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Old 13th September 2010, 03:09 PM   #111
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Originally Posted by JLH View Post
The big issue I've had is Celestion were complete A-holes and would not sell to us and would not provide the needed T/S parameters. Did I mention that Celestion were complete A-holes?

I really don't like the Misco JC5RTF-B much because what we need is a smaller speaker so we can get our spacing down. The closer you can get the mids to the compression driver, the easier the crossover becomes.

I thought the Misco RDC3T-A could work for us, but it has to be ordered in cases of 60 pieces and I was not willing to go alone on the cost if it did not work out. Cost is $6.44 each @ 60 pieces for a cost of $386.40 just to try it. The thing I don't know for sure about this speaker is if the horn loading will drop the Fs low enough. The higher you have to crossover to the compression driver, the harder the crossover gets because those wavelengths start to get real short above 1.5KHz.

I'm not willing to mess around with anything but sealed back mids because of the nightmare I went through trying to get open basket mids sealed and to work. No matter how careful I was, each one ended up with widely different T/S parameters.

The KM410 should work out perfectly - however a familiar problem arises again. We are having issues trying to buy the damn things. I was ready to jump on these things, but now have my doubts about FBT Audio.

Rgs, JLH
I know that it looks like a toy, but the Tang Band 2" woofers that I used in three of my Unity horn projects works really nicely. The small size of the voice coil will certainly impact power handling, but it will produce plenty of output for home audio. (And I'd really discourage people from investing the time and money in this project if your goal is proaudio. Tom Danley should get your business in that event.)

Of all the woofers I've used in Unity horns, the TBs are the easiest to work with, because you can use a very high xover point due to the geometry.

Having said that, the TB is *not* the ultimate solution, just one of the easiest. TB has a few other models with higher power handling, lower distortion, and higher cost that will work. And the Faital is nice too. But all of those will bump up the price and the complexity.

Also, what's the point of using a $4 woofer on a Unity horn?

The underhung woofers sound cleaner than conventional motors. And both the TB and the Faital are underhung.

Is saving $50 per speaker really that important in the grand scheme of things?

I mean, the crossover alone is going to cost $50-$100 per side, why use a $4 midrange?
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Old 13th September 2010, 05:54 PM   #112
JLH is offline JLH  United States
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Originally Posted by Patrick Bateman View Post
I know that it looks like a toy, but the Tang Band 2" woofers that I used in three of my Unity horn projects works really nicely. The small size of the voice coil will certainly impact power handling, but it will produce plenty of output for home audio. (And I'd really discourage people from investing the time and money in this project if your goal is proaudio. Tom Danley should get your business in that event.)

Of all the woofers I've used in Unity horns, the TBs are the easiest to work with, because you can use a very high xover point due to the geometry.

Having said that, the TB is *not* the ultimate solution, just one of the easiest. TB has a few other models with higher power handling, lower distortion, and higher cost that will work. And the Faital is nice too. But all of those will bump up the price and the complexity.

Also, what's the point of using a $4 woofer on a Unity horn?

The underhung woofers sound cleaner than conventional motors. And both the TB and the Faital are underhung.

Is saving $50 per speaker really that important in the grand scheme of things?

I mean, the crossover alone is going to cost $50-$100 per side, why use a $4 midrange?
I tried the Tang Band W2-852SH and had issues getting a consistent Fs from driver to drive when I sealed up the basket. Remeasuing T/S after sealing the baskets resulted in 30% to 35% spread - that's no good enough. The other thing I learned is as the driver gets smaller, ever small changes in the entery port size and shape make a bigger difference. When a change of 0.2cm in port lenght can create a 10dB notch in response, that's just not practical working conditions for a design. I'm working on another script using the RDC3T-A from Misco. It has a nice balance between size and workable design sensitivty. The main issue I'm running into is Akabak uses the physical voice coil placement as the acoustic center. In the real world the acoustic center of a compression driver exsists quite a bit forward of the voice coil. I've yet to figure out a way around this so the simulation will reflect real world results. I have a few leads and need to see if I can get the answer. That's the best I have right now.
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Old 13th September 2010, 06:20 PM   #113
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I read it as the point was always at the center point of the diaphragm, at the height of the suspension. For all but conical diaphragms.

If you specified a conical diaphragm AkAbak will adjust the point based on the frequency. This would put it slightly behind the diaphragm.

You could also add the T1= parameter to recess the driver with a quazi-throat chamber, and this would place the point at the center of the end of the T1 duct.

With a Duct or Horn added the position is always at the center of the cross-section at the mouth.

Last edited by soho54; 13th September 2010 at 06:39 PM.
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Old 13th September 2010, 11:12 PM   #114
JLH is offline JLH  United States
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Originally Posted by soho54 View Post
I read it as the point was always at the center point of the diaphragm, at the height of the suspension. For all but conical diaphragms.

