Bi-Amp success story

Hello all-

This is a follow-up to many threads I have posted already (using my e-mail address - before I signed up officially) Rather than tack this on at the end of any one of them I wanted to start a new thread summing up my experience. In doing so I will cover what I did and what worked and what didn't work for me.

My Gear (that matters to this discussion)

Yamaha CX-1000 pre-amp (I also use this for my d/a)
Yamaha MX-1000 power amp (330 wpc into my 4 ohm speakers)
and another MX-1000 power amp for bi-amping (effective 660 wpc?)
Paradigm X-30 line-level active crossover
Infinity Kappa 9 speakers.
Phoenix Gold ZEROpoint Reference II Inner Space reference speaker cable (2 10 gauge conductors) for the low end and Phoneix Gold 12 gauge for the highs.

(1) I tried bi-wiring and that produced no noticable effects for me. (using 1 MX-1000 amp) Maybe with better wire there might be a difference.

(2) I tried bi-amping using no active crossover, and while the soundstage was a bit better the amps were working hard for just a bit of extra volume and in my opinion without an active crossover before the amps it is just a glorified bi-wire.

(3) My final arrangement was very satisfying. My Kappa 9 speakers each have 2 12" drivers that cross-over at a low 80hz. I used the Paradigm x-30 with the 80 hz high pass (a choice of 50,80,120 hz) after the pre-amp and ran it to the right side of each MX-1000. Then I ran the sub-out for each side to the left side of each MX-1000. So one MX for the left speaker, one for the right. I chose this rather than the lows to one amp and the highs to another for a few reasons. (1) elimination of cross-talk (2) decrease in overall demand on each amp during segements with high bass or high highs.

The results were great! I have a much clearer soundstage, and I get a louder, clearer sound than I have ever had before. If I had the gear I would try putting a specialized amp on the lows/highs. One suited best for each purpose. But before I would go to that level I would upgrade everything I have except for the speakers. If I can scrape together the cash I want to try a Sunfire Classic Tube pre-amp and a Sunfire Signature Stereo amp in a non-biwired configuration too. If I like it better (as I am sure I will) I might liquidate my Yamaha gear. However I run my pre-amp "source direct" by-passing all tone controls. Since my Kappa 9's have a strong high-end it is nice to be able to compensate for that just by adjusting the level of the amp or the crossover.

Anyway thanks for all the advice that has gotten me this far!


Hi Joel; Thanks for sharing your experience(s) with bi-amping. The subject is quite interesting to me as I am planning a "passive" bi-amp set-up myself in the next month or so. I have Vandersteen 3As, and Vand. Audio highly recommends passive vertical bi-amping. Based on your experience, it sounds like you weren't too impressed with passive though. I guess I'll find out.

I'm no expert but I think your "active" bi-amp may have worked well mainly because you were able to set your active X-over at the same HZ that your speakers crossed over, ie 80 HZ. As to power rating, do your Yamaha amps actually produce 330 wpc into 4 Ohms? If so it should say so in your owners manual (ie, you can't just double 115 wpc and assume they are putting out 330 wpc into 4 Ohms unless they are designed to do so). And too, I don't think you can add 330 + 330 and claim 660 watts, because amp power is conventionally expressed in watts per channel. Also, if your amps are stereo amps (as opposed to dual mono), the bass side would likely be drawing much more power than the mid/treble side.

One of the main reasons to have powerful amps is that they can better handle the "transient spikes" in music that require much more power and occur especially in dynamic music with strong bass. Speaker impedence and sensitivity are important too. And of course the other reason is just simply to play louder. A speaker with nominal 4 Ohm impedence would likely have a range of something like 3 Ohms to 16 Ohms over their whole frequency range.

About "loudness"; it takes double the power to get a 3 dB increase in actual loudness. So if your amps were actually drawing 200 wpc (and at this point I think they would be very hot), it would take 400 wpc to get a 3 dB increase in SPL. But OTOH if they were drawing 10 watts at a given SPL level, then 20 watts would produce a 3 dB increase in SPL-- this would be a much more likely scenario unless you're running your system at absolute max.

