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In article <1235@eedsp.eedsp.gatech.edu> sjreeves@eedsp.eedsp.gatech.edu (Stan Reeves) writes:

>   The project would be to design and implement in hardware an equalizer
>   that takes the digital signal from the CD player, filters it according
>   to the equalizer settings, and feeds the digital output back through
>   the D/A in the CD player.  Any helpful advice would be greatly
>   appreciated.

Motorola has an application note that has a complete design for such an
equalizer for use with a Sony CD player (model CDP-605?).  It should work
as-is or with small modifications with just about any CD player.

I modified their design to use AES/EBU digital audio I/O, because I didn't
want to open my CD player and void the three year warranty, but if that
doesn't bother you then the Motorola note is exactly what you want.

Eric

--
Eric L. Smith      Opinions expressed herein do not necessarily reflect those
esmith@apple.com   of my employer, friends, family, computer, or even me!  :-)

sjreeves@eedsp.eedsp.gatech.edu (Stan Reeves) writes:

%I'm thinking about offering a senior design project in which students
%would design and build an internal CD equalizer.  I would like to get
%some feedback from people experienced with overseeing undergrads in
%design projects about whether this is too much for a group of senior
%EE's.

Well, I'm no prof, and I only TA'ed a theory class, but here goes anyway...

Ha!  Yep, it sure would be easy...  almost TOO easy!  All they have to
do is write

Motorola Literature Distribution
P.O. Box 20912
Phoenix, Arizona
85036

and ask for APR2/D, "Digital Stereo 10-Band Graphic Equalizer Using the
DSP56001".  Inside, they would find plans for hooking a 56001 into the
bitstream of a Sony 650ESD CD player.  Actually, these plans work for
any CD player that uses a serial bitstream (I think every Sony CD player
does... my Denon 1500 doesn't, even though it uses the Sony data decoding
chip (it uses it in parallel mode)).

Basically, you take a 56001, cut the serial bitstream going to the DACs,
connect it to the sampling clock (44.1kHz), the Word Clock, and the Bit
Rate clock, hook it to a 20 MHz crystal, an EEPROM, and a cheap ADC with
a MUX connected to several slider pots for your controls and you are
in business.  The app note leaves no stone unturned (no exercises for the
reader here!) and provides the source code to make this beast work.

I actually saw the beast the app note was based on at an AES show down
in LA a few years ago.  Quite interesting....  it's neat seeing a board
with monster processing power that has hardly any wiring on it at all.

%I have a good background in general
%DSP, but I'm not much of a hardware person.

That's where I was coming from, and I managed to build a dual 56001
platform with analog 2ch in/4ch out for doing Dolby Surround the
Right Way (tm).  These chips are so easy to just plug and play these
days it's almost like playing with Leggos.

%I expect to have around
%ten undergrads working six hours a week for twenty weeks on the
%problem.  Most will probably not have had a filter design course (it'll
%be a corequisite).  Senior status in electrical engineering is the
%basic prerequisite for this project.

Well, if your students are anything like some of the weenies I went
to school with (all theory, no practical makes Jack a dull boy), they
won't be able to handle building the project.  If you have a class full
of hacker type people who aren't afraid to just go for it and they have a
strong practical background, it'll be a challenge, but it'll be fun and
they'll love you for it.

Good Luck!  I'm not sure what your status is (prof/TA/etc), but I wish
I had taken such a class when I was an undergrad...  (but did they offer
one? Nooooooooo....)

-- 
Todd Day |   todd@ivucsb.sba.ca.us   |  ucsbcsl!ivucsb!todd
	It's not a matter of winning or losing...
	It's how much tread you scrub off your tires!

 
There is an application note on CD equalizers, it is for Motorola 56001.
The AN is published by Motorola. The program and hardware are not difficult,
but the realization of hardware calls for at least two level printed
circuit (due to the dense footprint of DSP processors), and the process
may take some time out of the twenty weeks. Be aware that there are several
internal types of connecting the bit stream from the error correcting 
circuit to the D/A converter. Serial types are easy to connect the equalizer,
paralell are not so easy (because the is no 16 bit paralell port in DSP
processor).  Anyway, quite a good project, maybe a bit too easy.

-- 
Sakari M. Mattila    71307.1525@CompuServe.COM
                     mattila@tik.vtt.fi    Sakari Mattila@3:663*371.0.FNET