BI-Amp my mains?

[Jeff R.]

I am setting my HT and have the capability of bi-amping my mains. I am not sure if my reciever can handle the load and also whether or not I will see a major difference in performance. Any advice or experience would be helpful.

My reciever is the Onkyo TX-SR 805 and I will be running my 5.1 system so I would be able to assign my extra channels for Bi-Amping. My speakers are definitely a load to run, MB Quart QLS 1030's. They are 4 ohm and 87 dB sensitivity. This reciever will be primarily used for TV and Movies, I will not be listening to much music for this application.

Thanks for the advice.

Jeff

 

[Chopin_Guy]

Jeff,

I would have to advise against the bi-amping of your mains through your SR805. That AVR does indeed have a very beefy amp section which is rated to handle 4ohm, but I would not want to double up a 4ohm load given how hot the Onkyos run normally, I think you could easily run into problems if you did this.

Secondly, what you are considering doing is known a 'passive' bi-amping which provides no performance advantage over just a single power source running into the speakers. True bi-amp situations utilize external crossovers splitting the signal outside of the speakers and then feeding the signal from each frequency range to the amp and then to the speaker...much different situation than passive.

I wold have to say that if you want the most from your speakers, I would look into an external amp as 4ohm 87db sensitivity is a fairly moderate load and taking that off of an AVR amp (even an amp as capable as the 805) and running the signal through a dedicated amp would give you more headroom....

 

[JCW]

ditto on what Chopin Guy says-

I've run major concert sound systems for 30 years and we certainly biamp to get more headroom, keep the sound clean, and ultimately get more volume. In a passive home setting, biamping can cause more problems than it solves IMO. You now have to balance the sound around the room equally when you may have only 1 sub in a corner.

While bass is generally non-directional, you will notice a big difference if you are in front of a biamped main (without low end) vs. on the side with the sub. In addition, now you have to get the perfect balance between the sub and the mains (without regard for the actual room differences based on location). I would get nice speakers and a nice separate power amp with plenty of power and run the speakers full range (plus a separate sub if needed). No gospel, just my recommendation. More gear is not always better. Quality gear is always better.

 

[Jeff R.]

Thanks for the advice. I have been considering adding a external amp for a while now. Do you think I will need to do a 3 channel amp setup to equalize my front sound stage? I would obviously like to get away with just a two channel for my fronts. My center is obviously much smaller than my mains, so the receiver can easily power it and my rears, I just do not want to invest into a 2 channel and not be happy with my purchase.

 

[JCW]

This gets down to personal taste and preferences. Personally, I'm not a big fan of center channel speakers. With that being said, I'd definitely go 2 channel and be happy. Regardless, I would still think you would be OK with a 2 channel amp and adjust the volume on your center speaker as needed. A much smaller center speaker is not going to see the benefit from the bigger amp like nice larger main speakers will see....IMO. It also depends on the acoustics, design, and set up of your room. Sure, at some point the 3 channel amp should be (somewhat?) better, but is it worth the extra cost? Personally, for me probably not.

That's my 2 cents worth and I'll back out and leave it for someone else to chime in.

Good luck!

 

[Chopin_Guy]

What are the specs on the other speakers....if all you MB's are 4ohm I say get a 5 channel amp and be done with it as channel balancing will be much easier with all channels through the amp. Now of the other channels are an 8ohm load and you want to ease up the amp on the mains then you could just do a 2 channel amp or even a 3 channel amp to be even across the front sound-stage which would probably be a good idea....

 

[Jeff R.]

My speaker are all the MB Quart QLS line. The front are only 4 ohms the center and dipole surrounds are all 6 ohm. My towers are very large and will pull signicantly harder on my amp than the center and rears. My towers are dual 6 1/2", 4" mid and a tweet.
My center is dual 5 1/4" with a tweet, the the rears are a single 5 1/4" with dual tweets.

