Why Bi-wiring Makes No Sense.

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O

Omicron

Junior Audioholic
Can't assume that. You are adding the woofer loop voltage and the tweeter loop voltage, but yet both of them are derived with the wire resistance as part. Your messing up the 2AB, both in magnitude and phase.
I used superposition and the properties of the 2 filters. But now you will claim superposition can't be used I assume? That way we can discuss till hell freezes over...

If my assumption was wrong then the results wouldn't be self consistent. They are.

Please enlighten us and show us how you calculate the powers in this simple circuit.

Equations John, not hand-waving. Equations!
 
O

Omicron

Junior Audioholic
Well then, where's the phase??
The Va, Vb and Ia and Ib are all functions in time. If you really want to you can write them in their A*sin(wt + phase) form. It won't change one single thing to this analysis.
 
J

jneutron

Senior Audioholic
I used superposition and the properties of the 2 filters. But now you will claim superposition can't be used I assume? That way we can discuss till hell freezes over...
Superposition assumes the output, then calculates the filters to match the expected output.

But superposition doesn't explain the difference in dissipation between mono and bi..

YOU are using superposition to prove superposition.. That is self supported hand waving..

If my assumption was wrong then the results wouldn't be self consistent. They are.
Anytime you assume the output is identical, you're going to be self consistent.

No matter how may ways you do it, if you assume the outcome, then the outcome is a given.
Please enlighten us and show us how you calculate the powers in this simple circuit.

Equations John, not hand-waving. Equations!

You make funnies...

Already provided the equations, guy. You ignored them.

Already showed exactly where the difference lies...you ignore them.

Already explained that the filter sections are orthogonal, you ignored that.

Already provided two states where the capacitive charging is either with the reisitive dissipation or against it, depending on the woofer current. you ignored it.

Already explained to you the circular logic you are employing..you ignore it.

I am not the one doing the hand waving..

But that point seems to have eluded you..

I'm still trying to post the schematic, but that eludes me...:p

Cheers, John
 
O

Omicron

Junior Audioholic
Already provided the equations, guy. You ignored them.
I haven't seen any except the one where you calculate the wire dissipation. I still wait for an equation that shows the distorted power in any speaker.

So stop blowing smoke.
 
J

jneutron

Senior Audioholic
I haven't seen any except the one where you calculate the wire dissipation. I still wait for an equation that shows the distorted power in any speaker.

So stop blowing smoke.
You mean, unlike the smoke you've been blowin??
GMAB..

You magically assume the crossover compensates for the reisistive wireloss component by setting the output as identical, therefore guaranteeing the crossovers compensate a resistive loss by magically producing the exact amount of power into the system as needed...without regard to phase shift..

You are practicing sleigh of hand..and accusing me of smoke..

You are indeed funny.

You ready to put a real, electrical-like test together to check my results..or is that smoke as well..

Remember, at this time, we are only discussing steady state...you forget the final application is not steady state??

Cheers, John

ps..I assume that at some time, I'll get to post the schematic..
 
J

jneutron

Senior Audioholic
I haven't seen any except the one where you calculate the wire dissipation. I still wait for an equation that shows the distorted power in any speaker.

So stop blowing smoke.
I know...lets use one of your equations...and plug some numbers in..

""Originally Posted by Omicron
Let us call Rwire + Rtweeter = Kt and Rwire + Rwoofer = Kw

So:

Pamp = (Ia + Ib)(Ia * Kt + Ib * Kw)"""

Ok, assign values..

Rwire = 1
Rtweet =10
Rwoofer = 10

you say Kt=11
you say Kw=11

So, 1 ohm wirefeed in series with two 10 ohm resistors in parallel...

5 ohms load, 1 ohm series, adds to 6 ohms loop.

Let's push 12 volts into the system...that makes 2 amperes current through the wire, 1 ampere into each load..

Applying your equation:

Pamp = (Ia + Ib)(Ia * Kt + Ib * Kw)

Pamp = (1 + 1) ( (1*11) +(1*11))
Pamp = (2) times (22)

Pamp = 44 watts from your equation..

Hmmm, 12 volts at 2 amps...isn't that 24 watts? The 1 ohm wire dissipates 2 watts, the 10 ohm loads each carry 1 amp, so they dissipate 10 watts each to total 24..

Am I missing something?

Your math supported your assertion, but I can't seem to get the numbers to add when I put in actual values..

Cheers, John
 
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O

Omicron

Junior Audioholic
Am I missing something?
Yes, you are missing the fact that the filters are there. All the voltages and currents are instantaneous values. So there IS a component in the filters that you need to calculate as well. This will be the 20 watts you are missing.

Remember, only the average power in the filters is 0, not the instantaneous power!

If you want to calculate the average power and assume RMS values for the currents, then that will work out as you say. But my equation does not deal with RMS currents or voltages, but with instantaneous values.

