Choosing Tweeters [message #61342] |
Fri, 06 November 2009 14:24 |
selahaudio
Messages: 56 Registered: September 2009
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Baron |
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Here's a good example of buying a tweeter and then finding out how well it performs for an array. I received a Beston RT001A tweeter today for evaluation. Anyone considering it for an array should look elsewhere. This is akin to using a typical inexpensive 3/4" dome - Fs is too high for crossing to an array, even with smaller woofers.
One interesting note is that the impedance was ruler flat giving no indication of what the Fs might be. At that point I ran some swept signals testing for 2nd/3rd harmonic distortion. Huge peak with the second harmonic @3.4K! The quoted 3.5K lowest crossover point is "optimistic" for this tweeter.
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Re: Choosing Tweeters [message #61357 is a reply to message #61342] |
Sun, 08 November 2009 09:46 |
Marlboro
Messages: 403 Registered: May 2009
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Illuminati (1st Degree) |
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Actually there is quite a bit of difference between these ribbon tweeters and a typical inexpensive Dome tweeter.
First of all I'm not really sure what the price of a typical inexpensive dome tweeters is. So I would be looking to find out which tweeter the poster considers typical and cheap, and which one he is thinking of as a comparison.
The Beston is *Power handling: 15 watts RMS/30 watts max *Impedance: 6 ohms *Re: 5.4 ohms *Frequency range: 3,000-40,000 Hz *SPL: 88dB 1W/1m *Minimum recommended crossover frequency: 3,500 Hz *Dimensions: A: 3.4" x 2.13", B: 2" x 1.5", C: 0.125".
and it comes in at $29.
Its hard to find an inexpensive dome tweeter to compare it to that also can allow the domes to be close enough together to avoid comb filter distortion. I looked through everything that both Madisound and PE has to offer and could only find the really really astoundingly cheap dome tweeter that is the ND20FA-6, which comes in at only $6. We know those can be taken down to 2500hz using a lot of them and a 24 db oct crossover, since their FS is only 2005, and that the Beston can't really go any lower than 3500 where their FR falls like a rock, so that can't be the comparison we are looking at.
If you look at the specs on this very very astoundingly cheap dome tweeter Dayton ND20FA-6(15 watts RMS/30 watts max *VCdia: 3/4" *Impedance: 6 ohms *Re: 5.2 ohms *Frequency range: 3,500 - 25,000 Hz *Fs: 2,005 Hz *SPL: 91.5 dB 2.83V/1m, 90 dB 1W/1m *Dimensions: A: 1-3/4", B: 1-5/16", C: 3/4") it has a better SPL too.
On this little item, of which your could buy 5 of them for each Beston. Zaph shows a pretty flat FR from roughly 1700hz out to 25000hz. Clearly not the inexpensive dome tweeter that the poster is commenting on. And your find exceptionally low harmonic distortion that actually is pretty comparable to many of the typical dome tweeters in the $30 - $90 range of price each. And of course, if you split the sound up so that each one covers onle 3% of the total tweeter sound per channel, everyone know that distortion increases as you increase the volume stress that the tweeter has to put out.
3/4 inch dome tweeters are hard to find, so i have to assume that the poster is actually directing his comparison comments to the Dayton ND20FA which is actually not a typical inexpensive dome tweeter, but a astounding quality dome tweeter in a totally crazy cheap price range.
I wouldn't use the Beston in a line array anyway, and if I was going to use a ribbon I'd go with the B&O Neo which blows away almost all dome tweeters cheap or expensive.
A better comparison would be to compare the Beston with other Ribbon tweeters in the same price line(apple to apples) rather that the comparison of apples to potatoes that is done here.
I know that the poster clearly has a preference for ribbons in line arrays, and often has made it clear that ribbons are way more appropriate. And I sometimes even agree. But I also am always interested in knowing what is being compared to what when one is making comments about how to put things together.
Clearly the compared dome tweeter is not the cheap
Dayton one since that one beats the crap out of the Beston Ribbon in question,but I really don't know which one we might be talking about if its not that one.
Just my two cents.
Marlboro
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