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post #1 of 21 Old 10-25-2013, 02:01 AM - Thread Starter
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Hey guys

Im running a 2.0 setup because I have full range towers. All other speakers are disabled.

My denon x4000 has a bi amp feature by using the surround channels and tying it with the front channels. If I do this, is the wattage going from 125 watts @ 8 ohms to 250 watts @ 8 ohms?

Or Is this diminishing returns? Are the wattage being delivered in bi amp mode lower than if it wasnt in bi amp mode since its all coming from the same power supply?

I would know the answer to this but unfortunately all reviews for the X4000 do not include power rating tests so im stuck here

Thanks guys
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post #2 of 21 Old 10-25-2013, 02:15 AM
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Biamp will deliver the same power to the HF and LF driver of 125 watts. The excess power sent to the HF driver will be dissipated as heat in the XO. The gains of this type of bia-mping is small to none. A 2 channel system can with with full range speaker or a 2.x system with sub/s.

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post #3 of 21 Old 10-26-2013, 12:52 AM - Thread Starter
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Quote:
Originally Posted by derrickdj1 View Post

Biamp will deliver the same power to the HF and LF driver of 125 watts. The excess power sent to the HF driver will be dissipated as heat in the XO. The gains of this type of bia-mping is small to none. A 2 channel system can with with full range speaker or a 2.x system with sub/s.

"Biamp will deliver the same power to the HF and LF driver of 125 watts."

I dont get it. Does this mean the total wattage has been doubled? 250 watts going into the speaker?

If so, could it be said without biamping, since the wattage per channel is 125 watts @ 8 ohms, that approx 62 watts is being delivered to the HF and LF drivers?

Also, since the receiver is doing the biamping does that mean the true wattage delivered will be lower than 125 watts? Because all the power is being sourced from one transformers within the receiver?

Thanks
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post #4 of 21 Old 10-26-2013, 01:40 AM
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At approx. 300 Hz the power distribution to the HF and LF diver is 50/50. at higher frequencies or in typical in home use the tweeter is using less than 5-10% of the power going into the speaker. That is why in general putting 125 or even 62 watts into the HF driver is a wasted since most of it will never be used. The XO network for a speaker will divide the power to the HF and LF driver in the right amount depending on the source and design of the network.

True bi-amping involves the use of an external xo. There are gains to reap from such an approach. But, a lot of R&D when into the design of the passive xo and in many cases this will deliver the best sound for your speakers. How good passive over active xo is depends on the speakers, components used, and were you are on the learning curve in setting up an active system. Leave the jumpers on if you have dual binding post and hook your speakers up and enjoy! I own multiple amps and don't go thru the trouble of active bi-amping with great results.

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post #5 of 21 Old 10-26-2013, 07:49 AM
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Originally Posted by music_to_my_ear View Post

My denon x4000 has a bi amp feature
No, it doesn't. If has the ability to parallel unused amps, so-called 'passive bi-amping', which doesn't do anything useful. True bi-amping uses an electronic crossover to separately amplify the highs and lows, while speakers for true bi-amping do not have internal passive crossovers. 'Passive bi-amping' is a marketing tool.
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If so, could it be said without biamping, since the wattage per channel is 125 watts @ 8 ohms, that approx 62 watts is being delivered to the HF and LF drivers?
Power density drops by 3dB (1/2) with each octave increase in frequency, so in most systems the tweeter will be receiving no more than 10% of the amp output. Diverting that 10% to the woofers will have no effect.

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post #6 of 21 Old 10-26-2013, 01:03 PM
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Originally Posted by Bill Fitzmaurice View Post

No, it doesn't. If (meant "it") has the ability to parallel unused amps, so-called 'passive bi-amping', which doesn't do anything useful. True bi-amping uses an electronic crossover to separately amplify the highs and lows, while speakers for true bi-amping do not have internal passive crossovers. 'Passive bi-amping' is a marketing tool.
Power density drops by 3dB (1/2) with each octave increase in frequency, so in most systems the tweeter will be receiving no more than 10% of the amp output. Diverting that 10% to the woofers will have no effect.

Question for you, Bill; does my Onkyo NR 717 work the same as you described, above? I thought I was special, because my AVR did bi-amping, but now I'm not so sure.

