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NuckingFuts
10-20-2004, 12:02 AM
Can someone educate me on why one would want to bi-amp their speakers? What are the advantages of doing so?

The only reason I can think of is if you had a 100watt amp running speakers rated for upto 250watts. You could then stack another 100watt amp signal into the speakers thus boosting your power to 200 overall.

Hmm, I wonder, does bi-amping allow you to control the power delivery to individual speakers within a box hence allowing more control over hi's/mids/bass??

School me if would! Thanks!

PolkThug
10-20-2004, 12:04 AM
You are correct sir!

Regards,
PolkThug

LittleCar_w/12s
10-20-2004, 09:58 AM
I'll put this because many people don't understand why bi-amping is better...

You have a 250w amp
you have 250w speaker, one mid-range and one tweeter, whatever configuration (both tweeter and mid at 8ohms, through a built-in crossover)

Let's say the amp can do 250x1 or 125x2

So when you give the setup the single output of 250, the crossover built into this speaker setup will give all mid-range signal to the mid and all high-range signal to the tweeter.

This is the same as A: giving the mid 250w and the tweeter 250w(theoretically), not the same as B:no crossover and giving the mid 125 and the tweet 125.

The only reason to biamp here instead is Headroom for your highs, correct?
A--In the first configuration if the mid-range signal rises to, say 85% of the voltage peak, then the tweeter signal can only use 15% of that voltage without distortion - this is the reality of the signal.
B--In the second configuration, you have the ability to let the mid use all of half the voltage, and the tweet all of half the voltage.

This affords you the ability to not only adjust the output to a more flat and correct response, but to also give that tweeter what it really needs and not share it's power. This is the reason for bi-amping. This however means that you only have half the voltage available to each.

To truly bi-amp a setup like this you'd need two 250 watt channels, one to each. BUT keep in mind that that tweeter was only meant to use, say, that 15-30% of the power to guess here. This is why if you put a tweeter to get the full-spectrum without a crossover it COOKS the coil instead of falling apart. You could be better off with 250w channel to the mid and 125w channel to the tweeter.

So yes, N.F. it'll let you balance that box out much better, but be carefull of underpowering the mid and overpowering the tweet. individual ratings help a lot here...
-Jerry

NuckingFuts
10-20-2004, 11:07 AM
Thanks for the explaination!!

Early B.
10-21-2004, 02:25 PM
Don't bother bi-amping. Just get a good amp.

Tour2ma
10-22-2004, 01:38 AM
Originally posted by LittleCar_w/12s
I'll put this because many people don't understand why bi-amping is better... And after reading this, they still won't... :confused: I read yout post twice and still don't know what you are saying.

... not the same as B:no crossover and giving the mid 125 and the tweet 125. Are you under the impression that bi-amping bypasses the x-over?
The only reason to biamp here instead is Headroom for your highs, correct? Ummmm, no... High's peak demands (although higher than one might think), still pale compared to deep bass' demands.
BUT keep in mind that that tweeter was only meant to use, say, that 15-30% of the power to guess here. Thus the need for its high headroom???
This is why if you put a tweeter to get the full-spectrum without a crossover it COOKS the coil instead of falling apart. This is a full three "bamboozler"... :confused: :confused: :confused: aw hell, make it four... :confused:
You could be better off with 250w channel to the mid and 125w channel to the tweeter. OK, this is actually semi-true (actually I'd put it that you can get a way with a 250/ 125 bi-amp scheme), but how you got here is beyond me...
it'll let you balance that box out much better, but be carefull of underpowering the mid and overpowering the tweet. individual ratings help a lot here... May have to go five on this summation..

Anyway...

NF (how no one nabbed that screen name in all this time is beyond me...),

Bi-amping can be a cheap means to increasing the power to your mains, be they in HT service or 2 ch. With the added power can come more authority and clarity.

Here are three old threads:
http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=7872&highlight=biamp+OR+biamp
http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=14548&highlight=biamping+OR+biamping
http://clubpolk.polkaudio.com/forum/showthread.php?s=&threadid=8274&highlight=biamping+OR+biamping

There are many more...

gidrah
10-22-2004, 03:06 AM
There are many benefits to bi-amping a system, or so I've read. I've tried bi-amping one time and the benefits were pretty apparent.