 

[j_garcia]

BUY an AMP, then you won't need to bi-amp them Your mains will most likely draw more current due to being 4 ohm, but biamping from a single power supply just means you are essentially putting the exact same load on it. It doesn't really matter the size of the drivers in the speakers to some extent, it matters what it actually draws and in your case I would say an amp might be appropriate, however if you have them crossed over, the are likely not going to be drawing all that much current. The real question here is, what are you after? If you aren't actually running up against some kind of sound issue such as clipping, then do you really even need more power?

All of my speakers are 4 Ohm and only my surrounds run off the receiver.

 

[OttoMatic]

BUY an AMP, then you won't need to bi-amp them Your mains will most likely draw more current due to being 4 ohm, but biamping from a single power supply just means you are essentially putting the exact same load on it. It doesn't really matter the size of the drivers in the speakers to some extent, it matters what it actually draws and in your case I would say an amp might be appropriate, however if you have them crossed over, the are likely not going to be drawing all that much current. The real question here is, what are you after? If you aren't actually running up against some kind of sound issue such as clipping, then do you really even need more power?

All of my speakers are 4 Ohm and only my surrounds run off the receiver.

While I generally agree with your post, I don't think you can generalize that "biamping from a single power supply just means you are essentially putting the exact same load on it". Yes, you are putting the same load on the power supply, but the implication there is that it's the power supply that's running out of gas, and that's not always the case. If it's the individual channels that are running out of gas, then it may be possible to get more power through passive bi-amping.

In the end, though, bi-amping isn't really going to make a difference, and you're right in that the user might as well just get a real amp with sufficient power.

 

[j_garcia]

I see what you are saying. I know that you would see a small reduction in demand and load on each channel in the biamping scheme on the receiver, however the speaker will need X amount of current to reproduce the SPL desired. And I am oversimplifying the part about one power supply, but the end result is that I haven't seen the typical receiver that is really up to the task of biamping. As I said, just getting a quality external amp will make a much bigger difference.

I use a 2ch amp for my mains and one mono for the center.

 

[Jeff R.]

How about some suggestions for an amp? I want to keep it as low cost as possible, ie less than $600. I would be willing to buy used also. I have looked at some Emotiva's on line. I really do not have much experience with amps. I actually saw a Sunfire Grand 200 on Ebay today used and it was a 5 channel set up, I have heard great things about those amps. The catch is that 1 channels not functioning on the amp, which I really could just use three channels and be happy with, I assume I can get it for a good deal since it has a channel damaged.

Suggestions please.

 

[OttoMatic]

You can send the Sunfire to the factory for a full overhaul for something like $300. If you get a great deal on that amp, you can have it refurbished for a little more. That's what I did with a Sunfire, and I'm very happy with it.

 

[Kitsum]

What if you running a 4 ch power amp instead of a receiver? Bi-amping will use all 4 channels but stereo mode uses only 2 channels. Isn't there an improvement in headroom DF?

 

[OttoMatic]

What if you running a 4 ch power amp instead of a receiver? Bi-amping will use all 4 channels but stereo mode uses only 2 channels. Isn't there an improvement in headroom DF?

Yes, that's possible. It's also true that you would be able to get more power out of the amp if you bi-amp. On the other hand, if you start with an amp that's big enough, you don't really need more power or more headroom -- you've started with enough in the first place. For me, 200WPC is sufficient.

 

[PENG]

What if you running a 4 ch power amp instead of a receiver? Bi-amping will use all 4 channels but stereo mode uses only 2 channels. Isn't there an improvement in headroom DF?

If you want more power and head room, on a per channel basis you are better off using a 400WPC amp than 2X200WPC biamp. If you believe in the perceived benefits of passive biamping scheme resulting from separating the low and high (to an extent) frequency signals, and you do not need more than 200WPC for the bass drivers, then you would take the 2X200WPC route. Passive biamping is not as effective as active biamping but it does provide two signal paths to the speakers, one for low and the other for the high frequencies governed by the speaker's internal crossover network.