Bi-wire/bi-amp

[highfigh]

Before everyone casts stones allow me to acknowledge I've read tons of posts on the subject.

Let me further state, I don't want to argue the semantics. What I am going for with this thread is the idea of frequency disturbance on speaker wire.

Long story short...my RTi A7's were a disappointment and prompted work.

After a frustrating few days I ordered a Parasound 2350 amp, against all advice I received from the esteemed members here, and promptly returned it with a loss of abt $60 for the trial. Needless to say...listen to those who know. After that I set about the basics...wiring.

Basically, any signal wiring I have seperated from AC power and have also included a drain to system ground in all pathways. That really made no difference, but it's good as a preventative measure.


Throughout I have been reading about bi-wiring/bi-amping. I avoided it as nearly all posts relegated it a waste of time.
This weekend, unfortunately at the end of a holiday weekend, I finally tried it after reading a 9 year old argument on the subject. One poster pointed out the frequency effect between low and high and the impact on a single cable feeding both. That resonated. It was logical so I tried it.
Wire the same, same length, wired up and the Onkyo TX RZ820 setting for bi-amp changed to "yes", (bi-amp is Onkyo's reference not mine).

Marked difference. I increased clarity at volume and overall quality. The low end is punchy and the high is not distorted at volume as it was before. The mid is clear, defined...none of it perfect mind you...far better out there, but the improvement is incredibly.

I will continue with the basics, wiring, while I find the better system. Still sub shopping.

In the meantime, any ideas on if the frequency between low and mid/high actually create issues in the high range? Or throughout.

I separated and made bold the parts I want to address-

-You can't avoid the semantics- describing a subjective experience requires words that aren't universally understood. WRT your comments about frequency disturbance on speaker wire, the easy way to find out is to get an oscilloscope and look at the signal but understand this- it will be very difficult to see it in a complex waveform at high frequencies unless you know how to make the waveform easier to view without it being too dense, on the screen.

-You were disappointed by the speakers and you're now looking at everything else as the cause- how much time did you take when you positioned the speakers? If it was more "set them in the same place as the last speakers" and less "I took the time to listen, adjust, listen, adjust", go back and do the latter- I have found that speaker position makes differences that can't be realized in any other way because it determines the way the room interacts with the speakers.

-You added ground paths to the signal cables- that can cause problems that didn't exist and sometimes, the audio and power supply grounds are isolated. Speaker cables can be close to power cords without audible problems, low level signal cables shouldn't be close and definitely not parallel. I wrote 'shouldn't' because 'can't ' isn't true.

-You posted that you heard a marked difference- The problem with this is that you knew what had changed and you also wanted to hear a difference. It's the way we think.

In theory, connecting the high pass and low pass to different channels with passive crossovers can make a difference because each band can receive the power from each channel, where it would have been shared, before. OK, you decrease distortion at the same total power and/or hear it as a bit louder when both channels are outputting the same as when you were using one channel. That shouldn't make the bass more punchy and in fact, hearing distortion at extremely high SPL is harder than listening at lower levels.

The speakers make more difference than the rest of the system because it all passes through them, regardless of what is used. They allow or prevent differences being heard, or not.

The thing you didn't do is describe the room and speaker placement- that's the big equalizer in any system, literally and figuratively.

 

[KEW]

I suppose it is possible that there is a defect in the channel you had beeen using to drive the entire speaker.
If that channel is now being used for the low frequencies, minor distortion would be less apparent ... and if the extra amp being used for the mid and high frequencies is functioning properly, you could expect an audible improvement.
This improvement would not be from bi-amping , but simply from the effect of marginalizing the influence of a defective amp channel!

