kantro21 Posted July 22, 2002 Share Posted July 22, 2002 Is there any real value in bi-wiring my rp-3's if I'm not bi-amping them? I'm looking to upgrade my cables, so any feedback is appreciated. I'm running them off an Onkyo HT reciever. Quote Link to comment Share on other sites More sharing options...
Soundthought Posted July 22, 2002 Share Posted July 22, 2002 What do you mean by "real value"? The idea is that Bi-wiring helps reduce what"s called IMD (intermodulation distortion) This occurs when at least 2 input signal frequencies interact to form new, non-harmonically related, output frequencies. Amplifiers are the major source of IMD in electronic circuts. In speakers, IMD can be caused by Doppler effect. Bi-wiring is just a way to avoid adding more IMD in the signal chain. If anything, you should hear a bit more clarity and definition. I have my RF7s and RC7 bi-wired. I can tell a difference. Or at least I think i can! Quote Link to comment Share on other sites More sharing options...
TBrennan Posted July 22, 2002 Share Posted July 22, 2002 Mdeneen---Agreed when using real bi-amping, not fools' bi-amping. You know. :-) Quote Link to comment Share on other sites More sharing options...
boa12 Posted July 22, 2002 Share Posted July 22, 2002 as for the rp-3 its a powered tower w/ a tractrix horn tweeter, 6 1/2" (i think) midbass driver & an amplified 10" subwoofer. the top speaker terminals run to the trac horn & midbass driver. the bottom speaker terminals run to the powered sub section. so when i tried these i ran an interconnect from the sub preout of the receiver to the lfe in (nonfiltered) jack of each rp. just ran speaker cable to the top speaker terminals & left on the gold straps to the bottom posts or replace w/ wire. bass & lfe seemed more dynamic that way. & you can daisy chain one rp to the other thru the lfe out of the 1st one. hopefully you are using a 5.1 receiver w/ sub out. & don't forget to put that on sub:yes. large vs small shouldn't make any audible dif here. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
BShelton Posted July 22, 2002 Share Posted July 22, 2002 I tried it on a pair of Monitor Audios I had. It didn't help them any! Its easy enough to try, though ------------------ -Billyc>s> Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 22, 2002 Share Posted July 22, 2002 These are controversial topics. My personal belief is that neither lead to worthwhile improvements. Others find merit, to different degrees. In my book, you should take a look at the money involved. If you have the bug to experiment, you might experiment with bi wiring, since it is relatively inexpensive. Bi amping is a big investment. I wouldn't recommend the latter unless your pocket book can stand the price of experimentation, and disapointment. Part of picture is money spent in making the system work better. What is a cost effective tweek. Instead of money spent on expensive wire or amps, an upgrade to a center speaker, better speakers overall, HTS, DVD, etc. could be had. Now those are really gonna really make a difference. Gil Quote Link to comment Share on other sites More sharing options...
kantro21 Posted July 23, 2002 Author Share Posted July 23, 2002 Thanks for all the advice. I think ill have to experiment with bi-wiring and see if i like it. Hopefully I'll be able to check out a good audio store that will demo the difference for me. I have heard good bi-amping, and its great, but it was a former sony exec's system with over $10k in amps alone. The shiny will have to wait. Quote Link to comment Share on other sites More sharing options...
boa12 Posted July 23, 2002 Share Posted July 23, 2002 kan, how do you have them wired now? are you using any of the rca jacks on the rp such as lfe in? & i assume your receiver has a sub out rca jack & are you using it? did you see my post above? if you do a search from the main page here on "rp" or such you should find a lot of wiring info on them. if you bi-wire both sets of speaker terminals on the rp & run a interconnects to their lfe ins, that's what we informally call tri-wiring. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
kantro21 Posted July 23, 2002 Author Share Posted July 23, 2002 Hi boa, Right now i have my sub preout connected to the lfe in on the rp-3's, and have them daisy chained. i have my speaker wire connected to the top input (hi) with the band running down to the low, and my settings on the amp are sub yes and fronts small, although i may switch them to large, cant tell much of a difference, need to experiment there. As for the sub connection, i just got some monster subw. interlink with a y connection, so no more dasiy chaining. i just need to get better speaker cable,been looking mostly at monster, bi wire and not, but i would like some suggestions for other brands, if anyone has them. money is an object, but so is quality. Quote Link to comment Share on other sites More sharing options...
