Are dedicated phono cables generally much different from shielded RCA interconnects in their construction?
Would I probably go in the wrong direction if I was to replace my phono cable with a good quality shielded RCA?
Are dedicated phono cables generally much different from shielded RCA interconnects in their construction?
Dedicated phono cables sometimes come with a ground wire attached. Other than that, I have found no difference. As with any cable, sound quality will vary depending on the cable and your tastes.
Personally, I opted for high-quality RCA cables and a separate ground wire made of 24awg solid core wire cut to length and stripped on both ends.
As I noted elsewhere on this forum, I had my FM tuner and iPad connected to my GainCell DAC with very, very cheap RCA cords—I believe the tuner was on a drug store/grocery store cheapo, and the iPad (streaming Idagio) was on a RadioShack cord. I replaced them with Adioquest Evergreens and my wife was the first to be astounded. She recognized a brighter high end, a wider range and a much better rendering of soft notes. She especially noticed a huge improvement in spoken content—announcers, news etc. I heard a richer sound, better balance and more detail.
+1 to comment above.
In particular, if you are using an MM phono cartridge, lower cable capacitance can be beneficial.
I swapped my 52pf / m (3.3ft) Supra phono cables to the 240 pf / m Zu Gede for a test and, well, the results were abysmal, and yes, I have an MM cartridge.
For my VPI Classic, I use Iconoclast OCC RCA cables with great results. I’ve tried some “phono” specific cables and they were a net loss in sq, so I returned them.
Phono cable need to do a few conflicting things and are not ideally RF proper cable if made for true analog applications.
-) first and probably the most important is to make sure that the outer “shield” (really a ground the way we use the cabkle for audio) needs to be a very low DCR to offset the wire we stick into the ground system. That wire DCR creates a ground imbalance that causes, you guessed it, hum. Look for a really low DCR outer shield. If it hums too much we can’t use it no matter how good it is anywhere else.
-) the cable also needs to address cartridge loading AND Vp linearity. The equation for Vp linearity suggests capacitance and resistance need to be managed. If we lower capacitance and/or resistance it hurts Vp linearity and this means we need to look at the center wire resistance for some help as a low capacitance is better for cartridge loading. This is why the better phono cables have a low capacitance for cartridge loading, but also need a HIGH DCR signal wire (smaller AWG) to improve signal coherence. It is a combination of R and C to get Vp linearity working well.
-) RCA phono is not a transmission line, so an “impedance” isn’t really important except that higher RF impedance cables have lower capacitance at audio, as the capacitance is the same at RF and audio once it is designed in. Low capacitance (indirectly the impedance at RF) by itself isn’t the “sound” of the cable. The center wire design has to be proper for analog, too. This separates a phono cable from a RF coaxial cable that has to maintain a do/di ratio between the inside shield dimension and the center wire size with a fixed capacitance that changes the insulation size requirement to meet an RF impedance.
If you want to know about RF, and why we have what we do for audio it is because we design to specific RATIO properties to get RF impedances, and we usually are stuck with them for analog. It isn’t most proper, but it will do most of the time as it is economical to use mass produced cable.
Go to cable a catalog, and look at the RATIO of the center wire size and insulation dimension with a FIXED dielectric size (that sets the capacitance and Velocity) and you’ll see that the ratio of the conductor to insulation size is always a fixed ratio at a given RF impedance for a RG59, 6 or 11 as an example. If I know the ratio of cable “A” I can change the attenuation at RF (add more wire surface area with a larger wire) by increasing the wire size and hold the same RATIO of insulation diameter to wire size. That will be the same impedance at RF.
The capacitance and Velocity can CHANGE as impedance at RF is Zo=101670/(C*V). We have a FACTOR constant in the denominator for a given impedance.
If we change the dielectric material and hold the same dimension, we also change C and V. They offset one another. Velocity is 1/ SQRT(e). The dielectric constant determines the capacitance. No different than the material between the metal plates of a capacitor changes said capacitance. A cable is a capacitor.
If we improve the “C” (make it lower) we INCREASE the Vp (decrease the dielectric constant to make it better) but the two are multiplied together and we rob Peter top pay Paul in the impedance equation. The RF impedance doesn’t change if the two are the same factor in the denominator.
