One way to make expensive speaker cables!

[serengetiplains]

Carlmart, I think I'm winning the argument. Hang in!

 

[Steve Eddy]

But what of actually crossing the zero line? Is there some bump of energy required to opposite-polarise or for that matter to polarise from an initial non-polar state?

Well, unless you're dealing with an electret, there's no net polarization to depolarize that I can see. And sure, it would require energy to polarize from a non-polarized state.

But by the same token, it would also require energy even if the dielectric were polarized. Far as I'm aware, the electric field from the signal adds to and subtracts from the field used to polarize the dielectric so the dielectric's polarization still changes due to the signal. And that change also requires energy.

Yes, which, in a transformer, avoids hysteresis loss.

In exchange for increased distortion and reduced level handling.

Perhaps dielectrics experience something analogous to remanence.

From what I've gathered, they don't seem to under what would be typical conditions for audio use. I know the various polarizing mechanisms (space charge, molecular dipoles, ionic dipoles and electric dipoles) have different relaxation times, but under conditions we're talking about here, I'm not aware of anything that would be akin to remnance.

Perhaps our resident Polyester Posthole Digger can shed some light on this. 🙂

se

 

[Steve Eddy]

It proves Absolutely Nothing, Steve. What *could* you be thinking? 🙂

That's Abso!utely, dude! 😀

se

P.S. I was always amused with HP's copyright notice which said that "NOT ONE WORD of the Abso!ute Sound may be copied etc. etc. without permission etc. etc."

I'd always wanted to take out an ad in Stereophile that just said:

"The^*" in huge letters.

The tiny footnote would read "^*Copied without permission of the Abso!ute Sound." 🙂

se

 

[Steve Eddy]

Carlmart, I think I'm winning the argument. Hang in!

Refresh my memory. What exactly is the argument?

se

 

[SY]

But what of actually crossing the zero line? Is there some bump of energy required to opposite-polarise or for that matter to polarise from an initial non-polar state?

No.

Ironically, the biasing takes the signal away from the most linear part of polarization. Not that it makes the slightest bit of difference to the signal...

 

[carlmart]

Condenser, (electrostatic), microphones work on a different principle entirely than dynamic microphones. Condenser microphones require polarizing voltage or they do not work.

Dynamic microphones are pretty similar to speakers, and indeed many intercom systems use one element as both speaker and microphone. Did you ever hear of anyone saying, "I ran 10 volts DC thru my Shiva and boy, did the bass ever improve?"* Me neither.

As for active speakers, all that amounts to is including the amplifier in the same enclosure as the speaker-there is no difference in principle at all.

Let me make it clear that I am taking no sides in this debate. I have not heard active cables, nor, truth to tell, even any name brand super cable, so I am neutral. I just wanted to comment on the previous message.

*Note to newbies-do not ever run DC voltage through your speakers. You run the risk of permanent damage to your speaker.

You should have realized that by active speakers in our context I meant electrostatic. You also made a mistake: active speakers are not those with the amp in the same enclosure, but speakers where each driver has a separate amp. Most of the times the amps are separate from the drivers, not together.

And of course dynamic mics are different from condensers. Dynamics generate their own, very low voltage when they are excited by sound waves, which is amplified by the mic preamps. Condenser mics use a diaphragm which is polarized with a small voltage (a few volts, in spite of most using 48v), which makes it more sensitive and generates larger signals.

So please let's stop this comparison with mics or speakers and concentrate on active cables. In my opinion they deserve some looking into, but this may not be shared by others.

Or are we going into a lazy stage?...

I better go see my files so I can put some real info in this matter.


Carlos

 

[moamps]

Condenser mics use a diaphragm which is polarized with a small voltage (a few volts, in spite of most using 48v), which makes it more sensitive and generates larger signals.

Hi,
Condenser mics usually have voltage converter inside witch generate ca 60V for plate(s) polarisation. 48V from console has relatively high output resistance (6k8)(also create microphone preamp input impedance) what cause voltage drop on mic's connector around 10-15V. Also, condenser mics have preamp/impedance converter built in.
Back-electret mic is another story.

