Can Good Amplifier Design Mitigate Sonic Differences Between Cables?

Would you feel comfortable buying an esoteric power amplifier with no protection?

  • Yes. I like to live on the edge. Hifi or Bust!

    Votes: 5 31.3%
  • No way! I want my stuff to survive an EMP blast if need be.

    Votes: 11 68.8%

  • Total voters
    16
Alexandre

Alexandre

Audioholic
I feel like there are more and more companies that are delivering digital solutions end to end. Dynaudio's powered speakers have embedded DACs, some are even wireless. I also think that Meridian has been going in that direction for a while — I might be wrong on that.
 
Alexandre

Alexandre

Audioholic
Wow… I'm not super technical (not in this domain anyway) but two things I can't get over…

First: geocities still operates?? ;)

Second: maybe I misread but he's talking about 2 cables connected to the same amp outputs and therefore I don't see how the 2 separate pairs of bindings on the speaker could possibly receive different signal. Now if one were to biamp, I could see that but biwired?!? Maybe I'm missing something (but I assume I'm not considering your choice of smiley). ;)
 
3db

3db

Audioholic Slumlord
Wow… I'm not super technical (not in this domain anyway) but two things I can't get over…

First: geocities still operates?? ;)

Second: maybe I misread but he's talking about 2 cables connected to the same amp outputs and therefore I don't see how the 2 separate pairs of bindings on the speaker could possibly receive different signal. Now if one were to biamp, I could see that but biwired?!? Maybe I'm missing something (but I assume I'm not considering your choice of smiley). ;)
I guess the emoticon wasn't sarcastic enough. :)
 
T

Tom._White

Enthusiast
I remember Jon Risch from Audio Asylum years ago. I always thought his mind must be a frightening place to dwell.

To be more clear, I thought he was pretty much full of it, but that's just me and my disbelief in exotic cables.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
I remember Jon Risch from Audio Asylum years ago. I always thought his mind must be a frightening place to dwell.

To be more clear, I thought he was pretty much full of it, but that's just me and my disbelief in exotic cables.
I know what you mean. I battled him for years before coming here. Bizarre beliefs for an EE. :eek:
 
highfigh

highfigh

Seriously, I have no life.
Yup I understand what you are saying and I definitely know all sound we hear is analog. I just thought that signal loss could be minimalized if the audio could remain digital until the very last stage (it hits the amplifier).

I don't know enough about the physics behind this method of using a lossless digital type connection to amplifier vs. RCA preout / XLR Jack... can anyone with knowledge in this area share their thoughts on this?
Thanks
A system using Tos-Link between the preamp and power amp was offered by a company called FROX, in the early-'90s and it included a 12 band EQ with an ambidextrous 'wand' controller using RF to communicate with the preamp/controller, all switching and audio controls performed in the digital domain. I don't remember if it was 6.1 or 7.1, but it was an interesting system. They didn't last long.
 
P

PENG

Audioholic Slumlord
Wow… I'm not super technical (not in this domain anyway) but two things I can't get over…

First: geocities still operates?? ;)

Second: maybe I misread but he's talking about 2 cables connected to the same amp outputs and therefore I don't see how the 2 separate pairs of bindings on the speaker could possibly receive different signal. Now if one were to biamp, I could see that but biwired?!? Maybe I'm missing something (but I assume I'm not considering your choice of smiley). ;)
You might have misunderstood his point (I refer to that one specific point). Just because two pairs are connected to the same amp output terminals does not mean they will get the exact same signal because there are filters at the other end. For speakers designed for bi-wire and passive bi-amp, when you remove the links, the crossover will be separated into two parts so each part imposes different impedance characteristics to the pairs of cable connected to it, hence the different signals in each. In single wire, the single pair carries the whole spectrum of the signal and gets divided at the speaker terminals anyway so that the lows go to the woofer and the highs go to the tweeter, but that does not mean what the guy said was wrong. Even though he was right in that specific point, I also do not believe there will be audible difference.

I thought the bi-wire debate was a dead horse. It must be fun to keep flocking it?:D
 
Irvrobinson

Irvrobinson

Audioholic Spartan
In most home audio systems, an analog audio signal is amplified in several stages, not all at once. A typical line level analog signal is about 0.1-0.3 volts. This is the level of the analog signal coming out of a typical audio source, such as a disc player + DAC. At the preamp level this signal is amplified to the range of about 2-8 volts. A typical audio amplifier has an input sensitivity as low as 1-1.5 volts, and amplifies the signal to as high as 100-200 volts depending on the amp power.

