Another Bi-amping question (pls help)

phipiper10

OK I've been doing a lot of reading and googling lately trying to understand bi-amping. I have a fair understanding at this point. I have somewhat of a technical question however.

Let me just say that for now additional amps are not really an option and I'd like to "experiment" with the bi-amping concept to see if I gain any real improvent/clarity.

Set-up:
Onkyo TX-NR901 (110wpc) (preouts to Rotel for FL&FR)
Rotel RB-990BX (2x200wpc)
RT800i (FL&FR)
CS400i (center)
Bose 301 (SL & SR) I know I know I'll get there eventually
HSU VTF-2 (on waiting list for B-stock)

Copprehead interconnects-gonna try diamondbacks next week(maybe silverserpents soon as well)
Audioqest x2 speaker wire w/bananas into the FL FR

So I've been considering Horizontal bi-amping - that is sending the Rotel to the woofers of the RT800i and the Onkyo to the tweeters.

Is the discrepany in power going to cause a problem? I've also been seing a bunch of stuff about interal crossover being active vs passive etc....then my eyes glaze over etc. I thought internally the woofer and tweets would be separate and nothing to worry about.

Can someone confirm if what I'm proposing seems problematic either for the reason I suggest of for some other reason.

See the below from the Wharfdale site:
Whilst this configuration will offer a performance advantage over using just one stereo power amplifier, because of the increased total current available, the amplifier driving both woofer channels will be working much harder then the one driving both tweeter channels – this will mean the bass will bottom out faster under heavy transients than it would if a vertical orientation were used – also crosstalk between amplifier channels is the same or worse than it would be with a single stereo amplifier

Seems in a "realworld" application there wouldn't be a problem with what I'd like to do but maybe I only know enough to be dangerous.

Thanks for your help! I've already found a wealth of info here!

Rich

schwarcw

Welcome to the Forum phipiper! Never done bi-amping. Someone here will be able to steer you in the right direction!

Holydoc

Rich,

I am just curious why you are considering bi-amping? The ROTEL is more than enough to push your RT800i's quite nicely. That would free up your receiver to only have to push the center and the bose surrounds. That set-up would give you a much better soundfield than having the 901 push the tweeters, the center, and the surround speakers.

Just remember your specs on your 901 is :
2x140watt per speaker of DYNAMIC power. Not only is DYNAMIC power some promotion spec that Onkyo created, it is very misleading.

Though Onkyo does not actually define what they mean by dynamic power, Sound & Vision testing measured the ACTUAL power ratings at only like 50watts per channel. This sounds a bit more reasonable from the results I have seen with my receiver.

So let the Rotel pump its pure power directly into the RT800's and free up the receiver's amp so that it only has to work the other 3 speakers. You should be much more satisfied and do not have to worry about bottoming out anything and a nightmare of wiring.

On a different note, I freed up my receiver completely from having to worry about pushing speakers and bought a 7x200watt amp. Changed my soundfield completely.

Good Luck

phipiper10

Nice Work HolyDoc,

I also see you are now in pursuit of a pre-amp! I'm jealous. I'm happy enough now with the new "used" Rotel.

Of course besides the disparity in "real" watts my thought was flawed in that I was thinking this would only apply in two channel where the Onkyo watts should be a lot closer to what they are rated than the 50 when powering all channels.

Of course this would require me changing wires anytime I wanted to watch something with all channels powered. So as stated just enough info to be dangerous.

Thanks, I'm just getting ambitious and trying to stay on budget.

Rich

Holydoc

phipiper10 wrote:

I also see you are now in pursuit of a pre-amp! I'm jealous. I'm happy enough now with the new "used" Rotel.
Rich

Rich,

To say that I am in pursuit of a pre-amp may be a bit overly pretentious. What I was trying to pursue was whether it was worth a sizeable investment now to replace my Onkyo with a pre-amp or another receiver.

