will bi-amping mains benefit for HT use!!

[firefighterchri]

I have been reading alot of different forums on here about biamping the mains of the polk RTI12's or for this matter any speaker. My question is if I biamp the mains will it be worth it for HT use? I watch more movies than listen to music right now. The reason I ask this question is because I set my receiver to have all speakers to small and X-over at 80HZ. Now if this being the case if I were to biamp the mains (receiver for the tweets and mids and mono blocks for the woofers) wouldn't this be a waste due to my woofers in the mains are not going to be active when the receiver is set to small? Or does it not work this way? Or will the monoblock amp add the woofer back into the eqation even if set to small? What about for 2 channel music when all speakers are set to large, does the monoblock now add additional power to the woofers in the mains. I need some clarification on this if possible.

Also every post I have written on here I have had nothing but GREAT results. This is the best forum out there for any audio lover! I plan on staying around for a long time so be prepared for many, many question and hopefully with some knowledge I have optained from here I will be able to help fellow newbies.

 

[MacManNM]

I have been reading alot of different forums on here about biamping the mains of the polk RTI12's or for this matter any speaker. My question is if I biamp the mains will it be worth it for HT use? I watch more movies than listen to music right now. The reason I ask this question is because I set my receiver to have all speakers to small and X-over at 80HZ. Now if this being the case if I were to biamp the mains (receiver for the tweets and mids and mono blocks for the woofers) wouldn't this be a waste due to my woofers in the mains are not going to be active when the receiver is set to small? Or does it not work this way? Or will the monoblock amp add the woofer back into the eqation even if set to small? What about for 2 channel music when all speakers are set to large, does the monoblock now add additional power to the woofers in the mains. I need some clarification on this if possible.

Also every post I have written on here I have had nothing but GREAT results. This is the best forum out there for any audio lover! I plan on staying around for a long time so be prepared for many, many question and hopefully with some knowledge I have optained from here I will be able to help fellow newbies.

Bi-amping will help. you can set the xovers lower, and gain a bunch. Those speakers are huge power hogs.

 

[Buckeyefan 1]

It's not as important for HT as it is for music. HT requires the deepest bass and midrange vocals. Music is much more demanding for mid bass. You need to look at your speakers crossover points to see if and why biamping would benefit. Here's the specs on the RTi12s.

Lower -3dB Limit 30Hz
Upper -3dB Limit 26kHz
Nominal Impedance 8 ohms
Recommended Amplifier Power 50-500 w/channel
Efficiency 90 dB
Crossover
(mid-high array) 1.8kHz, 12dB/octave low and high pass. 120Hz 12dB/octave high pass
Crossover
(subwoofer) 120Hz

Your tweeter handles everything above 1.8kHz. Your dual midranges handle everything between 120Hz and 1.8Khz - quite a task. Your triple 7" woofers handle to bass from 26Hz to 120Hz. Your existing amplifier cannot take advantage of the lowest end of your woofers right now due to a low spl rating. The triple woofers can handle a 500 watt monobloc amp - an amazing feat. Plus, by cutting them off at 80Hz in HT usage, they are only reproducing the 80Hz to 120Hz range - quite a waste of money for such great towers. Biamping them would bring out the 26Hz to about 45Hz where the receiver can take over for the midrange and highs. With a powerful two channel amplifier, you would be able to set your towers to large, and LFE+Main, and finally hear what these beasts can do. The issue is where to find that amplifier for a reasonable price. Since you are reproducing power for frequencies only up to 120Hz, distortion levels won't come into play. It would take a distortion level over 5% (some would argue 10%) before you would notice any at all. That means you can shop for a class D amp that delivers huge power and runs cool. These are the most efficient and work best for bass. Pick up a PA or DJ style amp rated at 300+ watts per channel and you'll be set. This will get you started.

http://search.ebay.com/amplifier_Power-Amplifiers_W0QQcatrefZC12QQfromZR3QQfsooZ1QQfsopZ1QQsacatZ64450

 

[jaxvon]

Another good option is the 200 watt M-Block from Outlaw Audio.