boa12 Posted July 23, 2002 Share Posted July 23, 2002 kan, that looks good. just like the large/small setting, with powered towers doubt you'll get much from biwiring as you already have the interconnects running to the sub sections which is all the lower posts also go to. you can always try it though. but iow, w/ the interconnects you're already biwired in effect. powered towers are a different animal w/ those powered sub sections that have their own connects. me the farthest i'd go is replace the gold straps w/ speaker wire, though i never heard any real audible dif there either. as for speaker cable just get good quality 12 gauge & don't spend "too" much. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 24, 2002 Share Posted July 24, 2002 Audioreality brings up an issue. It seems to follow those of the proponents of bi wiring. I can't really speak for either Audioreality or the ones by the big mysterious "proponents" and thus may be misinterpreting the theories. I certainly don't mean to attack Audioreality, or set up a straw man, easy to knock down. As I understand it, the theories seem to be that there is a problem created by resistance in the speaker feed wire. For example, you send along a very strong bass note to the speaker sent to the bass driver, and the resistance in the wire (there always is some minimal resistance, even with battery booster size cables) allows a voltage drop. This is true enough. There is some intuitive appeal. The next step in the reasoning is that this voltage drop in the bass note also causes a voltage drop in any treble frequency travelling along the same wire, which is sent to the tweeter. So the bass signal is modulating the treble and creating intermod. In real intermod, you start with F1 and F2 and wind up with F1 plus and minus F2: i.e. two new frequencies; or four frequencies total. Now, that isn't true with a resistor, there is no intermodulation, but let's continue. The theory is that you can prevent the, quite imagined, voltage drop of the treble signal to the tweeter by using a different set of wires to the tweeter. Or, make sure the feed wire has so low a resistance that there is no intermod. The falacy is that this is a purported solution to a problem which doesn't exist in the first place. In the world of electronics, resistors don't serve as the non linear devices needed to cause intermodulation when we need it. Rather the non linear slope of diodes when forward biased do. That a resistance can't cause intermod can be observed in common situations. For example, let's replace the run of speaker wire having, say, 0.1 ohm resistance with a significant resistance of 10 ohms. You can buy a 10 ohm resistor at Radio Shack. Put that in series with with the wire. Now you've increased the resistance by a factor of 100. Do you hear intermodualation? Nope. You may hear anomalies in frequency response, but no new frequencies are added. They would be grossly obvious if there. You may say, Gil, your added series resistance is oddball. Let's talk about our speakers. Fine. Consider that our bass drivers, or any driver, has an internal d.c. resistance of the voice coil of about 8 ohms, nominal. It might be twice or half that. It is in the loop with the feed wires. No one claims that such resistances cause intermod between frequecies sent to the woofer. Take a Heresy. The bass driver is handling 50 Hz and 500 Hz. Again, no one is claiming that the internal 8 ohm voice coil resistance is causing intermod between those frequencies. Looking backwards, we see that the internal voice coil resistance in the loop is far greater than anything which could be caused by feed wire resistance; yet it is not a problem, at least as far as creating new frequencies. It creates a conundrum. Fat feed wires, or bi wiring can't remove voice coil resistance. So we're stuck with voice coil resistance. But if the resistance intermod theory is true, it is caused by voice coil resistance as much as wire resistance. Yet no one thinks voice coil resistance causes intermod. In short, the bi wiring people seek to solve a problem which does not exist in the first place. Resistance doesn't cause intermod. If it did, the voice coil, which we can not remove from the loop, would be a far greater offender. But it is not. Gil This message has been edited by William F. Gil McDermott on 07-24-2002 at 12:39 AM Quote Link to comment Share on other sites More sharing options...
kantro21 Posted July 24, 2002 Author Share Posted July 24, 2002 Gil, That is fascinating stuff. Thanks for the input. But as for people that claim to hear a difference, is that just attributable to a sort of placebo effect? Or is there a possible side benefit to bi wiring, aside from preventing (possible) intermod? Quote Link to comment Share on other sites More sharing options...
