• New Patreon Tier and Early Access Content available. If you would like to support AVForums, we now have a new Patreon Tier which gives you access to selected news, reviews and articles before they are available to the public. Read more.

Bi amping/Do I need to disconnect the passive crossover in my speakers

@@@@

Active Member
artical reads

"Do I need to disconnect the passive crossover in my speakers?"
The answer is ... Yes, otherwise you are not really biamping at all.

Saw this while googling. Can anyone tell us all As the artical says have we got to actualy get into our speakers to disconect the tweeter cross over before there is any true noticable effect by bi wiring

c/w http://sound.westhost.com/bi-amp.htm

Generally speaking, the mid to high section needs to be retained since a typical biamp setup will only eliminate the bass to mid+high network. These sections are nearly always completely separate networks, although it may not seem like it when you first have a look at the board.

Equally important is the selection of the electronic crossover frequency. It must be the same as the original, within a few 10s of hertz. The only exception is where you might obtain information from the manufacturer of the speaker that allows the frequency to be modified. In general, I strongly suggest that you determine the original crossover frequency, and stay with it.

When the crossover is modified, make sure that you retain all the parts, along with the original connections. A drawing (including all component values) and photograph will be of great assistance when you want to restore the speakers to normal prior to selling them - it is unlikely that you will ever want to do this for your own use - not after you have enjoyed the benefits of biamping for any length of time.

Passive biamping (where two amplifiers are used in a bi-wiring connection) is, IMHO, a waste of money. Although there may be some moderate sonic benefits, they are not worth the expense of the extra amplifier.
 

Member 639844

Former Advertiser
Getting into speakers to do the bi wiring?:eek:
Sounds to me like this article is talking about altering non bi-wire speakers to become bi-wireable, you shouldn't need to get into the speakers themselves, Bi-wirable speakers have a removable crossover bar on the outside between the tweeter and mid speaker inputs.
Just buy some Bi-wire speakers if that what you want. It is true thought that if you bi wire any speakers, you need to remove the bridging bars, these only sever to carry the signal from the mid to the tweeter and if left on you'll probably blow your speakers.
You can also buy a Bi-wire compatable amp so you dont need to buy two amplifiers, although there is probably a fair amount of differing oppinion on whether a £500 bi-wire amp is better than a 2 X £250 amp setup.
 

BlueWizard

Distinguished Member
Plain simple bi-wiring, in my opinion, is pointless. If fact, the very thing it professes to overcome is actually exaggerated. It is a waste of time and money.

Bi-amping is another matter, and in the context of this discussion, we have two methods.

Passive Crossover Bi-Amping -

Meaning you simply remove the bridge connector that is tying the high frequency crossover input to the low frequency crossover input. When you apply power to the separate terminals, you are NOT applying power to the speakers but to input of the separate High and Low Crossovers.

We can speculate some very subtle to non-existent benefit to this, but I don't see it. You might have slightly better control since presumably you would have separate level and tone control for the High and the Low.

Active Crossover Bi-Amping -

In this case the Active/Electronic Crossover is placed between the Pre-amp and the power amps. The advantage is that you can custom tailor the crossover frequencies and the slopes, and probably even the type of crossover (Butterworth, Linkwitz-Riley, etc....).

In this case, you need to drive the speakers directly off the amps, so, yes, you do need to remove any passive crossovers that might be in your speakers, otherwise they are going to interfere with the active crossover.

You can set the crossover points and slopes any where you want them, they don't necessarily have to match the original speaker's crossovers. BUT BUT BUT, the parameters you set DO DO DO have to be within the working range of the speakers you are controlling.

Does that answer your question?

Steve/BlueWizard
 

@@@@

Active Member
Great Thanks for that.

What do you say about the guys opinion that i read which say How can you justify the expense for buying a separate amplifier for this. I read one guy seem to know what he was talking about. He said you be far better spending that £250 on something else more beneficial to your system. Than the rewards bi wiring will bring. He was sceptical.