FYI I bought my Onk which has a 7.2 setup standard, so I could bi-amp which would make my system 5.2. I have to tell you, based on my ears, the bi-amping really didn't sound any better, and if anything it was a bit brighter or harsher, but not better. I put the jumpers back and now run my speakers the way they were designed, and they sound great, and are plenty loud, with or without bi-amping.

It's hard to tell by my ears if the bi-amping had any effect, because the Onk's built in Audessey XT rolls back any real power gain anyway to balance the mains with the other speakers.

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post #7 of 21 Old 10-26-2013, 01:48 PM
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Good. You haven't developed audiophile "golden ears." You shouldn't have heard anything different. That's positive. Passive bi-amping is an invention by the home audio industry to have a new feature to sell. It has nothing at all to do with the sound of your system. All it does is increase the amount of wire in your installation. Biamplification is something used in the pro audio world. It involves putting an active crossover between the mixer and amplifiers so that the individual drivers can be isolated from each other electrically and can be individually amplified and adjusted for level. It has very little application for home audio although it is used by a few home audio enthusiasts. As mentioned above it would require you to disconnect the passive crossover inside your speaker cabinets, add an additional set or two of terminals and rewire the drivers. Somebody thought he could get a marketing advantage by introducing "passive biamplification" to the home audio world. Apparently it worked. So did exotic cables, outboard DAC's and Shun Mook discs.
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post #8 of 21 Old 10-26-2013, 04:07 PM
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Originally Posted by wvu80 View Post

Question for you, Bill; does my Onkyo NR 717 work the same as you described, above?
Does it have a way of setting the crossover frequency between the low and high frequency outputs? If it's a real bi-amp it has to.

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post #9 of 21 Old 10-26-2013, 07:51 PM
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Some Onkyo's do include a crossover inside. Still a question if you would hear the difference in a blind test. Doing an active system right is a lot of work.

Aside: The crossover does not "dissipate the extra power as heat". It rejects out-of-band energy by presenting a high-impedance load out of band, thus does not accept nor absorb power. Another way to think about it is the voltage swing is still there, but the crossover becomes a high-impedance load and does not draw current, so no (or little) out-of-band power. Finally, nearly all the energy past the cut-off frequency is applied to the drivers, not dissipated within the crossover.

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post #10 of 21 Old 10-26-2013, 11:24 PM - Thread Starter
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Quote:
Originally Posted by derrickdj1 View Post

At approx. 300 Hz the power distribution to the HF and LF diver is 50/50. at higher frequencies or in typical in home use the tweeter is using less than 5-10% of the power going into the speaker. That is why in general putting 125 or even 62 watts into the HF driver is a wasted since most of it will never be used. The XO network for a speaker will divide the power to the HF and LF driver in the right amount depending on the source and design of the network.

True bi-amping involves the use of an external xo. There are gains to reap from such an approach. But, a lot of R&D when into the design of the passive xo and in many cases this will deliver the best sound for your speakers. How good passive over active xo is depends on the speakers, components used, and were you are on the learning curve in setting up an active system. Leave the jumpers on if you have dual binding post and hook your speakers up and enjoy! I own multiple amps and don't go thru the trouble of active bi-amping with great results.

All I wanted to know was does this passive bi-amping feature deliver more wattage to my speakers

So, does it? Is the wattage increased by using the spare amps? Are the woofers receiving more wattage than a non-passive bi amp setup?
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post #11 of 21 Old 10-26-2013, 11:45 PM
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Quote:
Originally Posted by music_to_my_ear View Post

Quote:
Originally Posted by derrickdj1 View Post

At approx. 300 Hz the power distribution to the HF and LF diver is 50/50. at higher frequencies or in typical in home use the tweeter is using less than 5-10% of the power going into the speaker. That is why in general putting 125 or even 62 watts into the HF driver is a wasted since most of it will never be used. The XO network for a speaker will divide the power to the HF and LF driver in the right amount depending on the source and design of the network.

