[sdiy] Graphic EQs? (was Output circuit)

[Edu Silva]

Hi list

harry wrote:
> 
> Almost always*... the highest and lowest bands are shelving EQ... the
> lowest band is a HPF and the highest is a LPF so...


No. Almost allways there are only bandpass filters in the main EQ
section. Some good pro EQ´s, however, have variable LP an HP filters
too, in series with the BPs, in order to cut down the extreme highs and
lows to avoid damaging speakers, like Harry sugested in other message.


Chromatest Pantsmaker wrote:
> 
> I've seen several different graphic EQ's, but never really needed to
> use one, so never really gave them much thought.


Nice name! :-)

For protection purposes, you don´t need a commercial graphic EQ, just 2
filters: a hipass (40Hz, 18dB/oct) and a lowpass (15kHz, 18dB/oct), in
series. If you want wall-shaking bass, can use a crossover and send freq
up to, say, 80Hz to a subwoofer and he rest to the standard system.

You can find many DIY links to sites with projects of filters,
crossovers and subs in my site

http://audiolist.cjb.net

click in ELETRONICA and FALANTES & CIA and try the links on the left
side.

Good luck!

Edu Silva - audio maniac