Bi-wiring improvement in audio

[theredcommando]

I dont understand how properly/poorly designed crossover would make any difference when bi-wired.

Single or bi-wired, same signal is fed to crossover. Cross over still remains same and is not bypassed by any means. If crossover is eliminated in biwring or different signal is fed to HF and LF terminals(pre split HF and LF respectively) then it can give some improvement but not otherwise. Otherwise you are just running same signal through more cable. What am I missing?

 

[corElement]

What am I missing?

There are two types of bi-wiring,
a> A dedicated secondary output stage from the same amp for cleaner power input to the speaker terminal.This is usually how it's done when an amplifier has speaker zone A+B and when A+B mode is engaged, the amp works twice as hard and heats up twice as much and gain also has to be increased nearly 50% more.

b> Routing two cables out of the same binding post to separate binding post terminals

All my posts are for type A as this what the OP is most likely using since his amp has speaker zone A+B feature.

FR drivers do not reproduce the entire sound spectrum. They exhibit better low and high frequency response than others.

Subjective technicalities dependent on model and driver size and cone configuration.

If the premise here is that the bigger magnets are responsible for the FR reproduction then this is not true. And not all FR drivers have bigger magnets.

Indeed that is quite true not all FR drivers have bigger magnets and neither did I imply bigger magnets are responsible for the FR reproduction, there are many other things to consider.

You have worded this wrong. Irrespective of biwiring, this is the x-overs job, among others. So, to clarify, even if the speaker did not have posts for bi-wiring, wht you said - "the crossover section dedicated to the tweeter is responsible for suppressing all mid and low frequencies below a defined crossover point" - would still hold true

Again, you're going into subjective technicalities in a post where observations are generally stated. This isn't a debate, I'm just trying to give them a basic concept to grasp for them to do their own research. If you noticed the later portions of my post it refers to the crossovers ability to take advantage of cleaner power delivery. Many things determine this, I don't know about those variables and neither do I claim to.

What do you mean by "the most common type of 3 way". One thing confuses me - Polk claims that the TSi300 is a 3 way - surely it is a 2 way with that MTM configuration.!!!

The most common method of bi-wiring/bi-amping a 3 way is clubbing the tweeter and midrange together and leaving the woofer with additional power with a dedicated binding post. This normally is evident when low frequencies improve dramatically after bi-wiring with type A method. However the tweeter+midrange crossover has to configured in such a way that it is not overrun by the more powerful woofer.

As for less common ways, I have yet to see a speaker under 3k usd that is tri-wireable

You're assuming it's a 2 way MTM configuration against the word of the company and it's target audience, If it were not a 3 way, they'd be cheating their customers.
Why not ask the OP to confirm if you wish to find out?

 

[thatguy]

I dont understand how properly/poorly designed crossover would make any difference when bi-wired.

Single or bi-wired, same signal is fed to crossover. Cross over still remains same and is not bypassed by any means. If crossover is eliminated in biwring or different signal is fed to HF and LF terminals(pre split HF and LF respectively) then it can give some improvement but not otherwise. Otherwise you are just running same signal through more cable. What am I missing?

You probably forgot to read the only useful post in this thread (by Murali). Here is an explanation of the benefits of bi-wiring from the good folks at Vandersteen:

Answer 7

Additional experiments with a Hall Effect probe revealed that high-current bass frequencies created a measurable field around the wires that expanded and collapsed with the signal. We believe that this dynamic field modulates the smaller signals, especially the very low level treble frequencies. With the high-current signal (Bass) separated from the low-current signal (Treble) this small signal modulation was eliminated as long as the cables were separated by at least an inch or two. (To keep the treble cable out of the field surrounding the bass cable.)

My knowledge of physics is limited. So I am not in a position to have an opinion one way or the other.

 

[corElement]

Most people who say bi-wiring does not make a difference are usually talking about Type B which is simply a routing from the same output stage on amp to bi wired binding posts on speaker.

This is mostly snakeoil. However type a works 100% as an improvement.

 

[sunilchus]

Thank you all for your responses - makes things a lot clearer now.

corElement, Yes I am using the amp in A+B mode as you have mentioned.

 

[cmsajith]

"Type A" bi-wiring mentioned above is also unofficially called as passive biamping, connecting two amps to power the low and mid-high speakers but with same source (The proper biamping involves the active Xover with separate amps for each signal). This also depends on the speaker they are being connected, eg., Quad 22L2 makes difference with biwiring.

 

[2chFreak]

a> A dedicated secondary output stage from the same amp for cleaner power input to the speaker terminal.This is usually how it's done when an amplifier has speaker zone A+B and when A+B mode is engaged, the amp works twice as hard and heats up twice as much and gain also has to be increased nearly 50% more.

Even if its A + B, its still a TWO Ch amp. Bi-amping means 4-channels.

So, its Bi-wiring then

 

[2chFreak]

"Type A" bi-wiring mentioned above is also unofficially called as passive biamping, connecting two amps to power the low and mid-high speakers but with same source

Sir
Plz explain where are these 2 amplifiers within the Integrated amplifier ?
TIA!

 

[2chFreak]

Earlier, a back panel of Denon PMA-510 was shown with Speaker posts A + B.

Clearly mentioned in the Specs of this Amp,

45 + 45 Watts at 8 ohms

70 + 70 Watts at 4 ohms

Q : For bi-amping, 2 channels are required for the LEFT Spk & similarly for the RIGHT spk, hence 4 channels in total.
Where are the 4 channels in this amplifier we are speaking off ?

