Nuuk, Badman,
Fullranges have the problem of unavoidable beaming at HF and therefore suboptimal power response, and of course the advantage of crossoverless coherency. But people have reported good results using supertweeters - maybe above a certain frequency, say 10 kHz, the dispersion issue comes less into play. But it certainly does matter up to 5 - 6 kHz. Nuuk, if you are using dipoles they will have a better polar behavior (more directivity) anyway and you have an added advantage here.
I was toying with the idea of the Fostex for a while, when I had my Diatones with a dome helper tweeter. But frankly the Diatones left alone were already very good, and the system sounded best either by leaving them alone, or by crossing the dome tweeter fairly low, 1600-2500 Hz. Above that things became honky - the ear does notice the "hole" in the off axis response that gets filled up progressively by the helper tweeter. The Fostex would have been an interesting experiment.
FWIW the controlled directivity is one of the main purposes of dipoles, and to some extent of horns as well. Horns have the advantage of better efficiency, with the trade offs of next to impossible implementation in the deep bass, and a maybe too little room interaction to give a "reality" (they are here) feeling to the sound according to some (including Siegfied Linkwitz). Dipoles have the advantage of near perfect control of directivity with lessened, yet still noticeable room interaction, and the trade-off of decreased efficiency in the bass rolloff region. Both types well implemented, especially keeping the x-o's in regions of overlapping and similar directivity, should have a flat power response, and this seems to be a major factor for realism.
Fullranges have the problem of unavoidable beaming at HF and therefore suboptimal power response, and of course the advantage of crossoverless coherency. But people have reported good results using supertweeters - maybe above a certain frequency, say 10 kHz, the dispersion issue comes less into play. But it certainly does matter up to 5 - 6 kHz. Nuuk, if you are using dipoles they will have a better polar behavior (more directivity) anyway and you have an added advantage here.
I was toying with the idea of the Fostex for a while, when I had my Diatones with a dome helper tweeter. But frankly the Diatones left alone were already very good, and the system sounded best either by leaving them alone, or by crossing the dome tweeter fairly low, 1600-2500 Hz. Above that things became honky - the ear does notice the "hole" in the off axis response that gets filled up progressively by the helper tweeter. The Fostex would have been an interesting experiment.
FWIW the controlled directivity is one of the main purposes of dipoles, and to some extent of horns as well. Horns have the advantage of better efficiency, with the trade offs of next to impossible implementation in the deep bass, and a maybe too little room interaction to give a "reality" (they are here) feeling to the sound according to some (including Siegfied Linkwitz). Dipoles have the advantage of near perfect control of directivity with lessened, yet still noticeable room interaction, and the trade-off of decreased efficiency in the bass rolloff region. Both types well implemented, especially keeping the x-o's in regions of overlapping and similar directivity, should have a flat power response, and this seems to be a major factor for realism.
Thanks again MBK. I guess the answer to is to buy a horn tweeter and play around with the crossover point. I seem to have a bit of latitude with the full-range drivers so there's another thing for me to play with!
Another advantage of the OB's is that it is easy to change things around quickly!
BTW - is it my imagination or did you post from Hong Kong with your previous post?
Another advantage of the OB's is that it is easy to change things around quickly!
BTW - is it my imagination or did you post from Hong Kong with your previous post?
Not yet, but then again I have not had the budget lately to play around. I do however think that cutting them off is a must. They don't really have the power-handling or Xmax capabilities to do bass. I would say about 70Hz yo 80Hz would be good. The a pair of either the Stryke or the Dayton IB woofers on an open baffle would be a very nice idea.
Enjoy,
Deon
I do however think that cutting them off is a must. They don't really have the power-handling or Xmax capabilities to do bass. I would say about 70Hz yo 80Hz would be good. The a pair of either the Stryke or the Dayton IB woofers on an open baffle would be a very nice idea. Enjoy,
Deon
I've always been one for NOT NOT NOT NOT NOT padding down drivers. Better to match the sensitivity of the driver than attempt to adapt an unsuited driver (unless you free your rear by using an active crossover, in which case, fun abounds!). Coupla options for you: there are pretty decent 96dB soft domes at www.apexjr.com for a whopping $15 a pair or so. Another choice would be the t26affneo from www.maxspeakers.com, it would be in the appropo sensitivity range.
I'm not happy with the sound on-axis of these, due to the front directivity controller, I'm thinking I need to try mine with that removed, but they're very good so long as you're not directly on axis.
*EDIT ON*
Of course, the soft domes don't subscribe to the controlled directivity we were discussing..... the T26affneo is a dome, but has a tiny horn/waveguide, so crossed somewhat lower (3.5k maybe?), should be quite a good match
*Edit off*
I'm not happy with the sound on-axis of these, due to the front directivity controller, I'm thinking I need to try mine with that removed, but they're very good so long as you're not directly on axis.
*EDIT ON*
Of course, the soft domes don't subscribe to the controlled directivity we were discussing..... the T26affneo is a dome, but has a tiny horn/waveguide, so crossed somewhat lower (3.5k maybe?), should be quite a good match
*Edit off*
Nuuk,
Just want to point out that you can't cross a supertweeter at ~6k with a first order crossover.
You must go above 10k.
I doubt that you need to cross that low with your fullranges, unless you cross the fullranges too.
Someone suggested you a pair of Seas tweeters (with low FS), and it was a good recomendation, based on what you want to do
Just want to point out that you can't cross a supertweeter at ~6k with a first order crossover.
You must go above 10k.
I doubt that you need to cross that low with your fullranges, unless you cross the fullranges too.
Someone suggested you a pair of Seas tweeters (with low FS), and it was a good recomendation, based on what you want to do
Thanks Carlos.
I plan to try a few options with the tweeters. At present, my cheapo silk domes sound quite good with a simple 1 uF cap (that's with the Goodmans 201's running without any filter).
The other options will involve cutting off the top end of the 201's at different frequencies (say 6, 8 and 10K) in which case I will beusing a second order active filter for the tweeters (and some delay).
The Seas was top of my list but the Fostex horn tweeter has a lot going for it so I'm going to try that first. Although, if the Radio Shack tweeters are close enough to the FostexF17H, I may not need to buy the latter!
If I can justify the outlay, I will try the Seas as well and compare the two.
I plan to try a few options with the tweeters. At present, my cheapo silk domes sound quite good with a simple 1 uF cap (that's with the Goodmans 201's running without any filter).
The other options will involve cutting off the top end of the 201's at different frequencies (say 6, 8 and 10K) in which case I will beusing a second order active filter for the tweeters (and some delay).
The Seas was top of my list but the Fostex horn tweeter has a lot going for it so I'm going to try that first. Although, if the Radio Shack tweeters are close enough to the FostexF17H, I may not need to buy the latter!
If I can justify the outlay, I will try the Seas as well and compare the two.
Radio Shack "super tweeters.."
As far as I know (and I really don't know anything..) the RS supertweeters are as similar to the Fostex ones as the RS 40-1197s are to the Fostex 103's , which means they are pretty similar and most likely built by Fostex for RS (or perhaps "out of spec" Fosters sold off to RS rather than rework them?).
RS super tweeters
As far as I know (and I really don't know anything..) the RS supertweeters are as similar to the Fostex ones as the RS 40-1197s are to the Fostex 103's , which means they are pretty similar and most likely built by Fostex for RS (or perhaps "out of spec" Fosters sold off to RS rather than rework them?).
RS super tweeters
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