On to Bi-Amping - More Questions

nacam

Rotel got back to me regarding the RB-985 MKii and it is indeed common ground so I should be all set to go.

I just had a few questions regarding other members experiences of bi-amping these 1.2TL's. I first did a quick test of just hooking them up to 2 channels of the Rotel amp and they sounded superb and the 100 watt rating the Rotel claims is the loudest 100 watts I've ever come across.

Next I did a quick test of bi-amping by just splitting the input signals to the Rotel amp, removing the jumpers on the 1.2's and adding the other two channels. They sounded terrible! The highs/mids were way to over powering and the low end sounded put of phase. I may have screwed the wiring up but did not have time to check it but when my final set up is done (I am currently moving things around in my basement to get these into a better position) I should have the setup such that I can control the high/low input signals independantly.

With your experiences in bi-amping these with equal amounts of power, what were your best results in attenuating the high output signal to achieve the same sound of running these "just amped"?

Thanks in advance.

snow

I am assuming that you split the signals like this. left front and left surround matching for lows and highs on the left channel and right front and right surround for the lows and highs for the right channel?

I think that since your receiver or pre is sending the same voltage signal to all 4 channels of the amp equally if the amp outputs the power equally you should be getting identical amounts of power to the mids and tweeters.


Of course it may be that the amp is set up so that the two front channels actually output more power, most receivers do this.

To be honest with you I think you would be far better off selling this amp and getting a more powerful 2 channel amp.



REGARDS SNOW

nacam

snow wrote: »

I am assuming that you split the signals like this. left front and left surround matching for lows and highs on the left channel and right front and right surround for the lows and highs for the right channel?

I think that since your receiver or pre is sending the same voltage signal to all 4 channels of the amp equally if the amp outputs the power equally you should be getting identical amounts of power to the mids and tweeters.


Of course it may be that the amp is set up so that the two front channels actually output more power, most receivers do this.

To be honest with you I think you would be far better off selling this amp and getting a more powerful 2 channel amp.



REGARDS SNOW

The Rotel claims 5x100w on all 5 channels. It is an older amp, so these specs may have changed due to wear, who knows. When I have this finally set up I will be able to control the pre amounts to the 4 channels independantly. Hopefully I will be able to tune this to get the sound I was getting in the beginning. I would hate to have to sell this amp as I just bought it last week and I am liking the 2 channel sound so far. I am assuming I did something wrong with the hookup as I was in a rush to test it out.

I thought I saw someone saying that the tweeter array should be getting about 1/3 of the power of the MW array when bi-amped. Can anyone verify this?

Nacam

snow

nacam wrote: »

The Rotel claims 5x100w on all 5 channels. It is an older amp, so these specs may have changed due to wear, who knows. When I have this finally set up I will be able to control the pre amounts to the 4 channels independantly. Hopefully I will be able to tune this to get the sound I was getting in the beginning. I would hate to have to sell this amp as I just bought it last week and I am liking the 2 channel sound so far. I am assuming I did something wrong with the hookup as I was in a rush to test it out.

I thought I saw someone saying that the tweeter array should be getting about 1/3 of the power of the MW array when bi-amped. Can anyone verify this?

Nacam

It sounds like to me that you may have gotten the left/right speaker wires or IC's hooked up wrong somehow. You still havent said how you have them hooked up so it's hard to say. I have had my 1.2 TL's bi amped with a pair of identical amps and had no issues like you describe. I know Sal has his hooked up to a pair of Carver TFM-35X's in stereo one amp feeding the mids and one amp feeding the tweeters with no issues. I hooked up mine to a single Sunfire 300 X 2 and removed the jumpers and ran a set of wires from the current source speaker outputs to the tweeters and ran a set of wires from the voltage source speaker outputs with great success so I doubt that running identical amounts of power to the mids and tweeters are your problem here. here is a pic of the back of the Sunfire note it has XLR connections which is part of the reason I reccomended it to you.



REGARDS SNOW

snow

If your wondering why there hasnt been an overwhelming flood of responses to this thread it's most likely because it appears that you have asked for advice on what amp to use then turned around and ignored every ones advice and bought what you thought best. I am not trying to run down the Rotel brand because they make some very nice equipment in there price range but using a "multi channel HT amp" for bi amping is not going to give you what these speakers deserve sonically. Using a single more powerful 2 channel amp or a pair of 2 channel amps or a pair of mono blocks tied together is going to result in far better sound quality regardless of brand name. Most of us have tried many different combinations of receivers amps preamps etc with our SDA's and are attempting to have you avoid all the pittfalls of these failed atempts and point you in the right direction which will save you both time and money.



REGARDS SNOW

nacam

snow wrote: »

If your wondering why there hasnt been an overwhelming flood of responses to this thread it's most likely because it appears that you have asked for advice on what amp to use then turned around and ignored every ones advice and bought what you thought best. I am not trying to run down the Rotel brand because they make some very nice equipment in there price range but using a "multi channel HT amp" for bi amping is not going to give you what these speakers deserve sonically. Using a single more powerful 2 channel amp or a pair of 2 channel amps or a pair of mono blocks tied together is going to result in far better sound quality regardless of brand name. Most of us have tried many different combinations of receivers amps preamps etc with our SDA's and are attempting to have you avoid all the pittfalls of these failed atempts and point you in the right direction which will save you both time and money.



REGARDS SNOW

Well all I can say is that buying the amp I did was just the right time and $$ factor for me. I finally got things in order in terms of where these 1.2's are placed and I am going to wire them up this week where I can ensure the 4 channels I will be driving them with will be getting equal amounts of input. Like I said I did the test quickly and had to tear it down before I was able to test the setup properly so I was unable to check everything. If it doesn't work out I will consider selling this amp and getting a 2 channel and driving them that way.

Cheers;
Nacam