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Discussion Starter #1
I am wondering what type of benefit if any bi-amping will give me. When I talked to the QSC rep. he highly recommended it for various reasons. Here is some background. The speakers I own are QSC 2150 I'll post some specs later. They have an option when wiring your speakers to select either Passive or Bi-amp. Apparently the internal crossover takes over from there. I am wondering what difference I would hear if I ran a Crown XLS 1500 in bridge passive (1050 W @ 8 ohm, 1550W @ 4 ohm). Does the crossover automatically run both my HF, & LF at 8 ohms or 4 ohms. As you can see from the specs below each operates at a different level.



Here is a link to the 2150 specs, it did not appear as I formatted it. http://qsc.com/products/Loudspeakers/Dcs_Series/SC-2150/





Second question: Let's assume bi-amping would be beneficial. I'm not even sure how to do it. Is this correct? Would I wire one 4 pole Speakon cable with the +1 and -1 and use that for my HF and connect to output channel 1. Then wire my second 4 pole speakon cable with the +2 and -2 for my LF and connect that to output channel 2. Then wire them to my speakers bi-amp connections? If this is correct do I need a Y cable to connect both RCA ch 1 &2 outputs into the back of my AVR single input? And of course enter my amps setup and change to bi-amp mode.

This would be a much cheaper option and take up less space than buying 3 more Crown XLS amps and running them bridged. ie 6 separate amps. I was also considering the X1000 for $99.00 If I could bi-amp like above that would be awesome. I could buy 3 instead of 6.
 

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Discussion Starter #2
Bi-amp these?

I am wondering what type of benefit if any bi-amping will give me. When I talked to the QSC rep. he highly recommended it for various reasons. Here is some background. The speakers I own are QSC 2150 I'll post some specs later. They have an option when wiring your speakers to select either Passive or Bi-amp. Apparently the internal crossover takes over from there. I am wondering what difference I would hear if I ran a Crown XLS 1500 in bridge passive (1050 W @ 8 ohm, 1550W @ 4 ohm). Does the crossover automatically run both my HF, & LF at 8 ohms or 4 ohms. As you can see from the specs below each operates at a different level.

Here is a link to the 2150 specs, it did not appear as I formatted it. http://qsc.com/products/Loudspeakers...eries/SC-2150/

Second question: Let's assume bi-amping would be beneficial. I'm not even sure how to do it. Is this correct? Would I wire one 4 pole Speakon cable with the +1 and -1 and use that for my HF and connect to output channel 1. Then wire my second 4 pole speakon cable with the +2 and -2 for my LF and connect that to output channel 2. Then wire them to my speakers bi-amp connections? If this is correct do I need a Y cable to connect both RCA ch 1 &2 outputs into the back of my AVR single input? And of course enter my amps setup and change to bi-amp mode.

This would be a much cheaper option and take up less space using 3 Crown XLS amps and running them bi-amped vs. buying 6 and running each bridged mono. Leaving my Crown XLS 1500 bridged and sending 1050 watts directly to 1 speakers or "BI- AMP" the speakers and send 300 watts to the HF and sending 525watts to the LF. According to the specs that should be sufficient. IF it is just bridged how is it distributing the power through the crossover. How much wattage and what OHM to my LF and HF ?
 

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They have an option when wiring your speakers to select either Passive or Bi-amp. Apparently the internal crossover takes over from there.
Not exactly. I get the impression that you believe this speaker will be biamped the same way home speakers are. With home speakers, after taking out the jumper between the two sets of binding posts, two amplifiers are connected directly to the binding posts and the internal passive crossover still functions to divide the frequencies out to the drivers.

However, this is a professional speaker, and in pro audio “biamping” typically means an active system using an electronic crossover. The specs for your speaker show “Crossover Frequencies (biamp) 500 Hz active, 24 dB/octave to mid-high, 2200 passive.” Please note the word “active.” This tells me that the biamp switch bypasses the internal passive crossover between the woofers and the mid/high drivers, and is replaced by an electronic crossover set for 500 Hz with a 24 dB/octave slope. Each speaker will require two amplifier channels, one for the dual 15s and one for the mid/high drivers.

As to whether or not it will make a difference, that’s hard for me to say. The main benefit of an active system is greater sensitivity: Passive crossovers suck up a lot of power, so for a given input wattage an active system will play much louder than a passive system will. However, you don’t fully get this benefit with this QSC speaker because in biamp mode the mid/high section remains passively filtered.

