Official 88-Special Speaker Thread - AVS Forum | Home Theater Discussions And Reviews
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post #1 of 15 Old 03-16-2015, 07:41 PM - Thread Starter
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Official 88-Special Speaker Thread

The 88-Special

By Jeff Bagby

The original idea behind the 88 Special was to design a shallow 9" deep, high output speaker that could be used as a center channel with some of the bigger speakers. But the concept worked out so well that many people are using them for all 3 front speakers. We wanted to be sure the 88 Special could easily be powered by virtually any receiver on the market, yet still handle the power of an external amplifier if needed. Eminence helped out and made custom woofers that would give us a very high sensitivity speaker while still maintaining an 8 ohm load for your receiver.

The large SEOS-15™ allowed for a low 950hz crossover point between the woofers and compression driver. That gives the side by side 8” woofers excellent directivity at this frequency and allows them to match up very well to the directivity of the SEOS-15™ waveguide. You end up with a great polar response and a very wide “sweet spot” so that everyone hears the same thing without any significant changes in sound wherever they sit or move around in the room. Very few speakers can match the directivity of the SEOS-15™ waveguide.


The 88-Special was designed to perform best when paired with a subwoofer that can handle the lower frequencies.

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Last edited by Erich H; 03-19-2015 at 03:05 PM.
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post #2 of 15 Old 03-16-2015, 07:42 PM - Thread Starter
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post #3 of 15 Old 03-16-2015, 07:42 PM - Thread Starter
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post #4 of 15 Old 08-31-2015, 02:51 AM
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Great looking speakers and I'm considering building a trio from my room. The room itself is around 14ft x 22ft and the seating position is around 16ft from the wall. See below for a picture of the screen.

The one question I would have is since the bottom of the screen is 2ft 2" above the floor and I'd like to put the 88 Specials under the screen, should I angle them up slightly to face head height in the seating position (similar to the M&K Sound MP-150's) or would the wageguide create a big enough soundstage vertically?

The screen itself is around 136" and is 1ft 4" from either side wall (the bottom bar is 1ft from the side wall) and 10" off the back wall so I can't fit many speakers either side of the screen besides maybe the F4Q4's which would be similar in size to my current Monitor Audio Apex 40's.

I will be moving the room header.


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post #5 of 15 Old 08-31-2015, 03:21 PM - Thread Starter
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Yes you would want to give them a slight angle upwards, but at your distance it shouldn't be much. The 88-Special is quite a few steps above what you have now, you will be surprised at the difference.

I guess that's not an acoustically transparent screen?
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post #6 of 15 Old 09-03-2015, 12:17 AM
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Quote:
Originally Posted by Erich H View Post
Yes you would want to give them a slight angle upwards, but at your distance it shouldn't be much. The 88-Special is quite a few steps above what you have now, you will be surprised at the difference.

I guess that's not an acoustically transparent screen?
No it's not AT and there is a window directly behind it anyway so I could have only moved the L&R's up if it was the case. Is it possible to build the slight angle into the cabinet rather than an angled bracket as long as the volume is kept consistent with the current 88 design?
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post #7 of 15 Old 09-03-2015, 03:20 AM
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Also do you have a rough shipping weight for each kit but not including the flat pack? Can't see it on the ordering page.
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post #8 of 15 Old 12-30-2015, 09:25 PM
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88 Special to be Explored

Hi Erich,
I've just ordered an 88 Special out of sheer curiosity and to have some fun building and testing. I have a friend who is pretty knowledgeable and experienced (but not a speaker designer) who is absolutely convinced that the crossover of the 88 Special is not low enough to prevent serious lobing and narrow horizontal dispersion of the lower frequencies due to the horizontal configuration of the woofers. I'm game to find out for myself since nobody seems to be able to produce any off-axis measurement data. I'm hoping he's wrong because I'd like it to be a great find for my system. If he's right, I'll be disappointed.


I guess we'll see.
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post #9 of 15 Old 12-31-2015, 04:06 PM
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my $0.02

I just finished building the 88 Special for a center channel in a small (12x16 ft) home theater. I don't have any measurement data besides what my Anthem ARC software puts out but I have zero complaints about either sound quality or off-axis response...sound is very consistent throughout the seating area.

The 88 crosses over at 950hz and has woofer center-to-center distance of about 9". As long as the driver centers are within 14" of each other (one wavelength @ 950hz) it shouldn't exhibit lobing.



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post #10 of 15 Old 12-31-2015, 04:54 PM
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It won't lobe if it's less than 1/2 wavelength. But the tweeter contributes at 950hz and its centered. Plus the 8" woofers will offer some direcrivity on their own which will limit the amount of destructive interference.
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post #11 of 15 Old 01-05-2016, 06:19 PM
 
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Would this be ok for home karaoke ? I will hooking up with QSC 600watts but control by a Allen and Heath mixer.

I have tried some home speaker before for karaoke , most tweeter will burn in times.
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post #12 of 15 Old 01-07-2016, 04:27 AM
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would the 88 Special work better in a smaller narrow room than something like the Fusion 10? Im thinking the bigger waveguide would hold directivity better and thus be better in a narrow space? Or would the Fusion 10 be just fine in that department?

room size is 9.5 x 19 x 8.5

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post #13 of 15 Old 01-07-2016, 07:52 PM
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are these speakers a true 8 ohms load
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post #14 of 15 Old 05-03-2016, 12:37 AM
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Quote:
Originally Posted by tuxedocivic View Post
It won't lobe if it's less than 1/2 wavelength. But the tweeter contributes at 950hz and its centered. Plus the 8" woofers will offer some direcrivity on their own which will limit the amount of destructive interference.
Hi Tux,

I know you have done quite a bit of testing with this due to the side by side mids in the 1099. Can you elaborate on the 1/2 wavelength, and how much considered lobing?

Could the side by side woofer configuration with controlled lobing be used to control dispersion down to a lower than normal frequency (sub 1khz) to match with a large waveguide?

Thanks!
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post #15 of 15 Old 05-03-2016, 07:19 AM
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Quote:
Originally Posted by rhapsodee View Post
Hi Tux,

I know you have done quite a bit of testing with this due to the side by side mids in the 1099. Can you elaborate on the 1/2 wavelength, and how much considered lobing?

Could the side by side woofer configuration with controlled lobing be used to control dispersion down to a lower than normal frequency (sub 1khz) to match with a large waveguide?

Thanks!
I'm not exactly sure what you're asking. The 1/2 wavelength is only a generalization. These side by side mids speakers are very tricky to work with because their off axis response change change very rapidly. We're shooting for controlled infectivity but they can be totally uncontrolled.

The side by side mids or woofer can be used to extend directivity lower than a similar sized woofer, but as mentioned above, the directivity can be very erratic so i wouldn't blindly recommend it.

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