HornBlower Posted July 24, 2002 Share Posted July 24, 2002 Interesting discourse. One other possible side effect of not bi-wiring and to me, one that is much more likely: When you attempt to send a signal down a wire, your ability to transmit the shape of that signal is directly related to the ability of that wire to carry those electrons as sent. Since no wire is a perfect conductor, then the amount of stress placed by the electrons on the conductance of the wire can affect or smudge the actual image of the signal being carried- peaks and valleys for the various frequencies would not be as sharp as if I simply carried say a sine wave. Now, if I am really stressing the wire by carrying alot of high energy/high power signals, then the more subtle signals can have their crispness reduced. Thus if I somehow split the signals and send the very high energy/power signals down one wire, and the more subtle signals down another, and those wires actually route to separate speakers, then the clarity of the arriving signals should be noticably improved. To prove any of these points, we all should start investing in signal generators and analyzers- or at least fine a rental shop that carries them. Then I can see as well as *maybe* hear whether or not there is any real measurable affect.... ------------------ Amp: Integra 7.2 DVD: Toshiba SD4700 Fronts: RF-7 Centre: RC-7 Surrounds: old Advents! Sub: None TV: Dreaming of Plasma Quote Link to comment Share on other sites More sharing options...
Soundthought Posted July 24, 2002 Share Posted July 24, 2002 Gil, Nice post. Good food for thought. I've been studying cable theory and such for just a short period of time. Ever since I got my bi-wireable RF7s, I've been determined to understand it. But i will try my best to discuss this contraversal issue with you. Yes, i am a proponent of bi-wiring. The IM debate has been going on for something like 30 years. Leave it to the SMPTE. Apparently what can be measured may not be heard. Without going into elaborate detail my understanding is that the requirement for speaker cable is not very different than that of zip cord. PWK argued that his whole life. While it is true that actual signal loss due to wire resistance depends on the impedance of the load, even a relatively slight impedence in the speaker cable significantly lowers the damping factor seen at the speaker. Although this is only particulary noticable in long cable runs. It is still always relavent in faithful sound reproduction. We need not talk about "skinning" My thinking is that since different types and sizes of wire have different resonating frequencies, within proper bi-wire, frequency separation due to particular resonant factors of different cables can occur and thus putting less strain on a passive crossover. With bi-wireable speaker inputs we now can even appropriate the frequecies(more or less) to the right network within the crossover. As far as i can tell, the straighter and less obstucted the signal path, the more faithful the sound reproduction. I believe also that bi-wiring help reduce distortion that might be cuased by objectional harmonics. Namely-3rd-5th-7th order. While it's true they're produced by circutry not cables, the subsequent intrduction of new harmonics puts a higher demand on the crossover. Reducing the HD by allowing natural frequency separation should allow for less distortion. Ever so miniscule as it may be. It still allows for a cleaner signal path. And again, the less demand on the crossover, the more faithfull the reproduction. It's like pennies. Indivdually they're relatively worthless, collectively they have noticable value. Such is tweaks like bi-wire. What do you think? Intruging? How do frequencies relate within one conductor? I seem to be having a difficult time sorting that one out. Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 24, 2002 Share Posted July 24, 2002 Biwiring really can't help the damping factor issue either. That is to say that the damping factor of the amp really doesn't effect the damping of the speaker as much as you'd think. Nor does wire resistance. First we have to think about the electrical damping of a woofer. Particularly at the resonant frequency of the system, the diaphragm moves with greater excusions. Is there something which will damp it? The answer is yes. In most instances the voice coil and magnet act as a motor to drive the diaphragm back and forth in response to the voltage applied at the driver terminals. But particularly at resonance, the mass and spring of the driver drive the voice coil and magnet so they act as an generator. Now. More of an electrical load you put on a generator, the harder it is to turn. So the "generator" aspect of the driver is damped by the electrical resistance in the loop attached to the driver terminals. . . almost. It is actually total resistance in the loop. And that includes the voice coil resistance. It is nominally 8 ohms. Lets try to diagram the system. Ground--Voltage Source--output resistance--speaker wire--crossover--voice coil--ground. (Now that is a bit inaccurate because the gound connection between either end is through the speaker wire too, but hard to diagram. We'll lump it into the element of the speaker wire.) - - - The first three units are part of the amp. The voltage source is a theoretical generator which outputs a voltage regardless of a load. It has zero ohms resistance. The output resistance is what we call the output resistance of the amp. (As mentioned, the