All that is RF, thought, It isn’t important at analog frequencies. A factor here or there may be the same, but it isn’t by DESIGN. Two straight lines with a different slope will intersect somewhere after all but that doesn’t mean they are the same line when that point is reached, it is just a mathamatical coincidence.
All the differences for coaxial RF verses analog coaxial cable are in the math and known equations that describe the analog and RF electromagnetic properties. The argument, even at RF, is how good does it need to be for a given application? The math isn’t the problem. Better is better and that’s that but when and how much better is necessary?
This is why I think there could be some merit in Van den Hul’s carbon and recently, carbon nanotube conductors. High DCR, no drawbacks of copper or any metal for that matter.
Sure, Carbon nano tubes have no draw back because they are new, really? Proof is in the measurements not how new a material is. Why is metal a problem? Metal’s aren’t new enough?
We have a terrible trained bias to what isn’t “new”. We need to temper that away and evalute what’s on the table based on performance, new or old.
Metals are “problematic” because of grain structure mainly, I think. The best metal conductor will have to be very pure OCC, cryogenically treated…
Any copper oxide boundaries in a copper conductor will create distortion through rectification… All that.
I’m not touting carbon nanotube because it’s new. It sure has its own drawbacks, but not the ones of metal.
Show the facts that back up what you’ve just said.You’re repeating the analog audiophile mantra hook line and sinker with no proof other than an agreeable majority that wish it to be true, so it is gas lighted to be a “fact” and it isn’t.
How are you going to control the Vp differential with no DCR? Raise capacitance such that the T=RC time constant distortion is awful? The Vp differential equation is now untrue if it negates the advantage of a zero DCR material? DCR is always bad or worse than Vp linearity?
We test lower resistivity with fewer grains and altered tensile and elongation values of different copper. There is ZERO evidence of the so called diode effect on the B or E field in the time domain. None. The EM field is outside the wire ninety degrees opposed to the magnetic field in the wire. Which field is first? What one wags the tail of the dog?
The absolute proof of resistivity changes aren’t currently defined to either field. You don’t get to fill in the blank with a theory and claim it is now, “the reason” it is happening since no one can say you are wrong (or right).
Ask yourself some easy questions. What copper is in the devices you use? What’s the solder doing? What are all the wires on the components doing and what are they made of and on and on. We have factual test data that shows it is doing really well, all of it. Not perfect, but factually pretty good.
The drawbacks you say copper has aren’t valid, and certainly can’t be considered “worse” than a carbon nano tube just because a carbon nanotube is “new”.
We need to considered advances in design and materials on true, and repeatable tested facts and performance criteria. Until then, all you have is options that are yet to be understood…and most with no actual tested differences to determine that tertiary and underlying properties have changed. What are they? How did they change the EM wave?
I’m fine with actual tested differences that aren’t explained and left scientifically unexplained. The CHANGE has to be repeatably real and leave proof we are looking for something that caused the change(s). No answers to a phenomena doesn’t mean applying and saying a popular “solution” is true before one is proven. Best to leave the options open and immaterially add to each column as we go. That’s science. It never stops. We add new information to the old as well as the new over time and that can shift the best case and most accepted current solution. Nothing is ever considered “solved” but it is supported with evidence, not gas lighted majority opinion. Real solution aren’t driven from a false premise except to isolate all that are left. I little thought can determine which ones to start with, not necessarilly remove less likely ones from the list.
True differences in cable are fine. They remain constant no matter who does the tests. How we hear the changes is a tough nut to crack but we are working with actual differences. No matter who listens, the verifiable differences don’t change.
I genuinely did think that, for example, copper oxide boundary rectification is a real, verified form of distortion. It’s been said to be and I might have been misled.
And it’s not like I know much about carbon nanotube! I know that Van den Hul now makes cabling out of it and it’s VERY high DCR. I’m sure it has its unique effect on the sound in the end, but its properties, I don’t know. I’m just interested.
Grain boundaries aren’t copper oxide coated or the DCR would be WAY worse than it is. We measure resistivity as the “distortion”.