 

[Russdawg1]

That's a persisting misconception and might have been too often taken as fact due to hearsy!! As has been discussed on AH many times before, even in passive biamp configuration, you do send different signal currents through the two different pairs of wires due to the different impedance characteristics of the split up crossover network (jumpers removed) at the speaker end, vs sending the full spectrum signal through the same single pair of wire (in the "single wire wire/pair" configuration) at the crossover in the speaker with the jumpers joining the LF/MF/HF parts of the crossover. That is a fact so it is not disputable. What is disputable is whether this has any audible effects. IMO (just me), the effect is not audible if the passive crossover is well designed, and the amplifier used has more than enough power/current the speaker is designed for.

I was referring to signal, not exactly power/current based on differing impedances because the HF and LF sections are indeed different.

His argument was that you are separating HF and LF by passive Bi-Amping, which is false. They get the same exact frequencies through both wires.

 

[PENG]

Agreed, I did not truly bi-amp. From my reading the terminology on this is critical. It's actually bi-wiring I believe.

No, you are not bi-wiring since you are in fact using two amplifiers. Onkyo called it biamp correctly, though many would prefer to call it "passive" biamp. People who call it bi-wire probably intend to emphasize their point that passive biamp schemes make no audible difference and is practically same as just bi-wire (again, exaggerated to make their points)

It's not amplification because I tried that...it's separating the signal between high and low frequency. Again, there are many variables, I'm only curious about frequency interactions.

Imo the effects of the frequency interactions as well as the back emf parts are real albeit minute, will most likely not make an audible difference. The amplification part might have an audible effect because the tweeter (and mid in some cases) now has a dedicated amp not(or at least less) affected by the other channel that has to deliver heavier current in general to the woofers (and mid in some cases).

At low output level, say a couple watts average with peaks to the amps rated output level, it should make no difference. If you hear difference even at very low output level, then either you have the so called golden ears, or you are benefiting from the well know Placebo effects.

 

[PENG]

His argument was that you are separating HF and LF by passive Bi-Amping, which is false. They get the same exact frequencies through both wires.

In post#7, he said "My question is, if you expect 2 or more frequencies, which may step on each other, along the same wire...do they step on each other? "

So I assume, perhaps incorrectly, that he referred to the signal current in the wires between the amp terminals and the speaker terminals. As I mentioned specifically in my post, the output leads between the crossovers and the drivers would, or at least should get the same signal (or as you said frequencies) passive biamp or not, but not the case if he is in fact talking about the wires between the amps and the speakers.

 

[Irvrobinson]

I was referring to signal, not exactly power/current based on differing impedances because the HF and LF sections are indeed different.

His argument was that you are separating HF and LF by passive Bi-Amping, which is false. They get the same exact frequencies through both wires.

This is a specious argument. It is correct that all of the same frequencies are conducted to both amplifiers, but the relative levels of those frequencies in the amplifiers' outputs are so different that stating it this way is misleading. Assuming a typical LR-4 crossover in a two-way speaker, with a 2000Hz high-pass frequency, the tweeter's amplifier would see a 40Hz signal that would be over 100db below the level of a 4000Hz signal at the line-level inputs to the amplifiers in the bi-amp pair, assuming the two signals were at the same level at the amplifier inputs. -100db is probably lower than the SNR of the amplifiers themselves. This also means that the tweeter's amplifier is, for all practical purposes, not amplifying the 40Hz signal.

 

[Russdawg1]

In post#7, he said "My question is, if you expect 2 or more frequencies, which may step on each other, along the same wire...do they step on each other? "

So I assume, perhaps incorrectly, that he meant the signal current long the same wire between the amp terminals and the speaker terminals. As I mentioned specifically in my post, the output leads between the crossovers and the drivers would, or at least should get the same signal (or as you said frequencies) passive biamp or not, but not the case if he is in fact talking about the wires between the amps and the speakers.

I’m sort of lost here. Are we in agreement that Bi-Amping his way has done nothing to separate HF and LF signals?

 

[Pogre]

In post#7, he said "My question is, if you expect 2 or more frequencies, which may step on each other, along the same wire...do they step on each other? "

So I assume, perhaps incorrectly, that he referred to the signal current in the wires between the amp terminals and the speaker terminals. As I mentioned specifically in my post, the output leads between the crossovers and the drivers would, or at least should get the same signal (or as you said frequencies) passive biamp or not, but not the case if he is in fact talking about the wires between the amps and the speakers.

