Do these resonances come from cabinet design primarily?
If from the drivers can notch filters in the crossover solve this?
If from the cabinets I’d like to see what internal bracing would do to help.
Canada has always had a lot of people making a living from stuffing boxes with speaker drivers not knowing what the heck they were doing. I have bought some of these brands when just having a big stack of black components and big party blaster speakers were part of the ego accessories of a 20-something in the 1970s. There has always been a market for affordable speakers. That some brands rise from the dreck to become aspirational items, despite being inferior, is due to marketing and fashion. Some manufacturers learned something from the NRC association like Energy who made well measuring speakers but failed anyway. StudioLab made a decent speaker in its last incarnation after years of big boomy crap. But they too are gone. The hucksters and salesmen prevail. Well not all… thank god Nuance is long gone. Maybe ASR and its brothers who measure will eventually bring an end to the box stuffers and elevate audio speaker manufacturing to a respectable engineering based profession.
I’m enjoying your book. It is taking me a long time to get through with all the responsibilities of life coming before hobbies though!
Most audible resonances in most loudspeakers originate in transducers. Cabinet bracing is part of competent design, using scanning laser vibrometers to identify vibrations that radiate sound - not all do. The knuckle test does not work. Heroic cabinet materials and elaborate bracing schemes are mostly marketing handles.
Parametric equalization based on anechoic data can effectively eliminate audible resonances in loudspeakers. In-room curves cannot provide the evidence. This is why active loudspeakers, incorporating DSP are advantageous.
However, steady-state room curves are the definitive evidence for identifying and attenuating room resonances, which everybody deals with and which account for about 30% of our overall sound quality ratings. Rooms are arguably the weakest link in the sound reproduction process, and I am not talking about reflections.
I think it is fair to say that all countries have done their share of stuffing boxes with drivers and inventing stories to sell them. Several countries have also made some very fine, neutral loudspeakers. Thanks to the Canadian taxpayer supporting the NRC effort and HARMAN International continuing it - both allowing the research to be published for the world to see - there are now clear guidelines for designing timbrally neutral loudspeakers. That some companies do it better than others is a measure of engineering competence. If others choose to ignore the science - it is a free world and business is business. The scientific facts are real and will not go away.
But it is evident from Amir's and Erin's excellent measurements, and others to be found on
www.spinorama.com there are many loudspeaker manufacturers the world over who are not only aware of the guidelines but who are following them. The average sound quality of loudspeakers is definitely going up. Unfortunately, we are still saddled with stereo as the default medium - if one is speaking of weak links.
I'm pleased you are enjoying my book. The 4th edition will be quite different, with new insights.