Bi-amp limitations?

[wolven99]

I’m hoping someone could explain this to me.
My receiver was made for speakers with impedance between 6-8ohms. However it does have a low impedance mode which has to be selected manually for speakers under 6ohms.

When using Bi-wire
The manual states that the combined impedance should be 8ohms and if one of the speakers has impedance under 6 ohms I should press a button which will change the amp to low impedance mode.

So, here are the question: When bi-wiring.

If both speakers have 8ohm impedance is the combined impedance still 8ohms?
Most speakers with 8ohm impedance will vary at times and it can go as low as 3 or even less. Can this be a problem for my amp or speakers?
What would happen if speakers would once in a while get below 8 ohm and my amp didn’t like that. Can this damage the speakers or the amp?

Thank you for your time and knowledge....

 

[PENG]

So, here are the question: When bi-wiring.

If both speakers have 8ohm impedance is the combined impedance still 8ohms?
Most speakers with 8ohm impedance will vary at times and it can go as low as 3 or even less. Can this be a problem for my amp or speakers?
What would happen if speakers would once in a while get below 8 ohm and my amp didn’t like that. Can this damage the speakers or the amp?

Thank you for your time and knowledge....

Your first question is a little confusing. If a speaker is designed to be biwirable, the speaker's binding posts will have links that you can remove in order to bi-wire and you don't have to worry about the impedance change. The fact that you stated "If both speakers have 8 ohm impedance..........." makes me think you may be talking about wiring up two separate speakers in parallel. In that case, you are not biwiring at all and if the two 8 ohm speakers are of the same model with the identical characteristics then the combined impedance will be 4 ohms.

Regarding you second and lasts question, if you speaker has nominal impedance of 8 ohms, then it is unlikely, but possible that it may dip down to 3 ohms at certain frequencies. Whether that presents a problem or not depends on many factors, such as your listening habits (types of sources, how loud you listen to), room acoustics, at what frequencies the impedance dips low, whether you have a subwoofer and the crossover frequency if you do have a subwoofer, etc. In extreme cases, if your needs are much greater than what your system can provide, then it could result in poor sound quality and may cause damage to your amp. It is also possible that before damage is done, the amp's protective circuit may shut itself down.

 

[wolven99]

Thanks for taking your time and the response.

Let me clarify.
I will connect only 2 speakers. Each speaker has 4 connectors 2 high and 2 low. So, each will have 4 cables running instead of normal 2.
My amp has the connection for that.
The two speakers are the same, each speaker rated at 8ohm impedance.
Not sure if I used the terms correctly. My receiver has build in bi-amp and I want to hookup the low and high on speakers to take advantage of that.
So, in that case the impedance that the amp will recognize will be 8ohms or something else?
Hope this makes it clearer.
I have never had a problem with my old speakers they always worked fine so it should not be a problem with the new speakers either. Of course I never used the bi-amp either. There is a protective shut off build in. I’m not worrying about the amp it has worked for a decade. I’m just concerned for the new expensive speakers I’m about to buy.
My setup is simple computer (tosslink)- receiver – speakers. Don’t listen too loud. Of course the CD player, tape deck, turntable and, ipod doc are hooked up too. There are no other speakers in the setup.
Cheers

 

[PENG]

I have never heard of a receiver that has "build in biamp". Many receivers offer two sets of outputs for each of the L and R speakers. The two sets are normally internall connected to the same amp (just 1 not 2). If that is what you have then you can use those two sets of output terminals to biwire you speakers and the impedance seen by the amp should not change. Amps can damage speakers by either overpowering them or sending them clipped signals. The latter is generally due to the amp being asked to deliver more power (current) than it can handle. In that case, the tweeters are more vulnerable.

As long as you keep the volume of your amp below the point where you start to hear distortion you will be fine.

 

[wolven99]

Great to know.

I’m not that audio literate just sort of going by the manual and filling in the blanks…

Thanks

 

[Seth=L]

Bi-amping on a receiver will not likely yeild any noticeable results, though some have reported to hear a difference I fail to see how you would get anymore useful output from it. If there is a difference it's not likely to be so massive you will fall in love with all your music all over again. If you ever look at how a receiver benchtests in terms of power you would quickly see why no higher output advantage from bi-amping would be had.

