-=> Quoting Bob Allman to Dan Dunfee <=-
 DD> I have had them completed for about 4 months.   I use a
 DD> Clearview active crossover which duplicates the passive ones
 DD> designed for the original Carver version.  Because of the
 DD> geometry of the ribbon cavity, there is a resonance at about
 DD> 6k which is equalized by the Xover.  It also has a frequency
 DD> shaping control which changes the upper mids and lower highs
        Hi Dan.  As you may remember, I'm using the Carver AL-III
speakers with the 48" ribbon version.  At the moment, I have the 10"
woofers disconnected and I'm crossing straight to my Definitive
PF-1500 subwoofer.  The primary reason is running the woofers in
parallel with the ribbons from my TFM-35x amp (250 watts into 8 ohms
and 350 watts into 4) causes the amp to clip at high levels on a few
dynamic discs with a lot of low bass information.  This damaged the
right speaker ribbon before I figured out what was going on.  It has
since been replaced by Carver, but the problem remains.  Given your
DIY project with the Carver ribbons, maybe you can give me some
advice.
        Right now I'm considering options on how to deal with this
problem.  While crossing my sub around 90Hz to the ribbons which are
crossing at 150Hz works fairly well, I believe I have a fairly
substantial dip between 100Hz and 150Hz (1/2 an octave) due to the
rather large 36dB/octave crossover on the subwoofer and 14dB/octave
crossover on the ribbons.
        At first I was considering buying something like a Sunfire amp
that probably would never run into a clipping situation in the first
place.  However, this is not only a bit of an expensive solution, but
it ignores the peak/dip problems I get around 40-60Hz because of the
subwoofer reacting with the woofers over the same range.  What I need,
therefore, is a high pass crossover for the AL-IIIs.
        The way I see it, if I cross around 70-80Hz high pass to the
AL-IIIs, there won't be significant stress caused by low bass to the
main amplifier, and I may not even need a larger amp, since the
TFM-35x works fine with just the ribbons (woofer load removed).  I
went to see the new Sunfire Subwoofer (which suprisingly [due to the
positive hype currently surrounding this sub] I didn't really find
substantially better sounding than my current subwoofer).  The guy
there suggested an active external crossover that they could order
from Mirage that would plug into my preamp and have a separate
subwoofer output at 24dB/octave (adjustable from 50-150Hz), a
12dB/octave high pass crossover (also adjustable over the same range),
and phase switch.  
        The problem with this is there's no way to easily defeat the
internal subwoofer crossover, so I would be staring at a 60dB/octave
slope, which sounds useful at first, but I'm thinking at the higher
than "flat" bass level I tend to set my sub at, this might cause a
level shift of over 2x the volume over the course of one bass note,
which wouldn't be good.  The other thing I thought I might be able to
do is set the 36dB/octave sub low-pass crossover lower (say around
50Hz), set the 12db/octave high-pass on the Mirage crossover around
60-70Hz, and the 24dB/octave low-pass on the Mirage crossover around
90-100Hz or so, which might provide a larger, less steep transition
period and still provide the added benefit of keeping more higher
frequency information (even at reduced levels) away from the subwoofer
after the 10" woofers are ramped to full volume and the sub is rolled
off substantially.  What do you think?
        Another option might be to sell the sub and buy a sunfire,
which already has a low-level high-pass crossover built in and
according to most, is a substantially faster sub (although the demo I
heard couldn't confirm this for me, but then it wasn't optimally set
up nor did I have a lot of time to use it).  
        
        I'm interested in the Clearview active crossovers you used in
your project.  Exactly what was/is available and how did you choose
what you did?  Is the crossover adjustable?  Was it specifically
tailored by Clearview to be used with the Carver Ribbons?  Do you know
if the 48" ribbon has the same frequency dip (or is it at another
frequency)?  I'm not sold on the Mirage crossover and if Clearview is
better or has a more suitable crossover, I would certainly consider
that.  Perhaps they or someone else makes an external crossover that
is high-pass only I could put after the subwoofer and avoid the
steeper/extra low-pass combination box.  
        I'm also thinking at some point I may wish to switch to fully
active drive and bi-amp the AL-IIIs (tri-amp if you count the sub with
its own amp).  So, I might consider an all in one box if there is such
a thing (I don't know what's available).  
        That's pretty much the situation.  I'd appreciate any advice
you could offer on the matter or from anyone else that knows a lot
about active crossovers out there.  I don't want to spend a fortune on
crossovers, but anything reasonable I'd consider.  The Mirage
crossover in question is around $250 from this dealer.
 DD> I recommend them as a diy project.   Sadly, the price rose
 DD> about a month after they were ordered, but I feel they still
 DD> present very good value for money for anyone purchasing them
 DD> now.  I think the current price is about $450 each now. 
        When I had the ribbon replaced, I found out how much it and
the 10" woofer were going for.  The 48" ribbons are $350 each and the
10" woofer of the AL-III were $50 each (but that's the older
brand...they've since switched to a new brand because the older
company wanted them to buy higher volume than they were capable of at
current sales rates).  I don't know how much the newer woofer runs.
        Anyways, at the price I got my speakers, I don't know how
Carver is even turning a profit.  I paid $1175 plus $100 shipping
mailorder.  Tell me how you fit $800 worth of drivers in a real oak
baffleless wing that's 6 feet tall plus a woofer enclosure and sell it
to a dealer who then turns around and sells it to me for $1175 and
still make a profit?  Something just isn't right there.  I think they
may have since come to their senses as I see now Circuit City is now
carrying the AL-III and it's going for a flat retail price of $2000 a
pair.  My local hi-fi dealer has them for less than that.  And the
local Circuit City is only offering them in a rather AWFUL looking
flat black color (they look like charcoal towers).  Where's the nice
piano laquer black the Platinums were available in?
        I read somewhere the reason they quit selling the platinums
was because they weren't selling enough to make any money off of them
and Bob Carver was only charging $2500 a pair (can someone confirm
this?  I know I could have bought the Silvers locally for $1500 a
pair 3 years ago which was less than the AL-IIIs at the same place),
which wasn't a whole heck of a lot above cost.  I guess the
speculation was that raising the prices would sell even less.
Personally, I have the hunch that charging $80,000 for them might have
sold quite a few....  ;-)
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