Regards,
Wayne
 

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Discussion Starter #4 (Edited)
I was with you all the way to the very end Wayne, Im not sure about your last sentence. What do you mean by.. However, you don’t fully get this benefit with this QSC speaker because in biamp mode the mid/high section remains passively filtered. Does this mean bi-amping them would be the same as bridged mono? Before we get too technical since I will not be buying 6 amps just to "TRY" the bi-amped. My intention was to use both channels on my Crown XLS amp to bi-amp each speaker. ie. ch. 1 to my HF and ch2. to my LF is that possible? If not, im done there. lol IF it it possible I don't mind a quick experiment. I have the wire and speakon cables as well as a Crown amp to test with. IF its possible was my above description for wiring correct or incorrect.
Or would I need a piece of equipment between my amp and speaker, ie external crossover?

*the picture below does not belong to me*
 

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Discussion Starter #5
Would it be worth it to get extra bass from the dual 15's? They don't really put out bass like a 15" driver should. Some have said its because the crossover to the 15's are set so high. Would it make a difference if I bi-amped just for the LF?
 

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Re: Bi-amp these?

I am wondering what type of benefit if any bi-amping will give me. When I talked to the QSC rep. he highly recommended it for various reasons. Here is some background. The speakers I own are QSC 2150 I'll post some specs later. They have an option when wiring your speakers to select either Passive or Bi-amp. Apparently the internal crossover takes over from there. I am wondering what difference I would hear if I ran a Crown XLS 1500 in bridge passive (1050 W @ 8 ohm, 1550W @ 4 ohm). Does the crossover automatically run both my HF, & LF at 8 ohms or 4 ohms. As you can see from the specs below each operates at a different level.

Here is a link to the 2150 specs, it did not appear as I formatted it. http://qsc.com/products/Loudspeakers...eries/SC-2150/
The specs link above is broken, but I found the spec sheet. Stated passive impedance is 4 ohms. As usual, the curve will swing above and below 4 ohms throughout the spectrum. Yes, in "passive" mode, the internal crossover handles everything.
Second question: Let's assume bi-amping would be beneficial. I'm not even sure how to do it. Is this correct? Would I wire one 4 pole Speakon cable with the +1 and -1 and use that for my HF and connect to output channel 1. Then wire my second 4 pole speakon cable with the +2 and -2 for my LF and connect that to output channel 2. Then wire them to my speakers bi-amp connections? If this is correct do I need a Y cable to connect both RCA ch 1 &2 outputs into the back of my AVR single input? And of course enter my amps setup and change to bi-amp mode.
The on-line info on this is sketchy, but from the spec sheet here under Recommended Processing, there's a 4th order Linkwitz-Riley crossover 500Hz specified for the HF section that is to occur in the "QSC Processor", in other words, an active crossover device placed ahead of the HF power amp section. There's also a 30Hz 18dB/oct HPF called for the LF section. You should not run the HF section without the recommended crossover. Apparently, when you bi-amp, you'll bypass the LF/HF crossover section, but still have whatever passive crossover handles the two horns. Fortunately, the Crown XLS series has all that available built in, just don't forget to set it.

Again, don't run bi-amped without an active crossover.
This would be a much cheaper option and take up less space using 3 Crown XLS amps and running them bi-amped vs. buying 6 and running each bridged mono. Leaving my Crown XLS 1500 bridged and sending 1050 watts directly to 1 speakers or "BI- AMP" the speakers and send 300 watts to the HF and sending 525watts to the LF. According to the specs that should be sufficient.
Careful...the specs are calling out maximum continuous ratings, not recommended ratings. A quick look at the sensitivity figures shows you'll need way less than 525 watts for ear-damaging levels in the average room (unless you have a large screening room with 75 seats or so). At 15' you'll max at 118dB SPL...that's pretty hot. Careful on the HF side too, compression drivers do blow.
IF it is just bridged how is it distributing the power through the crossover. How much wattage and what OHM to my LF and HF ?
If you use the passive setting, you have to consider the speaker as a single complex load. Power distribution to all 3 drivers has been designed for within the on-board passive network. The load, as specified, is 4 ohms, but in reality will vary, from probably a bit below 4 ohms to possibly well above 8, depending on frequency. This is normal for all multi-way speakers. But you don't have to worry or think about it.

Frankly, you should end up equalizing all this anyway, and that will change the power vs frequency distribution.
 

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Discussion Starter #7
Re: Bi-amp these?