The link i supplied first this guy was saying Bi wiring is not to be taken lightly. Bla Bla

Then you have these guys are saying basically do it your speakers will sound fantastic if you if do it think might be a bit of an over statement.

http://www.ehow.com/how_2096904_biwire-speakers.html
 

BlueWizard

Distinguished Member
For Bi-Wiring there is no real advantage, none. How can you possibly offset the effect of the wire by adding MORE wire, you can't. Common 14 ga (AWG) wire is capable of sourcing 1800watts of power. I highly doubt that your amp is any where near 1800w per channel.

Forget Bi-Wiring.

For Simple Passive Bi-Amping you only need a common low powered stereo amp to drive your tweeters. It is the bass speakers that really require the power, tweeters can be driven nicely with a few watts.

So, you connect the second stereo amp to the variable pre-amp outputs of your primary amp (variable Tape or variable Aux Out), connect the secondary amp to your tweeters. Then when you adjust the volume on the primary, the secondary will change along with it. Now all you have to do is adjust the secondary(tweeter) so it is balanced with the primary (bass). In a sense the secondary Tweeter amp is acting as a glorified volume control for the tweeters. You can also adjust the tone (bass, mid if available, highs) on either amp to tailor the sound.

So, the additional cost of this is not that much. You have a wide choice of stereo amps for about £100 new. Any one of them will have far more power than is necessary to drive your tweeters.

But really what are you actually gaining. You main amp already has tone controls, and more than likely has tons of power more than you really need. I recently ran my amp at 60% turn of the volume control through my relatively efficient speakers, and measure the average power. It was 1w to 3watts. And it was WAY too loud for average listening, almost painfully loud. So, my point is, your primary amp, whatever it is, probably has surplus power available.

So, in short, I don't really see any advantage to this unless you happen to have a spare amp laying around and you are curious.

Active Bi-Amping is going to be very expensive. First you need a good Pre-Amp which will cost you as much as a typical amp (£300 to +£400), then you need an active crossover network which is not going to be cheap, then you need two separate stereo power amps (again £300 to +£400 each) . So, we are talking about +£1,600 to drive your speakers, plus the effort of by-passing/disabling the internal crossover networks.

If you win the lottery or a rich uncle dies and leaves you very well off, then Active Bi-Amping might be justified.

In all other cases, your just unnecessarily complicating things. If you have a spare amp and you want to try Passive Bi-Amping go ahead, but as I said, it is unnecessarily complicated for very little gain in performance and some risk to your system. If you like playing with stereo equipment and experimenting, then I say go for it. Otherwise, don't waste your time or your money.

Also, if you've got tons of spare wire laying around, it probably can't hurt anything to bi-wire, but I'm convinced any perceived benefit is purely psychological.

But then, that's just one man's opinion.

Steve/BlueWizard

PS: Here is a link to another discussion about Bi-Wiring, where I explain why it doesn't really work.
http://www.avforums.com/forums/showthread.php?t=587269&highlight=Bluewizard+wire+gauge
 

Nimby

Distinguished Member
In the case of manufacture-designed active systems one would hope the active crossover is carefully matched to the speakers' requirements and individual driver responses. Different models of speakers will require specially tailored crossovers to ensure the best possible voicing of the system.

Where a general purpose active crossover is simply inserted into a speaker system then there are no response-matching/shaping benefits.

The major theoretical advantages of going truly active is the removal of large passive crossover components in series with the drivers. These components normally isolate the drive units from direct coupling to the amplifier. The lower the passive crossover frequency the worse it usually becomes. In theory the active speaker should become easier to drive without the former complex phase effects cause by the passive crossover.

The benefits of bi-amping are in the ears and pocket of the punter (and his dealer).

Years ago I heard Naim-amplified Linn Kans in both passive and active form and actively disliked the active system in preference to the passive form.

I use an active crossover between my speakers and subwoofer. This is a completely different situation with other benefits which are not directly applicable here.
 

Member 639844

Former Advertiser
Heres a question for Nimby and Blue wizard then.

I have an Onkyo 875 AVR. Its Bi wire compatable. I'm thinking of buying a new front pair and am looking into Bi wire speakers like Monitor Audios GS20 floor standers. Are you telling me there is zero benefit from me Bi-wire/amping these speakers from my amp?
 

