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Multi-Way Conventional loudspeakers with crossovers

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Old 15th May 2012, 08:12 PM   #421
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Quote:
make sure you fully disconnect the amp so it can't make a path
Disconnecting them is one of the reason I haven't tested yet. Been too busy listening.
The FR driver really started to open up. They are doing some amazing things. Treble is still rough and may need something to take away some of the edge around 10k to 12k or higher.

There is this weird drop out if I tilt my head to one side, kind of like cancellation, but it's in the higher range. Never happened before until the Parts-Express RS180-8 FR drives were used. Moving the speaker back closer to the back wall helped reduce this effect.
I have to really lock my head in position to not lose the image. I heard this is common with FR drivers.

Any ideas why?
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Old 15th May 2012, 08:20 PM   #422
mightym is offline mightym  United States
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I believe what you refer to is the phenomenon called "beaming".

I counteract both the rising response and the beaming of my Fostex FE206E's by toeing in the speakers to a focus point in front of the listening position.

Hope this helps.

John
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Old 15th May 2012, 08:28 PM   #423
freddi is offline freddi  United States
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fullrange can beam at high frequecies where there's only a few degrees of latitude off axis before a significant drop occurs (and often, a "hole") The only graph I have handy is the old Eminence B102 - look at how it measures on-axis vs ~ 20 degrees off
Click the image to open in full size.

Nirvana's Super 8 has on-axis amplitude exceeding a Selenium ST324 slot loaded tweeter around 17KHz.
-here's FE206EN (stock) vs a stamped frame Nirvana Super 8 ~on-axis/in-room
http://imageshack.us/a/img100/1599/f...per8indrui.gif

Last edited by freddi; 15th May 2012 at 08:33 PM.
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Old 15th May 2012, 08:52 PM   #424
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Thanks guys. I've been mainly focusing the drivers behind my head.
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Old 15th May 2012, 11:48 PM   #425
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First is the slotted 6 driver sweep. Second is the full-range driver.
Not sure it's correct. I calibrated the WT3, but the results are always the same.
Attached Images
File Type: jpg SLOB_IMPEDANCE_SWEEP.JPG (125.6 KB, 838 views)
File Type: jpg RS180-8_FullRange.JPG (115.4 KB, 815 views)
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Old 16th May 2012, 12:11 AM   #426
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I re-calibrated and got a more realistic result.
This is the bass unit.
Attached Images
File Type: jpg SLOB_IMPEDANCE_SWEEP_1.JPG (144.9 KB, 721 views)
File Type: jpg RS180-8_FullRange_1.JPG (115.0 KB, 696 views)
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Old 16th May 2012, 02:46 AM   #427
freddi is offline freddi  United States
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cool - looks like a significant shift in resonance from ~41 down to 30 - if you hit "measure parameters" it will give the impedance curve and display system Q (~like a sealed box) -

could one dispense with the curved plenum innards like this for 10 drivers per side? (manifold might be too deep)
Click the image to open in full size.
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Old 17th May 2012, 02:00 AM   #428
mightym is offline mightym  United States
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I think that one of the reasons the 8" woofers were used is the Dipole peak is going to be much higher than a larger woofer. Making the plenum too deep would have the same effect AFAIK, lowering the peak.

I'm looking about for a suitable 10" driver to mount below some 12" Co & Tri-Axials I've picked up to try on OB. I have some aprox 40" X 3?" X 1" ply (off cuts I pick up really cheep ) to use as motorboards. with the single pair of 10" subs on a plate amp under each driver ( possibly 2 pr on different plenums if needed ).

I'm also considering a Tractrix front horn with Open Back for one pair of the vintage drivers. I'm keeping the details on that under my hat until I find out whether it works/integrates or not.... Think homage to WE theater bass horns....

John
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Old 17th May 2012, 01:45 PM   #429
hajj is offline hajj  Lebanon
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Quote:
Originally Posted by freddi View Post
cool - looks like a significant shift in resonance from ~41 down to 30 - if you hit "measure parameters" it will give the impedance curve and display system Q (~like a sealed box) -

could one dispense with the curved plenum innards like this for 10 drivers per side? (manifold might be too deep)
Unless you're crossing over very low to the woofers, I think you'll run into resonance problems at the frequency where 1/4 of the wavelength is equal to manifold depth.
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Old 15th June 2012, 05:16 PM   #430
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Default another SLOB variation ?

I am wanting to try the SLOB too but I don't have any 8" drivers , however I can get some fairly good 6" woofers that will work in OB config ....is it possible that I could get some feasibly good results using 8 per side giving me the same 24" slot that NP had ?
...also the size of the baffle is a challenge ..WAF so I would like to try a bit smaller
any thoughts opinions very appreciated !
thanks
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