Do you think its worth it to bi-amp the speakers? Would it offer more LF to the dual 15's? Im not so worried about the HF horns, those are plenty loud. Currently there is a sale on the Crown X1000 for $99.00 I could buy 3 of those for bi-amp duty. But ONLY if I can use 3 amps total. Using ch. 1 and ch.2 for bi-amping. (as asked in Question2) I don't want to buy 6 amps just for a negligible change is sound quality. I am using the speakers in a home theater room 26x16x9 with an AT 130" screen. I will use 11 ch on my Denon 4311 so I was hoping to lessen the load some. I also have a behringer I nuke 1000dsp but those fans are loud and its still cheaper to buy 3 crown X 1000's lol
I know you said don't run bi-amped without an active crossover.... Once I change the settings on my Crown amp, that is the active crossover correct?
I don't mind testing the speaker in bi-amp mode just to hear the difference, but I want to make sure im doing it correctly so I don't blow an amp or speakers. Assuming all is well, Is questions 2 above the correct way to wire my crown amp? Do I need an RCA Y cable to connect ch.1 and ch2. together and connect to the rear of my AVR.
 

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Re: Bi-amp these?

Do you think its worth it to bi-amp the speakers? Would it offer more LF to the dual 15's? Im not so worried about the HF horns, those are plenty loud. Currently there is a sale on the Crown X1000 for $99.00 I could buy 3 of those for bi-amp duty. But ONLY if I can use 3 amps total. Using ch. 1 and ch.2 for bi-amping. (as asked in Question2) I don't want to buy 6 amps just for a negligible change is sound quality. I am using the speakers in a home theater room 26x16x9 with an AT 130" screen. I will use 11 ch on my Denon 4311 so I was hoping to lessen the load some. I also have a behringer I nuke 1000dsp but those fans are loud and its still cheaper to buy 3 crown X 1000's lol
The XLS series has fans too. You can do the job with 3 amps, assuming bi-amped LCR. No need for 6. $99 is well below dealer cost if they're new, buy them even if you don't use them, resell and make some money. That price is literally a steal.
I know you said don't run bi-amped without an active crossover.... Once I change the settings on my Crown amp, that is the active crossover correct?
Yes, you can set the Crown DSP to work as the crossover. Study the XLS manual VERY carefully, double check your wiring, and make sure your settings match what the spec sheet calls for. There is a potential for damage here if an error is made.
I don't mind testing the speaker in bi-amp mode just to hear the difference, but I want to make sure im doing it correctly so I don't blow an amp or speakers. Assuming all is well, Is questions 2 above the correct way to wire my crown amp? Do I need an RCA Y cable to connect ch.1 and ch2. together and connect to the rear of my AVR.
I don't see the advantage of bi-amping these in your room, especially since you have the 4311, and will do a full Audyssey Pro cal (right?). You won't need the extra power of the Crowns, the speakers are quite sensitive enough for the 4311 to drive directly.

There's not likely to be any significant audible difference between bi-amping and passive, assuming the crossover settings are done right and levels adjusted correctly, especially after Audyssey.

If you want to try it, you can use the Crown's internal dsp as the crossover. Yes, you'll Y cord the inputs.
 

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As to whether or not it will make a difference, that’s hard for me to say. The main benefit of an active system is greater sensitivity: Passive crossovers suck up a lot of power, so for a given input wattage an active system will play much louder than a passive system will. However, you don’t fully get this benefit with this QSC speaker because in biamp mode the mid/high section remains passively filtered.

Regards,
Wayne
Ah, the old "passive crossovers suck power" myth. No, that's not how they work, and I would have to disagree with "Passive crossovers suck up a lot of power", and "an active system will play much louder". That would imply a passive crossover diverts the unwanted energy from a driver by absorbing energy and converting it to heat. That's not what they do. They divert energy from a driver by increasing impedance, in effect, blocking energy. The factor to be concerned with is the insertion loss of the crossover, which is quite tiny. If it weren't, we'd all have heat sinks on our crossovers with cooling fans.

It does depend on what you call "a lot of power" or "play much louder", however. The passive sensitivity of the 2150 is 99dB/1W/1m, the individual sections are at 100dB/1w/1m for the LF, and 102dB/1w/1m for the HF pair, which actually has to be compensated for in the active crossover to voice the speaker correctly in active mode. So, it's actually a 1dB difference, which sounds like a lot in terms of watts, but barely perceptible in terms of loudness.

Here's the data sheet.

Note also the sheet calls for an active Linkwitz-Riley crossover for the HF pair in active mode.

The advantage of active crossovers is the ability to fine-tune without swapping expensive passive components. It's not a power advantage.
 

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Discussion Starter #12
Re: Bi-amp these?

Thanks for your input. Its probably more trouble than its worth. The speakers actually had a "real" bi-amp crossover not just 4 binding posts. lol Yes, I do get plenty of power from my Denon I was just concerned when I run all 11 channels if Ill start to lose watts output. I know the manual states each channel "discrete" but still. So I wanted to ask before I went through the hassle of a futile attempt.
 

