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Go get two or four $3 piezos, hook one or two up to your main amp speaker wire with that capacitor, crossed over at 10000Hz, lay them on top of your speakers and see how they sound. like 'em or hate 'em, it's only $12 to experiment with, much cheaper than your open baffle. :) Move up the ladder from there if you don't like them. From what I understand, it's only harmonics up that high anyway.
I put ribbon speakers above 10khz in my system and I've never looked back.
All of a sudden the sparkle is there and the wider spray is total ear candy.
But do it if and only if you got the midrange and mid bass right.
Which fortunately for us, Altecs shine at. Buy the good ones...
3 dB is a doubling of power, not perceived...generally 3dB is accepted as the smallest noticeable increase..lots claim to hear better, but don't have controlled tests. Trained ears can obviously do better than untrained ones, so bear in mind the 3 db description doesn't apply, they are not the "average" listener, due to being outside the norm.
if you wanna use a crossover cap on peizos a parallel resistor is necessary, or an L-pad, so as to present an 8 ohm load to the xover. This would be in addition to a series resistor which is recommended.
Essentially a parallel set of peizos, with a 20 ohm series resistor, wired past an L-pad, is the simplest.
Trimming the flanges of the peizos so they couple better has merit.
The peizo has a "falling" impedance curve...40-50 Ohms, say, at 2K, falling to perhaps 8 at 40 KHz. This leads many ignorant marketers to claim no crossover needed, and the peizo's bad rep. They produce energy all the way down to 800 Hz or so, in a bad fashion. My opinion calls for 6-7 KHz or even higher usage. I use half a dozen stacked in a vertical array, with the flanges trimmed. Amazing how good they CAN sound when used properly, especially at the price.
Using piezo tweeters wisely: a "how to" - AudioKarma.org Home Audio Stereo Discussion Forums
Lynn and Steve's Piezo page
Do this-stack VERTICALLY. I like them closer together.
http://www.hostboard.com/forums/hbmc...2012/02/35.jpg
Horrible idea, do not do this! Comb filtering Hell.
http://www.hostboard.com/forums/hbmc...2012/02/36.jpg
Why a series resistor? 8 ohms at 40 K divided by 6...equals freaking out amplifier. Not many ruggedized pro amps will handle a load like that, much less home stuff.
Hi cradeldorf,
I had just typed out a nice long response and the darn thing timed out on me so I am just going to give you the highlights.
I am glad OG popped in to straighten some things out.
1. Don't bother with the G1. It is too much of a tweeter for the job, you will be wasting it. The G2 is their entry level unit and is perfect for the job.
2. I have never heard a piezo tweeter that didn't sound like a piezo tweeter. Even when persons tell me how important the XO is, I try the same thing as them and it still sounds like **** to me. There's a reason they are so cheap. There's a reason I have a bunch just sitting on the shelf.
3. I think the 2.0 cap is too big. You will have too much overlap and that will distract you. If it were me I would start with a 1.0 and if that din't cut it, go to 1.5. That being said, it's easy when you have this stuff on hand but the nice thing is, when you are ordering it, you'll notice how cheap the smaller caps are. Get extras, you may want to add series resistance and that might mean running a couple caps in series. It's easier than doing the L-pad thing.
OK, if you have 500 to spend on used supertweeters then you'll have no trouble getting a handful of caps and resistors, maybe even some test leads to make the switching easy. Just get 1.5's and 1.0's as you can always parallel two 1.0's to get a 2.0.
Take your time. Switch, listen, switch, listen... I have been working on a simple set of FR drivers with helper woofers and helper tweeters and do you think I can make up my mind when trying to voice these things? As of last night I finally said OK, enough is enough, they're not going to get better by switching anymore. It only took 4 weeks. :)
You don't want it coming in at 5K unless you are cutting off the 604 horn at 5K. You have already said you're not quite an electronics professor yet so let's try and avoid doing that.
An XO calculator can only tell you what happens at a given impedance. You don't know what the real impedance is at the intended XO point so it's easier just to bring your tweeter in nice and high.
Then get a tweeter more suited to the job.
Consider making it 12dB and reverse the leads.