Cardas XLR connectors - how important is shielding anyway?

[Skwisgaar]

This is my first post here but I am not a newb.

My own rule of thumb is that if you can't buy the cable's parts in bulk for a DIY job, then it is probably a ripoff.

I recently stumbled across Cardas's XLR connectors. Functionality aside, they are almost worth buying simply for the bling factor.

They are marketed as being non-magnetic and shielded. It does occur to me that the Neutrik XLR connectors everyone uses are plastic.

I intend to plug these cables into a set of active near field monitors. Until recently I was using a Sony Trinitron, and when I cranked the speakers up to moderate volume, I found that the image did jiggle a bit. So, the notion that shielded XLR connectors may improve my sound does seam plausible.

I am currently using a set of Hosa cables, as a stopgap while I consider my optimal purchase.

What does everyone think of the potential worthiness of Cardas XLR's?

Btw, I have no intention of using any of Cardas's overpriced retail cables. It's the Crosslink or nothing.

 

[highfigh]

This is my first post here but I am not a newb.

My own rule of thumb is that if you can't buy the cable's parts in bulk for a DIY job, then it is probably a ripoff.

I recently stumbled across Cardas's XLR connectors. Functionality aside, they are almost worth buying simply for the bling factor.

They are marketed as being non-magnetic and shielded. It does occur to me that the Neutrik XLR connectors everyone uses are plastic.

I intend to plug these cables into a set of active near field monitors. Until recently I was using a Sony Trinitron, and when I cranked the speakers up to moderate volume, I found that the image did jiggle a bit. So, the notion that shielded XLR connectors may improve my sound does seam plausible.

I am currently using a set of Hosa cables, as a stopgap while I consider my optimal purchase.

What does everyone think of the potential worthiness of Cardas XLR's?

Btw, I have no intention of using any of Cardas's overpriced retail cables. It's the Crosslink or nothing.

The speakers aren't shielded, are they? Do you see any weird colors on the monitor, or is it just the jiggling? If the speakers draw a lot of current, the voltage to the TV may drop enough to affect the picture. I seriously doubt the audio cables are causing a problem for the TV and the shielding on audio/video cables is there to keep noise from entering, not leaving. The shield on balanced cables isn't carrying any signal.

 

[Skwisgaar]

The speakers aren't shielded, are they?

They are shielded.

Do you see any weird colors on the monitor, or is it just the jiggling?

Just jiggling. Switching to an LCD has eliminated the problem.

I seriously doubt the audio cables are causing a problem for the TV

You aren't following the logic at all. If the speakers can make the image on the screen jiggle, then by inference the speakers are causing EMI on the line level signal that is feeding them. XLR cables are shielded, but a typical XLR connector is not shielded. Neutrik makes heavy duty XLR connectors, but the housing is steel, which can be magnetized quite easily.

 

[highfigh]

They are shielded.

Just jiggling


You aren't following the logic at all. If the speakers can make the image on the screen jiggle, then by inference the speakers are causing EMI on the line level signal that is feeding them. XLR cables are shielded, but a typical XLR connector is not shielded. Neutrik makes heavy duty XLR connectors, but the housing is steel, which can be magnetized quite easily.

You say I'm not following the logic but you didn't include anything about having unplugged the audio cables from the speakers, or not. THAT would have been a logical test. Moving the TV would be another good test. If it's proximity, you'll see it quickly.

By 'jiggling', is the picture shrinking, top to bottom or is it a different direction? If it's top to bottom, it's usually a voltage issue, possibly a rectifier. My desktop monitor (CRT) goes nuts when my cell phone rings or I make a call.

I don't know that the metal cased XLR plugs will actually improve the sound (unless you actually hear noise that's being allowed to enter) but as long as the shell is grounded, it should make noise less of a problem in the event that you move the system to another location or er-arrange it. Are any of the power cords wrapped in a fairly tight coil? That can cause problems. I installed a subwoofer and when the power cord was moved close to the audio cable (or vise-versa), it hummed slightly and if I moved them apart, it was quiet. Since this was induced EMI and the sub amp's inputs are unbalanced, separation is a good solution.