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Discussion Starter #13
I didn't meant to post twice but I wasn't sure "where" the post belonged. Its for home theater use but im using Pro speakers and Pro gear. "The Dilema" Im sure when these were built by QSC they were not meant for the "home AVR" but rather QSC pro gear. Although they do recommend this setup for "home" use. But im sure they want to sell their amps along with the speakers. Im sure they would recommend bi-amp as well. So I was curious if it would really make a difference, would it develop a larger more 3d soundstage, clearer vocals, etc. Running my amps in bridge mode certainly plays them louder. Not only can I hear it, but my spl meter proves it. So that's what had me thinking about bi-amping. I was curious if it would produce more bass given the extra boost of clean wattage directed ONLY to the LF and perhaps the HF would benefit. But it sounds like more myth than legend. lol It may be a few DB louder but it wont be any cleaner sounding and having extra power on tap doesn't sound like it will be use for anything.
Thank your for the replies. :)
 

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Discussion Starter #14 (Edited)
is it beneficial to run each crown amp in bridge mode for the purpose of headroom and less chance of clipping? I don't care about "loudness" they are plenty loud
 

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Discussion Starter #15
Is this a HT setup, or....?
This is a home theater setup. but now I am being told that pro gear setup for bridged mono is NOT a good choice to connect to my speakers. they are better left using my Denon AVR outputs (NO PRO GEAR). That its not the proper use of the equipment. Now I am even more confused. OK, if you say bi-amping wont do anything, Im ok with that....
But what is the difference if I use my AVR outputs. 150wpc OR if I use my Crown bridged mono (1050 wpc 8 ohms or 1550 wpc 4 ohms)? Other than playing a louder SPL which I will use Audyssey room correction, will it damage my speakers or AVR in some way?
The speakers are Pro speakers so why would pro amps be a bad idea? I was basically told to buy a 2ch, 3 ch, or 5ch commercial amp and not use any pro amps unless they are used with a mixer or used for DJ type use. They are NOT meant for Home Theaters? HUH
 

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This is a home theater setup. but now I am being told that pro gear setup for bridged mono is NOT a good choice to connect to my speakers. they are better left using my Denon AVR outputs (NO PRO GEAR). That its not the proper use of the equipment. Now I am even more confused. OK, if you say bi-amping wont do anything, Im ok with that....
But what is the difference if I use my AVR outputs. 150wpc OR if I use my Crown bridged mono (1050 wpc 8 ohms or 1550 wpc 4 ohms)? Other than playing a louder SPL which I will use Audyssey room correction, will it damage my speakers or AVR in some way?
The speakers are Pro speakers so why would pro amps be a bad idea? I was basically told to buy a 2ch, 3 ch, or 5ch commercial amp and not use any pro amps unless they are used with a mixer or used for DJ type use. They are NOT meant for Home Theaters? HUH
Have you checked out this... http://www.hometheatershack.com/for...ing-most-pro-audio-equipment-your-system.html I think the main issue is getting the gain correct. I have the Denon 4520, and I do not have the correct gain with my Yamaha P7000S amp for my subs. I found this out when I went to calibrate it with Audyessy. When I go to calibrate I have to turn the gain all the way up just to get the preferred 75db that Audyessy needs. It still sounds great as i don't need much power to hit reference bass levels but I think I would be better off with a balanced AVP or a non balance power amp.
 

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Discussion Starter #17
Have you checked out this... http://www.hometheatershack.com/for...ing-most-pro-audio-equipment-your-system.html I think the main issue is getting the gain correct. I have the Denon 4520, and I do not have the correct gain with my Yamaha P7000S amp for my subs. I found this out when I went to calibrate it with Audyessy. When I go to calibrate I have to turn the gain all the way up just to get the preferred 75db that Audyessy needs. It still sounds great as i don't need much power to hit reference bass levels but I think I would be better off with a balanced AVP or a non balance power amp.
I have plenty of power for my subs I was looking for more kick going into my dual 15" woofer located inside my QSC 2150 speakers. I'm not if the crossover inside itself is limiting the "punch" or not. That's why I was asking about bi-amping. To allow the crossover inside my crowns xls1500 to provide the LF to those speakers or I can use my Inuke 1000dsp. (either or, doesn't matter) but before I went through the hassle of doing so, I wanted to know if it is worth it? From those who have done it. The owners of Pro speakers with pro gear. Not the best buy owner that bought some off the shelf speakers and seen 4 terminals and said, hey, I'll bi-amp lol
 

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Ah, the old "passive crossovers suck power" myth.