So please let's stop this comparison with mics or speakers and concentrate on active cables.

My sugestion too.😉

Regards
Milan

 

[gmarsh]

From personal experience in the matter, cables indeed can have dielectric effects. In my line of work, we run kilowatts of RF power through coax.

In general, you can model a cable dielectric as a distributed capacitance and a distributed resistance. As the voltage on the cable gets closer to the dielectric breakdown voltage, the resistance term will become smaller. So in effect, cables can "compress" the signal going through them, and for very large signals, that can create distortion.

But unless you're running immense amounts of voltage through the cable, you won't be able to measure this - you have to get *very* close to the dielectric breakdown voltage before you can even measure it, and once you add a few more volts your cable just arced and died. I'm certain your your home stereo equipment isn't at risk of frying its cables, so I doubt you'll be able to hear any dielectric related distortion in your interconnects.

Adding a couple volts of bias to one of these cables won't change the sound, I guarantee. But assuming that dielectric distortion *did* matter (eg, if you made a cable out of MOVs or something) then adding bias would make the distortion asymmetrical. Which won't be good.

And 'zero crossing' in dielectrics doesn't exist. Otherwise the whole RF filter design business wouldn't exist. 😀

 

[phase_accurate]

Additionally cables will also exhibit microphony when DC biased. Apart from being nasty in certain applications (like audio signal cables) this might probably also be used as some form of sensor.

Regards

Charles

 

[kelticwizard]

You should have realized that by active speakers in our context I meant electrostatic.

Your statement was made in rebuttal to the following post by Steve Eddy:

Originally posted by Steve Eddy: In the case of the condenser microphone, the biasing isn't to make it better, it's to make the thing work in the first place. Cables don't need biasing to work as cables.

In rebuttal, your statment was:

You also made a mistake: active speakers are not those with the amp in the same enclosure, but speakers where each driver has a separate amp. Most of the times the amps are separate from the drivers, not together.

You are incorrect. Perhaps this is a language difference. In the English speaking audio world, the setup described above uses an active crossover. A separate amp is simply understood as being needed in any setup where an electronic, (active), crossover is used.

An active speaker is one where the amp is located in the same enclosure as the speaker. By far the most common example is the active subwoofer, which has it's own amp and crossover in the same box as the driver. Take the amp and crossover out of the box, (cover the hole, of course!), move them over to your stereo rack, buy a longer cable, and you no longer have an active subwoofer. You have a passive subwoofer with it's own electronic crossover/amp.

Let's put it this way. A passive speaker had to be hooked up to a power amp to work, even if that power amp is dedicated to that speaker exclusively. An active speaker can be hooked up to a preamp, CD player, or other line level device. There are some active subs that also have speaker level inputs, but they use only a tiny fraction of the wattage from those speaker cables.


Meridian and other makers make active speakers, (or used to), and the amps were in the box. Theoretically, you can make a multiway active speaker that uses passive crossovers, but it would be hard to imagine anyone wanting to do that.

Or are we going into a lazy stage?...

Nope. Just clarifying. And I am not saying that these active cables don't even work. But I felt your statements needed response.

 

[ThorstenL]

Konnichiwa,

Easy, easy. I'm friendly. (See how jumpy the naysayers have gotten us?) I don't doubt polarising works, I was just wondering as to your best guess why.

You see, this subject makes me angry at myself. I can observe the effect but I cannot explain it. Somehow neither MDI nor Dielectric Absorbtion explain enough and in my current commercial cables I can reliably exclude microphonics (in my earlier "air dielectric" diy cables I could not).

So, I am left to say "it works but I'll be damned if I know". As somewhat rightbrain domianted engineering type that is an uncomfortable place to be in, you can notice me squirming.

Sayonara

 

[ThorstenL]

Konnichiwa,

Adding a couple volts of bias to one of these cables won't change the sound, I guarantee.

Have you actually ever TRIED it? Or are you basing your guarantee on the often cited "common sense" and "basic electronics"?

