"Wally" wrote in message
...
I ordered a Behringer 3-way active crossover...

http://www.behringer.com/CX3400/index.cfm?lang=ENG

...on Sunday, and it arrived yesterday. I've set it up for phase 1 of the
tri-amping project - splitting the top/mid from the bass. The following is
what I wrote last night in an email to a couple of mates. (For those that
don't already know, the Arcam Alpha is an original Mk1 version, and the
valve amp is a Maplin Millennium 4-20 kit that I built a few years ago.
Speakers are Kef B139/B110/T27 in home-brew reflex boxes with DN12
crossovers, and source is CD through a Meridian 203 DAC.)

---------------------
Currently, the Cyrus 2 is driving the bass, and I'm using the Arcam Alpha
for the top/mid. I disconnected the wires going to the bass driver, and
soldered them to binding posts - they are directly connected to the Cyrus,
with no passive crossover components between amp and speaker. The top/mid
are still being driven through the original Kef passive crossover,
including
the bits that cut off the bass frequencies to the mid driver.

The Kef crossover frequency between bass and mid is 400Hz, but I've found
that setting the active crossover to this gave me a rather muddy sound on
the upper bass. Initial tweaking would suggest that something around
120-200Hz gives a better balance - need to play with this more.

Initial impressions are that the bass is more solid, and that the overall
sound is tighter. I'm surprised at the little Arcam Alpha - it's doing a
much better job with the top/mid than I expected. Gwyneth Herbert was
quite
striking - she was bang in the middle of the speakers and very 'present' -
getting this with most music. Everything seems more 'coherent'.

There's a feeling that there's more low bass, but playing the test CD I
made
with the sequence of single frequencies would suggest otherwise - the
noticable roll-off from about 60-70Hz downwards is still there. Whether
the
roll-off will be as pronounced when the bass drivers are reboxed (and
doubled up) remains to be seen - I suspect there will still be losses at
the
really low end, so I think some sort of EQ will eventually make its way
into
the bass end.

Just swapped over to the valve amp after spending the last few hours using
the Arcam - it definitely has better resolution. There's more detail, and
everything sounds a bit more real, more 'open' - a better impression of
the
acoustics of the recording room on some Sinatra tracks. The Arcam does
seem
to put a veil over the sound. The problem with the valve amp is that it
doesn't produce its best at higher volumes - it seems to struggle a little
where the Arcam was coping better. The difference was apparent when I
tried
Bailero by yon mezzosoprano at a fair old volume - her voice was a bit
roughish sounding through the Arcam, but more shouty through the valve amp
(it was this track that led me to change to the valve amp - the Arcam was
clearly not coping). Keeping the volume below the limits of the top/mid
amps, however, the valve amp kicks the **** out of the Arcam.

About the only downsides so far are a rather big pile of equipment, and a
fourth plateful of spaghetti hanging out the back. And the row of LEDs on
the crossover - these pro audio peeps need LEDs to tell them stuff about
the
gear when in dark venues, but I could happily do without them. I'm
thinking
of moving the power amps, the crossover, and the DAC out of the way (maybe
onto the corner of the desk), since I only really need the CD player, the
pre-amp and the Telewest box to be visible and easily accessible.

So far, then, the crossover looks like being a plus, with the potential
for
being a serious improvement when the rest of the kit is sorted out.
---------------------

Been looking at more Behringer stuff this evening, and their Feedback
Destroyer thingy looks interesting - it also functions as a stereo 12-band
parametric EQ. Maker's product page is here...

http://www.behringer.com/DSP1124P/index.cfm?lang=eng

It's a DSP jobbie and, from what I can gather, each band can be set to any
frequency, and at 1/60th octave increments, no less. If it can function
slely as an EQ (ie, feedback-killer function switched off) I'm thinking of
getting one for the purpose of sorting out the bass response - it would go
between the crossover and the bass amp. Does anyone have any experience
with
this bit of kit?

Never used the DSP1124 but I have a http://www.behringer.com/DSP8024/

great value for money!

Ben