BlueWizard

Distinguished Member
Moonfly,

Again, let's not confuse Bi-Wiring with Bi-Amping. With Bi-Amping you have no choice but the bi-wire your speaker because you are driving two speakers (in one cabinet - woofer, tweeter) with two amps, which automatically implies two separate wires.

Read the other discussion about Bi-Wiring and you will see why I don't think it matters.

http://www.avforums.com/forums/showthread.php?t=587269&highlight=Bluewizard+wire+gauge

When Bi-Amping, keep in mind that you need four amps, two stereo amps, two amps for the two tweeters, two amps for the two woofers.

I'm not sure modern A/V amps are capable of doing that, others will correct me if I'm wrong. So, in addition to your 875, you will need another stereo amp to drive your tweeters. I'm not sure how this plays out when you put in a movie DVD and switch to surround sound.

I think all of the 'bi-' features only come into play when you have absolute top of the line equipment and have eliminated every other possible variable that could effect the sound. I really don't see it as worth while for the average user.

Now, some users just like to play, they like to try various things just to see for themselves what the effects are, if you are one of the people and you have the money to spend, then go for it. You'll gain nothing but something to do on a Saturday afternoon, some fun, and some personal experience. That definitely has value, but don't expect huge leaps in sound quality.

Jut one man's opinion.

Steve/BlueWizard

PS:

I just realize I didn't directly answer your question -

"Are you telling me there is zero benefit from me Bi-wire/amping these speakers from my amp?"

Bi-wiring = no benefit. Why add two wires? Why not just add one much better wire? Again, 14 ga (AWG) wire is capable of delivering 1800 watts, that is more than 10 time the power you are ever likely to apply to it. How much better do you need the wire to be?

Bi-Amping = very little to none for the average user; extremely slight for the High End User, and also very expensive.
 

Nimby

Distinguished Member
Try it.

If you can hear a real difference then your time will not have been wasted.

I couldn't hear any difference between single and biwired NACA5 on my 753Fs. Yet I am convinced I can hear the difference between warm Naim amps and cold ones.
 

Mark.Yudkin

Distinguished Member
It's simple maths. Biwiring (two wire pairs on one amplifier have an equivalent radius of ~1.4 (sqrt(2)) times one wire. So if you have the 14 AWG wire (that's 1.63mm for the non-Americans), running two pairs is equivalent to running one 2.3mm. The usual recommendation of having 2.5mm wire therefore gives you 18% more area than biwiring with 14 AWG, but costs well under twice the price (2.5mm 99.9% OFC speaker wire costs £2-£3/m).

Biamping is a different matter, and for some amp / speaker combinations can give help by separating the power draw of the bass (where the ear is less critical of THD and power demands are higher) from the mid / high (where the ear is less tolerant but power demands are lower), thus cleaning up the sound. The same argument, incidentally is used to justify selecting a higher cross-over frequency for a subwoofer than the "bottom" of the main speakers (e.g. the THX norm is 80Hz).
 

HiFiRuss71

Distinguished Member
I'm not sure modern A/V amps are capable of doing that, others will correct me if I'm wrong. So, in addition to your 875, you will need another stereo amp to drive your tweeters. I'm not sure how this plays out when you put in a movie DVD and switch to surround sound.
Au contraire Steve - most modern AV Receivers (down to alarmingly low prices) offer the chance to re-assign the unused rear channels 6 & 7, for working in parallel with the main front channels 1 & 2.

Given that some receivers can barely muster their rated power all channels driven and frankly most don't actually sound very good (in the hifi sense), it's certainly of limited value IMHO. You'll possibly benefit from electrically isolating the drivers from each other (in the way the bi-wiring incorrectly claims to), but with the budget AVRs containing such weak power supplies and low quality power amps, it's value is dubious as extra amps drawing from an already limited power supply doesn't sound to clever an idea to me.

Moving up the range to the mid market stuff (around £1k) I certainly noticed a difference, but only really in terms of the sense of composure at high volumes resulting in a less fatiguing sound At moderae volumes to difference was negligable. It certainly, didn't compare to adding a 10 year old, but quality, 5-channel power amp to the equation - the blindingly obvious jump in quality was almost certainly a result of far higher quality components and in itself was a comment on the dire quality of the power amplification contained in even decent AVRs.