What you proposed would have the signal remain digital until going to the power amp. After conversion to analog it would still have to be boosted to preamp level before going to the power amp.

I believe these various voltage levels are conventions widely used by the audio industry to allow different components to be compatible. They aren't dictated by physics, however, there may be practical reasons why they are used.
This isn't really correct. Line level analog systems are supposed to be spec'd to hit 0db relative loudness at 2 volts (and that's just a convention not a rigorous industry standard), but what you state above doesn't line up. While I agree that a typical Bluray player or CD player will output a fraction of a volt into the 50K ohm load of a typical line level input for music, and theoretically up to 2 volts on peaks, preamps are not amplifying the 0.1 to 0.3 volts you use as an example to 2-8 volts. In fact, line-level preamps are mostly unity gain devices, and most of the time the volume control on the preamp is *lowering* voltage received from the inputs, not amplifying it. Most power amplifiers hit their rated output at 2 volts or less. Where the situation gets tricky is that many amps exceed their rated output, and the preamp must often drive more than 2 volts to get the amp to achieve it, though the voltage requirement to hit clipping varies from product to product. Amps are constant gain devices (e.g. 32db), unless they have level controls on the inputs or outputs. Personally, I like to see preamps that are capable of around 10 volts of output into 10K ohms, but I doubt that most preamps ever have to hit 2 volt peaks in most systems, no less 10 volts.

Your statement about analog amplification occurring in stages is true only for amplifiers and phonographs. Most solid state amplifiers use three gain stages, though some audiophile amps try to make-do with two stages. (I think Nelson Pass does this.) The rest of the signal path, save phonographs, is unity gain. As we all know, phono cartridges need a special preamp stage to hit the 2 volt peak-to-peak line level.
 
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3db

3db

Audioholic Slumlord
You might have misunderstood his point (I refer to that one specific point). Just because two pairs are connected to the same amp output terminals does not mean they will get the exact same signal because there are filters at the other end. For speakers designed for bi-wire and passive bi-amp, when you remove the links, the crossover will be separated into two parts so each part imposes different impedance characteristics to the pairs of cable connected to it, hence the different signals in each. In single wire, the single pair carries the whole spectrum of the signal and gets divided at the speaker terminals anyway so that the lows go to the woofer and the highs go to the tweeter, but that does not mean what the guy said was wrong. Even though he was right in that specific point, I also do not believe there will be audible difference.

I thought the bi-wire debate was a dead horse. It must be fun to keep flocking it?:D
This article is full of BS from the get go. I didn't make it past the first 4 paragraphs;

I agree that the removing the jumpers from the speaker terminals isolate the crossovers but that's it.

1) First of, it should be noted that speaker A and speaker B terminals are not seperate channels as incorreclty assumed by the author. They are in fact parallel taps of the output stage. So the output stage see's the speaker in its entirety, both woofer and tweeter when biwired.
2) Furthermore, the amplifier output sends full bandwidth signals across the speaker terminals because its both physically and electrically the same output stage. It cannot send different signal bandwidths from the receivers speaker terminals as they are connected electrically and physically across the same output stage.

"The situation is such that when the full range musical signal is applied to the terminals of a full-range speaker system, the woofer only gets sent low frequency signals, and the tweeter only gets sent high frequency signals. Once the crossover networks have been electrically separated, they still continue to function in the same manner, having a low impedance in their passband of application. This means that if separate speaker cables are hooked up for the woofer and it's portion of the network, and the tweeter, and it's portion of the network, not only have the speakers and the frequency's directed and divided for them, but the two separate speaker cables will now also carry different signals, the woofer cable mostly the lows, and the tweeter cable mostly the highs.

Once the highs and lows have been separated in this fashion, the strong current pulses and surges that a woofer demands when reproducing bass or drums will not interact with the delicate sounds of a flute or cymbal. The magnetic field of the low frequency signals cannot modulate or interfere with the highs, and to a lesser extent, the reverse is true. "
 
P

PENG

Audioholic Slumlord
This article is full of BS from the get go. I didn't make it past the first 4 paragraphs;

I agree that the removing the jumpers from the speaker terminals isolate the crossovers but that's it.

1) First of, it should be noted that speaker A and speaker B terminals are not seperate channels as incorreclty assumed by the author. They are in fact parallel taps of the output stage. So the output stage see's the speaker in its entirety, both woofer and tweeter when biwired.
Agree, if he assumed that then he assumed incorrectly.