I know based on the usal models of signal transmission biasing SHOULD not make a difference. Yet I observe one, which to me personally, for my own conviction I have established as being reliably detectable. I do not expect you (or anyone else) to adopt my position, I merely state it.

Now, having observed a difference that should not exist and which cannot be sufficiently explained by any of the proposed theories which mostly are an extension of the existing bog of muddy intertia called consus and common sense, I am forced to note that the existing state of understanding fails to explain observable phenomena.

Hence I would recommend to be carefull in offering any guarantees, unless you include the neccesary qualification "based on current theoretical understanding, which may or may not change drastically in the next the minutes....."

Sayonara

 

[fdegrove]

Hi,

I know based on the usal models of signal transmission biasing SHOULD not make a difference. Yet I observe one, which to me personally, for my own conviction I have established as being reliably detectable.

A big chunk of the effects noted by Mr. Pierre Johannet are related to Maxwell-Wagner effects hence the coining MDI which is in essence a side effect/consequence of this.

Cheers,😉

 

[carlmart]

Given these facts, I really don't see how you can say I should have realized that you meant electrostatic speakers. Steve's whole point was that electrostatic microphones were designed to be used with polarizing voltage: without it they cannot possibly work. When you answer that "dynamic speakers don't need any polarizing to work. Or speakers.", what can possibly be the conclusion other than you are referring to the normal, traditional, (electrodynamic), speaker?

And if you were referring to electrostatic speakers, than what electrostatic speaker do you know of that does not need polarizing voltage? Because you were talking about speakers that don't require it.


OK. Guilty for not being more precise. It would be tiresome and a time waste to discuss what I wrote and why. I can do so if necessary though.

Originally posted by kelticwizard
You are incorrect. Perhaps this is a language difference. In the English speaking audio world, the setup described above uses an active crossover. A separate amp is simply understood as being needed in any setup where an electronic, (active), crossover is used.

An active speaker is one where the amp is located in the same enclosure as the speaker. By far the most common example is the active subwoofer, which has it's own amp and crossover in the same box as the driver. Take the amp and crossover out of the box, (cover the hole, of course!), move them over to your stereo rack, buy a longer cable, and you no longer have an active subwoofer. You have a passive subwoofer with it's own electronic crossover/amp.

Let's put it this way. A passive speaker had to be hooked up to a power amp to work, even if that power amp is dedicated to that speaker exclusively. An active speaker can be hooked up to a preamp, CD player, or other line level device. There are some active subs that also have speaker level inputs, but they use only a tiny fraction of the wattage from those speaker cables.


Meridian and other makers make active speakers, (or used to), and the amps were in the box. Theoretically, you can make a multiway active speaker that uses passive crossovers, but it would be hard to imagine anyone wanting to do that.

I am not incorrect and it certainly is not a language difference. You are on the edge of being disrespectful just to defend an argument.

In the audio world, not just in the english speaking one, an active system is one that uses separate amplifiers for each driver. They may or may not use a crossover, so your apparent correlation between active and electronic crossover is wrong. You may not use any crossover, depending on the natural curve of the drivers to interrelate and you will still have an active system.

Putting amplifiers inside the speaker boxes is rather recent and it became more common with subwoofers sold as a separate item. A commercial reason.

Some studio speakers, which also got lower in price like Mackie or Behringer, also found a place on computer setups or small garage studios, and they call themselves active. But the correct application of "active" term can't and should not be directed just to that particular arrangement.

You don't need to explain to me what a passive or active speaker is, because I have been a professional sound recordist for the last 30 years. Particularly more because your explanation does not clarify the issue introducing a limiting concept. Professional systems have been active for years, sometimes using amps inside and some others outside. In fact being inside the speakers was a limiting factor quality wise, being only practical in certain situations. Serious studios used separate crossovers and separate amps in their racks to power it all.

Meridian and Naim, just to name two, sold commercial systems that took advantage of the active principle in the home audio market. But they were expensive and hard to sell.