 

[firefighterchri]

Buckeyefan1, so what you are saying is if I listen to HT more than music biamping shouldn't be much of a concern? What would be the base setting in my receiver if my system was biamped? Such as Xover and size for music and HT. Right now the way it is setup is I have all my speakers set to small and Xover at 80HZ for HT. For music I tend to go the 2 channel mode and set the speakers to large that way I can use the woofers in the mains and Xover at 60 or less. But like you said I don't think I have enuf power to really drive the woofers like they need to be driven for music, so biamping them will bring out the bass in the mains, right? Well only for music and not for HT because I set Xover at 80HZ. I am still a little (or alot) confused on some of this biamping thing. Does anybody know where I can read up more on this?

 

[jaxvon]

Ah, if you change your settings for 2-channel, then that's a different story. If your reciever has a "pure" mode, then that'd be the way to go. Not sure about a great resource for biamping info, but just poke around here some and I'm sure you can get a great response.

 

[Johnny Canuck]

I seem a little confused now too. Buckeye, my friend, you know I have the RTI 12's too. I have a NAD power amp on the woofers and my Denon 3805 on the highs/mids. The power amp on the fronts full range was way too bright, so i am only amping the lows..My settings are front small, crossover 80hz, "LFE + Main". I still am getting bass out of the woofers. Proof is when i hit the power switch on the NAD.

Are you saying it's better to have the fronts on LARGE and lower the crossover point? I notice the system has more bass when I raise the crossover point, not lowering it.

I will try it out just for curiousity but to my ears, 80hz and SMALL produces the best sound.

 

[Buckeyefan 1]

I seem a little confused now too. Buckeye, my friend, you know I have the RTI 12's too. I have a NAD power amp on the woofers and my Denon 3805 on the highs/mids. The power amp on the fronts full range was way too bright, so i am only amping the lows..My settings are front small, crossover 80hz, "LFE + Main". I still am getting bass out of the woofers. Proof is when i hit the power switch on the NAD.

Are you saying it's better to have the fronts on LARGE and lower the crossover point? I notice the system has more bass when I raise the crossover point, not lowering it.

I will try it out just for curiousity but to my ears, 80hz and SMALL produces the best sound.

JC,

You would be the man to tell us what sounds best. You have the system to test it out. I was hoping you'd jump in here, as you are one of the few who had biamped their Polk mains. I'd assume it would be based on the Polk's ability to reproduce a given frequency. If the 7" woofers have trouble producing (ie) 50Hz bass, then setting the crossover at 80Hz, or even 60Hz would piggyback the subwoofer into producing the full frequency range under 150Hz. Do me a favor, and set the fronts to "large", and the crossover at "60Hz", play some great soundtracts, and report back. This is very intersting.

 

[firefighterchri]

My main problem I can't seem to understand is, if a sytem is biamped does it not matter if you set speakers to small or large? Is biamping the mains worth doing for a HT if you have a awesome sub to handle to lows? If you biamped the mains for HT and left the amp that is biamped driving the woofers in the mains OFF will this provide better mids and lows for theater sound? For instance lets say my mains are biamped and I am watching a movie in DTS with THX and I set speakers to small and Xover at 80HZ(THX) and sub only on in the receiver, how does the Xover work? Does both the woofers and the sub handle 80HZ and below? Music in 2 channel I can see where it would benefit because I will be setting my speakers to large and Xover to 60HZ or less and probably sub+mains in receiver. Biamping them would make the mids and tweets sound better as well as provide better bass in the mains, right?

I'm sorry if I am still confusing anybody but I am trying to explain this the best I can in writting. Heck, I think I am starting to confuse myself!!! If anybody would be willing to help me out further please send me a private message and I will give you my phone # or I can go into more detail

 

[Azz123]

Hey Firefighter..

When looking from a HT perspective, don't forget your crossover setting in your amp is also responsible for your centre and rear surrounds...