Grain boundaries in metals usually increase electrical resistivity due to their different atomic arrangement compared to the grain interior. And the exact mechanism isn’t well understood which really means it isn’t at all. We can see the atomic differences, not the reason it has the effect on resistivity that is indeed changing.
Nanotubes are VERY temperature resistance mapped, like copper and change resistance based on the twist in the nanotube and aren’t low resistance by default. They are pretty problamatic at how they work consistently. Temperatures and the structure of the nanotube change everything.
For MM frequency response is highly depedent on loading. Cable capacitance is super important. You need shielding but that’s a given.
No there is no carbon oxide grain boundary rectification. The voltage along a whole cable is millivolts. At grain boundaries microvolts or nanovolts.
When you discover a diode effect that works at nanovolts be sure to patent it. It will be worth 10’s of $millions, probably more.
Well, we need to determine the SN ratio and THEN we can decide if a shield is needed in a perfect world. Since we don’t have that ability and RCA unbalanced needs a “return” anyway, may as well incorporate the shield at the same time.
XLR can have CUB, Capacitance UnBalance, to some extent (each leg isn’t 100% the same) and if the electric interference field is large enough, we may need to knock it down with an external shield before the twisted pairs CMRR balance does it’s magic.
UTP, Unshielded Twisted Pair, etherent work great in facory settings and no outer shields! Wow, it right. The technology is really good. If we shield that same cable, internal electrical cross talk gets WORSE by 6 dB on average, not better. , The noise we are shielding need to offset that increased internal crosstalk to be a net gain in performance.
We can alter the UTP design to gain back some of the NEXT lost from the shield, and even the increased impedance unifirmity that is also lost with a closwer ground plane and also attenuation but, that takes $$$ to do. All things the same, a UTP will exceed a ScTP cable’s electrical measure and BW UNLESS we have severe electrical interference and I do mean severe.
We can take a design to extreme to offset shielding and this is the CAT7 or CAT8 ISTP design. We offset higher attenuation and RL caused by shielding with a 22 AWG design. IBM even went farther and made it a 150-ohm impedance to FURTHER lower attenuation. The lowest impedance for attenuation is 77-ohm with a coaxial. Two in parallel is twice that impedance or 154 ohms. OK, we round it in practice to 75 and 150 ohm. The 22 AWG wire gets back that lost signal attenuation by brute force is the trick. The FOAMED dielectric also helps. The dielectric is thick enough we can move away from SOLID to FOAM and get some more attenuation improvements. It all adds up.
Next thing we shield each pair so internal NEXT is 80 or more dB down, Yes, this impacts impedance uniformity as the shield is on each pair increasing Return Loss, RL, but…we have that 22 AWG wire to keep atenuation in check. RL is another form of attenuation or less signal getting to the load. Now we add an outer shield to boot over the four shielded pairs. Yep, a killer cable that is really expensive to use, though.
The advantage, was when CAT7 ISTP was developed. kind of in parallel with the IBM 150-ohm type II design, it was WAY future proofed. Those that installed CAT7 can run CAT3 to 4 to 5 to 5e to 6 to 6e, 2.5G to 5G and 10G with the same cable! That in the end paid the higher upfront cost if the cable was installed earlier enough.
Shields can be a help for sure, but you need to REALLY pay attention to the signal verses the noise to take the plunge that it is always a benefit, It isn’t.
If I didn’t use a turntable or external phono amp (my system has an internal one) I wouldn’t have any RCA cables. As it is, I do, so I have two RCA cables, from a m/m cartridge to the phono amp and another one from the phono amp to the main amp.
The tonearm one is a standard Jelco thing that I bought with a Jelco arm about 10 years ago. I was thinking of an upgrade. I can easily get a loan item. I would like to try and follow your explanation, but I don’t know what DCR is, or for that matter Vp or T=RC. So I didn’t get very far.
Tonearm cables seem to go through the same precious metals bull/s (copper, silver, gold, unobtanium, etc.) as other cables, which I’ve never indulged in and hopefully never will.
Is there a layman’s explanation as to what to look for in a tonearm cable?
p.s. the cartridge is 2.3mV output and it only has to be about 0.75m.
This can be confusing, I agree.
