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Multi-Way Conventional loudspeakers with crossovers

What (if anything) is wrong with this woofer arrangement?
What (if anything) is wrong with this woofer arrangement?
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Old 8th December 2018, 03:26 PM   #1
mortron is offline mortron  Canada
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Default What (if anything) is wrong with this woofer arrangement?

I am a big fan of the high end Technics speakers of the late 70's and JBL's so naturally these came up on my radar. What has me bugging y'all is that I wonder about the arrangement of these woofers. It looks an interesting way to mount four drivers.

I know with MTMs and the like that lobing and such can be problematic. Would that be a non issue because of the frequency these are crossed at? Or is it an issue and the reason why we don't see this anymore?
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Old 8th December 2018, 03:31 PM   #2
marco_gea is offline marco_gea  Italy
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Nothing, as long as you cross them over low enough.
It all depends on what takes over from them.

Marco
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Old 8th December 2018, 03:38 PM   #3
etalon90 is offline etalon90  Canada
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center to center distance will limit how high you can reach with the arrangement
given they're 15" and there is around 2" between driver, that mean 17" distance

roughly 260hz shall be your upper limit. (1/3)

I'm actually going from dual 15" to quad 15" myself.

In 5-6 weeks, I shall be able to post measurement.
Keep looking at my site below for update.
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Old 8th December 2018, 03:55 PM   #4
The Space Egg Corp is offline The Space Egg Corp  England
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Cool Too cool for school !

.

WOW !

Eight 15s

Bet that sounds AWESOME !


Si.

t.S.E.c

.
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Old 8th December 2018, 04:29 PM   #5
marco_gea is offline marco_gea  Italy
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I did a bit of reading on that particular system :
Technics SB-9500の仕様 テクニクス

It turns out that:
- they are 35 cm woofers;
- only the upper pair are used all the way up to the (700 Hz) crossover point to the large horn;
- the bottom pair are used in a ".5" configuration as "helper" woofers for the lowest octaves only.

Clever :-)
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Old 8th December 2018, 05:59 PM   #6
mortron is offline mortron  Canada
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Oh wow... I tried to find info on them, interesting that they are .5 woofers on bottom. Its cool all the non conventional ways one can arrange drivers on a baffle. Am thinking about using a quad of 8" drivers for a speaker and the thought crossed my mind when reading someone else had done it and liked it. They never mentioned how whether they all played same though. I'll have to track them down and find out.

The SB6000a speakers from Technics I used to own were pretty awesome for what they were and can't help but think the quality is only maintained or increased up the line. No doubt the designers knew what they were doing when it came to the layout etc.
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Old 8th December 2018, 09:22 PM   #7
Charles Darwin is online now Charles Darwin  United Kingdom
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Like a larger version of these?
Attached Images
File Type: jpg Revox-BX350.3 - copie.JPG (778.8 KB, 124 views)
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Old 9th December 2018, 12:01 AM   #8
etalon90 is offline etalon90  Canada
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My version will have diamond pattern as well
Click the image to open in full size.

Having 4 or 2 woofer still create the C-t-C distance upper limit frequency (or live with a high Q dip)
To avoid the dip, only one shall play above ~250hz

Since I"m active, I'll be able to play the top one as independent (50-500) and the bottom 3 as 50-250hz.

More to come.

JBL Everest 66000 (double 15" side by side) use one driver fully and the 2nd one is a helper below 250hz...

My current dual 15" is toed-in (both driver 50-500hz)
the toe in minimize the dip but the dip is still present.

I've started with single 15" and going dual was a significant subjective upgrade (DYNAMICS). Hope the quad 15" will prove as beneficial... If not, mid-bass horn it will be

YMMV
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