I think Buckeye's first paragraph summed it up in a nutshell - "It's not as important for HT as it is for music. HT requires the deepest bass and midrange vocals. Music is much more demanding for mid bass."

I know with the speakers that I run (mains-32Hz-20kHz @ 91dB) the compromise on how low I set the crossover (60Hz) was based on the bass reproduction of the rears & centre, not the fronts.

Being relatively new to the HT "Audiophile" arena like yourself, the common piece of theory that Ive come across is the power thats required to produce the lower Hz frequencies to all channels, not just the mains. Hence regardless of capabilities of your speakers the "Small" setting is going to let your receiver supply power in the most efficient way possible when working in conjunction with a self powered Sub.

I'm not sure if you actually have a Sub or not, assuming you do, and it being self powered, it takes all that work away from the receiver in delivering that low down grunt giving your receiver so much more efficincy and headroom to deliver power (and volume).

Now Im basing the above on your listening habbits of HT over music - dont forget that youve got 5 speakers delivering sweet sweet sound, not just your fronts.

On numerous occasions when setting up my system I had to stop in the midst of the confusion I had gotten myself into and asked myself "What am I REALLY trying to achieve here?"

Food for thought.

A

 

[Johnny Canuck]

I tried setting my fronts to large and receiver crossover at 60hz. Bass seemed to cut in half. 80hz is definately the best with my Hsu STF 3. I had problems before finding a correct setting with a weaker sub, Polk 404. No such issue now. Even with an amp on my lows, set on small, sounds much better.

My thinking, correct me if I am wrong someone, is to use my Denon on the high's and midrange speakers, and power the 7" drivers with the amp for midbass, and my Hsu is for the low boomy bass. While it is true I may not be getting the most out of the power amp setting my fronts to small, it sounds better to my ears this way. I have considered scrapping the power amp all together and trying the Denon full range on the fronts to see if I hear any difference. My theory is the Denon is not being driven as hard the way I have it hooked up now.

I don't understand all this "efficiency" stuff and crossover points in my fronts. I may have this hooked up wrong, but to my ears, it sounds good.

Buckeye showed me something awhile back. If you want to see what those RTI 12's can really do, turn off the sub, set the crossover to it's lowest setting on the receiver, use the tone controls and EQ, crank up the bass and you will be amazed. Still not as good as using a sub, but you can get an idea what kind of bass those beasts push out.

Hope that helps. I still think I could have done better than the RTI12's for that kind of money, but I was new to HT and didn't know anything until I started reading this site. I do have to admit the brightness has been tamed a little with this amp and my hew house is carpeted compared to hardwood where i was before.

 

[firefighterchri]

Well I messed with the large and small settings as well as the Xover and I think for the way it is setup now (without being biamped) my whole system sounds the best set to small, Xover set at 80HZ, sub knob 1/2 way, and the LFE at zero. The receiver has set my sub volume in the receiver at -7.5. Now for 2 channel it sounds better set to large, Xover at 60HZ, receiver set to both, and everything else unchanged. I do have a few more questions as far as setup using theYamaha RXV2500. First, when using the auto setup, does it matter what field is displayed in the receiver such as pro-logic, neo6:cinema DTS, 2 channel, etc prior to doing the test? I do know that whatever field is on the receiver when you start the setup and then save it will name it with that field. I just don't know if it has any affect on the outcome of sound while doing the test tones. Can anybody explain what is the purpose of the surround initialize feature and how you use it? Also, it has a feature called the parametric equalizer. What is this for ( I assume it is to balance your speakers)? How are you suppose to adjust it and what are you looking for while adjusting?

 

[Johnny Canuck]

Not sure about the Yamaha 2500 as I have a Denon 3805.

You set your LFE to 0? Mine is at +10. I may fiddle with that today.

When I did the auto set up, my sub was at -5.5. Obviously that is not where i want it. I have my dial at about half, and adjust my sub volume with the receiver between +2 and +5 somewhere, depending on the source.

The auto set up , IMO, is not acurate. I only used it a starting point and made adjustments to taste later on. I also have the EQ off most of the time.