Biamping....

yenoorekim

I have biamped before, with cheap Panasonic receivers and Sony speaker in a purely analog stereo configuration, which I didn't mind experimenting with. I now own a Harman Kardon AVR-240 and want to biamp my 7.1 setup in the most SAFE and efficient way I can. Before I buy the second receiver and another 200 feet of 12 gauge wire, I'd appreciate some input from you fine people. First, I'll lay out my system to help visualize the situation: Polk Rti-12 mains, Csi-3 center,(possibly a Csi-5 also, if I biamp) Rti-8 surrounds, as well as Rti-10s for the surround back channels. (should have gone with another set of the easier driven Rti-8s or surround bookshelf speakers, I know...they were originally my mains so I'm stuck with 'em) 12 gauge wire is all 'round, using gold-plated monster banana plugs.

Here's the deal: In stereo mode, sound is very rich with plenty of high, mid, and low freq. sound. 7 channel stereo mode is acceptable, although a bit flat. With true surround mode for movies, bass drops off dramatically and everything sounds washed-out. Obviously these differences are because of the vastly increased speaker loads, the processor's actions, and the Rti-10's four 7" woofers sucking current from basically non-bass producing rear channels. Since biamping is actually cheaper than buying a single receiver with twice the power, I'd rather face some technical issues and go with biamping.

Now, to the questions:

1: My DVD player (Philips DVP-642) has optical and digital coax outputs. I'm not going to split an optical signal, so that leaves me with either splitting the coax, or using both. I'm thinking of optical for the mid\high receiver to get more clarity, and coax for the bass handling receiver. Will there be a difference in processing times between the two receivers using these two different methods? I am not sure.

2: Am I able to use a moderately more powerful receiver of the same family, say the AVR-340 or 435, to power those ten 7" cones of the mains and rear channels or should I use another AVR-240? Would there be adverse effects on my speakers by providing them with the two different wattages? (50W and 65W) Remember these are conservatively rated high current "Harman Kardon watts", so they are actually much more powerful than these numbers compared to most other manufacturers such as Sony, Panasonic, RCA,etc....

3: Should I use one receiver for mid\high and the other for bass, or blend the two to balance the load? (such as using receiver #1 to power the lows of the mains, but the mid and highs of the rear channels and receiver #2 to power the mid\high of the mains and the lows of the rear speakers, and selecting the individual large\small "speaker sizes" accordingly)

4: The internal crossover freq. of the Rti-12 is 120hz. When biamping and consequently bypassing (I believe) the internal crossover, do I need to change the settings on my receivers, or do I leave them at 120hz? Is there a crossover between the mids and the tweeters (I am assuming there has to be) and would this dictate new crossover settings for the receiver handling those speakers?

5: Is there an advantage to using a different DVD player that supports 6 channel direct analog inputs, or is the combined channels of optical better or identical?

Thanks in advance for any input you may have!!

-Mike.

jayman_1975

Hello and welcome to the forum. I assume your fairly new to us by the nature of your question. There are countless threads on this forum regarding how to properly power speakers and what to do when your reciever just doesn't cut it anymore. I'm sure if you try using the search on here you should be able to come up with a better alternative than the one your suggesting. I'll give you a little help...try searching "external amp". Good luck to you.

Paul in Canada

Hello Yenoorekim, I can't give you any advice on bi-amping, I'm just a rookie around here. There are a lot of knowledgable people posting on this site and I have learned a lot the last couple of years. Hope you stick around and do some posting because its nice to have someone else from Atlantic Canada around.

RuSsMaN

You are way over complicating things.

First, forget 7ch stereo. Stereo is 2ch.

Second, if one receiver doesn't cut it, power wise - add an external amp. If you can't (no preouts on your receiver), look at getting a separate amp AND preamp.

You're headed for a MacGuyver clusterf#$k, with the post above. Welcome to the boards Mike, and thanks for choosing Polk Audio.

Cheers,
Russ

Skynut

I would not use two avr's to bi-amp.
I would get two amps and split all the input signals two ways.
If you split your coax signal from the DVD player and use the processors in the avr's I would think you would run into issues with signals reaching the drivers at seprate times and the sound would be compromised.

Just my 2% of a buck.

Skynut

Oh yea and welcome to the club.

yenoorekim

Thanks for the warm welcome guys, I'll check out the external amps- I do have pre-outs for all channels. My old setup was accomplished by simply splitting the analog signal from my cd player and tape deck into two stereo receivers and it worked great, so I was assuming I could do the same here on a grander scale without much trouble. (I just liked the ability to do some extra tweaking for music) I understand that true stereo is simply 2 channels, but my H/K also has a '5 channel stereo' and a '7 channel stereo' mode, which seems to deliver a straight forward L/R stereo signal to all channels, which is great for music.... at least they all emit exactly the same music and vocals at the same volume; if I were blindfolded and spun around I wouldn't be able to tell which direction I was facing based on their output as I would in the Dolby surround modes. In any case, I'll go hunting for threads and see what I'm in for. Thanks again!

Mike.

F1nut

My head hurts.......:eek:

Welcome anyway.

janmike

Hey Mike, you're not from Cape Breton are you?

audiobliss

As others have said, you should go with an external amplifier or two (maybe a 2ch amp for mains and then a 5ch for the rest of your speakers). And since your AVR has preouts, you're golden!

Weclome, and the best of luck to you with finding the right amp(s) for you! You can find a wealth of into on it by searching.

Mike...but now we have way too many 'Mikes' in this thread....:p

yenoorekim

I've been looking at all sorts of external amps..... anyone have any suggestions? What should I be looking for to help determine which would be the ideal amp(s) for my setup?

Nope, I'm from the Halifax/Sackville area although I drove through Cape Breton once...... There are definitely too many Mikes around; there are 5 in my family (I'm Mike #5) and my gf's dad is named Mike too. In grade 6 there were 7 Mikes in my class alone..... I'm gonna name my kid Bemis (after my toilet) and save him the hassle of being a Mike... Just kidding, that would be cruel.... how about Bort?

janmike

How much $ do you want to spend?
So do you ever visit Peak Audio in Halifax?

Skynut

You want an amp with power. 200wpc or more.
I use a Sherbourn 7/2100 and I like it for now but when I get some extra money I want to get a Sunfire Cinema Grand signature series.

aaharvel

Skynut and Nacho are right on.

audiobliss

aaharvel wrote:

Skynut and Nacho are right on.

aaharvel

audiobliss wrote:

http://www.polkaudio.com/forums/showthread.php?t=40294&highlight=nacho

dipiazza

Question to kind of piggy back off of. Say i was powering an LSi HT setup. With LSi 9's as fronts, would i be better off Biamping the 9's with something like the Outlaw7125 7ch (190wpc in 4ohm). Or just single amping using the Outlaw 7500 5ch (300wpc in 4ohm)??

unc2701

In my experience, passive biamping usually results in modest gains and you're better off getting a bigger amp. If you have channels to spare, by all means go for it.

Part of the problem is that you don't need 190 watts to the tweeter. In passive biamping most of that just gets burned up as heat, whereas with a bigger amp (and no biamping), all your power gets balanced between the drivers. Now, if you do active biamping and get the passive crossover network totally out of the picture, you can expect big gains.

Bottom line: audition. You might find you like a bigass amp over a passive biamp setup... or the other way around. There's more to it that the simple physics.