Fusion 15 Sentinel or Alpha 12 Zephyr or Fusion 12 Tempest - Page 10 - AVS Forum | Home Theater Discussions And Reviews
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post #271 of 292 Old 12-28-2015, 06:02 PM
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I have the 88 specials and am very happy with the sound. I've run on-axis REW plots and my build lined up well with the graph on DIYSG for the 88s.

I am planning out my actual home theater and am looking at the 893 and 1099 that @tuxedocivic has designed as well as the Maximus 12 or I could stay with another set of 88 Specials. Part of this decision is the off-axis response.

I get the basic idea, but if someone can talk me through the proper test setup I could try to do some measurements. I'm not sure that I can do them outside on a ladder like tux (dropped to 40 degrees outside) but I have a 20 x 30 great room with vaulted 10 foot ceilings. Would that be adequate?
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post #272 of 292 Old 12-28-2015, 07:43 PM
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No, need to do outside like Tux does.

But above the XO the special 88 should be very good, just like the FUSION 12 and FUSION 15 that use basically the same parts.

I have the same compression drive and SEOS15 in a DIY project, and there is lots of threads out there using those parts and showing the performance. SEOS is good, and the DNA360 is good, especially at it's $80 price point. The wild card is the side by side drivers, but it's essentially a fusion 8 and a fusion 15 had sex and gave birth to conjoined twins.... haha. Side by side woofs can be challenging but the XO is also pretty low on that, I think it's below 1khz, so above that it's probably really good.

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post #273 of 292 Old 12-28-2015, 09:35 PM
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Going outside is to push the first reflection suffeciently low enough to get the information required. So, if you need to see 1khz, then a 10ft ceiling is really good. If you need to see 500hz, a 10ft ceiling is barely good enough.if you need to see 250hz then you need a first reflection at least 10ms away (~3.5m). And if suggest 15ms is where you can see 250hz in a clear way. That means go outside. A 10ft ceiling means you're at 5ft to the first reflection (actually more like 5.5ft). That's about 5ms which is about right based on my experience.
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post #274 of 292 Old 12-28-2015, 10:07 PM
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Quote:
Originally Posted by Mfusick View Post
No, need to do outside like Tux does.

But above the XO the special 88 should be very good, just like the FUSION 12 and FUSION 15 that use basically the same parts.

I have the same compression drive and SEOS15 in a DIY project, and there is lots of threads out there using those parts and showing the performance. SEOS is good, and the DNA360 is good, especially at it's $80 price point. The wild card is the side by side drivers, but it's essentially a fusion 8 and a fusion 15 had sex and gave birth to conjoined twins.... haha. Side by side woofs can be challenging but the XO is also pretty low on that, I think it's below 1khz, so above that it's probably really good.
Normally I/we would worry about the woofers being horizontal rather than vertical. But I hear that with the right design they can be horizontal. I can't remember the equation, but it has to do with the crossover being low enough and the woofers not being too large in diameter, and keeping the woofers really close to each other. In such a design, the two woofers will perform as one larger woofer with regards to dispersion, lobing, comb filtering, etc..
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post #275 of 292 Old 12-30-2015, 08:20 PM
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Quote:
Originally Posted by tuxedocivic View Post
Going outside is to push the first reflection suffeciently low enough to get the information required. So, if you need to see 1khz, then a 10ft ceiling is really good. If you need to see 500hz, a 10ft ceiling is barely good enough.if you need to see 250hz then you need a first reflection at least 10ms away (~3.5m). And if suggest 15ms is where you can see 250hz in a clear way. That means go outside. A 10ft ceiling means you're at 5ft to the first reflection (actually more like 5.5ft). That's about 5ms which is about right based on my experience.
Based on this it probably makes sense to wait to go outside. @Mfusick makes a great point, the polar should be very similar to the fusion 15 since both have the 360 and 15" seos. So above maybe 2kHz (crossover is at 1kHz) would the effect of the side-by-side 8" no longer be seen? My assumption is the crossover is rolling off the 8s to blend with the CD. We know the CD with the 15" waveguide has a good polar plot in frequency range. So the question is if there are any horizontal issues with the side-by-side 8"s. In this case the most important frequencies to get right would be 80Hz to 2kHz which I wouldn't be able to get properly inside.

