweeters.

The Speaker Array will have 6 Tweeters

Like a cheap LRAD copy is the idea.

Similar to attached image

I want them loud as possible.

The only sound going through them will be Voice(Talking) and high pitch alarm sounds.

Info needed.
-- what type of resistors are commonly used.
-- wiring of 6 tweeters all together with resistors.
-- size of amplifier needed to power 6 of these.
-- do I need to limit frequency ranges and easiest way to do this? I want to use as full range speaker but assuming its best to be in frequency range of tweeter?

Any suggestions, thoughts, things I need to look out for, etc... are welcomed and appreciated.

I am using these for IP Security Cameras.... powered pa speakers and 70v pa speaker systems are not an option for use.

Thanks all in advance for your help and suggestions.

Your question reminded me of this thread,
viewtopic.php?p=282256#p282256

They are tweeters so definitely not going to be "Full range" but could maybe work for some spoken word depending on your expectations.
Annoying alarms? Definitely capable!

We use similar piezo tweeters in a lot of Bill's designs, (same elements, different horn) crosover / high-pass set at 2,000Hz.
Going lower would also lower the voltage limit.

You won't need much power, depending on how you have them wired and what Crossover setting used, 50w- 100w would be way overkill.

Hi,
Interesting.

Most of the info you need is in the link that Kevin posted in his response.

The useful bit is: wired in parallel/series to increase power handling to 50V.
That's about 300W/8ohms, so there's your amp specs.

Since you're only using the piezo's, you don't need filters per se.
The piezo's have natural low and high fall off's.
But you should put a 4 ohm 5 or 10 watt ceramic resister in series to prevent high frequency oscillations in the amp.

Given that narrow band speech is in the order of 300Hz to say 4K, you've obviously got a deficit in response from 2K ish down because the piezo's can't and don't do that, so don't expect "natural" sounding speech with piezo's. Think "tinny" speech.

Also, I don't think you want speech and siren at the same level in terms of output.
I would use a small mixer with master at unity. The siren signal source to one channel of the mixer at unity. The speech input on another channel at below unity, as a base, but play with that to get acceptable speech volume and louder siren volume.
Mixer out to amp. Amp to cabs...