Transparent Audio Cable Network Boxes

Ron Resnick · Dec 10, 2017

Transparent Audio's website says that the network boxes control high-frequency roll-off, attenuate radio frequency noise, and alter the capacitance and inductance of the cable to account for changes in these parameters as the length of the cable changes.

http://www.transparentcable.com/design/audio_cable_networks2.php?catID=1&modCAT=1

Do the Transparent Audio network boxes also change the impedance a receiving component sees at its input?

Do the network boxes also somehow better match the output impedance of a sending component (such as a phono pre-amp) and the input impedance of a receiving component (such as an amplifier)?

microstrip · Dec 10, 2017

Ron Resnick said:
Transparent Audio's website says that the network boxes control high-frequency roll-off, attenuate radio frequency noise, and alter the capacitance and inductance of the cable to account for changes in these parameters as the length of the cable changes.

http://www.transparentcable.com/design/audio_cable_networks2.php?catID=1&modCAT=1

Do the Transparent Audio network boxes also change the impedance a receiving component sees at its input?

Although the question is not very clear I would say no.

Ron Resnick said:
Do the network boxes also somehow better match the output impedance of a sending component (such as a phono pre-amp) and the input impedance of a receiving component (such as an amplifier)?

Unfortunately no. You would need a transformer to better match impedance.

Empirical Audio · Dec 10, 2017

Ron Resnick said:
Transparent Audio's website says that the network boxes control high-frequency roll-off, attenuate radio frequency noise, and alter the capacitance and inductance of the cable to account for changes in these parameters as the length of the cable changes.

http://www.transparentcable.com/design/audio_cable_networks2.php?catID=1&modCAT=1

Do the Transparent Audio network boxes also change the input impedance a receiving component sees at its input?

Do the network boxes also somehow better match the output impedance of a sending component (such as a phono pre-amp) and the input impedance of a receiving component (such as an amplifier)?

Having designed speaker cables with these sorts of devices, but not knowing exactly what is in their boxes:

The speaker impedance is usually around 4-20 ohms. These devices will not change that significantly. It will have no effect on this.

The output impedance of the amplifier driver is not "matched" to the input impedance of the speaker by these passive components. The kind of "matching" your are suggesting is not relevant. The best scenario is 0 ohms output impedance and a reasonably high speaker impedance, like 4-10 ohms.

I can tell you what my "Black Boxes" do, but I will not divulge what is in the box. Some, and usually the best speaker cables have high-Q characteristics (high-Q means it will ring like a bell when stimulated with a HF transient). These types of cables are usually very low in inductance and resistance.

Transients in the music will cause reflections and standing waves on such a cable. The transients in the music are relatively low frequency compared to the HF effects in the cable, but they still occur. This is kind of like hitting a bell with a hammer made of rubber or soft wood. It still rings, but not as loud as if you hit it with a piece of metal. The hammer is the music and the bell is the cable.

To squelch this ringing, some manufacturers put filters and HF attenuator circuits in their cables. This works, but also impacts audio quality by rolling-off highs or affecting transients. The real solution to this is a "tuned" circuit that nulls out the reflection without impacting the audio frequency range. This is what is used in a transmission-line that is properly terminated. The termination kills the reflections usually by absorbing them. As far as I know, most manufacturers don't understand the transmission-line effects, so their solutions are useful, but not optimal. There is generally a sacrifice in SQ for reducing this effect.

Why do we care about reflected energy on the speaker cable? Because it drives transient current back into the driver, it can cause the driver to behave non-linearly. This can be audible.

Steve N.
Empirical Audio

jfrech · Dec 11, 2017

Ron Resnick said:
Transparent Audio's website says that the network boxes control high-frequency roll-off, attenuate radio frequency noise, and alter the capacitance and inductance of the cable to account for changes in these parameters as the length of the cable changes.

http://www.transparentcable.com/design/audio_cable_networks2.php?catID=1&modCAT=1

Do the Transparent Audio network boxes also change the impedance a receiving component sees at its input?

Do the network boxes also somehow better match the output impedance of a sending component (such as a phono pre-amp) and the input impedance of a receiving component (such as an amplifier)?

I wish I could answer your questions directly. All I can say is that if you get a new component that has a different impedance and get the cable tuned, it makes a significant difference in sound quality. This is not subtle either. For example, I had Lyra Atlas (~4.2 ohms) and switched to a Clear Audio Goldfinger Statement (~50 ohms) Sending the tonearm cable back yields substantial improvements in bass textures, detail retrieval, timbres and just over all enjoyment.

LL21 · Dec 11, 2017

Empirical Audio said:
Having designed speaker cables with these sorts of devices, but not knowing exactly what is in their boxes:

The speaker impedance is usually around 4-20 ohms. These devices will not change that significantly. It will have no effect on this.