A typical XLR plug DOES have a metal shell. I don't think I have used one that doesn't, in over 40 years of using them. The old ones were Switchcraft or Amphenol and the newer ones have been Neutrik or whatever they use on IXOS (a cable brand I used once- that will NEVER happen again).

 

[Skwisgaar]

By 'jiggling', is the picture shrinking, top to bottom or is it a different direction? If it's top to bottom, it's usually a voltage issue, possibly a rectifier.

It's top to bottom and it was volume level dependent. I didn't move anything until after I moved.

 

[highfigh]

It's top to bottom and it was volume level dependent. I didn't move anything until after I moved.

So, it shrinks/jiggles on hard bass notes and loud passages? Do you rent, or did you buy a house/condo? I would check the voltage- some areas have wild fluctuations and some houses/apartments/condos have electrical issues, like loose screws on the receptacles, receptacles that were "back-stabbed" (where the wires are poked into the small holes on the back, instead if using the screws to hold them in place) and in older buildings, aluminum wiring was used. If a screw is loose on anything between that receptacle and the breaker/fuse panel is loose and they wired the receptacles in series, this is a likely issue. You can check doe series wiring by turning off the main breaker or pulling the main fuse, disconnecting the hot at the closest receptacle to the panel in the room, turn the power on again and see if the rest of the room has power. If it's OK to the receptacle where you removed the wire but dead after, it's series wiring and this is the main reason parallel wiring of receptacles is preferred (this involves connecting the incoming/outgoing wires to each junction box and adding a pigtail for the receptacles in that box before making the connection with wire nuts).

 

[Skwisgaar]

So, it shrinks/jiggles on hard bass notes and loud passages?

I wasn't that careful in observation. I was thinking of the voume knob.

Do you rent, or did you buy a house/condo? I would check the voltage- some areas have wild fluctuations...

A brand new upscale apartment complex. I seriously doubt it has WWI era wiring.

The speakers were plugged into the voltage regulation only receptacles on a UPS. The CRT was plugged into a battery backed receptacle on the same device.

The speakers draw some power even when not in use. And yet there was never a problem then, or at low volume.

What makes a better basis for an RCA->XLR cable? An unbalanced or a balanced cable?

 

[highfigh]

A brand new upscale apartment complex. I seriously doubt it has WWI era wiring.

The speakers were plugged into the voltage regulation only receptacles on a UPS. The CRT was plugged into a battery backed receptacle on the same device.

The speakers draw some power even when not in use. And yet there was never a problem then, or at low volume.

What makes a better basis for an RCA->XLR cable? An unbalanced or a balanced cable?

Actually, aluminum wiring was used until the '70s in residential and if you look at the cabling from pole to pole, it's usually aluminum because of the lower weight and cost to the utility.

The CRT doesn't need battery backup- have you tried it in one of the non-backup receptacles?

If you have a source with RCA jacks and speakers that have XLR, it may be best to use an impedance matching transformer on a balanced cable. That way, you get the isolation from the transformer, the impedance isn't mis-matched and your levels will be OK.

Making a cable with RCA on one end and XLR on the other is OK, sometimes but not always. It's kind of like pounding a square peg in a round hole- if may go in but it's not the way they're supposed to be. Balanced signal conductors aren't connected directly to ground (not at ground potential), there's usually a resistance reading of about 50 Ohms to the chassis and then, the shield is grounded to the chassis of each piece. If a ground loop exists, pin 1 (the grounding lead) is lifted at the source device end but not at the mixer or amplifier end. Pin 2 is the sane as the center pin of an RCA and pin 3 is the same as the shield on an RCA. Usually, a device with unbalanced output will have output impedance of about 10K Ohm and a lot of balanced inputs are low impedance, or 600 Ohms. That's why the impedance matching transformer is the best way- while most unbalanced inputs are about 1K Ohm, some are higher or lower.

 

[Skwisgaar]

The CRT doesn't need battery backup- have you tried it in one of the non-backup receptacles?