@ Nimby - I don't think for one minute you're imagining the difference between warm and cold amps, or for that matter warmed up drive units. Prior to as little as 10minutes running, my system has a hard glassy edge to it that could strip wall paper. If I had any.

@ Mark - It is simple maths yes, but what difference are you expecting from doubling cross-sectional area, when 1.5mm2 is more than is actually required? The electrical properties of a speaker cable are so vanishingly insignificant over the length of the average domestic run, whether the cable is 1.5mm2 or 2.5mm2 seems largely a moot point. Your point about the single larger run being better value is well made, although I still wouldn't expect an audible difference unless the construction of the cable was horribly deficient.

Russell
 

Mr Forgetful

Active Member
I've been thinking about getting a 5 channel power amp so I can bi-amp my speakers, something like a Bryston 9B ST, do you think there would only be a very minimal gain??
 

HiFiRuss71

Distinguished Member
I think with the PMCs you'd experience a gain with the Bryston whether you bi-amp or not. The AVR-350 is a damn good receiver, but it's still a receiver and can't offer the poise and control of a separate power-amp.

Prod Crustyloafer as he uses an Arcam with a separate power amp.

Russell
 

Mark.Yudkin

Distinguished Member
@ Mark - It is simple maths yes, but what difference are you expecting from doubling cross-sectional area, when 1.5mm2 is more than is actually required? The electrical properties of a speaker cable are so vanishingly insignificant over the length of the average domestic run, whether the cable is 1.5mm2 or 2.5mm2 seems largely a moot point. Your point about the single larger run being better value is well made, although I still wouldn't expect an audible difference unless the construction of the cable was horribly deficient.
I was giving the maths for bi-wiring vs typical speaker cable widths. As you say, with 14AWG having around 8.3 Ohms / km resistance in copper, it will make little difference for conventional 8 Ohm speakers over the typical home run (my longest cable length is 12m, as it needs to run around the room).

It may be significant when using 4 Ohm speakers dropping to 0.7 Ohm (e.g. Martin Logan Summits at 20kHz as stated in spec) or otherwise having horridly varying impedance loads. Using 2.5mm2 copper reduces that resistance to around 3.3 Ohm / km. I'm running 2.5mm2 stranded 99.96%OFC costing CHF4.50/m into such speakers.

I do however fail to see why anybody outside the US would quote AWG when the international standard (IEC 60228) is mm2, and anybody else needs to look up an AWG table to work out what the heck it means. (The IEC standard also defines cable classes that help to determine their specific properties). No doubt you're going to get upset at me for being picky. :)
 

Member 639844

Former Advertiser
If it makes so little difference, then why are so many higher end speakers Bi-wire/amp-able. Surley if your amp is capable if this configuration (as mine is) your taking some of the load from one speaker output and sharing it.

I thought that when bi-wired, the amp would reconfigure itself to send slightly differnet signals to the seperate frequency drivers rather than mixing them all up. Surely this is an improvement in much the same way as using seperate drivers/speakers for the seperate frequency ranges is, no?
 

BlueWizard

Distinguished Member
Moonfly,

It is not that there is no technical difference between standard connections and Bi-Amping, it's just that there is little to no noticeable difference, and more than likely there are many things that are having a greater effect on the sound then that.

You may like what you hear when you bi-amp you A/V amp. But a lot of the reason to bi-amp is to bypass passive crossovers. Active crossovers and discrete power amps will give the best result. An A/V amp, bi-amped with passive crossovers, will give some noticable difference but I really don't think it will be huge.

Plain bi-wiring, makes no sense at all to me.

Keep in mind that if you can do it, and you want to do it, then do it. Just don't expect magic.

As to why speaker manufacturer offer this feature, I personally think it is just a marketing gimmick to make customers think they are getting high end speakers when the price alone should tell them they are getting middle of the road speakers.

Mark.Yudkin,

Why would anyone quote AWG (American Wire Gauge)? Possibly because they are American (or at least in the USA).

But let me ask, the standard you quoted "IEC 60228) is mm2", mm2 which I assume means mm^2 (millimeters squared) represents the cross-sectional area and not the wire diameter? So, 2.5mm2 wire is a measurement of, again, cross-sectional area.