I suppose the above sounds sort of negative, but I don't mean to be. I'm just trying to understand what you did so it might help in what I do in a month or so in my attemps at bi-amping. Again, thanks for sharing and Happy Listening. Craig

WOW, where do I start? At the beginning I guess. You may have good success with your passive bi-amping, but I would not expect too much. Probably not enough to justify an additional amp purchase. You will get better soundstage as a result of better stereo seperation by running your left and right on different amps. Probably not an audible increase in volume however. But let me know what you do find. I am very interested.
Whoops, I hit return by accident and published my comments. Oh well it will look like this is a popular thread then I guess. To continue, yes I have no doubt matching my active crossover to the speakers had everything to do with my results. That is critical because you are not messing with the passive internal crossover in the speakers, just easing the load on the amps by only having them work on the frequencies that they are responsible for. That has do do something to keep things clean sounding too.

As far as my amp specs go, yes I went by the manual. This is what it said----

8 ohms 260 wpc RMS, 0.003% thd, 450 wpc dynamic
6 ohms 295 wpc RMS, 0.007% thd, 560 wpc dynamic
4 ohms 330 wpc RMS, 0.02% thd, 740 wpc dynamic
2 ohm 960 wpc dynamic
1 ohm 1000 wpc dynamic

So I tried not to assume anything. I see your point regarding the bass taking more power. However that all depends on the crossover freq. I found some interesting numbers showing this break down of power (expressed as Freqency and % of average power needed for the running the speakers above and below that number)----

250 40%/low 60%/high
350 50%/low 50%/high
500 60%/low 40%/high
1,200 65%/low 35%/high
3,000 85%/low 15%/high
5,000 90%/low 10%/high

It is much more complicated than that and depends on efficiency of the drivers, differences in impedance etc. SO many variables. The best way to tell for your system is to run both sides of the amp at max levels (set the pre-amp for normal listen levels of course) and then reduce the volume for whatever seems out of balance. (ie too much bass, reduce the volume low side of the amp) If you have seperate controls for Left and Right levels on your amp this is a VERY simple way to get things adjusted just right.
But I figure I have (on average) 330 watts going to the highs and 330 watts going to the lows (I suppose I should say 'available for') on each side because it sounds just right with both *sides* of the amp set to the same level. But that is ALWAYS an estimate even for a single amp set-up anyway. (And I agree that the loads will vary depending on the fequency being reproduced. I have a response curve for my speakers and it is very obvious that 4 ohms is just an average as it varies between 9 and .9 ohms (yes, those numbers are right))

As for *loudness* I think that, yes I *have* doubled the power going to my speakers resulting in a 3 db increase in sound levels. I have not measured it yet, but I can tell. It plays louder at lower levels on the volume control for one thing. And my wife gets madder if that counts for anything.

I look forward to your continued dialoge.


Hi (again) Joel; Thanks for the detailed info. on your bi-amp setup. Your Yamaha amps are more powerful than I expected, especially dynamically. I don't know what order cross overs your Kappa 9 speakers use, but Vand. 3As use 1st order-- this is the steepest x-over.

An active electronic x-over cannot be used w/ Vandersteen speakers, because the signal cannot bypass the internal x-over. Because of your thread, I dug out my Vand. owners manual, and looked up specs., x-overs etc. R. Vandrsteen also says only slight to moderate improvements in sonics can be expected by passive bi-amping, and he goes on to say that a single higher quality amp will out-perform a pair of lesser quality amps-- I guess I'm about to find out about some of this, so we'll see!

