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Biamping question

post #1 of 15
Thread Starter 

Hi everyone,

 

Great forum. I have a question regarding bi-amping. I have 2 x Rotel rb970bx power amps (2 x 60 watts each). I would like to use them both to achieve BI-Amp... (1 for high and 1 for low frequency). However, according to the Rotel manual, I will need to use 2 x pre out (2 x left and 2 x right) to connect to back of my SR5007. Marantz SR5007 has set of pre out for a 7.1 ch amplifier connection (2 x front, 2 x Surround, 2 x Surround Back and 1 x centre, 2 x sub (which I won't use).

 

So I am assume I just need to use a splitter then.

 

In this scenario, would I be getting 120 watts x 2 as I'm using both Rotel power amps? Is it even worthwhile to do this, as I really want to bi-amp. I really need advice on this. Thanks in advance!

post #2 of 15

I'm not really versed in Bi-amping stuff.

But you could just use each Rotel as a Mono amp,

Have each amp dedicated to driving one speaker.

 

Here is a link to what I'm assuming is the latest revision of the Rotel manual, it might just match what you have.

http://www.rotel.com/content/manuals/rb970bx_eng.pdf


Edited by PurpleAngel - 9/27/13 at 2:42pm
post #3 of 15
Quote:
Originally Posted by Joostheizen View Post
 

Hi everyone,

 

Great forum. I have a question regarding bi-amping. I have 2 x Rotel rb970bx power amps (2 x 60 watts each). I would like to use them both to achieve BI-Amp... (1 for high and 1 for low frequency). However, according to the Rotel manual, I will need to use 2 x pre out (2 x left and 2 x right) to connect to back of my SR5007. Marantz SR5007 has set of pre out for a 7.1 ch amplifier connection (2 x front, 2 x Surround, 2 x Surround Back and 1 x centre, 2 x sub (which I won't use).

 

So I am assume I just need to use a splitter then.

 

In this scenario, would I be getting 120 watts x 2 as I'm using both Rotel power amps? Is it even worthwhile to do this, as I really want to bi-amp. I really need advice on this. Thanks in advance!

 

If you are using your 7.1 receiver in stereo mode, is there an option to re-map the pre-outs?

post #4 of 15

Normally when people bi-amp their speakers they use some sort of active crossover system and remove all (or nearly all) passive components from between the driver and the amp.  

 

If you are still using a passive crossover between the amp and driver, I don't really see the point in bi-amping. 

 

You asked if its worth it? 

If you do it right, almost absolutely yes. Well designed (even poorly designed) active crossovers that work in the digital domain absolutely butt-hurt all but the best passive crossovers. Setting them up represents at least a few days of honest work, and possibly a bit more, but once dialed in wow. 

One could argue that there are also advantages to using an analog active crossover, although digital does some things better (Digital filters can be made with no phase shift and usually offer more options for slopes, shelves, notches, etc) and cautions about setup still apply. 

If you do it wrong absolutely not worth it at all. The MFR of the speakers has no doubt built something that sounds at least passable to the majority of consumers. You can fuxor your **** real good if you do this wrong. 


Edited by nikongod - 9/27/13 at 8:06am
post #5 of 15
Quote:

Originally Posted by Joostheizen View Post

 

I have a question regarding bi-amping. I have 2 x Rotel rb970bx power amps (2 x 60 watts each). I would like to use them both to achieve BI-Amp... (1 for high and 1 for low frequency). However, according to the Rotel manual, I will need to use 2 x pre out (2 x left and 2 x right) to connect to back of my SR5007. Marantz SR5007 has set of pre out for a 7.1 ch amplifier connection (2 x front, 2 x Surround, 2 x Surround Back and 1 x centre, 2 x sub (which I won't use).

 

So I am assume I just need to use a splitter then.

 

Use a splitter - make sure you use one RB970BX for each side (ie front left>splitter and RCA>RB970BX>one wire each tweeter and woofer). In this set-up you're putting only one woofer/set of woofers on each amp, so theoretically there will be less current requirement on each amp. Whether differences are audible will depend on other factors, basically, whether each RB970BX was lacking in current to begin with and if so, will such a configuration get you enough headroom on each side, at the listening level you (and your neighbors) are comfortable with. Given you're coming from an HT receiver, chances are you might notice better driving of the speakers, although one RB970BX might be enough to do that (since stereo amps aren't as prone to BS measurements as surround receivers measured at 2khz with one channel driving a stable 8ohm load then the box says 160w x 5 (although that is a Marantz, not an old Yamaha or Onkyo).

Alternately, also try using both amps to power one Front and one Surround channel on each side, then try if the Receiver's amp (or through gain settings if you can reduce and level-match the others) can have the Center catch up and with no tonal difference between the Center and Front speakers. Or see how it does with a Phantom Center (not sure if your receiver has this either).

 

Quote:
Originally Posted by Joostheizen View Post

 

In this scenario, would I be getting 120 watts x 2 as I'm using both Rotel power amps? Is it even worthwhile to do this, as I really want to bi-amp. I really need advice on this. Thanks in advance!

 

It's worthwhile because you already have the amps and will only buy the splitters. However, take note that it's still going through the same crossover. Not that the passive crossover is such a bottleneck that it should be avoided all the time without due consideration to its benefits, but often if the speakers sound like they're driven better it's because you have an active crossover that sends an already limited range of frequencies to each amp channel without using the amp output to run the crossover (or parts of it getting in the way, like the caps), plus probably gain controls to suit your listening room or tastes. In my car, my Pioneer 860MP receiver splits the signal for the tweets and midwoofers (and also the sub), the 75watt channels get 2.5khz and up while the 150watt channels only get 70hz to 2khz (sub amp gets 50hz down). Then the receiver also applies -4db gain on the tweeter output and -2db gain on the sub (plus time alignment on each transducer, but that's only a requirement if you're in a car other than a McLaren F1). Result? A mostly (not literally) flat response where I only EQ-out some reflections reinforcing 5khz to 6.3khz.

post #6 of 15
Thread Starter 
Quote:

In this set-up you're putting only one woofer/set of woofers on each amp, so theoretically there will be less current requirement on each amp.