And is that how I will see wire rated in the UK when I go to buy it; 2.5mm2?

Just curious. knowledge is power.

steve/bluewizard
 

HiFiRuss71

Distinguished Member
I do however fail to see why anybody outside the US would quote AWG when the international standard (IEC 60228) is mm2, and anybody else needs to look up an AWG table to work out what the heck it means. (The IEC standard also defines cable classes that help to determine their specific properties). No doubt you're going to get upset at me for being picky. :)
Embracing international standards is in keeping with my cosmoplitan lifestyle. I'm not in the least surprised to see this attitude poo-pooed from an isolationist Switzerland.:D

FWIW, I wish we would commit fully to the metric system. I'm of that generation that can deal with both systems and convert in-head in necessary to explain it to the mathematically challenged and Americans.:devil: Personally, I feel there is no rational reason to remain imperial beyond appeasing a few geriatrics who still bemoan the passing of pounds shillings and pence. I couldn't care less whether I take one hour to commute 55 miles or 89km.

Russell
 

HiFiRuss71

Distinguished Member
If it makes so little difference, then why are so many higher end speakers Bi-wire/amp-able. Surley if your amp is capable if this configuration (as mine is) your taking some of the load from one speaker output and sharing it.

I thought that when bi-wired, the amp would reconfigure itself to send slightly differnet signals to the seperate frequency drivers rather than mixing them all up. Surely this is an improvement in much the same way as using seperate drivers/speakers for the seperate frequency ranges is, no?
Sort of right, but there's no reconfiguration going on. Exactly the same signal is sent to both halves (treble and mid/bass) of the speakers crossover/driver combinations by both amplifiers.

I'll ignore bi-wiring as the electrical properties of speaker cable are so vanishingly small, there is no separation, or isolation, of signals going on full stop.

Where the benefits are derived is that the treble driver is an easier load to drive due to it's vastly smaller current demands - it is a far lighter mass to control. It's not really about sharing the load as the tweeter is so little of it.

Imagine that a signal is required to make driver move, but a certain amount of power is also required to control the driver as it will to want to keep moving even when it's told to stop. This force the driver exerts works as a motor (thats all a speaker is) in reverse (a dynamo) and sends a signal back to the amplifier - a back electromotive force, and this signal can modulate (modify and therefore distort) the outward bound signal. Simplified I know, but for the purposes of visualisation, it will do.

By electrically isolating the tweeter with it's own amp, you protect the tweeters delicate signal from being modulated by the harsher and more demanding environment of the mid bass driver with it's big EMFs and distortion inducing high current, high cone excursion signals.

That's the benefit of passive bi-amping - the tweeter and it's amp get on unhindered reproducing nice clear treble.

It's success still relies on the quality of amps and to a very large degree on the quality of the power supply that they inevitably share in an AV receiver. If the power supply is average, which in receivers it can be, you may offset any potential advantages by simply taxing the power supply too much with yet more amplifier channels.

My advice is, if you have the facility to bi-amp, try it. If you don't hear a difference so be it, but what-ever difference you don't hear, it will still be larger than bi-wiring!

Russell
 

BlueWizard

Distinguished Member
Probably shouldn't waste valuable electrons on such a small comment, but to Russ.Will, excellent explanation of the advantages to Bi-Amping.

Though as you point out, doing it with discrete amps, or at least discrete stereo amps is best. Another point, it would be perfectly reasonable to have 100 watts driving you woofers and only 10 watts driving your tweeters for the very reasons Russ.Will points out. Though, you will likely have trouble finding a first rate 10 watt amp.

thanks for the info.

Steve/bluewizard
 
D

Deleted member 30535

Guest
Plain bi-wiring, makes no sense at all to me.

Me neither, but according to one design engineer at Bowers and Wilkins there is an advantage:-

"So when you have a loudspeaker which has a coil of wire moving in a magnetic field pulsing to a signal, that same speaker is acting in reverse (like a microphone) producing its own back current or EMF, this EMF can travel back up through the short 2" jumper links on the terminal tray at the back of the loudspeaker into the mid/high frequency crossover and induce very low level distortion that can blemish or mask the fine details evident in midrange & treble content.