Just one more Vand. "thing"-- their speakers also should not be horizontal bi-amped as mids will be "confused" (like me). I already have two high quality McCormack DNA-2DX amps(300 wpc 8 Ohms, 600 wpc 4 Ohms etc), and they are now in for upgrading at SMc Audio to Rev. A, when done, my amps should approach world class-- but still, I've got my fingers crossed that I'm going to like the "new" amps, and in a bi-amped configuration. I've enjoyed the exchange of info. Thanks. Craig
Craig, just for your info i had run a set of 4 way / 5 driver towers in a passive arrangement. I had two different amps from the same manufacturer horizontally configured. This gave me 400+ wpc on the top side ( 200 Hz and above ) and 600+ wpc on the bottom ( below 200 Hz ). Since these speakers are "thirsty", i could still drive the amps into compression if really cranking hard.

I then went into a set-up where i had identical amps on top and bottom ( both 600+ wpc ). I could still drive them into compression.

I later switched this configuration to running a single amplifier that is rated for 1200 wpc at the same impedance. Even though i had 900 to 1200 watts per channel driving the speakers before, going to one larger and more efficient amp made a MASSIVE difference. I could now play measurably louder and measurably cleaner with far less listening fatigue. The only drawback to this is that i did have greater bass impact with the specific amp that i was previously running on the bottom end.

In case your thinking that the first amps were just "wimps", take my word for it that these are STURDY. They can run bridged into VERY low impedance loads without any fuss at all. I have seen people running these models bridged into speakers that normally give unbridged amps a fit.

In plain English, i would not bother doing passive bi-amping ever again. To me, it was a waste of time, money and power. I wish you better luck in your efforts and ask that you keep us posted after you've played with your set-up for a while.
Sean; It's late, but I've got to know-- would you feel differently if the amps were 1200 wpc mono-blocs? I can easily arrange to have my DNA2s converted to 1200 wpc monos and use them as monos rather than passive bi-amping. The mono cost is not expensive-- about $500. per pair. Thanks Craig
Nice posts you guys! Here's my 2 cents. While most amps can play loudly very few can obtain a high SPL without distortion. Low impedance speaker design characteristics further tax amplification demands and as gain increases so does distortion. As I understand it, bi-amping should provide relief for the amps by dividing the driver load demand. Generally speaking, this should enable the amp to produce a higher SPL without as much distortion, resulting in cleaner and more focused sound. I think most people would be surprised at how much power is actually required for an amp to exhibit low distortion control over a box speaker loaded with many different dynamic drivers. Roger Sanders at has just released a new mono amplifier designed specifically for dynamic driver loaded box speakers rated at 1,100 watts into 8 ohms. Interesting reading.

Active VS. Passive: A passive cross-over contributes to the load on the amplifier and adds it's own sonic signature on the speaker. Like everything else in audio, it's only as good as the quality of the components implemented in the design. The amplifier exhibits control over the dynamic drivers through this passive cross-over. The way I see it, the biggest gain in using an active cross-over is by removing the passive cross-over from the circuit. This allows the amplifier direct control over the dynamic driver and in theory, should yield far better control and less distortion. Of course, your speakers should probably be designed for use with an active cross-over to achieve the full sonic benefits of this set-up. It's interesting that Joel found that the addition of an active cross-over prior to the passive cross-over produced a more satisfying musical presentation. My guess would be that the sonic signature of his active cross-over is yielding the sonic benefit, but I would think that the distortion yield on the amplification of the circuit remains unchanged from the original bi-amping he did.

Craig: For your application, I think Sean's comment is really worth investigating. I would call the people who are upgrading your amp right away and see what input they have about making these amps mono's. If they can be upgraded to mono's and retain their sonic signature that you love my advise would be to jump all over it! Good luck and if you have it done let us know how it turned out. Regards to all. -Jerie
While i have never run any amps in bridged mode myself, most of the manufacturers that i have spoken to tell me that sonics DO take a hit in the nose. Some manufacturers will advise against this even though they do acknowledge that it can be done. Like any other company, they are simply trying to give the customer the most options for their money even if they don't think that it shows their product at the best.

