Cables for RF-3s??????

[Stephen328]

Well, RF-3s early next year. Cant Wait. Been looking around at cables. First of all im incredibly cheap and i consider the $850 im spening on RF-3s a small, but well used fortune. Monster cable is nice but i really think its overpriced. Right now im running Acoustic Research professional with my JBLs, and im very happy with it. Ill be bi-amping the RF-3s with my Yamaha m-4 (120w x 4). It wont accept anything bigger than 14 gauge, and uses spring loaded connections. SO what i need is 4 runs of speaker cable, and two RCA cables. I want to use the same brand for the RCA and Cables, but I'm just not convinced by the value of Monster. It would be nice to wire them with Z series, as they are internally wired with them. Maybe I could use different cable for the HF and LF. I really need some solid advice. Thanks.

[Stephen328]

anyone???

[dbflash]

I don't think anyone is going to touch this.

This is going to be up to you.

What I like may sound like crap to you.

What don't you like about your system now?

Is your system bright? Is your system flat and dead sounding?

There is no good answer.

Danny

[Stephen328]

YOu do have a good point. I still dont think it would hurt to get a few opinions.

[dbflash]

Do you mean you are going to bi wire or bi amp?

I have never heard your speakers so I can't give you an answer for your system.

I did find that Audio Quest Type 4 for LF and CV4 for HF made a major improvement when I was using KLF20's and a SS(Parasound)amp.

When I was using a Onkyo CD player the best IC I found was Straight Wire RhapsodyII.

That said when I swapped speakers (Heresy's),Rega CD player and tube amps I had to change out all IC's and speaker wire.

I would use what you have, listen and then decide what you don't like. You will save alot of money. I have spent at least $2,000 since January on IC and speaker wire. Most of it is sitting in a closet.I think 70% of the people on this BB have wire that was recommended that now sits in a closet.

You don't have to biwire your speakers right out of the box. It will make a difference, but if you don't like the sound of your system biwire is not going to be night and day.

You sound like you know what you are doing, but I would look at this site to find out everything you ever wanted to know about biwiring or bi amping.

www.davidmannaudio.com

Danny

[Stephen328]

Im planning on bi-amping. My amp is 4 x 120 so might as well. Thanks for the advice.

[Invidiosulus]

Stephen,

How are you planning on bi-amping??

Does your amp have seperate inputs for the different output channels?

As far as I know true bi-amping uses an active crossover in a pre-amp or something so you have seperate low and high freq line level outputs which you would send to seperate amps, say a 50 watt for the highs and a 350 watt for the lows.

I could be wrong about this so please correct me if I'm wrong.

Peace, Josh

[Stephen328]

Youre thinking of active bi-amping, where an external crossover is used. Im planning on passive bi-amping where the speaks internal crossover does the work.

[Invidiosulus]

I see.

Is that different from bi-wiring?

Peace, Josh

[Stephen328]

Its differnt from bi-wiring in that I am using 4 independent amp channels (120w x 4). Bi-wiring only uses 2 amp channels.

[prodj101]

I say skip it. doens't make a difference, or at least I can't tell it.

[shoe11]

I say skip it. doens't make a difference, or at least I can't tell it.

I agree with prodj101 on this one. I'd be curious to know from you what enhancements bi-amping will provide as opposed to not. I mean I ran bi-wires on my RF-3's and even the "should I bi-wire" debate is an uncertain one in terms of improving sound quality.

~shoe

[Stephen328]

ill give ya a heads up after I try both methods. THanks.

[Deang]

Bi-Wiring 101 - BY JON RISCH

In order to explain how bi-wiring works, it is necessary to explain a bit about how crossovers work. It will also be necessary to contemplate more than the usual voltage output of the crossover sections, so do not assume that if you know the basics for crossovers, that you will know what this will be all about.

Let's look at a simple two-way system with a first order crossover, the simplest crossover and system we can examine. It will be relevant to other more complex systems, so once you understand this one, the others will fall into place. We will not address the issues of tweeter level padding, response EQ, etc., just the basic crossover function itself.

In a simple first order crossover, there is an inductor in series with the woofer, and a capacitor in series with the tweeter. These two components comprise the crossover system. Normally, these two components are connected to the same input terminals on the speaker, in parallel. Hence this type of crossover topology is called a parallel type crossover.

A full range voltage signal is sent down a speaker cable, and appears at the single pair of input terminals. A current is drawn based on the input impedance of the speaker system as a whole, which in most cases, will have a relatively flat impedance curve once we get above the bass resonance region, where the impedance will be dominated by the cabinet design resonance's. If we say that (for purposes of this discussion) the overall impedance of the speaker in the midrange and on up is relatively flat, then a consistent amount of current will flow through the single speaker cable all across the audio band.