The output impedance of the amplifier driver is not "matched" to the input impedance of the speaker by these passive components. The kind of "matching" your are suggesting is not relevant. The best scenario is 0 ohms output impedance and a reasonably high speaker impedance, like 4-10 ohms.

I can tell you what my "Black Boxes" do, but I will not divulge what is in the box. Some, and usually the best speaker cables have high-Q characteristics (high-Q means it will ring like a bell when stimulated with a HF transient). These types of cables are usually very low in inductance and resistance.

Transients in the music will cause reflections and standing waves on such a cable. The transients in the music are relatively low frequency compared to the HF effects in the cable, but they still occur. This is kind of like hitting a bell with a hammer made of rubber or soft wood. It still rings, but not as loud as if you hit it with a piece of metal. The hammer is the music and the bell is the cable.

To squelch this ringing, some manufacturers put filters and HF attenuator circuits in their cables. This works, but also impacts audio quality by rolling-off highs or affecting transients. The real solution to this is a "tuned" circuit that nulls out the reflection without impacting the audio frequency range. This is what is used in a transmission-line that is properly terminated. The termination kills the reflections usually by absorbing them. As far as I know, most manufacturers don't understand the transmission-line effects, so their solutions are useful, but not optimal. There is generally a sacrifice in SQ for reducing this effect.

Why do we care about reflected energy on the speaker cable? Because it drives transient current back into the driver, it can cause the driver to behave non-linearly. This can be audible.

Steve N.
Empirical Audio

Thanks for taking the time write this...very interesting reading.

cjf · Dec 13, 2017

Ron Resnick said:
Transparent Audio's website says that the network boxes control high-frequency roll-off, attenuate radio frequency noise, and alter the capacitance and inductance of the cable to account for changes in these parameters as the length of the cable changes.

http://www.transparentcable.com/design/audio_cable_networks2.php?catID=1&modCAT=1

Do the Transparent Audio network boxes also change the impedance a receiving component sees at its input?

Do the network boxes also somehow better match the output impedance of a sending component (such as a phono pre-amp) and the input impedance of a receiving component (such as an amplifier)?

Its been my understanding that many cables who use a network box are attempting to match the Characteristic Impedance of the cable with that of the speaker or fill in the blank with other component here. The theory in doing so, is that the cable then appears to be of infinite length which results in any and all "reflections" And other nasty stuff being absorbed and the resistance being reduced to almost nothing.

So they say. Its a pretty interesting topic when you start going down the rabbit hole and some will say Transmission Line theory doesn't apply for audio purposes.

BruceD · Dec 13, 2017

This thread harkens one back to the time when Corey Greenberg cut the Boxes open--interesting what was inside--

Is Google still our friend?--

BruceD

Speedskater · Dec 13, 2017

It's not the task of an interconnect cable to act as a Low Pass filter for interference. That's part of the input circuit of any well designed component.

Empirical Audio · Dec 13, 2017

Speedskater said:
It's not the task of an interconnect cable to act as a Low Pass filter for interference. That's part of the input circuit of any well designed component.

It's not a low-pass filter. Its a transmission-line termination if it's done right. Transmission lines can be terminated at the source or destination. If you see a box in the middle of the cable, I would be suspicious.

Steve N .

microstrip · Dec 13, 2017

cjf said:
Its been my understanding that many cables who use a network box are attempting to match the Characteristic Impedance of the cable with that of the speaker or fill in the blank with other component here (...)

I don't think so. The only cable that I know about that tried to match the speaker impedance were Ocos and the WA cables by Lux Corp. They had a trick : the insulator was resistive , decreasing significantly the typical speaker cable impedance - 100 to 500 Ohms at 20 kHz - to around 8 ohms.

In the typical formulas we assume R infinite and Zo simplifies to Z0 = square-root (L/C)

BruceD · Dec 13, 2017

microstrip said:
I don't think so. The only cable that I know about that tried to match the speaker impedance were Ocos and the WA cables by Lux Corp. They had a trick : the insulator was resistive , decreasing significantly the typical speaker cable impedance - 100 to 500 Ohms at 20 kHz - to around 8 ohms.

In the typical formulas we assume R infinite and Zo simplifies to Z0 = square-root (L/C)

Aha!--so that is why my friends Scintillas sounded so good---his Ocos cabling --Interesting observation

BruceD

cjf · Dec 13, 2017

microstrip said:
I don't think so. The only cable that I know about that tried to match the speaker impedance were Ocos and the WA cables by Lux Corp. They had a trick : the insulator was resistive , decreasing significantly the typical speaker cable impedance - 100 to 500 Ohms at 20 kHz - to around 8 ohms.

In the typical formulas we assume R infinite and Zo simplifies to Z0 = square-root (L/C)

So what is your hypothesis of what the box is doing? Why else would they be asking for source and destination components involved when purchasing and then ask you to ship back the cables when changing the same equipment?