A tone arm cable is a voltage signal, not much current at all as you point out. A speaker cable has a LOT of current so we consider INDUCTANCE that impedes current changes as the primary form of distortion.
For your turntable, we want to reduce CAPACITANCE as that is what distorts VOLTAGE signals. It slows down how fast they go up, and then drop back down.
To add to the confusion, a cartridge is a resonance circuit. The higher frequencies response is changed by the loading. The loading is the capacitance and resistance.
Fortunately, for MM type cartridges the cable capacitance is low enough that we USUALLY need to ADD capacitance so the cartridge response is FLAT. The specs will tell you the total resistive or capacitive LOAD. The total load includes the cable plus the head-amps settings. The cable resistance and capacitance by itself is low enough to be inconsequential to the cartridge loading.
What the cable design does, is adjusts the center wire resistance so the distortion caused by the cable’s inherint Vp non linearity is smoothed out as best we can. This is done by adjusting the center wire and cable capacitance, both.
Since we want low cable capacitance, we make that cartridge requirement adjustment in the phono amp. For total resistance we ADD the cable’s signal wire RESISTANCE and that is pretty low in a short cable. For all practicle purposes, the cable resistance is nearly “zero”.
Does the wire material matter? No, not so much as long as it is a reasonable conductor, Gold, copper or silver. To get the DCR we need to adjust the Vp response, the wire size would be different for all three metals to get the same DCR that is needed. The Vp equation doesn’t care what the metal is, just the DCR and capacitance your design. Of course, the cost varies.
Some will suggest differences in the sounds patina between the metals due to the grains in each metal (size and number) but there isn’t a reliable metric to describe those differences. You just have to try them.
We use for 30 AWG wires to best align the Vp linerity and keep capacitance low @ 17.5 pF/foot. Could we go lower? Yes, but that would change the Vp linearity and this makes a bigger change in the sound than the lower cap improves it so we keep the slightly higher capacitance. Remember, we actuallt need to ADD capacitance to make our cartridge FLAT over and above the leads total capacitance.
EXAMPLE - I use a SUMIKO high output MC that needs 100 pF to 200 pF to be flat. The leads add SOME capacitance so I use the 100 pF setting and that sets the TOTAL capacitrance to somewhere between 100 and 200 pF.
MC cartridges use the RESISTANCE to tune the response. Here the cable is nearly the center wire value in a LOOP DCR test. The braid is basically zero it is so heafty, so in the loop we see the BULK DCR is essentially the center wire. But, this is still too low to properly tune most MC cartridges. They need 100 ohm or so in the head amp + cable to have the flatest resoponse.
EXAMPLE - A Benz Ruby Z MC need greater than 400 ohms loading to be flattest. The cable 30 AWG wires can’t get any where near that high so we need to dial in some more at the head amp.
SUMMARY - the cable is designed to lower Vp linearity as best we can. The head amp is still needed to set the capacitance (MM) or resistance (MC) to get the flattest response. The signal wire material can vary to optimize the calculated Vp linearity (get the transmission speeds closer to the same at all frequencies).
The sound of the wire itself needs to be evaluated as we can’t really “test” that aspect at all like we can the cartridges frequency response with different loadings, that we can do. Use the manufacturer’s recommendations for those loading values.
We use copper for the value and a small 30 AWG size to adjust the Vp linearity. Use the series II ANALOG design for turntable leads. The series I with a single solid wire is DIGITAL.
If there are spots that are still confusing…let me know and we can get you up to speed. There are also some real good web sites that go through cartridge loading for MC and MM cartridges. I have one of each.
Thanks Galen, I sort of think I followed some of that, but I’ve got what seems like heavy flu that turns out to be Covid, plus earache, and my brain is not functioning well, not that it ever does.
You get back to DCR without saying what it is, but it seems I should look for a 30awg wire with low capacitance for my 2.3mV (moving iron) cartridge.
I had a look and there is a lot of b/s about metals and connection plugs, but few if any basic measurements.
What brand are the series II ANALOG ?
@stevensegal, so sorry to learn of your COVID bout. Hoping for a speedy recovery. My wife speaking with staff members in Herefordshire, noted that they mentioned a COVID outbreak there as well with two out unfortunately. Best of health to you Steven.