Dick Burwen had built audio equipment since the 1940's, and after WWII was a founding engineer at Krohn Hite, one of the first electronics companies to make audio analysis equipment at the same standard as General Radio and HP.
1. Burwen Noise Reduction System. Dolby won the professional noise reduction for analog tape recording marketplace, for music and film, with "Dolby A" of which the consumer version "Dolby B" was a very stripped down version. Burwen and dBX had alternative compansion systems that boasted far better specs....far better noise reduction and/or dynamic range. Some have blamed the "Dolby Mafia" including not just the corporation itself but the pool of studios already contracted to use Dolby who pressured others to conform to an inferior system. I have insufficient information to judge these different systems. It's possible the less impressive specs of Dolby correspond to a less "fragile" system, in which poorly maintained electronic or tape equipment or the like is better tolerated. There could have been reasons Dolby was better in practice, in the notoriously sloppy recording industry of the early postwar era (45-70). Dolby isn't perfect, but it's designed to have errors that are relatively inaudible. I'm sure Dick's system worked great on his own perfected circuits and properly maintained equipment, it's just a pity others were often not as good.
2. Burwen single ended noise reduction, "autocorrelation," etc. I'm not sure Burwen sold something like this actually. He talked about noise gating and things like that. I am fairly opposed to the weird sounds that can result from noise gating. I've never heard Burwen's system, if it existed, or the famous Phase Linear 4000, which has "autocorrelation" designed by Carver and associates, not Burwen. I've never heard that either but I have my doubts.
3. Burwen was a lifelong advocate of EQ, tone controls, and the like. I think he was largely correct about much of this, and EQ got a bad name ("complexity") with the emerging "High End Audio," (though, ironically, Burwen himself may have gotten many favorable reviews regardless...and he was a buddy and recording engineer for Mark Levinson...who later insisted had Burwen design the ultimate high end equalizer--the Cello Audio Pallette--and include his proprietary high frequency reverberation system which Levinson was the only way to make CD's listenable.
4. Burwen often boasts that we can hear EQ changes down to 0.1dB, and suggesting because his equalizers (especially the later digital ones) have that capability they are far better. He makes a refrain that we can hear better than many engineers realize.
Research has indeed shown midrange differences as small as 0.1dB to be audible...sometimes. We're talking very trained listener, perhaps even test tones. With constantly varying music...it's not so easy. And it's darned near impossible/unreliable without near instantaneous A/B testing.
Sure, we should do studies with 0.1dB accuracy as an experimental requirement. But let's not pretend it's easily audible. On narrow bands like 1/3 octave, changes may need to be 5dB or more to be very clearly audible on music.
So while I'd like to have my equipment provide 0.1dB adjustment resolution it mostly doesn't. 0.5dB is typical. That's not my choice, but I don't see it as a hugely big deal for the most part.
This is the one area where Dick is sticking his neck out beyond pure "audio objectivism." Has he proven he can hear these 0.1dB differences on music in double blind tests? Or is he relying on subjective listening tests, just like those he sometimes derides as "audiophiles."
Still, I'd love to have Burwen's EQ setup. Nobody but nobody did as much EQ adjusting as Burwen, and he designed his controls very uniquely from that experience. Plus the 0.1dB resolution is a plus.
5. Burwen was an advocate of normally reverberant listening rooms, like ordinary living rooms. So was Linkwitz and many others. Linkwitz said it's best to have a room that makes you feel good talking in. It's what I do also. But this could also be a reason why EQ is so important.
6. Burwen's high frequency reverberation sounds like a further enhancement of what dipolar and omnidirectional speaker systems do naturally. Dick's speakers were giant horns, so he needed this kind of thing even more than I do, for example.
He makes it clear that this "rough" looking high frequency response actually sounds smoother.
I think he may really be on to something with this, and it's a pity it's not more generally available.
My subjective finding is that supertweeters make the system sound smoother, perhaps on a similar basis.
7. But why are we adjusting the EQ? Burwen has no problem adjusting "to taste." The record producers didn't know what they were doing.
That's probably still true for much music. But I tend to think the music I listen to was very well produced. I am not doing EQ "to taste" for each piece of music. I am doing it to further perfect my system playing any and all recordings, pretty much assuming that the producer's intent was the best presentation.
And that is the way it seems like it has always worked for me, though it's true a few recordings seem to mandate different adjustments, it's just my general contention that if I found the best adjustments, sort of "in between," it would work for everything.
So it is different from my general approach, but maybe Burwen is right.
8. Like Linkwitz, Burwen identified the need for an upper midrange cut to make music sound less irritating. Burwen calls this "screech," and recommends a cut centered at 4kHz.
My finding so far is that quasi line source dipolar speakers need a rolloff from 2kHz at 3dB/octave.
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