Crossover - hard to find for biamping

I've had good luck with the DBX crossovers, just be sure you get the one with the audio connector not the 1/4 inch jack.

I’m bi-amping with tube monoblocks into the midbass and tweeters using the passive crossovers, then running a solid state amp into the woofers. I’ve split the preamp signal so that one leg feeds an active low pass crossover to the woofer amp. It’s a very inexpensive Pyle PLXR2B for automotive use, but using a suitable 12V wall wart it works remarkably well. It has low pass options of 50, 63, 80, or 100 hz, and a separate gain.  Not much to lose at $30.

You only need to adjust the levels if your amps have different gain.  There's a convention but not a requirement for that.

If not, any passive volume attenuator will work. Put it before the loudest amp. :)

Wait

You shouldn't need a crossover if you are using the existing built in crossovers just volume controls.  It might get tricky if the amps have a different gain profile as you adjust for one global  volume level and then if you increase or decrease the volume the bass amp and the mid tweeter amp are no longer in sync.  It may not be much of an issue as you can always just increase one of the amps volume level to compensate.

If you're thinking of leaving the frequency dividing to the internal passive x-overs and using the active x-over just for level control you may not need one. If you choose tube and SS amps with the same gain (e.g. 26db) they should power the drivers to matching levels (even if they have different power ratings). Perhaps other, more technically minded members can verify my thinking. Then you would simply have to "Y" the L and R outputs of the preamp into the two sets of amps. Generally, the less electronics the signal has to pass through, the better.

I doubt you will get much value out of this configuration.  Active biamping can be very rewarding with an active crossover and bipassing the passive ones in the speakers. Leaving them in, well all you are doing is combining amps. 

jji666

If the speakers have separate binding posts for low/mid-hi and any jumpers are removed then the amps will not combine. The low amp will drive the woofer via the internal low pass network and the high amp will drive mid/hi via high pass-separate paths. Assuming they are good speakers then a lot of thought and design went into tailoring those internal x-overs for the drivers. Additionally it would be a bit of a project to get inside cabinet and re-solder wiring to by-pass x-overs. The SS low amp will have good low frequency extension and control of woofers and the tube amps will give their tube magic to mid/tweets.

assuming your speakers are set up for biamping, the internal crossovers will be all you need.  as stated above, you'll need volume balancing but if the amp you need to adjust is an integraded, it has volume control.  if not, you'll need a passive volume control unit

Don't spend a lot of money until you've tried it and liked it.  Most people back out of it and go back to a single amp.

Jerry

The biamp ingredients I'm considering are a Conrad Johnson gat2, CJ art150 150 watt per chanel stereo amplifier, mcintosh mc611 600 Watt monos, and b&w 802 d3.

I like the idea of what Mcintosh has recently done with the combo ss/tube mono amplifiers.  Although the MC 901 they offer, while costly, is too damn big, and probably generates a ton of heat.  Basically it's a mono with 600 W solid state combined with a 300 W tube amp. I think the 300 W tube for mid range and tweeters is a bit of an overkill. And I already have their 600 W Monos.

Sublime audio:

https://sublimeacoustic.com/products/k231-stereo-3-way-active-crossover

you order the first set of crossovers installed and you can also order swappable crossover boards.  Kind of like tube rolling?  Find the crossover points that sound best, or just do the math/select by speaker capability.

Or just use fmod hi/low pass filters. Though, unless the amp has its own volume control, the fmods don’t give you the ability to “play with” relative power to each driver as the sublime does.

I bought my speakers wired for bi-amping though.  I have no idea how you would go about “retrofitting” non-production bi-amp capable speakers to connect different amps to separate drivers.