Thank you to Vern and Luca and to all. A safe, warm and Merry Christmas to all!!
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Today I have roughly 12 hours of mostly continuous listening to '70’s rock and still no fatigue.
Amazing to me that a wire can make the icing on the cake. Or maybe the wire IS the cake!
Merry Christmas Everyone!
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I second that emotion. My Gen Il SPTPC’s have settled in as well has the new DAC MkII. It was a bit of a roller coaster for a couple weeks (strident highs at times) but things seem good right now. Back to listening to music rather than judging the gear. A happy place.
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It is really satisfying to be able to just listen to the music instead of wondering what if. . .
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There were less comments on SPTPC series 2 than they deserve. So much great new gear showed up the last two months. Glad to hear yours sorted early the SPTPC series 2 broke In quickly. The synergy with the modded DS is a beautiful listen. Enjoy the music!
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It’s funny how you struggle with decisions, fuss things around here and there, move this and that a few mm, and then the key piece of the puzzle goes into place either by design or accident.
It is a case of the result being more than the sum of the parts.
Sound playback is certainly a strange thing and this feels like the first time I have it “right”. I am not nearly the tweaker as many here for a couple of different reasons. The main reason that is I cant tell the difference between many of the tweaks in or out of the system. Another reason is that I have some vision problems that make it difficult to deal with small bits and pieces.
Some tweaks I leave in place just because they “did no harm” and it doesn’t seem worth the effort to remove them. Others go into the bin of AV leftovers with no chance of seeing the light of day again.
I think this lack of perception on my part is a good thing. It keeps me out of the expensive tweaks that have almost no resale value if they dont get the expected results.
This last cable swap however was a sonic fidelity game changer.
Enjoy your Holiday!
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I know precisely what you mean and sometimes/often times maybe find myself in the same situation. One thing I tell myself, however, is that while each of these tweaks may not be discernable individually taken all together they may be.
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Well said. I have had similar experiences.
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As long as you can keep saying, “my system has never sounded better”, then the tweaks and fiddling are worthwhile in my view.
Cheers.
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We are proud to announce the latest addition to the Iconoclast/BAV family of products. This is a “very special” SPDIF cable. I don’t want to disclose too much but I believe that it will be the best sounding SPDIF cable you have ever listened to, at any cost.
True 75 Ohm - 12G-SDI - RCA terminated
Blue or Grey TechFlex
Please send me a note if you want to try one and see what we can do😊! You will be “shocked!”
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Interesting, Bob. But how can it be a True 75 Ohms? The characteristic impedance of an RCA connector is not 75 Ohms. 
Tony, my information is straight from the Tech Data sheet provided by Belden. The cord for our BAV SPDIF is a Belden "silver plated, RG-6, “75 Ohm,” 18 AWG coaxial cable. This is a plenum variant so that it utilizes an FEP insulation. If replacing the more commonly seen on a coaxial cable “F-connector” with an RCA connector significantly affects the impedance at RF then I don’t have a value for the finished product.
SPDIF is a/the standard and most SPDIF inputs on components are RCA. I can only assume this is as close to being a true 75 Ohm cable as you are going to get for providing a SPDIF connection to most components. In fact, I have never personally seen an F-connector/F-81 type connector on the back of an audiophile component in an audio application. I can assure you that the cord is a “true” 75 Ohm cable.
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Tony,
Yep, we know that RCA isn’t 75-ohm…
Also, the “line” from the innards of your equipment to the PC board has to be a 75-ohm line, too, and all that stops at a 75 ohm resistor at RF. RF impedance is SQRT (L/C) and the reactance angles cancel at RF leaving a whole number in the resistive vector for impedance.
We can’t redesign the equipment and what is on it, and how it is designed inside.
Best,
Galen
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What color is the jacket without the TechFlex?
I have no doubt about the cable, Bob. We used RG-6 all over the place in our military stuff back in the day. Terminated in BNC. I was just remarking on the terminology in the message. Some folks may take it to apply to the connectorized cable.
