stop this nonsense plsss... i have a neighbour also DREAMING to get more than 10k evry 4 month.. u know what.. THEY bombard me with SHIT on my land and car. u guys balik kampung laaa..dont plan anything stupid here..in the middle of the city.. how stupid was that??? we have son to take care k. dammn i hate swiftlet now...

Piezo tweeters are the cheaper type and widely used in swiftlet farming. The difference with coil tweeters is piezo technology is simple, low cost of making and very durable. Very unlikely to short out. It doesn't contain magnet like coil tweeters. Piezo is technically water proof. Though it will no sound when the IC part soak in water. When water dry up it will still works fine.  For entrance caller piezo is a must. I drill a hole at the back of my 45dg upwards piezo tweeter for water to come out. The sound from piezo is louder and crispier than coil.  It require less input to produce sound. So at the same output we're able to install more units of piezo than tweeters.
As for coil tweeters it produce more natural and realistic sound to human ears.  For example coil tweeter= black record.  Piezo=digital CD. Or maybe coil=vacuum tube amplifier VS piezo=electronic IC amplifier. Crystal Swiftlet recommended "Carbon Carbite" tweeters for best sound  qaullity. But I've no idea what type of tweeter is "Carbon carbite".
For piezo and coil so far nobody can prove which type is better for swiftlets' ears. Soon I'll try to prove it.  Guess what?  I will use both types of tweeters for my internal sound.  My email address: seeseng@gmail.com

Are you going to use expensive Kenwood sound system? I personally think for swiftlets the sound quality from expensive sound system and China made player/pre-amps won't make much difference.  For example MP3 is a lower quality sound format compare to CD. In real situation those IC players, SD memory card players which plays MP3 chirping sound perform equelly well as CD players.

my farm is in pahang but i work in KL.
i'm doing IT. which part of shah alam?