A good passive speaker is easier to setup with just one amp than an active one.

So my apology again for not having been more precise on my use of the word "active" for the context of our cable discussion.

And now let's get back to our cable program...


Carlos

 

[kelticwizard]

And you can get active versions of speakers as well as microphones.
Carlos

As you can see above, your quote in post #55 was for the term "active speakers". An active speaker is a speaker with the amplifier in the box. Period. Is that clear?

An active system is one where the amplifier is dedicated to each driver. The amplifier in an active system can be located inside or outside the box, usually outside. They usually contain electronic crossovers. Can you have an active system with drivers that roll off naturally? Yes. Does it happen often? No. The vast majority of active systems contain electronic crossovers as well.

If you are going to post on active speakers, as you did, then please keep the subject on active speakers. Do not try to pull a switcheroo and claim you were talking about active systems when your words were "active speakers".

I do agree with you, however, that this is sidetracking the conversation. I'm willing to drop it and let each individual forum member make their own mind up, if you are.

 

[gmarsh]

Konnichiwa,

Have you actually ever TRIED it? Or are you basing your guarantee on the often cited "common sense" and "basic electronics"?

What's a good way of adding a DC bias to an analog signal without introducing distortion into the signal? how can you say you're not hearing a difference introduced by the bias network?

 

[ThorstenL]

Konnichiwa,

What's a good way of adding a DC bias to an analog signal without introducing distortion into the signal? how can you say you're not hearing a difference introduced by the bias network?

Change the question a little and you find an answer. I do not bias the Signal conductors, but the Screens, which are not used to carry any signal.

Sayonara

 

[kelticwizard]

So you only use tubes for this method?

 

[kelticwizard]

Re: YAY...

Hi,

Is this claim about some of the properties of cable insultion technically valid?

"The electric field produced by the signal will polarise the insulation material, introducing distortion. The magnitude of this effect will depend on the polarisibility of the material (loosely correlates with the dielectric constant), the volume and proximity of the material to the electric field, and the strength of the electric field."

SOURCE OF THE QUOTATION

Cheers,😉

No expert in the field here, but isn't DC voltage usually used to polarize something? Wouldn't it be hard to polaize something using AC voltage, since it keeps reversing itself?

Just thought I would quote something about polaizing piezo elements. Notice they use a DC voltage:

http://www.ctscorp.com/components/Datasheets/piezotechprimer.pdf


Poling

Piezoelectric ceramic materials, as stated earier, are not piezoelectric until the random ferroelectric domains are aligned. This alignment is accomplished through a process known as "poling". Poling consists of inducing a D.C. voltage across the material. The ferroelectric domains align to the induced field resulting in a net piezoelectric effect. It should be noted that not all the domains become exactly aligned. Some of the domains only partially align and some do not align at all. The number of domains that align depends upon the poling voltage, temperature, and the time the voltage is held on the material. During poling the material permanetly increases in dimension between the poling electrodes and decreases in dimensions parallel to the electrodes. The material can be depoled by reversing the poling voltage, increasing the temperature beyond the materials Curie point, or by inducing a large mechanical stress.


Post Poling

Applied Voltage:
Voltage applied to the electrodes at the same polarity as the original poling voltage results in a further increase in dimension between the electrodes and decreases the dimensions parallel to the electrodes. Applying a voltage to the electrodes in an opposite direction decreases the dimension between the electrodes and increases the dimensions parallel to the electrodes.

I realize this is just one polarizing process, but it is hard to see how an AC voltage signal could polarize anything.

 

[Jennice]

Konnichiwa,



Change the question a little and you find an answer. I do not bias the Signal conductors, but the Screens, which are not used to carry any signal.

Sayonara

K.Y.W.,

Noe you've lost me...!
Unless you're referring strictly to balanced cables, you will have current in your screen also.
What you're experiencing may be the effect of the added DC on the input stage of thatever the signal cable feeds into ( maybe a poweramp?) This can move the operating point of your input stage.

Other than that, I don't get the point of the DC.

Jennice