Biamp question

panzrwagn - Looks like you are correct about the 180Hz. crossover point to the 7" driver, guess I missed that. I’m with you on using an active crossover, don’t you think the internal crossover split is at 180Hz. for bi-amping, not 2.8kHz.? +1 to check with Legacy first. I'd be quad amping with 4-way crossovers, but OP should NOT jump to this.

@backdoor 

agreed, bypassing crossovers can work and work well but DSP per channel with parametric EQ and knowing the driver's parameter are musts.  

DSP is also a rather large rabbit hole.  took me two years to fine tune my car's active 3-way plus sub system.  

The Legacy SE crosses from the woofers to the 7" mid at 180 Hz. 

Bi-amping without a crossover loses all the benefits of bi-amping. I.e. the additional 6dB additional headroom .

Baffle step compensation, impedance leveling, and frequency equalization are all lossy, passive functions attempting to fix basic design flaws already dealt with in the overall speaker design.

Biamp, but do it right - ask Legacy for their recommendation.

avanti1960 - I don't agree with the benefits you've listed, not even one. Nothing is going to give you a flatter impedance or response curve than eliminating those capacitors and inductors. Together with variable crossover points and or a DSP, you will accomplish everything you have mentioned much better and greatly reduce intermodulation distortion. I know you won't agree, but that's what this forum is about, sharing opinions and knowledge. Happy listening, no disrespect intended.

@backdoor 

"Thank you all! I believe I can manage the active crossover (possibly) but my chief concern is disabling the crossover in my speakers."

As it should be.  The crossovers do much more than dividing the frequencies.  They also may include-

1) Baffle step compensation (reduces front baffle reflected midrange and treble so as to even those frequencies with the bass, can be as much as 6db. 

2) Impedance flattening circuit.  Makes the woofers easier to drive and have a flatter response curve.

3) Notch / peak suppression filter.  Reduces the magnitude of driver break up frequencies or other frequency peaks that a typical crossover and slope cannot deal with. 

I'm doing exactly what you trying to do. I use a Parasound 21 for the woofers and a tube amp (set 300B's) for the tweeter and midrange. I looked at your preamp outputs. I run my Parasound with XLR outputs from streamer/Dac directly to the Parasound and  RCA outputs from streamer to my set amp. My streamer /Dac does not have an output selector so both outputs work at the same time. You will have to figure out if outputs from your preamp can be run simultaneously. Otherwise you will need a splitter. The gain from the XLR out will be twice what the RCA output is, so if your stuck using a splitter use XLR. Also, you are correct as the gain control on the Parasound can be used to set the woofer volume to match the tube amp output. I use a program called REW and microphone to adjust the output/volume levels on the Parasound to match the tube amp volume. But that's another "rabbit hole" No messing with the crossovers-Parasound to woofers and tubes to tweeter/midrange speaker posts. Sounds sweet. 

If the output of the Parasound is louder than the Rouge then you are good. But if the Rouge plays louder, turning the Parasound down won’t work.

I’ve bi-amped with two of the SAME amp, but slightly different minor versions, and felt even that sounded a bit disjointed. So I’d be surprised if a high power SS amp and a high power tube amp meshed well. That said, the Rogue tube amp sounds much more akin to SS amps than you might expect for tubes. And the A21’s gain control is certainly an asset for gain matching the two amps. IF you find the Rogue’s gain to be higher than the A21+ at its max level, you can drop the Rogue down a few dB’s by subbing 12ay7 in the V1 / phase inverter slots in place of the 12ax7’s. It works well; I've tried this. I like the red-label GE 12ay7 from 1962 or 1964, I think (very specific year on the red labels) :)

A 5751 sub its also good for a dB or 2 and sounds nice on its own merits (if you have a good triple mica black plates vintage).