I also am a firm believer in not experimenting with bi-amping on receivers as I have damaged a receiver in the past in the attempt to do so. Knowing what I know now the thought to try it would have never occured to me, but at the time I was a dumb kid and wanted "more watts". If you are not satisfied with the performance from your system then you need to upgrade (speakers, receiver, amplifier), not tweak. Tweaking will consume you, take it from someone who was once "tweaked".

 

[sawzalot]

Bi-amping on a receiver will not likely yeild any noticeable results, though some have reported to hear a difference I fail to see how you would get anymore useful output from it. If there is a difference it's not likely to be so massive you will fall in love with all your music all over again. If you ever look at how a receiver benchtests in terms of power you would quickly see why no higher output advantage from bi-amping would be had.

I also am a firm believer in not experimenting with bi-amping on receivers as I have damaged a receiver in the past in the attempt to do so. Knowing what I know now the thought to try it would have never occured to me, but at the time I was a dumb kid and wanted "more watts". If you are not satisfied with the performance from your system then you need to upgrade (speakers, receiver, amplifier), not tweak. Tweaking will consume you, take it from someone who was once "tweaked".

Just in case for some strange reason I ever got the notion I thank you for jolting my memory..

 

[wolven99]

...

Thanks for the info. I’m trying to join 21st century in the tech department, hehe.

 

[DD66000]

There is no benefit to bi-wire speakers, that's just a marketing thing. Its much better to use a more powerful amp instead, if you think the current amp lacks having enough power.

Even bi-amping is really not worth the bother, unless one is really experienced with using external crossovers, and EQs.
In the literature of JBL's new K2 s9900 ($44,650/pr) it states that although the s9900 does have bi-amp connections, they don't recommend it w/o having a lot of experience with using external XOs and EQs, as most people would never be able to produce an output as good as the passive biased internal class A crossover.

 

[wolven99]

Even bi-amping is really not worth the bother, unless one is really experienced with using external crossovers, and EQs.
In the literature of JBL's new K2 s9900 ($44,650/pr) it states that although the s9900 does have bi-amp connections, they don't recommend it w/o having a lot of experience with using external XOs and EQs, as most people would never be able to produce an output as good as the passive biased internal class A crossover.

A dealer for B&W speakers told me that the 683 speakers are supposed to be bi-amp'd and as I have been listening to different speakers at different stores they all have it hooked up like that, exception Focal. My receiver pumps 100w per channel.

I thought the only thing I would have to do is hook it up the way the manual shows and everything else would take care by itself.

Is that not the case?

 

[Lordoftherings]

Bi-amping option and bi-wiring

Bi-amping could be very beneficial in some circumstances.
If you are using speakers that are power hungry with large drivers or several drivers, bi-amplification could improve their performance without affecting the performance of your amplifier.
Bi-amping will give you much more power, up to twice the regular amount, so it will benefit those speakers.

Bi-wiring can also improve the performance of the sound from your speaker and amplifier by getting rid of the electro magnetic feedback (EMF or ELM) of the x-over, from the low frequencies of the woofer driver going to the high frequencies of the tweeter driver. Because it does not appear at the preamplifier circuit stages, the ELM stay out of the tweeter driver, stopping any noise contamination to infiltrate the high frequencies. So you are gaining a cleaner sound with less distorsion.

For a better look at this phenomenon, check Audioholics on Bi-amping and
Bi-wiring section. Also Google these two terms.

Please, forgive my less than perfect and short explanation, but rest assure of it's positive implementation. I do bi-amp when available and I do bi-wire also when available, and the results speak for themselves, excellent.

________ Bob

 

[bandphan]

Bi-amping could be very beneficial in some circumstances.
If you are using speakers that are power hungry with large drivers or several drivers, bi-amplification could improve their performance without affecting the performance of your amplifier.
Bi-amping will give you much more power, up to twice the regular amount, so it will benefit those speakers.

Bi-wiring can also improve the performance of the sound from your speaker and amplifier by getting rid of the electro magnetic feedback (EMF or ELM) of the x-over, from the low frequencies of the woofer driver going to the high frequencies of the tweeter driver. Because it does not appear at the preamplifier circuit stages, the ELM stay out of the tweeter driver, stopping any noise contamination to infiltrate the high frequencies. So you are gaining a cleaner sound with less distorsion.