So there are several elements to the total circuit formed by the amp output terminals, the speaker cable, and the speaker system and crossover network. A signal appears at the amp terminals, represented by a voltage, the impedance of the speaker system causes it to draw an amount of current proportional to it's impedance for a given drive voltage, and this current flows through the speaker cable.

Now in order to examine what happens when we bi-wire, it will be necessary to go into some of the detail as to how a crossover "crosses over". If we look at just the woofer, and it's series inductor, the inductor provides little impediment to low frequencies traveling through the inductor, and a high amount of impediment to the higher frequencies. Looked at another way, the inductor impedes the highs but not the lows. If we examine an impedance curve of just the woofer with its series inductor, we would see that the impedance was pretty much just that of the woofer in the low frequencies, and would rise with frequency as the inductor impeded more and more of the highs. For this situation with just the woofer, for a given voltage drive level, a certain amount of current would be drawn at low frequencies, and this amount would decrease as the frequency went up, due to the rising impedance.

If all that was hooked up to the amp was the woofer and it's associated inductor, then the current flow in the single speaker cable would follow the impedance curve, a certain amount of current flow at low frequencies, tapering off at higher frequencies. Perhaps a glimmer of the true situation with bi-wiring is beginning to appear.

Now let's just look at the tweeter, and it's associated capacitor in series. At low frequencies, a capacitor tends to impede the flow of current, and at high frequencies, it provides little impediment. Hence, when we hook up just the tweeter and it's capacitor to the amp terminals through the single speaker cable, there is little current flow at low frequencies, and an increasing amount as the frequency goes up. At some higher frequency, the current draw is determined by the impedance of the tweeter alone.

Now just to make sure that it is understood, it is the current flow through a dynamic driver (one with a magnet and a voice coil) that causes it to move. A voltage applied that had no current capability would not cause any movement. This means that in order for the voltage at the amp terminals to cause a speaker to move, it must have a relatively low source impedance, so that when a given voltage appears at the amp output terminals, a given amount of current can flow into the load's impedance. That is why when the crossover components impede the current flow, they cause the output of the driver to drop off, hence the crossover function is achieved.

Note that the woofer and it's associated inductor, and the tweeter and it's associated capacitor will function independently, they roll-off the frequencies out of the driver's operating band without regard to whether or not the other half of the crossover is present or not. When both sections of the crossover are present, and connected in parallel, the overall impedance curve looks relatively flat, as when the tweeter section has it's impedance going up in the low frequencies, the woofer has it's impedance going down. At the crossover point they are more or less equal, and this is the point in frequency at which the impedance's of the two sections in parallel equal approximately half that of either section alone. This is how two 8 ohm drivers can be connected together through a crossover, and not equal a total load of 4 ohms.

By now, you should be getting the idea about bi-wiring. Instead of one speaker cable, or just one of the drivers and it's associated crossover component being connected to the amp's output terminals, two separate speaker cables are connected to the same amp output terminals and run to the now separated crossover sections. With different impedance's being presented across the audio band, each cable carries a different signal than a single speaker cable. The separate cable for the woofer carries mostly the LF currents, and the separate cable for the tweeter carries mostly the HF currents. This is due to the differing impedance's we discussed above.

Now if all you think of is the voltage at the amp terminals, and how the two cables are carrying the same voltage to the woofer and the tweeter sections, then it still may seem that the same signal is being delivered to the drivers as through one speaker cable. IF the speaker cables were perfect, and had zero impedance, infinite mass, and no digressions from ideal LCR behavior (DA, DF, hysterisis, etc.), then it may be that this would be the case. Since the cables we have available to us are not perfect, there are losses in the cables.

The $64,000,000 question is, how much does the real world speaker cable compromise the performance of a speaker compared to bi-wiring?

To make this easy to figure out, we will ignore the effects of inductance and secondary effects, and focus strictly on DCR effects. Let us assume that a cable sufficiently large enough to keep speaker system impedance variations from affecting the amplitude response by more than 0.1 dB was used, meeting the Krueger criteria. In many cases, this is a very large cable, usually at least a 14 gauge, and often 12 gauge OR LARGER.

For a copy of the Krueger criteria see: http://x42.deja.com//getdoc.xp?AN=450322078&CONTEXT=927059192.1901920287&hitnum=6

(I should warn that I do not agree entirely with Arny's criteria, it completely ignores inductance, which typically gets worse as a ratio of DCR to HF impedance of the cable as the gauge gets smaller, or larger zip cords)

How quick do the gauge requirements add up? If you have only 10 foot cables, and a speaker with a minimum Z of 6 ohms, then a 14 gauge wire is necessary to prevent any more than a 0.1 dB amplitude variation due to the cable DCR. If the speaker Z minimum hits 3.7 ohms, you are now up to 12 gauge. Anything longer in terms of the speaker cable, or lower in terms of the Z, will require larger than 12 gauge to reduce the amplitude variations due to voltage drops to less than 0.1 dB.

