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Eeyore

wrote:

Eeyore wrote:
wrote:
Eeyore wrote:

A 50W continuous rated horn ? There are plenty of commercial products that bi-amp at
that level. The second amp is probably cheaper to build than a decently made passive
crossover.

I'm a pro-audio consultant so I should know !

I haven't built an amp since the 70s.. or 80s using 70s designs! I remember the
Tiger series...

Do you have a schemo for a decent 50 watt or so amp? A "simpler than an xover"
amp? I hear power FETs have simplified things somewhat.

Just use one of the National chip amps in the 'Overture' ? series. Google "gainclone" and
you'll find ready to build kits.

Plus I need to make a filter, got something on the latest in Link-Riley what
evers?

Typical Linkwitz Rileys are simply 2 cascaded Butterworth 2nd order filters IIRC. Again
go to National.com and use the WEBENCH design tool but use a sensible audio optimed
op-amp say the LM883, NE5532 etc and scale those R values down and C values up to keep
the noise low. Use close tolerance Rs e.g. 1% and the closest tolerance Cs you can afford
or the output will not sum correctly ( another problem with passive xovers ). Note that
the -3dB point of the Linkwitz Riley filter is not the Fc of the individual 2nd order
butterworth filters so you'll have to do some modelling.

Personally I use Bessel filters though but you have to cross them at -4.5dB to get a flat
SPL vector sum.

http://en.wikipedia.org/wiki/Linkwitz-Riley_filter

Graham