Good Morning, the cord is black. The TechFlex is very tight to the cord and looks great.
As mentioned in the article, the Canare RCA really does a great job at getting close to a 75Ohm plug because the signal travels on the cable conductor most of the distance of the plug. It’s an ideal design for digital applications. Of course if your equipment does use BNC connectors I can absolutely use those with this same cable, I just sent RCA terminated stuff to Bob for demo purposes. Remember here at BJC/Iconoclast, it’s all built to order and always has been!
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What’s the pricing on these and can you do a BNC if I needed one at some point ?
We are still working on the pricing. As mentioned in my previous post, I can terminate with BNC connectors.
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RCA don’t have the same Do/Di ratio all the way through the plug, and why they aren’t 75 ohm. The distance from the surface of the center conductor pin to the inside surface of the shield determine the through impedance, and RCA connectors change that ratio.
The RCA resets to the connectors center pin, not the cables conductor, to the inside surface of the outer compression barrel’s inside surface and not the inside surface of the cable shield. Not all RCA are even mechanically the same dimensions so we have that, too.
This impedance variation doesn’t impact RCA’s use as intended for low frequency analog, but go high enough into RF and it will generate return loss reflections of much higher measure than a proper connector designed for RF. This will limit the distance before we hit the BER, bit error rate, due to signal distortion compared to a true RF design 75-ohm connector.
The good news is the typical LENGTH is short, so we still have a large ACR, attenuation to cross talk, level that keeps the signal well above the noise even with less than ideal RF impedance. Some of that perfection is traded away for an easier connector for consumers to use.
People talk about impedance matching but what is really happening, anyway? Most don’t really know. Let’s assume we want to go as far as we can…and take a look at the signal loss due to both return loss, RL, and structural return loss, SRL.
Return loss is measured into an exct 75-ohm resistive load. Ideal RF looks purely resistive because the SQRT (L/C) is impedance, and the L and C reactance are equal and opposite so we have a pure resistance vector defining IMPEDANCE.
SRL is different. It MOVES the load resistance until we see the lowest RL reflection. This can tell you how perfect the structure is, but the intended impedance is missing the 75-ohm mark.
Below is a PLOT of 401 points of a twin axial Ethernet cable. What does this tell us?
The points are swept from 1 MHz to 100 MHz (this is a 5e 100 MHz design). The X-axis is the reflection magnitude in dB. The vertical axis is the impedance associated with thew RL (we use a FIXED 100 ohm resistor in this case).
What we need to see, is we can have 100-ohms (all the value across the 100-ohm line) at different RL values. Why? Because the 100-ohm value of real cable isn’t exactly 100-ohm, we have a reactance vector that is still 100-ohms, but it has an angle (reactance) attached.
The value approaching -60 dB and 100-ohm is the most resistive vector. Values to the right approaching -10 dB are the most reactive impedance vectors and have the worst reflections.
But also notice, we can have SEVERAL impedance with the SAME RL! How? Look at the -30 dB RL as reference point and see that we have impedance values well above and below 100-ohm. A more “resistive” 909-ohm cable can have the same or better RL than a reactive 100-ohm cable at a specific frequency.
The final RL reflections aren’t always best at 100-ohms due to the effect of the real to imaginary components, and thus we can’t always say a 100-ohm cable is “better” unless we know it is more RESISTIVE than a comparative cable and across the frequency range we want to use.
In the example, we can see a cable at -30 dB RL is from 108 ohm to 95 ohm. Across that range all the cables have the same RL. We could add a third axis to include FREQUENCY to add even more complexity.
When you look at two cables just the impedance doesn’t tell you much. This is where variable loads (SRL) come in. The load is varied to maximize the signal transfer and it may be above or below the intended resistive impedance. There are circuits that allow tuning this load to each cable attached to get the most out of the termination.
Best,
Galen
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