(Spk Binding Posts A) & (Spk Binding Posts B) are just PARALLEL CONNECTIONS off the 2 channel amplifier internally. Hence, the restrictions pasted on the Back Panel that if using (A + B), DO NOT go below 4 ohms. Otherwise, the amp would just die!

You can take 8 to 16 ohms rated pair of spks & have them in the Living Room. They can be wired to Terminals A.
Now, you can also take 8~16 ohms rated another pair of spks & have have them in the Dining Room, wired to Terminals B.
In this scenario, you can either select A or B separately or even play A & B together. The total load per channel to the amp would not be below 4 ohms.

However, if you have a set of spks with 4 ohms impedance, then, only A or B can be used. Never, A & B together. The amp would heat up & blow as the net load to the amp now is 2 ohms. Its not designed to handle 2 ohms.

But there arent 4 channels of internal amplifiers present in this Denon PMA-510AE for passive bi-amping.

 

[theredcommando]

Site says -

We modified a speaker's crossovers to accept two sets of cables and present different load characteristics to each set so that the low-frequencies would be carried by one set of wires and the high-frequencies by the other set of wires.

This is mystery. How can crossover be modified so that one wire carries HF and other LF? This is absurd. In case of crossover, wire carries all the spectrum, crossover allows either LF or HF. But BEFORE crossover, signal is unchanged.

For amplifier, it would always see the combined load.

At the actual crossover frequency, the output from the amplifier would be divided equally between the two inputs as they would both have the same impedance at that frequency. Because of the different reflected impedances of the cables, the crossover between the woofer and midrange actually occurs at the wire ends where they connect to the amplifier.

How is this possible? Unless there are two separate amps, combined load would be seen by the end single amp.

I am not sure about the A+B mode. If there is single amp inside, then pretty much think that they have just split the signal to give 4 terminals for convenience only. Can anybody show internals of such A+B amp?

 

[2chFreak]

I am not sure about the A+B mode. If there is single amp inside, then pretty much think that they have just split the signal to give 4 terminals for convenience only. Can anybody show internals of such A+B amp?

Pictures are from the net

1. in the 2nd pic, mounted on the Heatsink are Pair of complimentary transistors with 1 driver in the centre hence its a 2 channel amplifier.

2. the speaker posts A & B are all paralleled as seen from the pic.

 

[corElement]

Thank you all for your responses - makes things a lot clearer now.

corElement, Yes I am using the amp in A+B mode as you have mentioned.

Glad my loose descriptions helped you understand :lol:

 

[cmsajith]

Sir
Plz explain where are these 2 amplifiers within the Integrated amplifier ?
TIA!

My statement was to explain the concept and by considering A and B as separate amps, if they are not then its a normal biwiring.

 

[keith_correa]

I read and re-read all that had been posted and realized that our "desi" English is to blame for all this confusion.

One lesson that I have learnt and will follow from all of this - always to point to articles on the Net that explain these concepts. At least I hope they will be more coherent than us explaining or trying to explain and taking liberties with facts.

 

[jls001]

So why is it not possible to bypass the Xover at all?

Go back to the source and amp - the source gives the full range of frequencies. The amp amplifies this full frequency as faithfully as it can. The two pairs of speaker cables (assuming the case of bi-wiring and not bi-amping) carry that full frequency to the two set of binding posts of the speaker.

BUT in the case of multi-way speakers, no single driver can faithfully reproduce the full frequency. Hence it is split into two or three or even four bands. This primary job of the crossover is to split the frequency into smaller bands.

If one were to bypass the crossover, then each driver will receive the full frequency, which defeats the purpose of having multiple drivers in the first place (as each driver is optimised to reproduce a subset of the full freq spectrum only).

 

[thatguy]

Site says -

This is mystery. How can crossover be modified so that one wire carries HF and other LF? This is absurd. In case of crossover, wire carries all the spectrum, crossover allows either LF or HF. But BEFORE crossover, signal is unchanged.

Hmm. One way to do it would be to have an independent filter for each driver (parallel crossover topology). In that case, if you run separate set of wires, the two wires will carry different frequency components of current (which apparently is the culprit). The voltage sould be identical, except for the tiny drop across the speaker wire. Don't understand what you mean by the word 'signal'.

 

[nshankar]

From personal experience with my setup, replacing the metal connection plate at the rear of the speaker box with speaker wire gave a better experience for me, almost same as biwiring.

Biamping using two spare channels resulted in further improvement, but I did not stick with it as the bass was a bit higher than my comfort zone in my living room.

 

[2chFreak]

I read and re-read all that had been posted and realized that our "desi" English is to blame for all this confusion.

:thumbsup: AND :signthankspin:

 

[theredcommando]

Hmm. One way to do it would be to have an independent filter for each driver (parallel crossover topology). In that case, if you run separate set of wires, the two wires will carry different frequency components of current (which apparently is the culprit). The voltage sould be identical, except for the tiny drop across the speaker wire. Don't understand what you mean by the word 'signal'.

By signal I meant original full frequency audio signal. When both LPF and HPF are in circuit, wire would carry entire frequency range. But if only HPF is in chain then wire would carry only HF frequency and vice-versa.
In that case, if connection between HF - LF terminals is removed, only woofer or tweeter should work with single wire. Will try that and bi-wiring.

In such a case what it(site) suggests is that speaker cable cannot carry both HF and LF simultaneously correctly without loss. This could be avoided using bi-wiring.

But A+B mode of the amp is not different than simple bi-wiring(I am generalizing here).

 

[keith_correa]

OK, I got driver configuration from Polk. They say that the config. of the TSi300 is M-T-W. So, 3 way it is.