 

One guy I asked this question to said that the voltage of each amp would be the same and the resistance of each portion of the passive crossover network would be the same, so the power would be the same. This is all very confusing. I'm not a technical boffin. I'm just telling you what I heard someone tell me on another audio forum. Suffice it to say, he is against passive biamping.

post #7 of 15
Quote:
Originally Posted by Joostheizen View Post
Suffice it to say, he is against passive biamping.

 

Excluding situations where your amps are struggling to drive what you have now, what advantage is there to passive biamping? 

 

You still have the passive crossover with is associated faults, you are using much more power from the wall, and you have the added expense of 2 power amps where you formerly had one. Is now a good time to mention that you add yet another place where you could create a ground loop? All this for what gain? You have not eliminated any problems - power was not a problem and you still have the passive crossover. The only thing you gain is system complexity. 

post #8 of 15
Thread Starter 
Quote:
Originally Posted by nikongod View Post
 

 

Excluding situations where your amps are struggling to drive what you have now, what advantage is there to passive biamping? 

 

You still have the passive crossover with is associated faults, you are using much more power from the wall, and you have the added expense of 2 power amps where you formerly had one. Is now a good time to mention that you add yet another place where you could create a ground loop? All this for what gain? You have not eliminated any problems - power was not a problem and you still have the passive crossover. The only thing you gain is system complexity. 

Is it true what I said earlier about the power being the same ie 2 x 60 watts instead of 2 x 120 watts?

post #9 of 15

Could you clarify what you are looking for, this thread confuses me. 

 

You say you want a biamped system, but have made absolutely no mention of SQ - which is the primary reason people use different amps for each driver. 

You have mentioned "more power" on several occasions, is that what you really want? 

 

If you really just want more power why not just set your amps up in Bridge-Tied-Load mode? According to the manual you get 180w into 8ohms that way. 

post #10 of 15
Thread Starter 
Quote:

You say you want a biamped system, but have made absolutely no mention of SQ - which is the primary reason people use different amps for each driver. 

You have mentioned "more power" on several occasions, is that what you really want? 

 

I've been told that biamping is the way to go as far as SQ goes and people claim that power can increase. I'm just asking questions at this point. but I'm gettting a lot of conflicting opinions over the net.

post #11 of 15
Quote:
Originally Posted by Joostheizen View Post
 

 

I've been told that biamping is the way to go as far as SQ goes and people claim that power can increase. I'm just asking questions at this point. but I'm gettting a lot of conflicting opinions over the net.

So far the only way I can see for possibly bi-amping with the Marantz's Pre-outs.

If you go into the Marantz setup's "Amp Assign", and set the Marantz to "SPKR-C" it might route the correct signals to the pre-outs.

So in the pre-outs on the Marantz the front speaker "FR" &"FL"  are outputing the lower frequencys, which would feed into the Rotel amplifier, which would connect to the lower posts (woofer) on the speakers.

And the pre-out Surround Back "SBR" & "SBL" would feed into the Rotel amplifier, then to the high posts (tweeters) on the back of the speakers.

 

Might try asking here about what setting to use with the Marantz SR-5007.

http://www.avsforum.com/t/1432327/marantz-sr5007-owners-thread

post #12 of 15
Quote:
Originally Posted by Joostheizen View Post

Is it true what I said earlier about the power being the same ie 2 x 60 watts instead of 2 x 120 watts?

That's also why I suggested running surrounds on each side with it. That has to do with the wiring from the preamp and then into the speaker, essentially, that the main bottleneck to true bi-mapping is the passive crossover. Also the signal fed into it is being split passively. What's more likely to be approximate to 120w x 2 is the power consumption.
post #13 of 15
Quote:
Originally Posted by Joostheizen View Post
 

Hi everyone,

 

Great forum. I have a question regarding bi-amping. I have 2 x Rotel rb970bx power amps (2 x 60 watts each). I would like to use them both to achieve BI-Amp... (1 for high and 1 for low frequency). However, according to the Rotel manual, I will need to use 2 x pre out (2 x left and 2 x right) to connect to back of my SR5007. Marantz SR5007 has set of pre out for a 7.1 ch amplifier connection (2 x front, 2 x Surround, 2 x Surround Back and 1 x centre, 2 x sub (which I won't use).

 

So I am assume I just need to use a splitter then.

 

In this scenario, would I be getting 120 watts x 2 as I'm using both Rotel power amps? Is it even worthwhile to do this, as I really want to bi-amp. I really need advice on this. Thanks in advance!

You might do better if you sell off the Marantz Sr5007 A/V receiver and get a pre-amplifier, it might be better designed/dedicated for bi-amping and as it comes with less stuff on the inside (like speaker amps) it might provide a cleaner analog audio signal to the Rotels.

post #14 of 15
Quote:
Originally Posted by nikongod View Post
 

You say you want a biamped system, but have made absolutely no mention of SQ - which is the primary reason people use different amps for each driver. 

You have mentioned "more power" on several occasions, is that what you really want? 

 

If you really just want more power why not just set your amps up in Bridge-Tied-Load mode? According to the manual you get 180w into 8ohms that way. 

 

This, if the amplifiers are bridgeable, why not just bridge them and use one per speaker. No need for splitters and no compromise of SQ.

post #15 of 15

Lots of dumb advice here.  You can configure the Marantz to biamp mode and the surround back preouts work for front mains .

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