Too late to try that now. Why would it make a difference?

If you have a source with RCA jacks and speakers that have XLR, it may be best to use an impedance matching transformer on a balanced cable. That way, you get the isolation from the transformer, the impedance isn't mis-matched and your levels will be OK.

An impedance matching transformer is exactly what Eventide tech support once told me never to use when connecting an unbalanced line with a balanced one.

Balanced signal conductors aren't connected directly to ground (not at ground potential), there's usually a resistance reading of about 50 Ohms to the chassis and then, the shield is grounded to the chassis of each piece.

I'm not sure about balanced line level, but there's no standard output impedance for unbalanced line level audio, but it is typically from 8 to 50 ohms. It's kind of an archaic connectivity that I wish nobody used anymore. If I were Augustus, I would decree that only XLR and AES connections are permissible.

Usually, a device with unbalanced output will have output impedance of about 10K Ohm and a lot of balanced inputs are low impedance, or 600 Ohms.

An output of 10k is for an electric guitar. I'm not plugging an electric guitar into active speakers. Standard practice for an RCA connector on a balanced cable ties the shield to the negative conductor, and that is bad. So I would lean towards an unbalanced cable.

 

[highfigh]

Too late to try that now. Why would it make a difference?


An impedance matching transformer is exactly what Eventide tech support once told me never to use when connecting an unbalanced line with a balanced one.


I'm not sure about balanced line level, but there's no standard output impedance for unbalanced line level audio, but it is typically from 8 to 50 ohms. It's kind of an archaic connectivity that I wish nobody used anymore. If I were Augustus, I would decree that only XLR and AES connections are permissible.


An output of 10k is for an electric guitar. I'm not plugging an electric guitar into active speakers. Standard practice for an RCA connector on a balanced cable ties the shield to the negative conductor, and that is bad. So I would lean towards an unbalanced cable.

The battery backup side may affect the ground and/or hot & neutral, relative to the side that's only surge protected. I was just suggesting possible causes- hard to know if the voltage and other connections aren't checked. If you can move the TV and speakers apart and it fixes the problem, it's basically a free solution.

I'd like to hear the reason for not using an impedance matching transformer, other than from the standpoint of possible signal degradation. These have been used in recording studios, radio stations and PA systems for decades.

What are you connecting as a source to the speakers and what is the output impedance of that? What is the input impedance of the speakers?

There's a lot of equipment that has 10 KOhm output impedance, not just guitars and even then, not all guitars have that exact impedance. Plus, a lot of guitar amps and effects have extremely high input impedance, in the area of 1 MegOhm. Line level is used to describe variable output from a preamp/receiver/integrated amp preamp section or from a mixer and it's also used when referring to record out signal from any of those, too. Unfortunately, it's not correct when referring to record out.

It would be great if the manufacturers would have actually come up with standards that were more compatible but before ANY of the standards were adopted, there were none, at all. Everyone had their own idea of how things should be connected and what the electrical characteristics should be. That wasted a lot of time for the advancement of audio equipment but the AES and IEEE have made it their mission to standardize everything, as much as possible. The old standards couldn't really be eliminated because so much equipment was out there and still in use, though.

I've been on a campaign to get rid of RCA inputs for a long time- I feel your pain. The problem is that RCA was in the position to get it shoved through at the time and had the money behind their ideas.

Re: the negative tied to the shield- that's going to be hard to separate from the XLR because pin 3 corresponds to the signal - (inverted) and when hardwiring from an RCA to XLR, pin 1 and pin 3 are sometimes connected to the shield. If it hums, pin 1 is disconnected.

 

[Skwisgaar]

I'd like to hear the reason for not using an impedance matching transformer, other than from the standpoint of possible signal degradation. These have been used in recording studios, radio stations and PA systems for decades.

I don't recall and I didn't save the email. But I think those transformers are for using high Z mics with modern mic cables. Doesn't fit my situation at all.

What are you connecting as a source to the speakers and what is the output impedance of that? What is the input impedance of the speakers?

