I once put two paper drivers aside for a few months not realising that one was exposed to sunlight. That one looks washed out and old, but it doesn't sound different as far as I can tell.
There are 'code' tags available that use monospace characters.
Code:
[U]2226H 1[/U]
SPL = 97
R(e) = 4.868
F(s) = 55.18
Q(ts) = 0.435
Q(es) = 0.504
Q(ms) = 3.183
L(e) = 2.33
M(ms) = 93.53
V(as) = 3.439
After running some sims in WinISD it looks like the older woofer doesn't have quite the bass response of the newer one - but they are very close. It looks like a good size for the test box will be about 200 litres with a vent tuned to 35 Hz. I shall endeavor to put one together in the next couple of weeks.
I looked through the forum helpfiles in hopes of finding something demonstrating just what you show there, but I couldn't find it. There is a button to wrap table tags, but with HTML turned off I don't know how to use them.
Could you possibly give me a link or some other direction explaining the code tags for the 'monospace characters'?
I looked through the forum helpfiles in hopes of finding something demonstrating just what you show there, but I couldn't find it. There is a button to wrap table tags, but with HTML turned off I don't know how to use them.
Could you possibly give me a link or some other direction explaining the code tags for the 'monospace characters'?
Now that I've separated out the bass bin, it's time to think about the mid and tweet.
VAS for the 6MD38 is listed as and measures as 0.1 cu ft. WinISD shows response falling off at 500 Hz with a 3db point at 220 Hz, which suits me fine. Vance Dickason lists the 3 db upper frequency limit for the 2226H (15 inch) as 661 Hz, but the JBL spec sheet shows beaming beginning at 500 Hz. Since this is for a 3 way it is a simple decision to put the lower crossover at 500 Hz, which the 6MD38 covers with ease on simulation, even at higher SPL.
The upper crossover point is a bit trickier to decide. Vance doesn't list an upper limit for a 6.5 inch driver, but he lists 7 inch at 1540 Hz and 5 inch at 2051. This gives me an estimate of around 1750 Hz. - perhaps someone has a better number?
At any rate, obviously time alignment is critical at this frequency. The wavelength at 1750 Hz is about 7.5 inches, which is close to the horizontal displacement between D220Ti with the horn and the 6MD38 – but it's actually closer to 6 inches. Definitely will have to mount a mid and tweet and run some tests to determine the common ZDP point, if any, since I'm in the neighborhood. Then I can see about factoring in baffle effects.
Any ideas on a quick way to proceed with this?
VAS for the 6MD38 is listed as and measures as 0.1 cu ft. WinISD shows response falling off at 500 Hz with a 3db point at 220 Hz, which suits me fine. Vance Dickason lists the 3 db upper frequency limit for the 2226H (15 inch) as 661 Hz, but the JBL spec sheet shows beaming beginning at 500 Hz. Since this is for a 3 way it is a simple decision to put the lower crossover at 500 Hz, which the 6MD38 covers with ease on simulation, even at higher SPL.
The upper crossover point is a bit trickier to decide. Vance doesn't list an upper limit for a 6.5 inch driver, but he lists 7 inch at 1540 Hz and 5 inch at 2051. This gives me an estimate of around 1750 Hz. - perhaps someone has a better number?
At any rate, obviously time alignment is critical at this frequency. The wavelength at 1750 Hz is about 7.5 inches, which is close to the horizontal displacement between D220Ti with the horn and the 6MD38 – but it's actually closer to 6 inches. Definitely will have to mount a mid and tweet and run some tests to determine the common ZDP point, if any, since I'm in the neighborhood. Then I can see about factoring in baffle effects.
Any ideas on a quick way to proceed with this?
You are figuring the upper limit on the drivers based on their directivity. You don't want the mid to beam at the crossover and yet you are crossing to a device with a more narrow beamwidth. Maybe you could run the 15 up beyond that point and cut out the midrange?
