[rec.audio.high-end] 1/3 Octave EQ query

erich@inmet.inmet.com (11/01/90)

Is anyone aware of a 2 plus channel 1/3 Octave EQ with spectrum analyzer.
It would be desirable to have both analog and digital inputs and outputs
and I would prefer digital rather than analog internal circuitry.

Any information would be appreciated.
Thanks...

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hunter@work.nlm.nih.gov (Larry Hunter) (11/02/90)

  Is anyone aware of a 2 plus channel 1/3 Octave EQ with spectrum analyzer.
  It would be desirable to have both analog and digital inputs and outputs
  and I would prefer digital rather than analog internal circuitry.

I've just been looking at this sort of thing, mostly pro (analog)
gear.  [I've never seen a dedicated digital EQ, but all of the fancy
dsp gadgets can do EQ.]  My local pro store is running a sale on Rane,
and I'm tempted to buy their 1/3 oct eq.  They come one channel at a
time, but that means you can buy one channel with spectrum analyzer
(pink noise, callibrated mic, etc.) for ~$400 and one without (~$280?
I forget).  They also sell a two channel, 2/3 octave beast for about
$450.  If you want more info, send email & I'll try to remember to
bring the model numbers, specs etc.  Also have nice parametrics on
sale.

BTW, one of the good things about the Ranes is that you can switch
between active +- 12(?)db, and passive 20db cut only modes.  

--
Lawrence Hunter, PhD.
National Library of Medicine
Bldg. 38A, MS-54
Bethesda. MD 20894
(301) 496-9300
(301) 496-0673 (fax)
hunter@nlm.nih.gov (internet)
hunter%nlm.nih.gov@nihcu (bitnet/earn)

drm2@mvuxn.att.com (David R Moran) (11/02/90)

In article <7360@uwm.edu>, erich@inmet.inmet.com writes:
> 
> Is anyone aware of a 2 plus channel 1/3 Octave EQ with spectrum analyzer.
> It would be desirable to have both analog and digital inputs and outputs
> and I would prefer digital rather than analog internal circuitry.

Why, for heaven's sake? It is probably possible to simulate in software
and with DSP all of the work done in a good 1/3-octave RTA, but a
good Reticon filter bank built around a PC (as in the dbx RTA1, now the
Sound Technology 4000 RTA) or equivalent hardware architecture is 
much more than accurate for 1/3-octave work, at least with pink noise.
And good analog constant-Q 1/3-octave equalizers are available...
Maybe there are other arguments for digitizing this kind of analysis
but I cannot think of what they are.
There are some arguments for digitizing equalization, but the usual
argument is that 1/3-octave is not fine enough (it is, but you can't
convince anyone who believe otherwise). The "phase" arguments usually
show that the arguer does not understand what happens in the so-called
time domain when transducers play back within an enclosed space. But 
there is some validity to doing EQ digitally.

Analog is very, very good for many thing in audio -- quiet, versatile,
easy to manipulate, sensibly expensive or inexpensive, etc.; many things 
that digital is not, or not always, or not easily. If this question 
arises from an uninformed pro-digital bias (and it may well not, it may 
have sounder reasons behind it that I am missing), I would point out that 
sometimes it is useful, whenever you see the word digital or thrill to 
using it yourself, to substitute "numerical" instead. As in numerical-ready 
speakers, or in this posting, numerical inputs and outputs...