As such, i would contact Steve and see what he thinks about your situation. He should be the most familiar with his products and know what to expect out of them. He might not be bridging them but doing something else.

As a point of comparison, I have disabled one channel of two identical stereo amps and then run them as monoblocks before. This gave the entire power supply that was designed to run both channels over to just one channel. No real power gain but more "oomph" on the bottom end with better control and stability into tough loads. This is most beneficial to amps that are not "big brutes" in the power supply area to begin with. Some examples as to what this works well on are old Phase Linear's, Quad's, etc...

As long as your comparing apples to apples with amps of similar sonics, i would rather have two big monoblocks than two smaller amps passively biamped. If i took that one step further, i would rather have two good sized amps actively biamped. Obviously different speakers and situations can negate some of these options. Like i said, try giving Steve a call and you might even want to run your options by Richard Vandy. Advice is a LOT cheaper than first hand experimentation, especially if you don't like the results and have to back-peddle. Sean
Thanks for the response(s) guys. In the course of arranging to have my amps upgraded, I have had several long talks with Steve McCormack. There are four (main) options:
1. Upgrade, and use, only one amp.
2. Upgrade both amps and vertical biamp.
3. Upgrade both amps and convert to monoblocs.
4. Bi-amp with no up-grade (no matching either)-- but I consider matching very important, but shipping two 100 lb. amps is expensive just for matching.

Where two amps would be used, matching would be done as closely as possible by SMc. S. McCormack said he had a slight preference for the mono-bloc route, but that the other two methods are excellent also. Richard Vandersteen said, and I quote "only an idiot or a drunk would hook up that kind of power to Vandersteen speakers" (RV was referring to the 1200 wpc monos).

Well, decisions had to be made and in continuing discussions with Steve Mc., and the fact that I already owned two DNA2s, we decided that upgrading the amps to Rev. A, matching the amps, and then vertical bi-amping would be an excellent way to go-- and that's the route I'm taking. I emphasize that the the DNA2s are very powerful as is, ie 300/600/1200 wpc into 8, 4, 2 Ohms. These amps will even put out 2400 wpc into 1 Ohm. I also note that these amps are a true dual mono design-- they are not conventional stereo amps.

Steve, Richard V., and I all agreed that going to monos would be of little or no benefit for my purposes and would even likely be overkill. A notable benefit of identical amps for biamping is that if I don't like the biamping, I can sell one of the DNA2s Rev. A and keep one for my own use, whereas monos would have to be sold as a pair.

R. Vandersteen recommends 1. bi-wiring, 2. vertical bi-amping, and 3. short as possible speaker cables with Vandersteen speakers. BTW Sean, in the short term, at least, I'm staying with my 14 ft. spkr. cables, and 4 ft. ICs. One last point-- while my DNA2s are gone, I'm using a stock DNA.5 (I do have a Syn, Res. MC cord on the .5), and it's sounding great. Maybe all this expense and hassle with big amps is not needed-- but hey, I'm an audiophile: ).Thanks again for the interest in my "project"-- guess I should have started my own thread on it-- maybe after I get the amps back. Cheers. Craig.
I think it's great when someone joins in with their "projects" or experience in similar threads. While it might divert a small amount of information away from the original post, i think that it typically gives them even more info that they they might not have considered or asked in the first place. As long as it's done in good taste, i don't think that anybody here objects to such posts.

Don't take my word for ANYTHING. I only know what has worked for me in my systems. Your components, installation and personal tastes might be measurably different than mine. As such, you have the opportunity for a GREAT learning experience at your disposal. Don't pass it up. Sean
Craig: Bravo! Common sense rules the day! Perhaps Richard Vandersteen summed up my position best and I suppose I'm guilty as charged! :) Still, just think how outstanding those amps would sound driving a great pair of ESL's! {{{Shudder}}} But I guess you'll cross that "bridge" when you come to it. -Jerie