I'd be careful with and active crossover that doesn't fail safe. A Behringer DCX2496 will fail to work but not send the wrong signal to the wrong place. I only use an active XO in my Bass management system. I find there is a lot better protection with a passive XO for mids and high. 300 hz and below I'm direct coupled too. No passive crossover. I don't recommend it, out of the gate though.. Hook up your amps and be happy. Quit making it complicated.. You want to mess around later, you always can.

Regards

You can bypass the crossover in the speakers or you can leave it the way it is. The danger of disconnecting the internal crossover and running just copper wire between the low end and mid/high frequency drivers is the risk of damage to the midrange driver (the 7" in your case), should a power amp or the active crossover fail. You cannot bypass the upper midrange and tweeter drivers because that would mean you will need to tri or quad amp. I'm tri-amping with 3 stereo amps and a 3-way crossover, I also have 3 subs. The sound improvement with running just copper wire between the drivers and amplifier outputs, for me, is worth the risk of damage to any or all drivers. I recently lucked out during a very rare, (first time in 43 years) when the active crossover in one channel failed sending 500 watts into one woofer and 300 watts into one midrange for about 5 seconds. The tone was relatively high, about 900Hz., but any longer the drivers would have been damaged. Luckly, the tone was below the crossover frequency of the tweeter, so a clipped 200-watts rms signal was not seen by the tweeter! My suggestion is to take small steps. Leave the crossover in the speakers as is and as you get more educated and confident, you can try bypassing the internal passive crossovers one at a time. Enjoy!

Thank you all! I believe I can manage the active crossover (possibly) but my chief concern is disabling the crossover in my speakers. 

oldhvy is correct in the bi-amp method, but an active crossover like russ69 mentioned is the better way to do it. You can limit the bass going to the mid/high frequency amplifier, reducing power and intermodulation distortion. This will make both the low and mid/highs much cleaner. An active crossover will also give that much greater ability for you to match the levels of each band. So many crossover choices, from DBX223, TDM24CX-2, many Ashley’s up to the Marchand, Bryston and First-watt at the top, in my opinion. You also have the choice of digital, Behringer and so many other DSP’s. We are all here to help, good luck!

And I’m pretty sure I am the most confused person in the room right now. 

I looked up your loudspeakers, they are designed to be bi-amped. Just take the strap off of the speaker terminals. They will work with or without a crossover but the proper way is with. 

Doesn't your preamp have 2 variable stereo outputs?

If so, just connect one amp to each (no need for a Y-Splitter).

DeKay

I do have one last question. I am assuming that both amps inputs go to the same preamps outputs. Is that a correct assumption?

Yes! 

I bi-amped a pair of Legacy Focus speakers for years with no problem. I used the XM9 Electronic Crossover (marchandelec.com), instructions here Electronic (marchandelec.com). I used a Cary tube amp for the high frequencies and a Parasound amp for the low frequencies.  You pick the crossover frequency when you order the crossover. It’s easily changed if you like with a $10 chip. Easy-peazey. Only reason I went back to a single amp was because I downsized my listening room and the heat from the tube amp was unbearable (I live in FL). I don’t really miss bi-amping though since there are many great amps that make it unnecessary.

I have also read that when you go with passive biamping that since the crossovers being used are at the speaker level that the preamp still gives the speakers the full range of high and low frequencies. I can’t seem to wrap my head around that since one amp is going to hf and the other amp is going to lf. Seems like crossover of the speakers would prevent any upper frequencies from going to the lf and lower  frequencies from going to hf. Apparently the built in crossovers of the speakers cannot prevent that from happening in the same way active crossovers can? If that’s true is it because preamp sends everything and speaker crossovers can’t filter properly? And if that’s the case it would seem I would lose the implied benefit of the tube amp handling hf and ss handling lf. And I’m pretty sure I am the most confused person in the room right now. 