ground is really part of the speaker wire.) We know the amp is made of real components like transistors and power supplies. None the less, they are modeled by a perfect voltage source in series with an output resistance. It works for this analysis, though not all. Amplifiers with negative feedback act more like the output resistor is low in value. - - - How do we know what that amp output resistance is? A: The damping factor of the amp is DF = 8 ohms / output resistance. So if there is a DF of 100, Output Resistance = 0.08 ohms. - - - The fourth element is the speaker wire. Let's assume speaker wire resistance is 0.4 ohms. - - - The last three elements are part of the speaker. Crossover resistance is 0.4 ohms. Voice coil resistance is 8 ohms. - - - Total resistance in the loop is 8.88 ohms. That 8.88 ohms is the total ACTUAL electrical damping of the speaker. Note that the largest part of it is the voice coil resistance. - - - Can we improve things? Maybe. We can buy a different amp with a greater damping factor of 200. Now the output resistance is 0.04 ohms. And suppose we double up the wire so it has a resistance of 0.2 ohms. Maybe bi wiring does this, but I doubt it can be that great. In any event, now the total loop resistance is 8.64 ohms. (Earlier it was 8.88 ohms.) As you can see, despite the change in the amp and the wire, the load seen by the "generator" in the speaker has been reduced by only 2.7 %. That is not enough to alter the damping significantly. It is true that an amp with a damping factor of 1 will have an effect. Its internal resistance is 8 ohms. Now the loop resistance has increased by 100 %. However, now the feed wire resistance has even less effect overall. - - - An import issue is that you have to be careful about what to expect, electrically, when moving from an amp with a low damping factor to a high damping factor; or fat wire. Going from 1 to 10 or 100 damping factor makes a big difference in the loop resistance. But going from 100 to 200 makes practically none. You can do the math. The reason is that the voice coil resistance dominated the loop. This also shows why fatter wire (or bi wiring) doesn't do much for the overall damping either. Gil Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 24, 2002 Share Posted July 24, 2002 Okay, I can see part of the conceptual problem. I think the issue is as follows. Let's assume the bass is causing the amp to put out 10 volts. The treble is causing an additional 1 volt. They both go to the load of 10 ohms through a wire with a 1 ohm resistance. If the 10 volt bass is switched on and off, doesn't that "modulate" the 1 volt treble? Or if the treble goes on and off, doesn't that modulate the bass? This "modulation" would be seen by the load, or speaker. But let's see if that is so. The signal combination means the voltage source has a number of possible values. (I'm picking those numbers at random. They might make the math easier.) 0, 1, 10, 11, depending on what is at a peak. Somewhat like the hardware in the post above, but leaving out the output resistor. Ground -- Voltage source (0,1,10,11) -- 1 ohm wire -- 10 ohm load-- ground. Total loop resistance is 11 ohms. We resort to Ohm's law to calculate the current in the loop. Please note all the current goes through the load. Amps = Voltage / Ohms. Ohms total is always the same. So current in the loop is 1/11 of the voltage from the voltage source. And again note all the current flows through the load. - - - Also according to the same Ohm equation, restated. Volts = Current * Resistance. This holds true for the voltage across the 10 load resistance. So we see that the voltage in the load = current in the loop /10. (A) If the voltage source is 0, the current is zero and the voltage at the load is 0. (Easy one!) ( If the voltage source is 1, the current is 1/11, and the voltage at the load is (10/11) = 0.90909 volts. © If the voltage source is 10, the current is 1*10/11, and the voltage at the load is 10*10/11 = 9.0909 (D) If the voltage source is 11, the current is 11/11, and the voltage at the load is 10*11/11 = 10.00 - - - We're almost there, so hold on. - - - - The situation in A to B is where there is no bass 10 volts from the source, but there is the 1 volt treble, on and off. The voltage at the load resistor went from 0 to 0.90909 The situation in C to D is where there is 10 volts bass from the source. The voltage at the load resistance went from 9.0909 to 10. That difference is 0.90909 volts . . . which is the treble signal we were so worried about being distorted by the wire resistance. However, it is perfect. (There is a bit of a round off issue. The "90909090" numbers repeat to infinity.) The bottom line is that the treble has not not been effected by the bass at all. - - - Another issues is whether the wire is "stressed". No, it really isn't at these frequencies. On the other hand, the question shows a hunch about wire which is totally accurate at very high frequencies and long lengths. The wire pair does have capacitance and inductance. This means that there is some analogy to a rubber hose passing water under pressure. The hose has to "filled up" to its capacity (the electric field), and it will bulge from elasticity (the magnetic field from inductance). However, we're not at frequencies or lengths where those effects come into play. Gil This message has been edited by William F. Gil McDermott on 07-24-2002 at 11:57 PM Quote Link to comment Share on other sites More sharing options...