Peng... is there likely going to be an audible improvement in sq bi amping a speaker with passive crossovers built in? End of the day I think that's the salient point here. I've had some back and forth with op and (along with others) suggested replacing his Polk PSW108 as that appears to be the weakest link in the system. What's your take on it? Keep experimenting with amps, wiring and cables or try a new sub?

 

[highfigh]

I’m sort of lost here. Are we in agreement that Bi-Amping his way has done nothing to separate HF and LF signals?

I hope so.

 

[PENG]

I’m sort of lost here. Are we in agreement that Bi-Amping his way has done nothing to separate HF and LF signals?

Me too. I am not sure if we are really saying more or less the same things. Let me try one more time in a different way.

Passive biamp would result in:

A) the wire connecting the amp (for the LF) and the LF speaker terminals would carry the lower range signal enforced by the LP filter of the crossover, that has the jumpers removed.
B) the wire connecting the amp (for the HF) and the HF speaker terminals would carry the higher range signal enforced by the HP filter of the crossover that has the jumpers removed.
C) the signal's frequency spectrum for each driver should be the same if the amps in both bi-amp and non bi-amp schemes if the amps are operated well below their output limits.
D) I don't believe such facts (A+B) alone could, or would result in audible difference for reasons that have been cited on this and other forums many times in the past.

I think we may be having trouble agreeing on A) and B), but please note I highlighted the key words, as that's what I assumed the OP referred to when he mentioned "wires". I don't think he referred to the short wires between the crossover outputs to the drivers that are not not easily accessible.

 

[Russdawg1]

Me too. I am not sure if we are really saying more or less the same things. Let me try one more time in a different way.

Passive biamp would result in:

A) the wire connecting the amp (for the LF) and the LF speaker terminals would carry the lower range signal enforced by the LP filter of the crossover, that has the jumpers removed.
B) the wire connecting the amp (for the HF) and the HF speaker terminals would carry the higher range signal enforced by the HP filter of the crossover that has the jumpers removed.
C) the signal's frequency spectrum for each driver should be the same if the amps in both bi-amp and non bi-amp schemes if the amps are operated well below their output limits.
D) I don't believe such facts (A+B) alone could, or would result in audible difference for reasons that have been cited on this and other forums many times in the past.

I think we may be having trouble agreeing on A) and B), but please note I highlighted the key words, as that's what I assumed the OP referred to when he mentioned "wires". I don't think he referred to the short wires between the crossover outputs to the drivers that are not not easily accessible.

Okay I think I understand now, and one of the posters above also mentioned it.

I guess that it does indeed separate HF and LF due to the crossover. I guess I don’t have as strong as an understanding regarding crossovers as I thought. So I’ll cede there.

But yes, we definitely agree passive bi-amping cannot create such a night and day difference as he is saying.

 

[Verdinut]

Me too. I am not sure if we are really saying more or less the same things. Let me try one more time in a different way.

Passive biamp would result in:

A) the wire connecting the amp (for the LF) and the LF speaker terminals would carry the lower range signal enforced by the LP filter of the crossover, that has the jumpers removed.
B) the wire connecting the amp (for the HF) and the HF speaker terminals would carry the higher range signal enforced by the HP filter of the crossover that has the jumpers removed.
C) the signal's frequency spectrum for each driver should be the same if the amps in both bi-amp and non bi-amp schemes if the amps are operated well below their output limits.
D) I don't believe such facts (A+B) alone could, or would result in audible difference for reasons that have been cited on this and other forums many times in the past.

I think we may be having trouble agreeing on A) and B),but please note I highlighted the key words, as that's what I assumed the OP referred to when he mentioned "wires". I don't think he referred to the short wires between the crossover outputs to the drivers that are not not easily accessible.

