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Re: [OM] audio obsession, was Siddiq's PAD - Jan 1 2014

Subject: Re: [OM] audio obsession, was Siddiq's PAD - Jan 1 2014
From: Ken Norton <ken@xxxxxxxxxxx>
Date: Wed, 8 Jan 2014 11:56:33 -0600
> Yea, the guys who need to make it work for living have stuff that's the real 
> deal. They have actual standards to meet.

The nice thing about "standards" is that we have so many to choose from. ;)

But from the context of this discussion, the eyes can prove just how
easy it is to fool the ears. I can usually survive an A/B comparison
test only if I've been able to identify something first and then I'll
listen for that thing. But if you do a double-blind A/B comparison
test, where we don't know WHAT is different, it's exceptionally
difficult to identify the difference.

Do note, that when I put together A/B tests, I would do so in such a
way that there was a seamless change between them, with only time-code
as the differentiation point. Hehehehehe. I'm tough.

I've written about this before, but one day I was puzzled by what MPEG
Joint Mode was doing. Something didn't quite square up with me. (AM
stereo is actually a variant of Joint mode). So, I ran controlled
tests with sweep generators. What I found was that the Left-Right
channels were one sample off, which put the channels out of phase with
each other at the the point where the low-pass filter kicks in. There
were other errors in the algorithm which I documented and wrote an
entire white paper on. It caused quite an uproar in broadcast industry
as we were using joint mode (up to that point) for everything we
could. My white paper also addressed a fault in the algorithm that
would occur if you fed an out-of-phase signal into the compression
algorithm. Nasty, nasty, nasty. The real beasty part to this is that
the algorithm was burned into a chip that was installed in nearly
every pro-audio device in the '90s. So, the entire industry had to
switch over to MPEG Stereo Mode (non-joint) to get around the fault.
The fault was eventually corrected by some device manufacturers, and
eventually the soft version (computer based) was mostly corrected, but
not entirely. The out-of-phase problem will still choke Joint mode
horribly. One particular company, that manufactured the chips probably
put a bounty out on my head and may have contributed to my
disappearance from the industry.

The point is that without extremely accurate analytical tools and
fancy prototype digital editing gear, I would never have been able to
identify the problem, much less get around to actually figuring out
how to test for it.


> It's interesting that you picked those three, in that order (welcome to my 
> club!). Most people don't realise how much the room helps--or more often than 
> not, hinders. After that, speakers are the biggest thing, followed by the 
> amp. I'd say that's a 90/split. Then of course, it's garbage in garbage out, 
> so whatever you're playing has to be pretty decent. Sure most of is it 
> livable but the few recordings that are truly well mastered really come alive 
> and are a joy to listen to.

The room is critical. VERY critical. It floors me how many recording
and editing studios are junk, acoustically because of the walls of
relay racks holding unused equipment in the control room, but are
there for appearance sake. That's OK, though, because all it takes is
to slap a few sheets of SONEX up somewhere on the wall (again, to look
pretty) to fix everything. Riiiiiiiiight. Bass Traps in a STUDIO?
PLEASE!!!! A properly designed studio/control room should never
require bass traps. Period. Again, consider a device like a bass trap
to be a band-aid which DOES color the sound. It's a PASSIVE PROCESSOR.


> You do have to hand it to them that they can take such cheap components yet 
> make it sound decent.

Mine are of a pretty early generation and the components are actually
quite good. Bose was/is able to use low-cost materials and very small
housings to achieve a BIG sound, but the requirement there is that the
room be pretty decent and the speakers be up where the sound gets to
move around a lot before getting absorbed. The speakers themselves are
very small, but HEAVY. They achieve a lot of volume by aggressive cone
movement. The advantage is that since the housings are so tiny (no
face plate to contribute to distortion or directionality), the
coverage pattern is very uniform and off-axis is no problem. The
disadvantage is that the cone moves so much (being so small) that you
literally get Doppler distortion with higher frequencies.

Speakers, like the 901s can be simply awesome to listen to if the room
is right. I stayed overnight in the home of one of Bose's chief
engineers and inventor of multiple technologies. His in home listening
room was built around the speakers. It was one of those "Top 10
listening rooms you would die for" with hundreds of thousands of
dollars worth of equipment and a pair of 901s. I would say that
listening to that system was pretty much a religious experience. He
was a little cagey about how custom those 901s were, but I found out
from other sources that they were stock, but hand selected. Trust me,
that system had PLENTY of highs and lows.

I've wanted a pair of 901s ever since. Still do.

-- 
Ken Norton
ken@xxxxxxxxxxx
http://www.zone-10.com
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