Does this sound right?
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post #276 of 292 Old 12-30-2015, 09:17 PM
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You've got it correct, except that you probably don't need to be concerned below about 200hz. They'll surely be omni by then.
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post #277 of 292 Old 12-31-2015, 07:29 AM
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I'd like to see measurements of that and with a 10' ceiling you'll have "good enough" data for the 500-1khz region. Outdoor would be best, of course, but myself and I'm sure others would be willing to help you get setup correctly either way.
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post #278 of 292 Old 12-31-2015, 08:01 AM
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Quote:
Originally Posted by bitmap42 View Post
Based on this it probably makes sense to wait to go outside. @Mfusick makes a great point, the polar should be very similar to the fusion 15 since both have the 360 and 15" seos. So above maybe 2kHz (crossover is at 1kHz) would the effect of the side-by-side 8" no longer be seen? My assumption is the crossover is rolling off the 8s to blend with the CD. We know the CD with the 15" waveguide has a good polar plot in frequency range. So the question is if there are any horizontal issues with the side-by-side 8"s. In this case the most important frequencies to get right would be 80Hz to 2kHz which I wouldn't be able to get properly inside.

Does this sound right?
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You've got it correct, except that you probably don't need to be concerned below about 200hz. They'll surely be omni by then.
The question it seems about the 88 is what its off-axis response is from the crossover region down to about 200Hz. That 2+ octave range is in the fairly critical mids and really needs to be smoothly dispersed across the listening area. Why does it seem to be so tough to get any info on this? I have a friend who has quickly crunched the numbers on this based on the crossover frequency and the 8" diameter of the woofers, and tells me there will be significant lobing in that mid range. He says the crossover is not low enough to free the 8" woofers from the necessity to be vertically aligned rather than horizontally...therefore they will suffer lobing and horizontal dispersion from them will also tend to be narrow horizontally.

I don't have a single seat theater. I have two rows of four seats that I have to cover as smoothly as possible across the entire spectrum. I guess one has to invest and test. Kind of sounds like "We have to pass the bill so that we can find out what's in the bill."
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post #279 of 292 Old 12-31-2015, 08:43 AM
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You could always Fusion 8 instead of the 88 if you were overly worried.

Or max 10.

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post #280 of 292 Old 12-31-2015, 09:43 AM
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Quote:
Originally Posted by Mfusick View Post
You could always Fusion 8 instead of the 88 if you were overly worried.

Or max 10.
Which I bet are excellent designs. It appears that the Fusion-15 does well off-axis as well. If the Fusion-12 is much like the Fusion-15, it should do well, too. In my case, the niche I have for the center will not fit them...but will an 88. Depending on the success of testing the 88, I certainly will be considering the Fusion-15, Fusion-12 (preferable due to same designer), or Max 10 (if they come up with a flat pack for it) for L/R!
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post #281 of 292 Old 12-31-2015, 12:51 PM
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I'm sure Jeff would have this data, has anyone asked? I haven't seen it either, but Jeff would have at least considered this in the design.
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post #282 of 292 Old 12-31-2015, 12:55 PM
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Quote:
Originally Posted by tuxedocivic View Post
I'm sure Jeff would have this data, has anyone asked? I haven't seen it either, but Jeff would have at least considered this in the design.
I have no idea how to reach him, and I've heard he doesn't come around here much.
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post #283 of 292 Old 12-31-2015, 01:03 PM
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Quote:
Originally Posted by Cam Man View Post
Quote:
Originally Posted by tuxedocivic View Post
I'm sure Jeff would have this data, has anyone asked? I haven't seen it either, but Jeff would have at least considered this in the design.
I have no idea how to reach him, and I've heard he doesn't come around here much.
Fair enough. I think he's had some health issues and hasn't come around the forums very much, which results in unanswered questions like this. I think Erich would answer except he probably doesn't have the answers. It's the XO designer who gets the data for Erich. I don't think I've ever provided a "complete" data set to Erich. Mostly cause I don't want people looking at something the wrong way and getting the wrong impression. It's possible Jeff kept it to himself and then got sick.

If someone has this speaker and willing to do the work, like Nate said, we could walk them through it.
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post #284 of 292 Old 12-31-2015, 01:10 PM
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Quote:
Originally Posted by Jeff Bagby over on TechTalk
I don't have a graphs of the horizontal polar response to show, but it's not as wide as a speaker like my Tempest. I normally don't like side by side woofers, but this design was done to create a shorter speaker. Trade-offs. I lowered the crossover to below 1kHz but you are still limited to what two side by side 8" drivers can do. Modeling indicates a decent 45 degree window. However, I walked back and forth across my room and didn't really hear any drop-outs that concerned me over a pretty wide field.
http://techtalk.parts-express.com/sh...00#post1988800
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post #285 of 292 Old 12-31-2015, 01:18 PM
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Quote:
Originally Posted by tuxedocivic View Post
Fair enough. I think he's had some health issues and hasn't come around the forums very much, which results in unanswered questions like this. I think Erich would answer except he probably doesn't have the answers. It's the XO designer who gets the data for Erich. I don't think I've ever provided a "complete" data set to Erich. Mostly cause I don't want people looking at something the wrong way and getting the wrong impression. It's possible Jeff kept it to himself and then got sick.