True bi-amping involves the use of an external xo. There are gains to reap from such an approach. But, a lot of R&D when into the design of the passive xo and in many cases this will deliver the best sound for your speakers. How good passive over active xo is depends on the speakers, components used, and were you are on the learning curve in setting up an active system. Leave the jumpers on if you have dual binding post and hook your speakers up and enjoy! I own multiple amps and don't go thru the trouble of active bi-amping with great results.

All I wanted to know was does this passive bi-amping feature deliver more wattage to my speakers

So, does it? Is the wattage increased by using the spare amps? Are the woofers receiving more wattage than a non-passive bi amp setup?

No.

I don't need snobs to tell me how to think, thank you!
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post #12 of 21 Old 10-27-2013, 07:51 AM
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at any given volume, the speakers have to be receiving exactly the same power. Or the volume would be different. As explained above, there is maybe a potential for a ten to twenty percent increase in available clean power to the woofers by offloading the tweeter to a separate amp. Less than a single decibel louder. One notch louder, to most folks, is three dB, or double the power.

And again, if you turn up to the same level, you will absolutely never use any of the extra power because you are not calling for it. The speaker gets as loud as the amp tells it to. So for example when your volume control is at zero the amps are putting out zero watts whether they are 10 watt amps or 1000 watt amps. at 85 dB I'm probably using two watts or less per channel in my system . . . whether the amp is a 20 watt amp or a 1000 watt amp
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post #13 of 21 Old 10-27-2013, 03:42 PM - Thread Starter
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I still don't get why passive bi amping doesn't double the wattage delivered.....unless....since the jumper braces were removed and the wattage usage is dependent on the crossover design, hf crossover using only a small amt of the wattage and dissipating the rest in the ceramic resistors whereas if the jumpers were in place the unused wattage would be passed to the woofers, it is a culmative delivery of 250 watts into the speaker where watt usage is determined by the crossover design so really passive bi amping is NOT efficient at all and isn't really that glorified...for the HPF drivers that is. I'm sure the LPF drivers are receiving more juice with this method though but does depends on how much juice the receiver is able to deliver given a receivers power supply constraints.

SO....I would guess with passive bi amping, the woofers MAY receive a bit more juice than the regular amping but it's benefit is subjective because unless the wattage is doubled and a 3db increase is noticed, passive bi amping is moot in method.


There...I think I made sense of it for myself. I think the only REAL noticeable effect of passive bi amping would be the receiver getting hotter tongue.gif

Damn, I have to say that marketing of passive bi amping sure got me believing......OH and I guess another small benefit of passive bi amping in a receiver could be the reduction in cross contamination of frequencies or something...but to really prove that I think it would best to test it out using scientific methods and ewuipment I would never own haha
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post #14 of 21 Old 10-27-2013, 07:58 PM
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post #15 of 21 Old 10-27-2013, 10:21 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Does it have a way of setting the crossover frequency between the low and high frequency outputs? If it's a real bi-amp it has to.

Yes, it does. In the Audessey setup the FIRST thing it wants to know is if the speakers are "standard" or "bi-amped".

It then wants to know if the speakers are "4 ohms" or "6 ohms." According to the manual, if any of the speakers are 4 ohm, then that's the setting which should be used. I'm not sure why, since most of my speakers are 6 ohm and only the center is 4 ohm. I tried it both ways, and could not hear any difference.

I can also set the crossovers for every speaker except sub at full-range, 40, 60, 80, 100, and 120 hz. If the mains are full range, I can choose the option for setting double-bass output.

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post #16 of 21 Old 10-27-2013, 11:00 PM
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Originally Posted by wvu80 View Post

Quote:
Originally Posted by Bill Fitzmaurice View Post

Does it have a way of setting the crossover frequency between the low and high frequency outputs? If it's a real bi-amp it has to.

Yes, it does. In the Audessey setup the FIRST thing it wants to know is if the speakers are "standard" or "bi-amped".

It then wants to know if the speakers are "4 ohms" or "6 ohms." According to the manual, if any of the speakers are 4 ohm, then that's the setting which should be used. I'm not sure why, since most of my speakers are 6 ohm and only the center is 4 ohm. I tried it both ways, and could not hear any difference.