1.5-2K Hz is a frequency chosen for a two-way ,and a midrange can go till 5 KHz ,as it's not designed to move big amounts of air .
Opposite to what Tinitus did , I would put a High-pass to preserve its integrity ,not a low-pass (but he did need clean trebles for the ribbon ,so different situation ).
Opposite to what Tinitus did , I would put a High-pass to preserve its integrity ,not a low-pass (but he did need clean trebles for the ribbon ,so different situation ).
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The 6MD38 is a large midrange. WinISD simulation shows it only going to less than half it's Xmax at 500 Hz @ 200 watts - it could actually go nearly an octave lower, but I want to utilize all the usable 2226H output to maintain as low distortion on the 6MD38 as I can. Yes, it's rated up to 6kHz but looking at the facts of the size and response graphs 6 kHz is very optimistic. The response graph also shows a nasty 9 db breakup at 5 kHz - I wouldn't dare go over 3 kHz
The HC23-25 horn actually has excellent dispersion, based on the spec sheet and the reviews.
The HC23-25 horn actually has excellent dispersion, based on the spec sheet and the reviews.
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Also, the highest recommended crossover point on the 2226H is 1200 Hz. The D220Ti is rated down to 1 kHz (@ -6 db) and the HC23-25 is rated down to 750.
This doesn't actually sound too bad. My fear however is (1) that the range between 500 and 1200 Hz will simply be lost off axis and (2) the D220Ti becomes vulnerable to distortion and even burn-out at high SPL (>100 watts).
Given these considerations I determined a mid was necessary for my design goals.
This doesn't actually sound too bad. My fear however is (1) that the range between 500 and 1200 Hz will simply be lost off axis and (2) the D220Ti becomes vulnerable to distortion and even burn-out at high SPL (>100 watts).
Given these considerations I determined a mid was necessary for my design goals.
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Yup ! I've just (nearly......) finished a 3 way design ,and I did some errors ,like :
I put the vent frontally ,near the woofer ( but with some damping stuff inside ,it's okay )
I made the cabined fat ,but not tall ,otherwise ,I should have followed this design
The Forum Speaker 1
which gives better dispersion etc etc etc.
I put the vent frontally ,near the woofer ( but with some damping stuff inside ,it's okay )
I made the cabined fat ,but not tall ,otherwise ,I should have followed this design
The Forum Speaker 1
which gives better dispersion etc etc etc.
WOW! Nice looking speaker.
I nearly went with a Fostex midrange, but I'll tell you why I didn't - foam surround. In my 'Classic 3 way', I wanted something, well, you know, classic. One of the standards of those old big box 3 ways - at least the better ones, IMO - was cloth surrounds. They also are immune to surround rot, which is just another plus to me.
So, when cost, Xmax, power handling, dispersion, and surround was considered, I came up with a somewhat different decision.
My listening room is rather small. Because of this I'll have little choice but to put my speakers against the wall, which means I'll have little choice but to have them vented in the front.
I'll design the the cabinet response accordingly.
I nearly went with a Fostex midrange, but I'll tell you why I didn't - foam surround. In my 'Classic 3 way', I wanted something, well, you know, classic. One of the standards of those old big box 3 ways - at least the better ones, IMO - was cloth surrounds. They also are immune to surround rot, which is just another plus to me.
So, when cost, Xmax, power handling, dispersion, and surround was considered, I came up with a somewhat different decision.
My listening room is rather small. Because of this I'll have little choice but to put my speakers against the wall, which means I'll have little choice but to have them vented in the front.
I'll design the the cabinet response accordingly.
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I'm definitely thinking of going with a taller design - have to, to put all that volume somewhere.
