[sdiy] equalizer

[Johannes Öberg]

In reply to cheater cheater:

Well... you may find yourself wanting to "kill" different bands very
> frequently when playing dynamic music. Then, a simple filter wouldn't
> work that well.
>
> There's much more to music than just BD :P ;-)


Well, that's why the filter should be switchable between hi- and lowpass
modes. Now, of course you would probably want a variable bandwidth bandpass
as well, but I was trying to keep the featurelist as realistic as possible
:-) (When I say "kill the bd" I really mean to add "or the hihats, or etc
etc etc" but I was trying to save everybody some time...)
What styles are you playing? I know hiphop has very different requirements
from trance, etc. Personally, I'm into techno, acid and trance so I could
use a bit of both, but I'm also dead set on playing from my old 300 Mhz
Pentium 2 with DJS :-) Therefor an external mixer is the only option for me.

Who said anything about fixed crossovers? :-)


Hey, that mixer of yours is going to look like an ARP2600 :-) Anyway,
indeed, an 24 dB/oct eq with tweakable crossovers and -oo kills would be the
most versatile, I'm just concerned about the usability aspects, and the
hardware complexity. If you're going the analog route, I'd say the latter
should be your main concern, especially if you're not experienced in the
field...

Also, buttons for killing bands are nice too. And they're going in my
> mixer for sure :-)


There exists these nice 3-position switches which are
(locking)ON-OFF-ON(temporary) which bounces back to OFF from the lower
position. Perfect for kill switches imho.

uCs are real cheap! c'mon


Yup, but there are lots of other costs, like development equipment... Not to
mention the labour!

> That's how the P&G faders have to be used anyways. The ones used as
> crossfaders aren't even sold as audio-taper, I think.


Sorry, I misunderstood; I guess I don't know what P&G faders are.
Anyway, if I'm alowed to dream some more :-), there is the option of making
an optical crossfader with a lamp and LDR's (or LD-something-else's), that
would have no wipers at all. I don't know if these exist already; I haven't
seen them, but then I'm not an active DJ. I don't know about LDR
sluggishness issuess either.

No way!
> DSP is no fun. DSP costs a lot. DSP breaks. DSP doesn't have an analog
> sound. DSP isn't easy to change on your workbench. And I'm not
> interested in learning DSP.


I don't know about the fun, but the cost is probably about the same these
days. And why would it break? I also think that analog sound is quite
overhyped, especially in an application like this, since the only thing it
could add are phase-errors in the crossovers - which would do no good to the
sound. And it sure is easier to reprogram an EPROM!

But then again, if you're not into DSP, thats reason enough. I'm not either
in this case, but then again, I would be happy with something simple (my
current mixer doubles as a pink noise gen). However, I think you would
probably have to drop the digital control dreams, or it gets way too
complex.

There's always use for a simplified first version when it comes to this kind
of projects...

> Digital control over
> > analog filters seems to me to be a very cost-ineffective way to do
> things
> > these days.
>
> Why?


Because microprocessors are so fast these days (hey, even a $5 Atmel is
faster than my first PC!), if you already put one in there you could just as
well save on the filter parts by doing it in DSP. Look at the AVR synth
project, here on the sdiy list, for inpiration.

No - that's exactly why I want an analog mixer.
> With VSTs, even with ASIO2 you still realistically get 10-20 ms of delay.


Isn't that only because of MIDI? Everything else is dependant on system
settings, isn't it? IIRC, the Behringer controller runs via USB, and should
have no real latency. If I'm wrong on this one, I'm sure there is some other
controller.

Actually, that's where I would do your "set up the permanent EQ for
> the track" part. You can get VST equalizers in much better quality
> than you'd be able to build with any sane amount of time and effort :P


Yup, good idea. Run a multiband compressor here, and never worry about
anything.

Lets dream on :-)
/J
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