[FSMR4EARS]

Is the 1,200-2,000 BBC dip something considered valuable and used when designing XOs done by GR Research?

[Hobbsmeerkat]

Nope, Danny prevers a flat linear response across the  entire frequency range.

[S Clark]

The BBC dip is an adjustment to bring things more into balance off axis.  Danny is one of the designers that works hard to keep off axis response as smooth as possible, so a BBC dip would be solving a problem that doesn't exist. 

[jjss49]

https://www.youtube.com/watch?v=7WQ6Ig9j_y0

this may help inform a bit

[Barryg443]

My guess is that Ask Paul video is what prompted this thread!  Thread created within a day of Paul releasing that video!

Barry

[Hobbsmeerkat]

I thinking he's talked about the BBC dip a couple times over the years.

[S Clark]

As I understand, a BBC dip is supposedly more pleasant than a true response?? If this is so you could improve a full range instrument like a piano sound if you dampen strings from 300 Hz to 1500Hz?   

[subsonic1050]

I find it interesting that Paul claims that a speaker with a BBC dip sounds more real. By definition, a speaker with a flat frequency response sounds the most real - any fluctuation in the frequency response is altering the original sound. Some people may prefer the sound of a dip in that area, but that doesn't make it "more real". You can't make something "more real" than the original sound. In this case you are intentionally suppressing the most important frequency range for human listening. I'll be honest and state I haven't done listening comparisons, but to me that sounds like an absolutely terrible idea. It seems that you'd only do that if you are having trouble designing a proper crossover, or you have some other limitation with your drivers.

[Cheytak.408]

People forget why the BBC dip was introduced in the first place.

Most speakers back in that era had limited low frequency response and terribly erratic HF response.  Off axis (room response) frequency response was not a consideration because the room influence was not a consideration.  With low frequency response rarely reaching below 50Hz the mid range of speakers seemed prominent, especially in the 2.0K - 3.2K range where the ear is most sensitive.  Sibilants, fricatives and plosives have a lot of energy in that area.  Slightly depressing that range made for a more "pleasing" sound.

It is of interest that the LS3/5a did not have this dip.  The BBC recording engineers chose to bump up the 60Hz - 85Hz region to psychoacoustically compensate for the upper mids, which were (are) basically flat and the tweeter rolled off the upper octave.  This is one of the reasons that the LS3/5a was (and is) highly regarded as a good image producer.  Ergo: baffle step compensation and very slight HF roll offs when necessary.

The presence of psychoacoustic influence and recognition thereof is part of what separates present day crossover designers and the great products they produce from the old stuff.  Danny is a master of knowing what and how much of what makes a speaker sound good.