For a better look at this phenomenon, check Audioholics on Bi-amping and
Bi-wiring section. Also Google these two terms.

Please, forgive my less than perfect and short explanation, but rest assure of it's positive implementation. I do bi-amp when available and I do bi-wire also when available, and the results speak for themselves, excellent.

________ Bob

niether of what you said is benifical, as most do passive biamping(which has zero benifit) Bi wiring would be even less benifical(less than zero)

 

[Lordoftherings]

Who said anything about passive bi-amping? And bi-wiring has the advantage of
using the x-over in your speaker, if it's a good one, as opposed to the one in your preamp.

I also suggest that you do some research before committing yourself to wrong
comments.

 

[bandphan]

Who said anything about passive bi-amping? And bi-wiring has the advantage of
using the x-over in your speaker, if it's a good one, as opposed to the one in your preamp.

who said anything other than that, ive not seen a post with an active crossover mentioned, and unless used that is passive biamping

 

[Lordoftherings]

Well then, sounds cool to me.

 

[bandphan]

There are two types of biamping.

The first requires that the speakers allow you connect separately to the high and low pass passive filters. The passive crossovers are still inline and the advantage of biamping is lost usually. Unless you have speakers where the crossover point is at the power divide point which is around 400 Hz, then the amp driving the high pass filter, delvers very little power, and you still have the disadvantages of the original passive crossover.

The real benefit of biamping or triamping comes with the design of a speaker that has no passive crossover. The crossover is powered and goes ahead of the amps. The amps are connected directly to the speaker drive units.

With this approach much better results are possible. There is no insertion loss from the crossover, the response of the crossover can be better tailored as active circuits can boost and cut. Passive circuits can only cut. The amp speaker interface can be designed as a unit, and perform when there are no passive components between amp and speaker.

The first approach usually talked about in these forums is a waste of time and effort.

Well say you had a speaker, that was a three way. And the low pass filter, handed over to the band pass filter at 400 HZ. If when you removed the terminal straps, one set of terminals connected to the low pass filter, and the other to the bandpass and high pass filters, the power between two amps would be evenly divided. Now you would double the power available to the speaker. So it would play 3db louder. If the amps were afflicted by inter modulation distortion, modern amps should not be, then that would be reduced as well.

The problem is, in the range of a tweeter, the power draw is not significant enough to amount to a row beans. Then you just have the chance of sound degradation from errors, such as slightly different gains on the amps, unbalancing the speaker.

And the passive components in the X-over provide for losses, no matter how you put it, even if they are small, it will be audible....
By going fully active this is eliminated....

Tue, but electronic crossovers have most of the same evils. The main advantages are less amp inter modulation distortion, a mute point with modern amps, and better coupling of amp to speaker. However the evils if time shift and phase shift are the same. So there is no difference in the worst evils.

You can't adjust an active crossover usually, that is generic, to replace a custom crossover. The reason being the response has to be the inverse of the driver roll offs. Often this requires changing orders, like starting second order and then changing to first order roll off for instance. Also driver break up peaks often have to be dealt with by notching, especially those just above the pass band of the woofer, in the roll off zone. These are just some of the issues. This can all be done active, but it means a custom design. The problems to be solved are the same, passive or active.

Now as digital filters come of age this will change the situation drastically. I think eventually you will see filters and amps custom designed for the drivers used.

We went through this last week and the week before. There is is no benefit to to wasting an amp powering a tweeter. The result is likely a worse outcome.

Just connect your speakers normally, enjoy them, and forget you ever heard of passive biamping.

some comments from another member/s

 

[Lordoftherings]

Can I ask you this. Did you personally ever did bi-amping and bi-wiring?

 

[bandphan]

I also suggest that you do some research before committing yourself to wrong
comments.

ill not comment much, but i am sure of what im speaking of...

 

[bandphan]

Can I ask you this. Did you personally ever did bi-amping and bi-wiring?

My B&W are bi wired for nothing else other than speaker wire doesnt cost me anything... As for bi-amping, ive never been in a situation(speaker design) that has called for it, though in some applications it works well

 

[Lordoftherings]

Well I do both presently in my system, and to my good ears, it sounds better
than without!