Possible bennies with stock crossover (passive bi-amping):
Removing that ****ty jumper
Doubling surface area of contacts
Doubling surface area of wires
Be able to curtail your wires to better suit each application
Reducing the load on each amp
Reducing the bandwith of the wires often results in greater detail
I've also read about how using 2 amps of the same wattage does more than double the wattage. It has to do with the relationship between voltage and current or something like that.

Possible bennies of using an external crossover (active bi-amping):
All of the above
Greater diversity in choosing amps
Separate volume controls
The reduction of load is even greater
Adjustable slope on the better models
Possibility of better components

There's probably more but the microwave just dinged and I don't want to get chicken fat all over my keyboard.

Good luck!

LittleCar_w/12s
10-22-2004, 01:00 PM
(all the above from my firts post for detail...)

It's true that biamping can allow you to safely put twice the power into the set than you could sending them one source of power... the reason:
(if your tweeter is good quality and can match the wattage your mid is rated for... thanks Tour for pointing this out.)

You can safely put 500 watts into your 250 watt set by giving up to 250 watts to each driver. This allows you to avoid having the two drivers compete for power from a 250 watt source. (if your mid signal goes too high, your high's get clipped off..)
Your driver set is measured for 250 max, because at one given instant, one of the two drivers might experience the full 250 watts through the crossover. BUT, if you give it to them separately, you can enjoy the benefits of running them both to their potential.

So you can enjoy 500w of power at a full crescendo, and you will still get the best quality possible, not to mention a full tuneable system

Tour.. also, are YOU under the impression that the crossover divides the voltage somehow? it ONLY split's bandwidth... you tweet CAN get the full wattage, or your mid, not both, but that depends on the signal, not the crossover.

Tour2ma
10-22-2004, 08:23 PM
are YOU under the impression that the crossover divides the voltage somehow? it ONLY split's bandwidth... Nope... I understand that Voltage applied does not diminish across parallel circuits, unlike current which does divide. For a given spl, single amp or bi-amp makes no difference in the voltage potential applied to a given driver. Bandwidth and voltage are two entriely different things.

It was your comment about what a full range signal would do to a tweeter that threw me. The only reason I could imagine that would make it worth mentioning is if one thought that bi-amping eliminated the x-overs from the circuit, and clearly, taint so. Each driver receives the exact same signal FR in a bi-amp mode as it does in a single amp mode. The x-overs simply shunts aside/ around the bandwidth it will not let pass.


It's true that biamping can allow you to safely put twice the power into the set than you could sending them one source of power... ... and...
You can safely put 500 watts into your 250 watt set by giving up to 250 watts to each driver.Now you are implying that speaker ratings are maximum power ratings and that exceeding that rating puts ones speakers in peril. Fact is that speaker ratings are continuous power ratings and any driver worth its salt can handle short duration power surges, i.e., transients, 2, 3, even 4 or more times greater than their continuous rating.

Julian Hersh (RIP) regularly tone-burst tested the speakers he reviewed. By comparing the reproduced tone to the source tone he determined a speaker's limits. Any 60 W rated speaker is far safer running on a 600 wpc amp than it is on a 60 wpc amp. Why, because clipping is taken out of the equation. And it makes no difference if the 600 wpc comes from a single channel or two 300 wpc ch's...


(if your tweeter is good quality and can match the wattage your mid is rated for... thanks Tour for pointing this out.) You're welcome, except that is not what I said. You seem determined to send the message that tweeters are by nature substantially more delicate than mid-woofers, which, simply put, is false.

The mechanical demands on a tweeter are less from an excursion standpoint, but the rapidity of movement they are called upon to make is mind-boggling. And, in the course of doing their duty, the power applied to them can be as great as is the case for a mid-woofer. Normally it is not, but it can be... (I've got a link somewhere that shows this.)


(if your mid signal goes too high, your high's get clipped off..).) OK, now I'm afraid to get in a discussion on the nature of clipping, too. Clipping has nothing to do with a mid-signal.

Honest to God, LC_w/12, I am not trying to bust your balls here, but you are implying, if not outright stating, things in your posts here that you beleive to be correct, I am sure, but they are not... And doing that in response to questions from newbies just perpetuates misinformation. I am just trying to present what I know, or at least believe I know, to be the facts. And I've been through enough of these discussion here to feel I am correct....