At my current abilities I would be very hesitant to use an active crossover since I would actually have to get inside the speakers and disconnect built in passive crossovers in them. The nice 7 year Legacy warranty goes out the window and if I make a really bad mistake potentially a pair of $9000 speakers go south. I guess when I started this I was looking for an easy way to use these 2 amplifiers that would make a sonic difference without adding active crossovers and opening up my speakers. 

Buy-amping is an especially effective marketing tool for electronics manufacturers.  

You do not need a crossover- just let the speaker do the work.

The crossover allows you to set the crossover frequency, adjust levels, and remove the unwanted frequencies from going to each amp. It's the most flexible setup.  

Thank you all. I have not tried the st 100 by itself yet. Are you saying that not only is it stout enough to drive the bass on the legacy’s but that you also prefer the sound of st 100 over the a21+?

Yes just split a full signal out to your preamp to you SS and Valve power amps. RCA or XLR. What ever you use.

Enjoy..

You do not need a crossover- just let the speaker do the work. 

connect the bass amp to the bottom speaker terminals and the mid/treble amp to the top set of terminals. 

you may have a gain issue that causes a miss-match- 

You would need an RCA Y-cable to spilt the preamp signal.  

PS I have owned the a21+ and the Stereo 100.  Have you tried just the stereo 100?  I found it as powerful as the a21+ and your speakers are very efficient.  Try just the ST 100 if you haven't.  

I do have one last question. I am assuming that both amps inputs go to the same preamps outputs. Is that a correct assumption?

Oldhvymec thanks for your advice and input. I will give that a try. Thanks to everyone else who commented for your input as well. This has all been quite illuminating. 

You’re fine OP. You don’t need anything BUT two amps and cables. You have a good idea. SS for the bass and Valves for mids and highs. The Parasound will have the greater gain. It is a plug and play thing. It will take more time to route the cables than anything else. Remove the jumpers between lows and highs on the speakers and plug in. Adjust the Parasound. DONE.

Side Note:

You need two of the same for vertical bi-amp. You're using them horizontal. I've biamped for 40 years horizontal, NEVER vertical.
I quit using Valves for bass 40 years ago too. Just a bad idea in reproduction, not to mention the heat.
Only one time I didn't bi-amp and I fixed that soon enough. BIG fan of bi-amping with SS and tubes. 

I forgot, Merry Christmas and Enjoy...

Regards

I have a pair of custom speakers that are very similar in design to the Legacy Focus using Eton drivers on top and Peerless 1259 12" woofers.  The Peerless are a bit less efficient so bi-amping is pretty much a necessity.  I've used the internal crossovers without issue.  Since the bass drivers are less efficient, I've always used separate volume controls for the satellite section (tweeters, mids, midbass drivers) and the woofers.  

My sources have all had built-in volume control so that has been the main volume control while the bass section has either been an integrated amp with its own volume control or a separate preamp to drive the woofer amp.  Currently my DAC is an Audio Alchemy DPA 1.  I run the balanced outputs to a Red Dragon S-500 driving the satellite section while the RCA outputs drive a Kingrex PREference preamp into a D-Sonic M3a-800S.  This allows me to adjust the bass output to suit my taste.  The Kingex is fairly cheap but is quite transparent and articulate in the bass range so works very well in this application.  You could try biamping first with your 2 different amps using the 2 pairs of outputs from the Rouge preamp and see how that works.  If the bass isn't satisfactory, then you could do as I've done and ad another volume control device between your pre and the bass amp or perhaps you could do that from your source to avoid running the signal through 2 preamps.

Now I’m thinking/wondering if you need to have 2 amps that are exactly the same to use internal crossover wiring method. 

I’ve never used internal XOs (I built my speakers without XOs), but my understanding is that they are in the speaker, so if you connect to the speaker terminals you will be using them.

So you could just connect the Parasound to the LF terminals on the speakers and the Rouge to the HF terminals, adjust the Parasound to match volume, and you’re done.

