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Bi-Amp success story

Hello all-

This is a follow-up to many threads I have posted already (using my e-mail address - joelm@charter.net 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!

Regards,

Joel
a71spud
sean
6,229 posts
 
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.
garfish
1,840 posts
 
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
jerie's avatar
jerie
54 posts
 
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 Innersound.net 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
sean
6,229 posts
 
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
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garfish
1,840 posts
 
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.
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