Reading the replies, I think I will back off of that purchase until I have done a few other things:

1. See what features are available on a pre- or receiver that I am lacking now. For instance I have no DVI or HDMI switching capabilities currently.
2. Wait until the new HD-DVD arrives to determine if the item will need to be married up with certain capabilities in the receiver.
3. Seriously pursue whether any upgrade to the receiver will improve the performance of my home theatre given that the primary purpose of my system is HT. I would hate to purchase a $5k item to discover I hear marginal or even just "perceived" sound improvement.

Take care and enjoy your system. After all, pure listening pleasure is what this hobby is all about!

Holydoc

Oh btw...

Welcome to the Forum, Rich. The people who frequent this forum are both curteous and truly amazing with their knowledge of stereo and HT systems.

Enjoy!

Ferres

Depending on how revealing your speakers are, bi-amping can give out very noticable benefits.

The sq from 2 parasound 1200II is much better than that of one parasound 2200II. Everything just sounds much tighter, and detail is revealed with less effort. The soundstage seems more forward.

wingnut4772

I thought that unless you disable the crossover of the speakers that bi-amping was not supposed to be effective??

Ferres

wingnut4772 wrote:

I thought that unless you disable the crossover of the speakers that bi-amping was not supposed to be effective??

crossover on the reciever side?

I guess it would be less effective if some of the lows are being filtered out. Bi-amping would get a better pay off with more full range speakers capable of going below 40hz. I think towers really get better with bi-amping. They can really make use of that extra power.

unc2701

wingnut4772 wrote:

I thought that unless you disable the crossover of the speakers that bi-amping was not supposed to be effective??

Passive biamping (leave the speakers the same, add another amp) will only marginally improve your sound. If you hear a huge difference, the single amp probably had issues.

Active biamping (remove the components of the speaker's crossovers that aren't needed and add another amp _and_ an active crossover) will frequently get you a noticable improvement.

In passive biamping, the load on the amp isn't very different, you just get additional power (assuming the two amps add up to more than the single). The amp still sees most the crossover and it still has to amplify a full range signal.

Active biamping works because there is no crossover load on the amp and each one only sees part of the signal.

My friend sells Dynaudio studio monitors and we spent an afternoon **** around with hooking up bryston 14b's & 4b's and comparing. The actively biamped monitors always sounded better. We could tell a single 14b vs a 4b, but not a biamp 4b vs a 14b.

steveinaz

wingnut4772 wrote:

I thought that unless you disable the crossover of the speakers that bi-amping was not supposed to be effective??

You're right; to do effective horizontal bi-amping, you should use active crossovers; the key word being "effective."

wingnut4772

That's what I thought. I don't see myself doing any passive bi-amping with the 600w per channel into my Lsis with the Cinenova:p

McLoki

Much of the benefit of bi-amping can be realized by using a single decent amp and replacing the metal jumper plate between the posts of your speakers with some good speaker wire.

Just a thought and worth testing if nothing else....

Michael

phipiper10

At the very least I will be removing the stock jumpers this weekend and toss in some Audioquest wire to connect posts.

As stated the 200 watt Rotel should be doing the job on the RT800is, right?

Thanks,
Rich

steveinaz

Oh yeah, your Rotel is fine.

Bi-amping results will be very subtle, if at all audible unless you go all out and do it properly.

I horizontally bi-amped for years (w/o active crossovers) and finally just went back to a single amp setup. The only reason I did it was that I already had 2 identical amps, so I figured, what the heck. I can't say definitively, that I heard any difference.

Ferres

If you got two identical amps. Why not just use them as monoblocks and bi-wire them. The benefits might be equal if not better than bi-amping.

multifidus11

in passive biamping using different amps does nothing. total power is all that improves the quality or actually the undistorted volume. if you want to see improvement you must increase the power, by 4. ie 100W to 400W. this way creates much waste as heat and changes all kinds of things. active biamping removes passive crossovers and replaces them with electronic crossovers prior to amplification. nothing is lost between amplification and the driver, and much less power is required due to the seperate waveforms not causing additive effects.