2) Furthermore, the amplifier output sends full bandwidth signals across the speaker terminals because its both physically and electrically the same output stage. It cannot send different signal bandwidths from the receivers speaker terminals as they are connected electrically and physically across the same output stage.
I did not say the amp could send different signal bandwidths nor did I see the author (Jon Risch) of that article saying it. I am saying that the amp will send that same signal, but through two different pairs of cables in the bi-wire configuration, such that each pair would carry signals of different magnitude and different frequency spectrum. I understood that's what Jon was saying and he wasn't wrong on that, but I did not vouch for everything else he might have said. His claims on audible sound quality may in fact be considered BS, I also do not believe there is audible difference.

The vector sum of the currents in the two pair of cables will equal the current that would have flowed in the one pair of cables in the non bi-wire configuration so yes as far as the amp is concern it is sending the very same signal/current overall. We are both EE so we both know Kirchoff's law, superposition theorem, Norton's theorem and Thevenin's theorm, aside from Ohm's law. So we should both know that just because two pairs of cables are connected to the same amp output terminals does not mean the currents flow in both pairs will be the same.

My post was directed towards Alexandre's, see post# 24 and I did quote the part where he asked:

"maybe I misread but he's talking about 2 cables connected to the same amp outputs and therefore I don't see how the 2 separate pairs of bindings on the speaker could possibly receive different signal."

but then I might have misunderstood his points too lol.
 
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Alexandre

Alexandre

Audioholic
Wow! I go hike in Yosemite for three days and when I come back, the thread's gone wild!

To be clear, I believe I understood 3db's sarcasm and disbelief in the original post.

I do software, not EE (and I studied chemistry and CS in school so that doesn't help much ;) so I did not realize what Peng said, that the current in the 2 cables would not be identical.

Interesting, now I guess I should go read about those laws you're both referring to. :)
 
3db

3db

Audioholic Slumlord
Wow! I go hike in Yosemite for three days and when I come back, the thread's gone wild!

To be clear, I believe I understood 3db's sarcasm and disbelief in the original post.

I do software, not EE (and I studied chemistry and CS in school so that doesn't help much ;) so I did not realize what Peng said, that the current in the 2 cables would not be identical.

Interesting, now I guess I should go read about those laws you're both referring to. :)
You went to Yosemite??? Lucky b?stard. :) How was it?
 
T

Tom._White

Enthusiast
I know what you mean. I battled him for years before coming here. Bizarre beliefs for an EE. :eek:
I remember you from that forum as well. I used to get a bit of a "kick" out of you two, and others, going about your "debates". Never posted much there. Too many people forgot music is about enjoyment.
 
mtrycrafts

mtrycrafts

Seriously, I have no life.
I remember you from that forum as well. I used to get a bit of a "kick" out of you two, and others, going about your "debates". Never posted much there. Too many people forgot music is about enjoyment.
Hard to debate enjoyment. ;) :D
 
3db

3db

Audioholic Slumlord
The first link is probabally the most important link to show why the transmission line model does not work in audio frequencies.

http://www.allaboutcircuits.com/text...mission-lines/

Basically, it has to do with cable lengths or what the article describes as electrically long or electrically short. If our interconnects and speaker cables approached the quarter wave length of the highest audio frequency, then that cable would be considered electrically long. Do get an idea how long this, I punched in 20 KHz into the calculator in this link; http://www.1728.org/freqwave.htm and I got an electrical wavelength (not an acoustic wavelength) to be 1.4999 e^4 meters or 14.999 kilometers. To meet the minimum requirement for "electrically long", divide this by 4 to get our quarter wavelength definition which will be 3.75 Km. Based on these numbers, it would be safe to say that most of us have speaker cables that are electrically short.

In an electrically short cable, the voltage/current is considered constant through out the length of the cable at a given instant in time. The voltage/current does vary with time but if one could freeze time and take out a voltage meter and measure along the cable length, one would get the same reading along any point on the cable. This means that the amplifier doesn't see the affects of the capacitance or inductance of the cable but it does see the resistance of the cable and the load attached to the end of the cable. This resistance is relatively small compared to the speaker and can be ignored if appropriately sized for the cable run length and the power its expected to carry.

Its stands to reason then that if the effects of the speaker cable is invisible (except for resistance) to the amplifier, then any wire would work and there would be no difference in sound.


I know the original post was brought up as a joke by Gene to show how lunacy prevails in audio. I thought I would post this here anyway since it does deal with cables and sound.
 
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