The Patent articles for MIT technology suggest as much at the minimum. I haven't even brought up the CVT Terminator Tech yet that both MIT and Transparent use.

microstrip · Dec 14, 2017

cjf said:
So what is your hypothesis of what the box is doing? Why else would they be asking for source and destination components involved when purchasing and then ask you to ship back the cables when changing the same equipment?

The Patent articles for MIT technology suggest as much at the minimum. I haven't even brought up the CVT Terminator Tech yet that both MIT and Transparent use.

Yes, patents are not supposed to tell us what is being done, but how it is done so no one can do it the same way.

We do not understand how a simple cable subjectively affects sound quality, except for extreme cases that result in measurable effects. If we are not able to explain simple devices, how can we think about finding an explanation for an object that adds complexity to a simple cable?

Speedskater · Dec 14, 2017

Empirical Audio said:
It's not a low-pass filter. Its a transmission-line termination if it's done right. Transmission lines can be terminated at the source or destination. If you see a box in the middle of the cable, I would be suspicious.
Steve N .

If a transmission line is done correctly, the source, the cable and the destination all have the same impedance. But we are not trying to send low distortion radio frequency signals from one analog component to another. So all we need is a Low Pass filter inside the receive end component.

Speedskater · Dec 14, 2017

microstrip said:
I don't think so. The only cable that I know about that tried to match the speaker impedance were Ocos and the WA cables by Lux Corp. They had a trick : the insulator was resistive , decreasing significantly the typical speaker cable impedance - 100 to 500 Ohms at 20 kHz - to around 8 ohms.

In the typical formulas we assume R infinite and Zo simplifies to Z0 = square-root (L/C)

Exactly, the common Radio Frequency Characteristic Impedance formula, is actually the short form formula. It's only good at frequencies near one megahertz and above. At audio frequencies a cable doesn't have a Characteristic Impedance, it's impedance is different at each frequency.

Speedskater · Dec 15, 2017

Thinking about it more. More likely RFI will enter a RCA input stage on the shield rather than the center conductor. Way too many hi-fi components have poorly designed RCA input stages that allow the RFI camel to get his nose into the tent.

Empirical Audio · Dec 15, 2017

Speedskater said:
If a transmission line is done correctly, the source, the cable and the destination all have the same impedance. But we are not trying to send low distortion radio frequency signals from one analog component to another. So all we need is a Low Pass filter inside the receive end component.

That is correct for RF frequencies, but we have a mixed bag here. There are ultrasonics and higher on the cable if its a high-Q cable. IME, it falls in-between and transmission-line and a low-frequency cable. There may be standing waves or reflections on the cable that may affect the driver or the perceived impedance, even though these anomalies are higher in frequency.

I have tried filters of different sizes and in different locations. I found it to be non-optimal to locate the "termination" near the destination. I also found that the optimal termination changes with the cable length.

If this were simply a filter, these affects would not occur.

Steve N.
Empirical Audio

Speedskater · Dec 15, 2017

Empirical Audio said:
That is correct for RF frequencies, but we have a mixed bag here.

Very true, an analog interconnect system will never function as a well behavied transmission line system at any frequency!

There are ultrasonics and higher on the cable if its a high-Q cable. IME, it falls in-between and transmission-line and a low-frequency cable. There may be standing waves or reflections on the cable that may affect the driver or the perceived impedance, even though these anomalies are higher in frequency.

How many hundreds of feet long are your cables? Even SP/DIF cables don't start acting as transmission lines until their length is over 30 feet. Lower frequencies don't have standing waves or reflections. Why? It's because their frequencies are too low. At these frequencies the signal voltage changes so slowly it doesn't reflect.

I have tried filters of different sizes and in different locations. I found it to be non-optimal to locate the "termination" near the destination. I also found that the optimal termination changes with the cable length.
If this were simply a filter, these affects would not occur.
Steve N.
Empirical Audio

Most likely the interconnects are acting as interference antennas and these terminations change the effective antenna length and sensitive interference frequency. But that won't stop them from being good antennas at some other interference frequency.

Empirical Audio · Dec 15, 2017

Speedskater said:
Even SP/DIF cables don't start acting as transmission lines until their length is over 30 feet. Lower frequencies don't have standing waves or reflections. Why? It's because their frequencies are too low. At these frequencies the signal voltage changes so slowly it doesn't reflect.

Reflections occur on my 1.5m S/PDIF cable, even if the impedance is matched. No transmission line is perfectly terminated. My risetimes are 400psec. There are harmonics up to several GHz. This is how I achieve 16psec of jitter. Very important to have low-loss cable and good impedance match. [/QUOTE]

Sablon Audio · Dec 16, 2017

Perhaps Kevin is presupposing the use of the correct bnc terminations rather than rca plugs / jacks that many manufacturers implausibly fit on their spdif implementations. I have compared identical 0.6m spdif cables with both bnc and rca terminations on the same equipment and the rca one sounded quite poor in comparison.

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