If you specified a conical diaphragm AkAbak will adjust the point based on the frequency. This would put it slightly behind the diaphragm.

You could also add the T1= parameter to recess the driver with a quazi-throat chamber, and this would place the point at the center of the end of the T1 duct.

With a Duct or Horn added the position is always at the center of the cross-section at the mouth.
No, the acoustical center point (phase = 0 degrees) has absolutely nothing to do with the actucal physical position of the voice coil or diaphragm. You are confussing time alignment (time of flight) with phase alignment (degrees).
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Old 14th September 2010, 12:26 AM   #115
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No, the acoustical center point (phase = 0 degrees) has absolutely nothing to do with the actucal physical position of the voice coil or diaphragm.
I never said it had anything to do with the voice coil. I was paraphrasing where AkAbak places the acoustic center depending on the Diaphragm used. They all use a set point except for the conical which gets calculated.

Phase and Time Alignment are connected. You can't get the absolute of either without the other.
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Old 14th September 2010, 01:18 AM   #116
tinitus is offline tinitus  Europe
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if there were only one driver, and no crossover, it would

but still, it changes with frequency, and isnt a fixed point

makes things real tricky to handle
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Old 14th September 2010, 02:52 AM   #117
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Originally Posted by JLH View Post
I tried the Tang Band W2-852SH and had issues getting a consistent Fs from driver to drive when I sealed up the basket. Remeasuing T/S after sealing the baskets resulted in 30% to 35% spread - that's no good enough. The other thing I learned is as the driver gets smaller, ever small changes in the entery port size and shape make a bigger difference. When a change of 0.2cm in port lenght can create a 10dB notch in response, that's just not practical working conditions for a design. I'm working on another script using the RDC3T-A from Misco. It has a nice balance between size and workable design sensitivty. The main issue I'm running into is Akabak uses the physical voice coil placement as the acoustic center. In the real world the acoustic center of a compression driver exsists quite a bit forward of the voice coil. I've yet to figure out a way around this so the simulation will reflect real world results. I have a few leads and need to see if I can get the answer. That's the best I have right now.
Click the image to open in full size.

JLH, it's time to make some sawdust! You've spent far too long playing around with Akabak. John Sheerin hasn't built a Unity horn in something like ten years, and ever since I started working at home, I've lost interest in making them as well. (Since all of mine were designed for the car, and at home I have a set of Summas.)

You're the last candidate now! (I hope someone gets the reference )

While I acknowledge that Akabak sims will show some crazy peaks and dips, in the real world, it's not as black and white. Some configurations that shouldn't work WILL, and some that should work perfectly WON'T.

Once you get in the ballpark with Akabak, it's time to build a prototype, refine it, and measure it.

Last edited by Patrick Bateman; 14th September 2010 at 02:54 AM.
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Old 14th September 2010, 06:17 PM   #118
JLH is offline JLH  United States
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Originally Posted by Patrick Bateman View Post
Click the image to open in full size.

JLH, it's time to make some sawdust! You've spent far too long playing around with Akabak. John Sheerin hasn't built a Unity horn in something like ten years, and ever since I started working at home, I've lost interest in making them as well. (Since all of mine were designed for the car, and at home I have a set of Summas.)

You're the last candidate now! (I hope someone gets the reference )

While I acknowledge that Akabak sims will show some crazy peaks and dips, in the real world, it's not as black and white. Some configurations that shouldn't work WILL, and some that should work perfectly WON'T.

Once you get in the ballpark with Akabak, it's time to build a prototype, refine it, and measure it.
I’m further along than you know. I’ve delayed sharing a lot of information because I don’t want to play “show and tell” or “20 questions”. I know exactly where I’m going with this, but have not been convinced enough to lay out the cash to make it real. I do have the compression drivers and the horn dimensions. I’ve settled on the Misco RDC3T-A as the best mid I can trust. I’ll need to split the order with another willing buyer(s). The wife already thinks I spend too much time and money on audio. The biggest problem is my measurement system has been broke for quite some time and is not worth fixing. I need a new measurement system that can support gated measurements, phase measurement and has provisions for a mic calibration file. I'd like to buy a package deal like the Smith & Larson Speaker Tester, but $650 is too much to swing right now.
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Old 13th October 2010, 05:54 AM   #119
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hi guys
do you think this 5" closed back OK?
ACR 5145

cheap only $3
thanks, panjilaras.
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Old 13th October 2010, 10:57 AM   #120
JLH is offline JLH  United States
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hi guys
do you think this 5" closed back OK?
ACR 5145

cheap only $3
thanks, panjilaras.
No - read post #110 above
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