That and I did stay at a Holiday Inn Express last night...

nemos2
10-22-2004, 08:43 PM
Ok, Just a question here.....

ALL current polks have internal hardwired crossovers correct? Those crossovers / and binding posts (at least those that are bi-wired) DO NOT SPLIT the top set of binding posts from the bottom binding posts, so......even if you do Bi-amp, the current supplied to the top posts and bottom posts still pass through the same crossover correct? It's not like the top binding posts supply power to the tweeter, and the bottoms to the mids...etc, at least not on polks correct?

SO...to trully bi-amp you would need seperate binding posts for each driver, and an external crossover.

So, most Polks are not really bi-amp-able, but they are Bi-wire-able which could be a good thing...(but that is a different bag of worms...)

;)

hamzahsh
10-22-2004, 10:50 PM
Get the Amp and bi-wire your speakers, forget bi-amping.

Tour2ma
10-23-2004, 01:36 PM
Originally posted by nemos2 ALL current polks have internal hardwired crossovers correct? Yes...


Those crossovers / and binding posts (at least those that are bi-wired) DO NOT SPLIT the top set of binding posts from the bottom binding posts, so......even if you do Bi-amp, the current supplied to the top posts and bottom posts still pass through the same crossover correct? No... When bi-amping the parallel signals pass through different sections of the same x-over...


It's not like the top binding posts supply power to the tweeter, and the bottoms to the mids...etc, at least not on polks correct? No and yes... Excepting the "xxxxp" series (where the dual posts feed the passive and active sections of the speaker in parallel), the top posts do feed the tweeters and the bottom pair the MidWoofers... The only connection between the two pairs is provided by the external jumper "bars", which a few Members do leave in place even though they "bi-wire" (strickly speaking it's not bi-wiring with the jumpers in place...not sure it has a name). Most members either remove the jumpers for bi-wiring, or replace them with homemade wire jumpers and use one speaker wire run per ch...
In bi-amping you MUST remove the jumpers.


SO...to trully bi-amp you would need seperate binding posts for each driver, and an external crossover.
So, most Polks are not really bi-amp-able, but they are Bi-wire-able which could be a good thing...(but that is a different bag of worms...) ;) No, but an external x-over between a pre-amp and one or more pairs of stereo power amps is another way to go... It does require "surgically removing" the built in x-over your speakers have.
In one of the thread links I posted we got pretty deep into this conversation. Done right it makes sense (to me anyway) that this could be superior to bi-amping using the speakers internal x-overs... but it ain't simple going this route...

Hope this helps...

NuckingFuts
10-23-2004, 04:10 PM
Originally posted by Tour2ma

NF (how no one nabbed that screen name in all this time is beyond me...),



:D

HBombToo
10-25-2004, 09:41 AM
WoW this thread is upside down!!!


Removing the external strap on a Polk speaker seperates the high and low pass filter sections into two independent circuits, a low pass and a high pass circuit. With the strap in place voltage across the two sections are applied equally and the current is split. The current demand per section is entirely dependent on the frequency of the passage being played and the frequency reponse of the high and low pass sections. This could tend toward exausting the capabilities of the amp in a heavy low pass demand which then there is not enough current to drive the high pass section.

By removing the jumper and providing two independent power amps per each high and low pass section the listener is afforded the certainty that low pass demands will never limit the high pass demand. Low pass demands are far geater than high pass demands and this is the reason I bi-amp.


HBomb

LittleCar_w/12s
10-25-2004, 03:46 PM
Thanks HBomb 100x for finding a simpler way of putting it. My long'windedness tends to get the best of me. (If I had a job where I could use my knowledge, I would be burned out by the end of the day...)
-Jerry

HBombToo
10-25-2004, 03:53 PM
Originally posted by LittleCar_w/12s
Thanks HBomb 100x for finding a simpler way of putting it. My long'windedness tends to get the best of me. (If I had a job where I could use my knowledge, I would be burned out by the end of the day...)
-Jerry

no problem and this is the reason I drink heavily...:p

HBomb

Pinktulip7
10-28-2004, 01:10 PM
Try out for u'rself first,thats the only way to find out dude!!