I can also set the crossovers for every speaker except sub at full-range, 40, 60, 80, 100, and 120 hz. If the mains are full range, I can choose the option for setting double-bass output.
You did not answer bills question. You did not show where you can set a crossover on the biamped speakers beteween the high freaq drivers and the mids/lows. What you described is a normal set up and a passive biamp config which is a waste of time. There is no audible benefit to biamping without using an active crossover before the speakers. If anything, because you are using more channels on your avr, you are limiting the potential available power to your speakers, and we all know avr wattage ratings per channel decreases the more channels that are used.

If you are serious about biamping, rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.

I don't need snobs to tell me how to think, thank you!
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post #17 of 21 Old 10-28-2013, 02:48 AM - Thread Starter
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Originally Posted by 67jason View Post

You did not answer bills question. You did not show where you can set a crossover on the biamped speakers beteween the high freaq drivers and the mids/lows. What you described is a normal set up and a passive biamp config which is a waste of time. There is no audible benefit to biamping without using an active crossover before the speakers. If anything, because you B]rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.
[/B]e more channels that are used.

If you are serious about biamping, rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.[/quote]

, rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.[/quote]


Would this yield better sound quality than high quality crossover components? Since the quality of the material aspect has been removed? Just curious.....maybe it would be wiser for audiophiles to do this
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post #18 of 21 Old 10-28-2013, 03:02 AM
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Quote:
Originally Posted by 67jason View Post

You did not answer bills question. You did not show where you can set a crossover on the biamped speakers beteween the high freaq drivers and the mids/lows. What you described is a normal set up and a passive biamp config which is a waste of time. There is no audible benefit to biamping without using an active crossover before the speakers. If anything, because you B]rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.
[/B]e more channels that are used.

If you are serious about biamping, rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.


, rip the crossover out of your speaker, wire the drivers directly to the binding posts and add an active crossover between the amps and the speakers.[/quote]


Would this yield better sound quality than high quality crossover components? Since the quality of the material aspect has been removed? Just curious.....maybe it would be wiser for audiophiles to do this[/quote]

not sure i fully understand what you are asking, but i can say that any perceived sound differences after a crossover mod would be subjectively considered better or worse. just too many variables including personal taste to conclusively state it would be better.

for biamping, to do it right you need an active crossover so you can dial in the exact frequency range going to the high freq drivers and the mid|/low freq drivers. not separating the frequencies before the speaker wont net any audible change, you will be running a full range signal to both sets of binding posts.

I don't need snobs to tell me how to think, thank you!
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post #19 of 21 Old 10-28-2013, 07:34 AM
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Aside: The crossover does not "dissipate the extra power as heat".
As a matter of fact, it does. Some is burned off as heat via the resistive component of pass-through inductors, some by the shunting of out of bandwidth frequencies to ground. The technical name for the power dissipated by a crossover is 'insertion loss'. With well designed and constructed crossovers it tends to be minor, but with poorly designed and built crossovers it can be as much as 2dB. That's about a 35% power loss.
Quote:
Yes, it does. In the Audessey setup the FIRST thing it wants to know is if the speakers are "standard" or "bi-amped".
I can also set the crossovers for every speaker except sub at full-range, 40, 60, 80, 100, and 120 hz. If the mains are full range, I can choose the option for setting double-bass output.
If it's not allowing you to set the crossover frequency between the midbasses and tweeters, which would occur somewhere between 1.5kHz and 3kHz on average, it's not bi-amping. The only crossover you're setting is that between the subs and mains.
Quote:
I still don't get why passive bi amping doesn't double the wattage delivered.
Watts don't matter. Voltage swing does. The average consumer doesn't know that, a fact that the marketeers take advantage of when trying to convince them of the non-existent benefits of passive bi-amping.
Quote:
All I wanted to know was does this passive bi-amping feature deliver more wattage to my speakers
The pertinent question is whether it delivers more voltage swing. The answer is no.
Quote:
Would this yield better sound quality than high quality crossover components?
The main advantage to active versus passive crossovers is lower distortion, both THD and IMD, from the amps. Another benefit is that actives tend to have much steeper filter slopes, which reduces THD and IMD sourced by the drivers themselves. Next comes lower the lower THD and IMD that an active crossover itself has compared to a passive. The last benefit is the lack of insertion loss created by passives.