Computer soundcard. The impedance specs are not provided, but when I looked at the manual for the speakers, I see pin 1 is a no connect. LOL!

Since I've come this far let's suppose for a moment that pin 1 was ground.

From what I've read and from Eventide once told me, you have to tie pins 1 and 3 together, or you get noise or hum or something. The most elegant way to do this is to stick a TS cable in a TRS jack. If one isn't available, and given you don't want to tie the shielding to the negative conductor, I think the best solution is to put an adapter on an RCA cable.

 

[highfigh]

I don't recall and I didn't save the email. But I think those transformers are for using high Z mics with modern mic cables. Doesn't fit my situation at all.


Computer soundcard. The impedance specs are not provided, but when I looked at the manual for the speakers, I see pin 1 is a no connect. LOL!

Since I've come this far let's suppose for a moment that pin 1 was ground.

From what I've read and from Eventide once told me, you have to tie pins 1 and 3 together, or you get noise or hum or something. The most elegant way to do this is to stick a TS cable in a TRS jack. If one isn't available, and given you don't want to tie the shielding to the negative conductor, I think the best solution is to put an adapter on an RCA cable.

The thing about connecting XLR cables to anything is that sometimes, pin 1 needs to be lifted. Pin 1 is always the ground connection on XLR but I have seen pins 2 and 3 reversed. Pin 2 is supposed to be the hot (normal signal) and pin 3 is supposed to be the cold (inverted signal), pin 3 being the closest equivalent to the RCA's shield, so it's connected to that. If the source has a TRS jack, using a TS cable is the easiest but some TRS jacks are parallel with the XLR jack and still low Z/balanced. Connecting a sound card or other high Z device's RCA jack to the low Z jack won't necessarily yield the best signal level or noise level.

If there's resistance between the ground of the source and the device it's connected to, a ground loop will exist if pin 1 is connected. Some recommend using a ground lift adapter on the power cord but this isn't safe. This is common when connecting two guitar amps to the same effects board or stereo effect, especially when one amp is old enough to have a ground polarity switch (this switch should be disconnected and a grounding power cord installed). I have seen the EbTech HumX recommended for ground loop elimination but haven't used one.

As long as the RCA shield connects to the chassis and there's no appreciable resistance from the jack to the chassis, it should just dump any noise to ground, in theory. When the resistance increases, the noise increases but it does work. As long as the shield to chassis connections are good and the devices being connected have no resistance on their ground (or neutral, when the plug has no ground pin), it's like an internal connection in one piece of equipment. Manufacturers only use a shield when it's needed- other signal connections are bare wire or a signal trace on a circuit board.

 

[Skwisgaar]

The thing about connecting XLR cables to anything is that sometimes, pin 1 needs to be lifted. Pin 1 is always the ground connection on XLR but I have seen pins 2 and 3 reversed. Pin 2 is supposed to be the hot (normal signal) and pin 3 is supposed to be the cold (inverted signal), pin 3 being the closest equivalent to the RCA's shield, so it's connected to that.

Modern RCA cables, even cheap ones, do not use the shield as a conductor. Instead the shield is not connected to anything. Some cables use a twisted pair and others use an inner ring for the negative conductor.

 

[highfigh]

Modern RCA cables, even cheap ones, do not use the shield as a conductor. Instead the shield is not connected to anything. Some cables use a twisted pair and others use an inner ring for the negative conductor.

That first part is not true in most cases. If the shield isn't connected to ground, it doesn't do what is intended but some RCA cables do have a twisted pair and some have twisted pair with an external foil or braided shield, which is sometimes connected at one end, often with some marking as to where it should go. The first ones I saw like that were Stinger, from AAMP of America and they called them "Quasi-balanced".

Cannibalize a cheap cable and you'll be able to measure continuity from the ring to the braid (not always braided, either- generally, it's just spiral-wrapped strands). When compression ends are installed on Liberty, Genesis, Belden, AudioQuest and most other brands of cable, the ring is absolutely connected to the shield.