The advantage of active crossovers is the ability to fine-tune without swapping expensive passive components. It's not a power advantage.
Since you’re using the speaker’s spec sheet to prove your point, I have to wonder if you have any hands-on experience relating to this? If so you’d know that if you connect a driver through a passive crossover, then bypass the crossover and connect the speaker wire directly to the driver itself, that there is a noticeable increase in SPL.

“Sucking power; “blocking energy;” insertion loss” – call it what you will but it’s no myth that a given speaker with passive crossovers will deliver noticeably less output with a given wattage than the same speaker ran as active with electronic crossovers. It’s common knowledge in pro audio circles (and I expect DIY home speaker-building circles as well), which is why the professional sound industry has used active systems in their touring PA systems, practically universally, for literally decades.

I have my doubts that even DIY home speaker building enthusiasts endure the significant expense of additional amplifiers and electronic crossovers simply to avoid swapping out comparatively cheap “expensive passive components.”

Regards,
Wayne
 

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I was with you all the way to the very end Wayne, Im not sure about your last sentence. What do you mean by.. However, you don’t fully get this benefit with this QSC speaker because in biamp mode the mid/high section remains passively filtered.
See previous post – you can’t get the primary advantage of an active system – increased efficiency (read SPL) - if passive elements remain in place between two of the drivers (the MF and HF in this case).


Does this mean bi-amping them would be the same as bridged mono?
Not following your thought there – biamping has to do with the speaker, bridging has to do with the amplifier. Bi-amping requires two amplifier channels; that’s obviously impossible to accomplish if an amp has been bridged for mono operation.


Before we get too technical since I will not be buying 6 amps just to "TRY" the bi-amped.
If you’re talking about six stereo amps all bridged mono, that would be a colossal waste. The increased efficiency bi-amping brings means you can get the same SPL output with less power, so there’s no good reason to use bridged amps. I remember reading literature from an audio manufacturer many years ago (forget the exact product or manufacturer) that an active three-way speaker would get the same output from 25 watts per driver (i.e. 75 watts total) as it would with passive crossovers and 250 watts.

That said, the big uncertainty with this particular QSC speaker is the hybrid active/passive thing you get with its biamp mode. The biamp mode must bring some benefit or I doubt QSC would bother to make it available, but with passive filters left in place I don’t see how it could be as effective from a maximum SPL perspective as a fully active system.


My intention was to use both channels on my Crown XLS amp to bi-amp each speaker. ie. ch. 1 to my HF and ch2. to my LF is that possible?
Certainly. However it’s more typical to put say, the high freq drivers on their own, lower powered amplifier, as it’s more efficient from cost and power standpoint. However, for the sake of experimenting you could do things as you’ve proposed, bi-amping with a single amplifier.


IF its possible was my above description for wiring correct or incorrect.
Or would I need a piece of equipment between my amp and speaker, ie external crossover?
Yes an external electronic crossover will be required to replace the passive one, either built into the amplifier itself or a stand-alone unit.


The speakers are Pro speakers so why would pro amps be a bad idea? I was basically told to buy a 2ch, 3 ch, or 5ch commercial amp and not use any pro amps unless they are used with a mixer or used for DJ type use. They are NOT meant for Home Theaters? HUH
”HUH” is right. That person has no idea what he’s talking about, unless he was saying that your AVR doesn’t have enough signal voltage from its main-channel RCA outputs to drive the amps. Refer to Part 7 of the article ellisr63 linked to determine whether or not that’s an issue with your AVR.

Regards,
Wayne
 

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Discussion Starter #20
Thank you Wayne, that made much more sense. Im not sure what benefit I would receive from bi-amping. I was curious since the option is actually built into the crossover. I was hoping for more LF power/excurions/head room. When I am running with my AVR only, I hear them clip every now and then during an intense explosion scene. Ie, Start Trek, Pearl Harbor (during the attack) Im not sure if my Denon just cant offer enough juice or if its a setup issue. I was hoping bi-amping would solve the problem. In the mean time I could just run them bridged mono and see if I get the same result. Crown X1000 are still on sale so I could buy 3 of those for either bi-amp duty or bridged mono.
Wayne - Is there a difference between running the Crown amps in Stereo vs. bridged?
Just to be clear I am NOT looking for more SPL (the speakers are loud and efficient) I am looking for cleaner and more headroom. The safest way possible of course.

http://www.musiciansfriend.com/pro-audio/crown-x1000-stereo-2x300w-power-amp
Guaranteed Minimum Power: 300W (per channel) @ 4 ohms / 200W (per channel) @ 8 ohms / 600W bridge mono @ 8 ohms
 
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