boa12 Posted July 24, 2002 Share Posted July 24, 2002 kan, & to add, you're in effect already bi-amping. the lower freqs are going to a seperate amp in the speaker & your mids/highs are coming from the amp in your receiver. ------------------ My Home Systems Page Quote Link to comment Share on other sites More sharing options...
Soundthought Posted July 25, 2002 Share Posted July 25, 2002 Quite interesting Gil. You hypothesis is true. A good read BTW! Yeah that number keeps on truckin. I'm having a hard time disputing the numbers. The numbers can't lie, thats a fact. But does the small amount that's rolled off in any way help build harmonics? In terms of articulation of higher frequencies and sculpting and texturizing lower ones. Doesn't the fractional high octave loss somehow affect the overall sound quailty? Even though it's inaudible and basically immeasurable, does it not have some harmonic value? What do you think of frequency specific cable? Or cable directionality? This topic is quite interesting. Your feedback has been duly noted and quite appreciated. Quote Link to comment Share on other sites More sharing options...
HornBlower Posted July 25, 2002 Share Posted July 25, 2002 I thought all this stuff was of major interest to me, and that it would make a vast difference in my listening enjoyment. Sigh. Alas, it's not yet the end of the month, and I can't afford to replace the now vastly degraded batteries of my hearing aids..... Do I sell my RF's so that I can hear them better???? ------------------ Amp: Integra 7.2 DVD: Toshiba SD4700 Fronts: RF-7 Centre: RC-7 Surrounds: old Advents! Sub: None TV: Dreaming of Plasma Quote Link to comment Share on other sites More sharing options...
WMcD Posted July 25, 2002 Share Posted July 25, 2002 Audioreality has a bit of prose going there. I like it. If you look at the numbers closely, you'll see that the resistance is causing a uniform loss, regardless of the level of the combined signals. The "output" is always 90.9090% of the "input." Hidden in the numbers and equations is the fact that the resistor circuits are "linear". There is always that 90.909% relation, which is an attenuation. However, a perfect amplifier could have a gain of 10 or a 1000% relation. The "linearity" is that Ohms = Volts/Current (Ohm's law). It is like high school geometry with graphs. We could graph Volts on the y axis (here output) and Current on the x axis (here input). This is where the teacher asks, what is the slope of the line? The slope is rise / run. Just like y = mx + b. Or y/x = m + b. (b=0) the m is the ohms, the relation between the voltage and the current. Look at how this works: y is voltage across the load and x is current in the loop. "Ohms" describes the slope of the line, and it is a line, or linear. A bigger question is why a non linear system causes the creation of other frequencies. If the system is nonlinear two things happen. Both are because the output waveform is not a duplicate of the input waveform, scaled and added. 1) If there is a single frequency input of F1, the output contains harmonics at F*2, F*3, F*4, etc to varying degrees. These are the odd and even harmonics. Always multiples of the original. 2) If there are two frequency inputs of F1 and F2, the output contains those two and F1 + F2 and F1 - F2. This is intermodulation. But lets go back to the orignal issue of sending two or more frequencies down a lossy, but linear, feed line. At the receiving end, does one signal "hurt" the other? No. We saw that in the math. Cable TV is an example. Channel 4 is a low frequency range. Channel 30 is higher. We know that those two, and everything in between and higher, get sent to our TV receiver by the cable company. We never see interference between the TV channels because of losses in the cable. E.g. Pay for view porn does not modulate the Sci-Fi Channel Twilight Zone marathon. The images don't overlap on the TV screen receiver. Or vice versa. (This is humor. But consider the possibilities. Which would be more disturbing?) Gil This message has been edited by William F. Gil McDermott on 07-25-2002 at 11:49 PM Quote Link to comment Share on other sites More sharing options...
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