[miklorsmith]

My Zu Definition Pro speakers have a main array that runs naturally down to 40 hz.  The subwoofers, unequalized, play to 1 khz.  I've found by playing with the XOs in my TacT preamp that I like a 65 - 70 hz, steepish filter better than the 40 hz built into the speakers.  With the TacT it's a piece of cake but without it I need an external filter.

Some amp manufacturers are building these into their products.  Roger Modjeski has 2 outputs on some of his amps, one for full-range, and one with a bass limiter.  The Firenze amp Srajan just reviewed has a variable high-pass filter inside, adjustable by USB laptop connection (very slick).

Something like this should be pretty easy to build.  I bought some Harrison Labs Fmods at 70 hz and don't like them much as they close everything in.  But, the RCA in/out concept is exactly what I'm looking for.

How would I build something like this?  I have a soldering iron and I've built interconnects and such but that's the extent of it.  I'd like it to be sonically invisible to the maximum extent feasible (duh).

Little help?

Mike

[konut]

http://www.marchandelec.com/xm46.html

These are what I use. Transparent, simple, passive 1db insertion loss. Either in kits, already built, or Vinnie Rossi built mine. You can specify any frequency you want, although my 70hz ferrite pot cores took a little longer as they were custom wound. Mine are 24db per octave slope but others are avaliable. It would be neat if you could get that same functionality of the Firenze without the amp. AV123s' R-DES bass equalization system has the same kind of functionality but is a bass equalization system. Theoretically a full range unit with high and/or low pass capability is possible, but no one has offered one for sale yet.

[miklorsmith]

I want to check yours out.  It's hard to tell from the pricing how much the thing would actually cost.  Is it $100 or $600?

[konut]

XM46-A      Passive filter board, mono,  assembled.                   $  95.00
XM46-K      Kit.                                                      $  65.00


You need 2 of either the A or K, and then a cabinet and RCA chassis mounts. I had 2 of the A's sent to Vinnie and he built, assembled, mounted in a cabinet and tested everything and charged me $200, though that was before he got so busy. It wouldn't hurt to ask him if he would take it on now.

[ryno]

Will these passives sound better than marchands actives?
Ryan

[Russtafarian]

ACI has hi pass filters on their website for around $40 a pair if I remember right.  I've used them and they work pretty well.  

I ended up building my own to get a higher filter frequency.  I put them together with poly caps and dale 1% resistors and they sound a little more open and transparent than the ACI filters.

Russ

[miklorsmith]

How did you build them?

[Russtafarian]

Will these passives sound better than marchands actives?
Ryan

I can say that the passive high pass filters I've used (ACI and my own) sound much better than the high pass output of my Outlaw ICBM.  I Don't know how the ICBM compares to the Marchand.

Russ

[JoshK]

My pedestrian knowledge of xo's would lead me to think that passive xo's (even most actives) would interact with the xo in your speakers.  I'd be interested to hear some people with more knowledge than I to comment on this.

[miklorsmith]

There is no XO in the speakers except a simple filter below 12 khz for the supertweeters.

[Russtafarian]

I use the recipe that Corey Greenberg talked about in his Stereophile review of the NHT Superzero years ago.  A quick search for the review at Stereophile.com will get you there.

Russ

[rajacat]

http://www.audioc.com/accessories1/misc/hipass.htm

[miklorsmith]

Those look just like the Harrison Labs Fmods I have that are not transparent in any way.  They're the same price too.

[konut]

Will these passives sound better than marchands actives?
Ryan

I've never heard the actives. It has been my experience that passive line level xos have less potential to mangle the sound than actives, all other things being equal ie correct implimentation.

[ryno]

Too late for me to change anyway. I ordered a pair of XM9 boards friday.
Ryan