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post #20 of 21 Old 11-01-2013, 08:59 PM
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Quote:
Originally Posted by derrickdj1 View Post

At approx. 300 Hz the power distribution to the HF and LF diver is 50/50. at higher frequencies or in typical in home use the tweeter is using less than 5-10% of the power going into the speaker. That is why in general putting 125 or even 62 watts into the HF driver is a wasted since most of it will never be used. The XO network for a speaker will divide the power to the HF and LF driver in the right amount depending on the source and design of the network.

True bi-amping involves the use of an external xo. There are gains to reap from such an approach. But, a lot of R&D when into the design of the passive xo and in many cases this will deliver the best sound for your speakers. How good passive over active xo is depends on the speakers, components used, and were you are on the learning curve in setting up an active system. Leave the jumpers on if you have dual binding post and hook your speakers up and enjoy! I own multiple amps and don't go thru the trouble of active bi-amping with great results.


What about a true 4 way speaker system that has a sub, midbass, mid and tweeter? I have a pair of JBL L7s that I have been passively bi-amping for about 15 years. When simply removing the jumpers, the LF posts power only the sub and the HF posts power the rest. The crossover frequency is 150HZ. The owner's manual from JBL encourages you to use the built in crossover and to use amps of the same power rating for LF and HF. They refer to this (incorrectly?) as multiple amp bi-wiring. These speakers have a 2 part crossover that first separates the sub from the other drivers and an other board that goes to the midbass etc. The sub crossover board has a jumper in it so you can actually bi-amp them with a 2 way external crossover. From what I have read and experienced about these, they are very power hungry speakers that really wake up as you put more power into them. JBL recommends an amp rating of 35-450 watts. I first had a Harmon Kardon PA-5800 amp (5 channels X 80 watts which seemed underrated) that at first I used to run 5 speakers with until I decided to give the passive bi-amping a try and used 4 channels of it to drive them and to me and anyone else that heard them agreed that it made a significant difference. I have since replaced the HK with an outlaw 7200 (7 channels X 200 watts) and continue to do so with it. Most people say just to buy a bigger amp. However going from 100-200 watts to 300-400 watts is usually a significant increase in price. From all the discussions on this subject that I have read most people seem to agree that it is a waste. I agree that with a 2 or 3 way speaker system it probably is especially if you are talking about using the amps in a typical AV receiver. I also agree that receiver manufacturers are putting that bi-amp feature in their products as another feature and selling point to make their product appeal to people who have a 5.1 speaker set up so they will buy a 7.1 receiver and it gives them something to do with the 2 unused channels. If you think about it, this makes their usually overrated power figures not quite as far fetched since those 2 extra channels if used won't be doing much.
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post #21 of 21 Old 11-01-2013, 09:12 PM
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Quote:
Originally Posted by Bill Fitzmaurice View Post

Quote:
Aside: The crossover does not "dissipate the extra power as heat".
As a matter of fact, it does. Some is burned off as heat via the resistive component of pass-through inductors, some by the shunting of out of bandwidth frequencies to ground. The technical name for the power dissipated by a crossover is 'insertion loss'. With well designed and constructed crossovers it tends to be minor, but with poorly designed and built crossovers it can be as much as 2dB. That's about a 35% power loss.

Yes, but the comment was not talking about insertion loss but the power supposedly delivered to the speakers. That is, the implication was a 100 W amp used in a bi-amped system and delivering say 10 W to the tweeter was dissipating 90 W in the crossover. I hope not! The (well-designed) crossover presents a high impedance to the amp for out-of-band frequencies; it does not dissipate power that is not actually generated. Maybe I misinterpreted the original comment.

And yes some out-of-band energy is shunted and dissipated; no practical crossover is ideal.

And yes I know you know all this, just clarifying for others who may not.

And I have seen a few smoked crossovers from my days on the live sound board so agree the loss can be significant in some cases. I have also run across one poorly thought out design that, when bi-amping, tapped at the wrong place and bypassed the series LF block and tied into the inductor shunt that should have been the second element in the HF path. I discovered this troubleshooting an amp that seemed to have a hard time with its output shorted to ground at LF...

"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley
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