Whatever I do, this thing'll look like a chest of droors. 🙁
Whatever I do, this thing'll look like a chest of droors. 🙁
LafeEric,
Take a look at the chart in the middle of the page on this link. It shows the 6 db down angle for drivers. It looks like an "ideal" crossover to a 90 degree waveguide would be about 2.5KHz. B200 a bit shouty
YMMV
Doug
Take a look at the chart in the middle of the page on this link. It shows the 6 db down angle for drivers. It looks like an "ideal" crossover to a 90 degree waveguide would be about 2.5KHz. B200 a bit shouty
YMMV
Doug
Are you talking about this chart:
I don't really understand it - can you explain it to me a little?
An externally hosted image should be here but it was not working when we last tested it.
I don't really understand it - can you explain it to me a little?
It suggests that if you cross a 15" driver to a 100 degree horn you'd look at around 1kHz and 6 1/2" a little over 2kHz. So, the idea is to wait until the driver beams by the same amount as the horn.
Beaming happens acoustically at the driver level. The crossover cannot prevent this as far as I know.
I could see where 'matching beaming' would have commercial sound reinforcement applications, though all of this is really new to me.
That said, it seems every dispersion diagram I've ever seen showed the greatest dispersion at the lowest frequency of the radiator (direct or horn) and the narrowest dispersion at the highest frequency of the radiator, as a function of the physical size of the radiator relative to the frequency being emitted.
So, the frequency that a 15 inch radiator gives 90 degree dispersion will be MUCH lower than the frequency that a 3 inch radiator will give 90 degree dispersion at. In other words, there is not single frequency where the dispersions will match, unless you have two radiators of the same size.
Or am I missing something?
That said, it seems every dispersion diagram I've ever seen showed the greatest dispersion at the lowest frequency of the radiator (direct or horn) and the narrowest dispersion at the highest frequency of the radiator, as a function of the physical size of the radiator relative to the frequency being emitted.
So, the frequency that a 15 inch radiator gives 90 degree dispersion will be MUCH lower than the frequency that a 3 inch radiator will give 90 degree dispersion at. In other words, there is not single frequency where the dispersions will match, unless you have two radiators of the same size.
Or am I missing something?
Well, only that horns are not the same. When designing speakers with piston type drivers like many do, they would want to stick to 180 degrees because that is attainable due to the baffle. When we use horns, the 'baffle' is folded in on itself so to speak and we get to work with a more narrow beam.
Not just for commercial sound reinforcement, horns are probably more valued there for their sensitivity. But at home, there are walls close by for the sound to bounce off so we have the chance to reduce this sound, and to at least provide the reflections with a balanced tone.
Not just for commercial sound reinforcement, horns are probably more valued there for their sensitivity. But at home, there are walls close by for the sound to bounce off so we have the chance to reduce this sound, and to at least provide the reflections with a balanced tone.
Ahh. I guess I did miss that. Thanks!
Well, I can't actually see the chart right now because I hosted it at photobucket and I can't see photobucket at work - and the other sites no better, the original being hosted at flickr.
At any rate, for this speaker I should actually be matching the mid to the horn, which has an effective piston diameter of about 5 inches.
Though I am committed to building the 'Classic 3 way', I must say though that all your suggestions have made an impression. I am already planning my next set of speakers as MTM with an active woofer, and a 2 way 15/horn after that.
If I was to make this into a 2 way I would definitely go with a different horn driver - probably the Selenium D2500Ti-Nd-8.
For the MTM I'd probably stick with the drivers I have, but I'd have to look at it closer at that time.
Well, I can't actually see the chart right now because I hosted it at photobucket and I can't see photobucket at work - and the other sites no better, the original being hosted at flickr.
At any rate, for this speaker I should actually be matching the mid to the horn, which has an effective piston diameter of about 5 inches.
Though I am committed to building the 'Classic 3 way', I must say though that all your suggestions have made an impression. I am already planning my next set of speakers as MTM with an active woofer, and a 2 way 15/horn after that.
If I was to make this into a 2 way I would definitely go with a different horn driver - probably the Selenium D2500Ti-Nd-8.
For the MTM I'd probably stick with the drivers I have, but I'd have to look at it closer at that time.
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