See:

Bi-Wiring Attenuation of Inter-Driver IM

If we were to look at the simple change in DCR from merely doubling up on the cable, then distortion would only go down 6 dB, from halving the DCR and nothing more.

Of course, once we start using real music, with more than just two frequencies, and real world cable situations that might have even more DCR, and the inductance differences between a single zip cord and two high performance speaker cables, the amount of distortions in a single speaker cable go up considerably, and the amount of reduction in distortion is increased for the bi-wire comparison. This means that we might be into 2% IM or more, and with multiple frequencies, which make it even worse sounding.

All of the above totally ignores any potential magnetic field interactions, many of which would be time delayed and would smear out transients and large signals. The magnetic field distortion reduction would come from the separation of the LF currents and the HF currents.

The time delayed and resonance associated signature would tend to make these distortions even more noticeable than the self-IM of the cable due to voltage drop.

I think it is easy to see that a multidriver system with higher order crossovers will react similarly to this very simple first order two-way system that has been analyzed.

It is interesting to note that higher order crossovers tend to have a similar input impedance for each section as a first order, and it is the output signal of the various sections of the crossover that are made to roll off steeper. In essence, the reductions in current for each cable in a bi-wire pair will be at a 6 dB/octave slope almost regardless of the crossover order.

Last ditch explanation for those who still don't get it.

Assuming that you have read the above information, and have the beginings of an

understanding of how a crossover works, and how it divides the frequencies to the speakers, lets try this:

Traditionally, a crossover cirucit for the woofer, and a crossover circuit for the tweeter are hooked up together inside the speaker (wired in parallel, hence the term parallel crossover is used for this type of network) and one set of terminals are present on the outside of the speaker box. In a bi-wire capable speaker, these two crossover sections are electrically separated, and a separate pair of terminals made available on the back of the speaker, one pair for the woofer, and one pair for the tweeter.

At each one of these separate pair of terminals, the LOAD seen by the amp is

different: for the woofer, the majority of the LOAD is in the bass, with little loading in the treble for that separate circuit and driver. If you hooked up just one cable to the woofer terminals, then the current draw from the amp would be almost all in the bass region, with little or no current draw in the treble region. The woofer crossover is high impedance on the input to the woofer at high frequencies, and hence does not draw very much current. Compared to the traditional speaker system, with it's two crossover sections in parallel, this single cable to just the woofer section would only tend to draw current from the amp at low frequencies, while the full range crossover would draw current all across the audio band.

If we were to hook up a speaker cable to just the tweeter section on a bi-wired

speaker, then this connection would draw very little current in the bass, as the

tweeter crossover would be high impedance in the lows, while in the highs, where

the tweeter provides output, there is some current being drawn from the amp. Again, just the tweeter section of the crossover and the tweeter only tend to draw significant current in the high frequencies, and very little in the bass.

Now, if we hook the two sections back together AT THE SPEAKER, we have

essentially provided the traditional speaker/crossover hookup, and the single

speaker cable will once again carry current at all frequencies, not just the bass, or not just the treble.

HOWEVER, if we run a separate speaker wire to each of the bi-wire terminal pairs

at the speaker, each cable will now carry a different signal than a single cable, as the load at each pair of terminals, the woofer pair, and the tweeter pair, is different. The cable from the amp to the woofer will carry a lot of current in the bass, but hardly any in the treble region. This is a direct consequence of the way the crossover functions, and the fact that a dynamic speaker needs current to work.

Note that even if the cables were zero resistance, and zero inductance, etc., they would still carry different signals, due to the differing current draws vs. frequency.

This ties in with the diagrams at:

http://www.geocities.com/jonrisch/page9.htm

Which shows first the current draw of a single speaker cable, and then the current draw through a set of bi-wire cables connected to the same speaker, only bi-wired.

Because real world speaker cables do have some resistance, and do have some

inductance, they will exhibit voltage drops bassed on this current flow. The voltage differences would be quite small for low DCR/low inductance cables, but still present nonetheless. The variations in the voltage portion of the signal may be -40 db or -50 dB or more down, but this is not as low as one might think, and since the IM distortion that would arise due to bi-wiring is not at any single frequency, but will be occuring at many different frequencies. This raises the potential audibility of the total amount of IM that occurs, and makes it more likely to intrude into the musical presentation.

Again, see the web pages I reference.

There is no doubt that differing currents are flowing in the two cables of a bi-wire set-up, and since current flow sets up a magnetic field, and magnetic fields interact with current flows, the oportunity for IM and other deleterious interactions is present.

The IM part has been measured, and I present this on my web site.

Start at :

http://www.geocities.com/jonrisch/page7.htm

Perhaps this will all make more sense to you now.