To find the average power you need to plug in a concrete function for Ia and Ib (say a sine) and then integrate the resulting expression to obtain the average over time.

Let me know if my explanation isn't clear.
 
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J

jneutron

Senior Audioholic
Let me know if my explanation isn't clear.
Oh, it's clear allright..

The correct answer was:

""John, you have accidentally applied a dc analysis to an ac circuit..let me explain...

Using DC circuit theory, the two loads are in parallel, equalling 5 ohms, and that is in series with the wire which is one ohm, for a total of 6 ohms. When the amplifier puts out 6 volts, the current splits evenly between the two equal loads, and the amplifier sees a load of 6 ohms at all times.

For the circuit we are talking about, there are two distinct paths that two frequencies will take...so the analysis requires examination of each independently.

First, let's apply 11 volts AC low frequency (peak, average, rms...it makes NO difference, so let's talk peak..)..to the circuit. The tweeter has no involvement (as the capacitor isolates it), so the amplifier is putting 11 volts into a circuit which has a 10 ohm load and a 1 ohm wire, so the woofer circuit sees one ampere..

Next, repeat this calcuation for the tweeter circuit..the woofer doesn't see anything, 11 volts hf produces 1 ampere in the tweeter circuit.

Now, if we add both signals, the amplifier is putting out 22 volts, each load sees one ampere, and the wire sees 2 amperes (summation).

So calculation of the powers results in:

1.. The amplifier is delivering 22 volts peak.

2. The amplifier is delivering 2 amperes peak.

3. The wire is seeing 2 amperes peak.

4. Each load is seeing 10 volts peak.

5. Each load is seeing 1 ampere peak.

Let's calculate power.

Load total power is 10 + 10, or 20 watts peak.

Wire total power is 4 watts peak. (2 amperes and 1 ohm)

Total power dissipated between the loads and wires is...24 watts peak.

The amplifier however, it has 2 amperes and 22 volts. For a total of 44 watts peak.

If we say lossless wires, it becomes 20 watts load, and 40 watts amp..

(This disparity is why biamping is so good, btw..)

That was the correct explanation...

Let me know if my explanation isn't clear.
Hmmm. you missed the correct explanation, given the numbers and explanation I used..

(sorry... it was a test..) The answer was quite simple, I set you up to correct me, and I was more than happy to take the "mistake hit". Your response means:

1. Either you do not understand the circuit very well, so provided floobydust.

2. You are posting the work of others and do not understand it.

3. You are posting in haste, and you missed the obvious.

Personally, I'd prefer to think that it was #3. Unfortunately, this statement:
If you want to calculate the average power and assume RMS values for the currents, then that will work out as you say. But my equation does not deal with RMS currents or voltages, but with instantaneous values.
Is in conflict with my assumption that you erred as a result of haste. As, using a DC analysis cannot result in the correct numbers, regardless of rms, peak, average, phase, whatever (correct me if I'm wrong here)...so saying that "it will work out as I say..well.."hmmmm."


Can you put some numbers into that explanation for us to verify it does indeed work? I'll post it again..

Yes, you are missing the fact that the filters are there. All the voltages and currents are instantaneous values. So there IS a component in the filters that you need to calculate as well. This will be the 20 watts you are missing.

Remember, only the average power in the filters is 0, not the instantaneous power!

If you want to calculate the average power and assume RMS values for the currents, then that will work out as you say. But my equation does not deal with RMS currents or voltages, but with instantaneous values.

To find the average power you need to plug in a concrete function for Ia and Ib (say a sine) and then integrate the resulting expression to obtain the average over time.
Cheers, John

ps...The best part about missing the obvious is the crow ya gotta eat..Believe me, I am no stranger to that..you should meet my co-workers..:eek:
 
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O

Omicron

Junior Audioholic
Can you put some numbers into that explanation for us to verify it does indeed work? I'll post it again..
John, the equations I provided are valid for instantaneous power only. Ia and Ib are functions of time. This kind of analysis is universal, it has nothing to do with AC or DC analysis.

The instantaneous power contribution of the filters is not zero. Off course the numbers will not work out if you keep ignoring them. Loot at the formulas I have derived for you and look up the power term of the filters. Plug your numbers in it and discover the missing 20 watts.

Honestly, this is getting a bit silly.
 
J

jneutron

Senior Audioholic
John, the equations I provided are valid for instantaneous power only. Ia and Ib are functions of time. This kind of analysis is universal, it has nothing to do with AC or DC analysis.
Well then plug in some instantaneous numbers.. I'll wait..


The instantaneous power contribution of the filters is not zero. Off course the numbers will not work out if you keep ignoring them.
Who said it's zero??? Do you actually understand the equations you posted?

When looking at the filters significantly far from their breakpoints, their contribution is rather small. If you wanted to, you should be easily capable of assigning values to the filter comps, calculating their reactances (1/jwC or jwL), then ascribing a "power" to them based on the currents and voltages..