The higher the volume, the greater distance the bass drivers voice coil moves and so the greater the EMF is produced, and the more bass drive units you have, even more back EMF produced.

So, by removing the jumper links and extending the cables (say 5 metres) all the way back to the amplifier by using separate runs of cable to drive the low frequencies, and a separate run to the treble, this EMF is dissipated through the (5m) run of cable back to the amplifier instead of the 2" jumper lead.

Now, bi-wiring is more evident in a 3 way system because you are effectively splitting the bass away from the midrange AND treble, however in a 2 way and 2.5 way system you are only splitting the treble signal away.

I would always recommend bi-wiring where possible with high quality loudspeaker cable to reduce the cross-distortion and offer the best performance."


On the subject of bi-amping I had sent him the link to the web page that @@@@ alluded about (passive-bi-amping). The considered opinion of the B&W engineer regarding my DM604s3's was this:

"Bi-amping offers an improvement over bi-wiring where the stresses usually associated with an amplifier to drive the bass units, (which is used for the driving of the midrange and treble units) will be reduced, therefore offering an improved presentation of sound.

There are two methods of bi-amping:

Passive:

Utilising the inbuilt crossovers in the DM604's

Active:

The method shown on the attached website is an active bi-amping method, where the full range signal has been filtered before being amplified, this is acceptable and in theory an active version of a loudspeaker will be better than one utilising passive crossover filters and a single amplifier. To put this theory into practice it requires the combined skills of an acoustics and electronics engineer to design a specific active crossover, for the particular loudspeaker, that incorporates the acoustic and electrical properties of that loudspeakers drive units into its design. By comparison, using an 'off the shelf' active crossover can only give second rate results that may well be surpassed by the original passive design.

I note that on detail 1.13 that the main emphasis for bi-wiring/amping has been more centred on the issues related with crossover components rather than the actual drive unit voice coil.

Back EMF is present in every loudspeaker. Crossovers, no matter how good their design will not filter out the back EMF produced by the bass drivers voice coils.

I would recommend bi-amping over bi-wiring if funds are available."


Well, it may have passed a few minutes reading for you!!

FWIW I noticed a huge difference in bi-amping on my DM604's At higher volumes there was greater control and clarity. Night and day compared to "normal".
 

BlueWizard

Distinguished Member
Mr Incredible,

Well, who am I to argue with an engineer at Bowers and Wilkins. That said, that is exactly what I am doing, to an extent.

I'm not saying their is absolutely zero effect to bi-wiring. I'm just saying that for the average listener psychological impression is going to be far greater that actual measurable difference. Your going to think it sounds better far out of proportion to how much it really does sound better, which is very slight.

The B&W Engineer said -

"this EMF is dissipated through the (5m) run of cable back to the amplifier instead of the 2" jumper lead."

How is it dissipated? There is no appreciable resistance in the wire. There is no appreciable additional inductance in the wire. Exactly what is dissipating this back EMF? 'Dissipating' implies the consumption of power or signal, and I really don't see that happening.

Also, people tend to think of signal moving through wire like a car driving down the road; a discrete package moving. That's not quite how it works. Think of a circular tube filled with marbles, if one marble moves they all have to move. That's the way electricity is, when it flows, it flows instantaneously in all part of the circuit. So, this Back-EMF is going to be presented at the Amp terminals and that means it is going to be presented on the tweeter wires.

This guy is an engineer, but to convince me, he is going to have to explain how that section of straight heavy wire can dissipate anything.

Now, his statements on Bi-Amping are right on the money. There is some limited benefit to passive bi-amping. The real benefit comes from true active bi-amping with discrete stereo amplifiers. One high powered stereo amp for the woofers, and one medium powered amp for the Tweeters, and active crossover, and a pre-amp to drive it all. Using an A/V amp is functional but not ideal.

For what it's worth.

Steve/BlueWizard
 
D

Deleted member 30535

Guest
I'll send the engineer a note and ask him! Can't do any harm to ask!
 

The latest video from AVForums

Guardians of the Galaxy Xmas Special, Strange World, Bones and All, and Cabinet of Dr Caligari in 4K
Subscribe to our YouTube channel

Full fat HDMI teeshirts

Support AVForums with Patreon

Top Bottom