Room EQ to eliminate the BBC dip?

I read an older but very perceptive post on the thread about smooth speakers:

[09-19-07: Audiokinesis
A speaker can be made to sound smooth by designing in a frequency response dip in the lower treble region (somewhere around 2 kHz to 5 kHz). The Silverlines mentioned by Zapper and Bondmanp often have a pronounced dip in this region and I think that Shahinans do as well, and a lesser dip is present in many British speakers (and I would guess something like that is present in most of the other speakers mentioned in this thread that I'm not familiar with). Maggies have a broader, gentler lower treble dip that smooths the presentation.

As Mrtennis points out, there are tradeoffs involved. To my ears, a speaker with reduced energy in the lower treble region is lacking in upper harmonic energy on many acoustic instruments, and so it doesn't have as much "life". I find myself wanting to turn the volume level up louder to hear the harmonic richness that I expect.

I used to own Quad 63's, and would not describe them as an especially "smooth" and forgiving speaker - they could sound somewhat aggressive with some program material. Quad 57's are smoother, and I haven't heard the latest Quads.

Speakers that are free from peaks in the 2-5 kHz region (whether on-axis or off-axis) are likely to sound fairly smooth without trading off too much upper harmonic energy. But if you want a speaker that sounds smooth even with a harsh recording, you'll need a speaker whose response dips signiifcantly in the lower treble region.


I own B&W 802D's, which have a dip in the 2-5 kHz range. I use an Anthem D2V with ARC, and am currently correcting room response up to 5K. So I am eliminating the dip with room correction software. Kind of wonder what people think about this issue. I understand it's a personal preference, but do you think I am changing the "personality" of the speaker for the better or worse?

This also raises for me a second question, which is what speakers would be best to have when used in a system with room EQ. Obviously if you use a sub and room EQ, the bass extension/accuracy of the speaker is less important. I guess one would want even on-axis and off-axis frequency response above the level at which you stop applying the correction. Which high end speakers are the best for this? I am often amazed that some very expensive speakers don't seem to do this well, when you look at their in-room response.
Diw said, "I own B&W 802D's, which have a dip in the 2-5 kHz range"

How do you know this? What program are you using to measure this?

As I indicated, I use the Anthem ARC to measure and correct my in room response. I thought the dip was a well undestood feature of B&W speakers. I think it was also obliquely alluded to in the stereophile measurements.
It is not that simple. Your speakers are fairly flat on axis. The BBC dip occurs off axis - with greater dip at greater angles. It comes from using a woofer that is too large for the midrange (a 5 inch or more and running it up to nearly 4 Khz, where it "beams" severely - just like B&W use).

Think of your speakers mid range as a narrow beam flashlight - sure you can put in higher power batteries to raise the overall brightness to compensate for the narrow beam, however, this makes the narrowest part of the beam particularly intense and may be a problem even if the room is better lighted overall.

Besides most people prefer the BBC Dip, which is why so many speakers are made this way. B&W are a great company and they know what they are doing (making speakers sound teh way people like them to sound)
My room EQ measurements do show a dip between 2 and 5k. With the Anthem ARC you do measurements from different locations, which I guess allows the system to assess offaxis response. However, it only displays 1 curve per speaker. I guess the question is whether you would want room eq to try and correct for an off axis dip.

It's using the room eq program for speaker correction, not just room correction. There is a thread over at AVS forum where Sean Olive from Harman says that using room Eq to correct this issue results in increased listener preference.

Thanks for thought provoking reply
I have not known B&W speakers to sound particularly smooth. I always thought their sound was fairly flat with a lively treble. Early KEF speakers have that smooth sound especially with Krell.
"I have not known B&W speakers to sound particularly smooth. I always thought their sound was fairly flat with a lively treble."

Absolutely. Layman has some excellent posts on the 'Gon (among other sites like AudioAsylum) regarding the sound of B&W speakers. Very interesting stuff.
I believe that both Audyssey and ARC will EQ to flat FR, so any deviations in the speaker's anechoic response will be EQ'd, even if they are "designed in". If you don't want that result, you might consider the Lyngdorff (McIntosh) room EQ system. That one EQs to the speaker's near field FR, so that intentional deviations from flat EQ are maintained post EQ