The way that you describe A & B is rather confusing. Both A & B carry the low and high frequencies and those frequencies are separated only when they pass through the relative low and high pass filters.in the speaker cabinet.

 

[Irvrobinson]

But yes, we definitely agree passive bi-amping cannot create such a night and day difference as he is saying.

With well-designed speakers, meaning in this regard speakers that are designed to present amplifiers with a reasonable load, audible differences are (IMO) quite unlikely. There are cases of speakers that present such unreasonable loads that even powerful amplifiers can have their output quality compromised. For example, the Legacy Audio Focus:

In the Stereophile review I've copied this graph from, John Atkinson called this load "amplifier crushing". But speakers like these are rare exceptions.

 

[PENG]

Peng... is there likely going to be an audible improvement in sq bi amping a speaker with passive crossovers built in? End of the day I think that's the salient point here. I've had some back and forth with op and (along with others) suggested replacing his Polk PSW108 as that appears to be the weakest link in the system. What's your take on it? Keep experimenting with amps, wiring and cables or try a new sub?

I would say if the amp(s) have more than enough output for the speakers already, bi-amp won't change a thing in most cases (may be in some unique cases). In trying to respond to the OP's specific question, I might have gone overboard already so please just refer to post#30.

 

[PENG]

The way that you describe A & B is rather confusing. Both A & B carry the low and high frequencies and those frequencies are separated only when they pass through the relative low and high pass filters.in the speaker cabinet.

As Irv explained in more details than I did, yes they both carry lows and highs but one has much more highs than lows and the other has much more lows than highs because in passive bi-amp scheme, the LF and HF sections are separated. Did you read my post about the difference between electrical current and water flow?

 

[Verdinut]

As Irv explained in more details than I did, yes they both carry lows and highs but one has much more highs than lows and the other has much more lows than highs because in passive bi-amp scheme, the LF and HF sections are separated. Did you read my post about the difference between electrical current and water flow?

I still don't understand your thinking. How can one cable carry more highs and the other more lows between the amplifying section and the speaker cabinet unless there is some filtering? My understanding is that with passive bi-amping, both amps carry the full frequency spectrum to the speaker cabinet and the frequencies are split then by the filters relative to each of the drivers.

 

[j_garcia]

I get that the amp channel actually does only "see" what it reacts to on that driver and what is carried on each wire is slightly different as a result, but I still don't see that as having a significant effect, as I noticed in my own testing. This was with a bookshelf speaker and large amps though, not a huge reactive load, but still the difference was not really audible.

 

[Pogre]

I would say if the amp(s) have more than enough output for the speakers already, bi-amp won't change a thing in most cases (may be in some unique cases). In trying to respond to the OP's specific question, I might have gone overboard already so please just refer to post#30.

Well op bought a parasound amplifier and discovered on his own what everyone already told him before he bought it.

I'm reading the back and forth in this thread and my take away from reading your replies is that maybe I should be bi amping my speakers now too...

 

[Verdinut]

With passive bi-amping, I agree in that each amplifier works on separate LF or HF portion of the spectrum and also some signal relative to the other part of the spectrum as passive crossovers are not brick walls and use filtering slopes.

 

[Irvrobinson]

I still don't understand your thinking. How can one cable carry more highs and the other more lows between the amplifying section and the speaker cabinet unless there is some filtering? My understanding is that with passive bi-amping, both amps carry the full frequency spectrum to the speaker cabinet and the frequencies are split then by the filters relative to each of the drivers.

Because an amplifier's output current at different frequencies is determined by the input impedance of the crossover at those frequencies. Assuming the tweeter's crossover has a high-pass filter at frequency X hertz of 24db/octave, the implementation of the crossover will cause the impedance the amplifier sees to be much higher at a frequency of X/2 than at X, so the amplifier will output much less current at X/2 than at X. Are you thinking that the amplifier power delivered to both crossovers is identical, and the current representing the lower frequencies are just dissipated as heat in the components of the tweeter's crossover?