Dip in frequency response, fix ideas? - Page 3 - diyAudio
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Old 3rd December 2012, 01:31 AM   #21
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Hey great studio by the way.
I could have rocked out my guitar there.....
I lived around DC for 14 years.
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Old 4th December 2012, 07:17 AM   #22
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Quote:
Originally Posted by Melo theory View Post
Yeah, they have a low Fs but they can only produce 72 db max each.
You would need 250 of them to produce 99db at a 1kHz crossover.
Its not only CTC spacing that causes CF, its the fact that its a lIne source.
Its the different arrival times along the line that causes CF.
You need a rising response in the drivers to stay flat with a line source, or you will have to eq.
99db? I don't need them to be that efficient.
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Old 4th December 2012, 07:18 AM   #23
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Originally Posted by Melo theory View Post
Hey great studio by the way.
I could have rocked out my guitar there.....
I lived around DC for 14 years.
Thanks man. Yeah, that's too bad. Could have also built some speakers!
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Old 4th December 2012, 12:34 PM   #24
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Quote:
Originally Posted by nonsuchpro View Post
99db? I don't need them to be that efficient.
That was a miss type I made there. They would be at 93db.
You will need to match sensitivity to the hi waves if going passive, yes?
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Old 7th December 2012, 10:44 PM   #25
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Hey, check it out nonsuch!
HiWave HiBM65C20F 3-1/2" BMR Wide Range Driver Measurements and Impressions
Maybe these would be great in a line array.....look at the rising response
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Old 8th December 2012, 05:55 PM   #26
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Originally Posted by Melo theory View Post
Hey, check it out nonsuch!
HiWave HiBM65C20F 3-1/2" BMR Wide Range Driver Measurements and Impressions
Maybe these would be great in a line array.....look at the rising response
??? Those are the same drivers dude.
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Old 8th December 2012, 06:19 PM   #27
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Haha! I know.
I meant to word it like this.
Maybe these would be great in a line array.
I was confirming the validity of the drivers, because of the rising response.
Ben also says that the dip isn't audible. It is a very narrow BW.
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Old 31st December 2012, 12:08 PM   #28
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Default BMR 4.5 inch driver

Happy new year ( 's Eve!)

I am getting great results with line array's using 8, 12, or 16 drivers per channel using the 4.5 inch BMR.
Here are a few important points that took me a while to fully appreciate:

(1) DSP / Eq is a must. There is no way passive Eq / crossovers / notches etc can do it without hideous complexity, cost, size, and loss of efficiency.

As a minimum try the Eq in JRiver media (or similar VST host), or even better Blue Cat Audio or similar studio grade plugins, Blue Cat do great free plugins to start you off. Reaper, Fab Filter etc are all great to.

(2) For full range music with av / peak SPL's at around 85dB to 105dB, size matters...The Sd of the 4.5 inch is 60cm square, a typical 12 inch driver has an Sd of around 550 cm square...Eight 4.5 inch BMR's = 480 cm square, 12 BMR's = 720 and 16 BMR,s = 960 cm square.

(3) All my designs are "on wall" and use curved cabinets which curve back to meet the wall, this almost eliminates the baffle step issue. Plus it gives you "free" low and low / mid frequency boost. I have measured solid bass ( +- 4dB) down to the high 30Hz low 40Hz depending on Eq and number of drivers. It sounds even deeper than it mearures...!

(4) Comb Filtering is a non issue. Yes you read that right! In real rooms ( not anechoic chambers ) and on wall location, the 4.5 inch BMR line arrays simply flood the entire space with seamless low distortion music. They are dynamic, detailed and so supple & liquid its delightful and astonishing in equal measure.

(5) The smaller BMR's just do not have the ability ( Sd and power handling) to generate the SPL's and dynamics. You have to push them so hard they sound ragged and stressed.
Also the big ferrite magnets really obstruct the back wave and muddy the midrange. The Neo magnet versions are way better in this respect, so pure and natural, but they are way more expensive...

Hope the above helps.
All the best
Derek.
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Old 2nd January 2013, 06:13 PM   #29
Dave R is offline Dave R  United States
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Does this dip occur when the drivers are flush mounted?
How about a chamfer or roundover around the mounting hole on the rear side?
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Old 2nd January 2013, 07:38 PM   #30
JMFahey is offline JMFahey  Argentina
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Quote:
Comb Filtering is a non issue. Yes you read that right! In real rooms ( not anechoic chambers ) and on wall location, the 4.5 inch BMR line arrays simply flood the entire space with seamless low distortion music.
Seamless or not, phase is phase.
Physics laws hold true.
Now, if you mean that a real world room will have so many peaks and dips because of multiple reflections that comb effect on the frontwave becomes hidden/masked/irrelevant yes, I can agree with that.
But in that case, the original 4dB or so 1.5KHz dip also becomes irrelevant by comparison.

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They are dynamic, detailed and so supple & liquid its delightful and astonishing in equal measure.
Poetry of the highest grade, I think I will hire you to write my brochures
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