For example, if I use a 680 henry inductor and a .001 uf capacitor, run a microhertz and a megahertz, the energy absorbtion (and effective "power" )in each component as a result of the other's frequency is trivial to calculate. It would even be easy to determine the step function response to the system given different initial conditions of DC current in the inductor.

All easy to do. So...do it..

Loot at the formulas I have derived for you and look up the power term of the filters. Plug your numbers in it and discover the missing 20 watts.
Who is missing the 20 watts??? You didn't realize the difference between the correct AC analysis technique upon which YOUR equations were based, and the DC analysis I asked you about..you said my analysis was ok for specific conditions... Wrong, it was not. That mistake in itself tells me a lot.

Now you ask about the 20 watts as if I am looking for it??? Diversion is unbecoming.

Honestly, this is getting a bit silly.
You are the one harping and harping on about equations for this, equations for that...when you don't appear able to understand the correct application of the equations you posted in a real live analysis...

Your right, it is silly.

You should have come in ready to discuss....not stealthily, acting like a "newbie", knowing all along that you were gonna try to "slam" me with verbage from 2 years ago (or was it 3?).

Be nice, get nice. You wanna come in blasting, make sure you're wearing the appropriate 40 cal PPE..

Cheers, John
 
O

Omicron

Junior Audioholic
Well then plug in some instantaneous numbers.. I'll wait..
Ok.

Ia = 1
Ib = 1
Rwire = 1
Rtweet =10
Rwoofer = 10

Kt=11
Kw=11

Pamp = (Ia + Ib)(Ia * Kt + Ib * Kw) = 44W

Pspeakers = sqr(Ia) + sqr(Ib) = 20W
Pwire = (sqr(Ia) + sqr(Ib) + IaIb*2)*Rwire = 4W
Pfilters = Ib*Ia*(Rwoofer + Rtweeter) = 20W

44W = 20W + 4W + 20W

My math all works out perfectly.

If you want to discus, put your math where your mouth is and show us YOUR analysis. Equations remember. I've shown you mine and they clearly show your hypothesis about some hidden distortion is FALSE. Case closed.
 
J

jneutron

Senior Audioholic
Ok.

Ia = 1
Ib = 1
Rwire = 1
Rtweet =10
Rwoofer = 10

Kt=11
Kw=11

Pamp = (Ia + Ib)(Ia * Kt + Ib * Kw) = 44W

Pspeakers = sqr(Ia) + sqr(Ib) = 20W
Pwire = (sqr(Ia) + sqr(Ib) + IaIb*2)*Rwire = 4W
Pfilters = Ib*Ia*(Rwoofer + Rtweeter) = 20W

44W = 20W + 4W + 20W

My math all works out perfectly.

If you want to discus, put your math where your mouth is and show us YOUR analysis. Equations remember. I've shown you mine and they clearly show your hypothesis about some hidden distortion is FALSE. Case closed.
Wow..I don't see any integrals or deriviatives..

Amazing that you are able to so easily calculate the filter power..and it's exactly what you calculated it to be...

Oh, I forgot...you assumed the output power, then back calculated..
Nice try.

Integrate the stimulus on the inductor and capacitor, show us exactly how they appear to be 20 watt elements. Specifically, if you choose a frequency high enough, do the calc, then slide the frequencies both an order of magnitude...AND WOW, holy mackeral...the cap and inductor STILL show as 20 watt elements..no matter what frequency you choose...

Amazing...

Learn to do it without making foregone conclusions or circular logic..

Cheers, John
 
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O

Omicron

Junior Audioholic
Learn to do it without making foregone conclusions or circular logic..
Really now?

Care to show my exactly where I did that? Point to me any step in my derivation where I assumed ANYTHING at ALL about ANY power in the system.
 
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J

jneutron

Senior Audioholic
Really now?

Care to show my exactly where I did that? Point to me any step in my derivation where I assumed ANYTHING at ALL about ANY power in the system.

You popped the equations up...you show. You're the one who didn't spot the error in application..

Simple..

Start with V =L di/dt.

and I =C dv/dt..

And work your way up to the 20 watts..

Cheers, John

ps.. why do you keep on dancin around the circular logic..sheesh..face it, you have no idea how to work the math by the energy, do you..Hey, it's not something to be ashamed of, most people don't.
 
O

Omicron

Junior Audioholic
ps.. why do you keep on dancin around the circular logic..sheesh..face it, you have no idea how to work the math by the energy, do you..Hey, it's not something to be ashamed of, most people don't.
The derivation I presented in post 369 doesn't assume anything about the powers, hence there is no circular logic. It calculates all the powers based on the currents and the voltages.

My equations are out there for all to see. That's more than we will ever get from you.

Have a happy life John. Whatever you've been smoking lately, it must be good!
 
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