But I've never done this so if I were you I'd wait for someone else to confirm

Honestly I am not sure how to use the built in crossovers of the speakers. Seems the connections would be different. Please excuse my ignorance on this topic. 

I guess I won’t know that until I try it. On the crossover question, I want to get a crossover that already matches the crossover points of the speakers.

External XOs are adjustable. I use the First Watt B4, Marchand makes them, and several other manufacturers.

Typically on these XOs there is one input (connected to your preamp out), and two outputs connected to your Parasound and Rouge amps: High frequency and low frequency. So 20 Hz - 20 KHz (nominally) goes from your preamp into the XO and you set what range of frequencies comes out of the LF and HF outputs. So you can set the outputs to match the XO points the speaker manufacturer designed.

Note that this discussion about external XOs is only if you will not be using the internal crossovers built into your speakers.

I guess I won’t know that until I try it. On the crossover question, I want to get a crossover that already matches the crossover points of the speakers. Is that pretty accurate?

The gain on Parasound is adjustable so I believe I should be able to match the gain by adjusting on the Parasound to match the Rogue.

If the output of the Parasound is louder than the Rouge then you are good. But if the Rouge plays louder, turning the Parasound down won't work.

The gain on Parasound is adjustable so I believe I should be able to match the gain by adjusting on the Parasound to match the Rogue. I’m pretty green here so not sure that makes sense or not. 

If I’m not mistaken don’t you need to make sure that both apps have the same amount of gain?

My experience with using very different amps (LF = PP KT88, Class D GaN, Class AB SS and HF 2A3 SET) that within my listening range (75 db - 100 db) they all match within a db or so. So the "gotta have the same amps" thing is something I don’t believe in, but you must have a way to adjust either the HF or LF output so the two match.

What I do is measure the outputs to make sure the high and low outputs track:

I use a RS meter about 1 foot in front of the HF driver with the LF amps turned off and adjust the main volume so the meter reads 85 db when playing a 2K Hz tone.

Then I put the meter about 1 foot in front of the LF driver with the HF amps turned off and adjust the output of the LF amps so the meter reads 85 db when playing a 500 Hz tone. Now the outputs are matched at 85 db.

Then I adjust only the main volume and play 75 db, 80 db, 90 db (already baselined at 85 so no need to do that again), 95 db, 100db measuring LF at 500 Hz and HF at 2K Hz and see how close they track.

If I’m not mistaken don’t you need to make sure that both apps have the same amount of gain? Whenever I have by amped I’ve always used the same amps or apps from the same manufacture. That way they generally have the same amount of gain as you turn the knob

OP you can bi-amp using the internal crossover within the speakers, just remove the jumpers between the LF and HF terminals. That’s not how I would do it, but it is possible. For me, I would follow russ69’s advice. What russ described is not hard at all and would yield the best results. You can use any number of crossovers including DSP’s but I prefer analog crossovers. I’m not positive what crossover russ is using, but if I recall it’s a DBX223. Looks like the crossover frequency in the speakers you mentioned is 2.8kHz., but you should check your owner’s manual. Literally there are 100’s of choices for an active crossover. I’ve been multi-amping for 42 years using analog active crossovers and I will never go back to using a single amp again. Enjoy!

Do you need to pay attention to the crossover points or are they going to be pretty standard?

You will have to figure out where the crossover points are for your speaker. Looks like 2.8 K is where your speaker splits but double check that.  

Do you need to pay attention to the crossover points or are they going to be pretty standard?

I thought I could. I’m just not sure about the logistics exactly. 

It's not hard. Out of the preamp into the crossover. Out of the crossover into each amp. DBX makes a very affordable crossover. You can spend more but the DBX does the job. 

I thought I could. I’m just not sure about the logistics exactly. 

Why not. You'll just need a crossover, the amp, and some cables. I like simple systems but you have a nice combination and maybe some tube rolling and a tube amp for the top end will get you to the next level. Not a fan of bi-amping (even though I do) but this application sounds good.