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BBC Dip
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Old 26th August 2015, 02:02 AM   #11
infinia is offline infinia  United States
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Sreten likes to make up stories based on his POV. On another occasion he claimed the so called BBC dip was in fact a peak at the upper HF end, I tried to wrestle with him on this claimed story and he said he knows it b/c he's British. You can study the LS3/5A history and all the different driver suppliers and then look at its xover schematics early revisions (note all the level taps), I figure depending on which years production sample an audio reviewer had their mits on, every version likely had their own sonic signature (maybe like a 'vintage' series). It's probably just another Myth still making the rounds via the internets.
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Old 26th August 2015, 02:11 AM   #12
rayma is offline rayma  United States
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Quote:
Originally Posted by sreten View Post
BBC speaker voicing on the other hand does prefer basically a gently falling response,
2dB/3dB over the range, but this is not the "BBC dip" phenomena, its just overall voicing.
Acoustic Research also provided this response at the "normal" setting of their mid/high controls.
When turned to maximum, the controls gave a "flat" response.
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Old 26th August 2015, 02:53 AM   #13
system7 is offline system7  United Kingdom
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@ infinia.

I must admit I thought the BBC Dip was a gentle 4dB frequency response rolloff across the band as exemplified by Troels Gravesen's voicing with the LR2 ScanSpeak-3W-Discovery.

It apparently reduces sibilance and fatigue. FWIW, the BBC employed BW3 filters which have increased power response at crossover compared to LR2 and LR4. Maybe that is where the dip at crossover idea might come from, but it's news to me, and I prefer BW3 flat on frequency response.

Earl Geddes says that a (slope) dip is particularly applicable to high dispersion tweeters. The more I learn about speakers, the more I learn that EVERYTHING is a compromise.
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File Type: png Troels Gravesen SS 3 way.PNG (88.2 KB, 937 views)
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Old 26th August 2015, 03:00 AM   #14
infinia is offline infinia  United States
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pip pip .. ye old smiley faced EQ ...I do say ol chap
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Old 26th August 2015, 04:42 AM   #15
PeteMcK is offline PeteMcK
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BBC - Food - Dips recipes
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Old 26th August 2015, 05:56 AM   #16
ScottG is offline ScottG  United States
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Quote:
Originally Posted by system7 View Post

I must admit I thought the BBC Dip was a gentle 4dB frequency response rolloff across the band as exemplified by Troels Gravesen's voicing..
There were 3 "major" compensation curves used by the BBC - Troels design was one of them. I believe that the dip you are describing was actually in use the most for far-field near-field adjustment.

Engineer Keith Gundry developed the presence region compensation curve.

You can read more about that here:

http://www.diyaudio.com/forums/multi...tml#post972549
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Old 26th August 2015, 01:13 PM   #17
infinia is offline infinia  United States
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Originally Posted by ScottG View Post
There were 3 "major" compensation curves used by the BBC - Troels design was one of them.
Troels did work for the beeb?
only 3 ? I get there was one for every speaker design. I fear giving them "labels", counting them, or deciding what was major and minor is a big problem bud!
from all Ive read (a lot) in the final analysis I say its all myth building from the clinger-ons.
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Last edited by infinia; 26th August 2015 at 01:39 PM.
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Old 26th August 2015, 01:19 PM   #18
fishball79 is offline fishball79  Singapore
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Quote:
Originally Posted by kspv View Post
Is it true that some speaker manufacturers deliberately provide for what is known as "BBC dip" in their speakers' frequency response.
You can see for yourself in Stereophile's measurements of their reccomended 2.5 or 3 way speakers for 2014. The common trend I see is a dip ~100hz to 1khz except for the YG Acoustics.

Vivid G1 Giya
Click the image to open in full size.

Wilson Audio Alexandria XLF
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YG Acoustics Sonja 1.3
Click the image to open in full size.

Joseph Audio Perspective
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Sonus Faber Venere 2.5
Click the image to open in full size.

Revel Performa3 F208
Click the image to open in full size.

Goldenear Aon2
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Old 26th August 2015, 06:49 PM   #19
ScottG is offline ScottG  United States
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Quote:
Originally Posted by infinia View Post
Troels did work for the beeb?
only 3 ? I get there was one for every speaker design. I fear giving them "labels", counting them, or deciding what was major and minor is a big problem bud!
from all Ive read (a lot) in the final analysis I say its all myth building from the clinger-ons.


Ok, poorly said.

Troels design utilized one of the major compensation curves used by the BBC.


Yes, the "BBC dip" was probably "coined" by an audio reviewer.

In the BBC probably the 1-3.5/4 kHz would have been called the Gundry dip, or Harwood's presence curve/dip.

I think Harwood (BBC Engineer) was researching this around the time Blauert (Academic Doctoral) was. It could be that one influenced the other.
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Old 26th August 2015, 08:38 PM   #20
sreten is offline sreten  United Kingdom
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Quote:
Originally Posted by system7 View Post
Factorising the product of two prime numbers efficiently looks interesting.
How hard can it be really?
Hi,

Well good look with that. You don't seem to understand the problem.
If it was easy cryptography would be fatally fundamentally flawed.
There is no efficient "crack" to the problem, that is the point.

rgds, sreten.

Last edited by sreten; 26th August 2015 at 08:50 PM.
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