If someone has this speaker and willing to do the work, like Nate said, we could walk them through it.
I see. Well, I hope he is okay/recovering.

I've got one ordered...and I have OmniMic. My interest in it is for my system center. I love what I have which is a DIY re-configured JBL S2C (because it has to fit in a square-ish niche), but I thought it would be fun to build again...and maybe see some new technology that would surpass the S2C. After all, those are pretty old components. If the 88 convinces me that it's a significant step forward, I'll be researching the other models.

What would be a reasonable listening test for lobing in the horizontal off-axis in the <crossover? Full-bandwidth pink noise running while moving horizontally in the front row?
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post #286 of 292 Old 12-31-2015, 01:31 PM
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Quote:
Originally Posted by antisuck View Post
Thank you very much! Finally, there we are; from the horse's mouth. It will take a listening test across the first row to decide whether the 88 is a keeper for me.


I wonder if Jeff or anyone considered designing this as a 2.5-way speaker. One of the woofers crossed in the lower mids, and the other taking it the rest of the way down. McIntosh did this way back when with the HT-1 to smooth out the mid off-axis with their two side-by-side woofers.

Last edited by Cam Man; 12-31-2015 at 01:38 PM.
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post #287 of 292 Old 12-31-2015, 01:38 PM
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Pink noise is a reasonable choice. Also dialogue. Particularly speech that is difficult to understand. Sit in an off axis location and listen for the intelligeability.
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post #288 of 292 Old 12-31-2015, 01:41 PM
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Quote:
Originally Posted by antisuck View Post
Quote:
Originally Posted by Jeff Bagby over on TechTalk
I don't have a graphs of the horizontal polar response to show, but it's not as wide as a speaker like my Tempest. I normally don't like side by side woofers, but this design was done to create a shorter speaker. Trade-offs. I lowered the crossover to below 1kHz but you are still limited to what two side by side 8" drivers can do. Modeling indicates a decent 45 degree window. However, I walked back and forth across my room and didn't really hear any drop-outs that concerned me over a pretty wide field.
http://techtalk.parts-express.com/sh...00#post1988800
Sounds like he didn't measure it, but if his modeling matches my 1099 measurements accurately then that would be similar. The 1099 also has about a 45 degree listening window at the woofer XO (in the horizontal center configuration) and it works. It is a trade off as it's not a perfect 90 degree match to the rest of the speaker but it's fair. The 1099 has this behavior a bit lower in frequency, where we're less sensitive, but still shouldn't be a big deal.
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post #289 of 292 Old 12-31-2015, 03:55 PM
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I might be able to grab a few hours this weekend to try this out.

Here would be the setup. Of course I'd like to match what others (especially @mtg90 , @tuxedocivic , @EricH ) have done since it would be nice to be able to compare the 88 Specials, Fusion 15s, 893s, and 1099s.

Speakers up off the ground approximately 5 feet (center vertically in room to be able to measure as low as possible before reflections interfere)
Speaker about 5 feet from the back wall... and about 15 feet from either side walls
Speaker connected to right channel (other not connected) in stereo mode
Mic would be 10? feet away with height of the mic centered on waveguide (or I could center it between wg and the woofers)
Umik-1 pointing towards the speaker, pointing straight up, or pointing at 45 degrees towards speaker?
Amplifier:
Choice A: Denon x2100 in Direct Mode (direct should eliminate processing)
Choice B: Old Dolby Pro Logic Amplifier that can be set to no processing
Levels set to 75dB pink noise

Rew sweep with speaker in the following angles:
On-Axis
15
30
45
60
75?
Not sure if there are a few more angles that would be helpful.

I will do a frequency sweep from 60 Hz to 20 kHz just for completeness, even though the most important numbers are under 2kHz.

In REW do I need to change the Impulse response window times?
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post #290 of 292 Old 12-31-2015, 04:53 PM
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Is there any benefit to close placing mic at about 3' in that set-up?
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post #291 of 292 Old 12-31-2015, 05:16 PM
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I think those angles are good. Is use the mic straight on and only 3 to 4ft away. Set the gate time to about 6ms and see what you get.
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post #292 of 292 Old 01-01-2016, 09:40 PM
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Hey guys I read this entire thread as a result of a search for info or reviews of the Maximus 12-lxe. Can't find any real solid data on it. Anyone have any feedback? It seems Jeff may be unable to spend much time here. Thx guys. This was a great read.


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