mic cable thin tails and shock mounts

[studer58]

Greetings Remotesters,

I'm using reasonably thick Belden and Canare star quad cabling and find that it seems to compromise the isolation from vibration that the elastic mic suspensions (shock mounts) provide, by being too inflexible and thus provide a direct transmission path to the mic, despite being taped to the head of the mic stand a few inches below the suspension. I'm thinking that a solution might be to make up a few 'tails' of thinner cable (not sure what length these should be either, but for the purpose they would only need to be a foot or so ?) and then connect these to the thicker quad main cables so that the tails allow the suspensions to 'swing in the breeze' as they are intended to do ! Is anyone using these thinner tails, and if so what gauge cable and construction is it...regular twin or subminiature star quad ? I'm keen not to compromise the screening properties of the quad by introducing a 'weak link' of thinner cable that might allow RF into the chain, but the need for effective suspension function is great too...since currently floor vibrations can travel directly up the mic cable and negate the suspension's function. What lengths of tail are folks using out there ? A neat (but pricey and perhaps fiddly) solution is provided by Rycote with their Connbox....see: Modular Suspension Connbox

and I'm intending to buy some of their Invision suspensions, so I'm wondering if I can home make a similar version to this, minus the box ? The main issue with the thinner cables available is their strength and their sreening, which tends to be served (spiral wrapped) rather than braided like the star quad...and I have concerns about it's longer term reliability with flexing. Anyway, I hope I've described the dilemma well enough...and thank you in advance for your advice.
Ray

[Don S]

The new invision mount is excellent at isolation. I used the larger one (INV6 - I think) on the end of a boom pole with the cable (star quad) looped at the base of the mount, and it was dead quiet. From both pole and cable.

[LX3]

You could always add a short (2 or 3ft) cable made of thinner, flexible "patch cable", just before the microphone, and tape that to the stand. Should isolate the mic from cable-borne disturbances, yet you still get to use star-quad for the main run.

[Whoops, just realised that's exactly what you're saying. Why don't I read the OP a little more thoroughly? Sorry!]

[studer58]

Originally Posted by LX3

You could always add a short (2 or 3ft) cable made of thinner, flexible "patch cable", just before the microphone, and tape that to the stand. Should isolate the mic from cable-borne disturbances, yet you still get to use star-quad for the main run.

Yes, thats my intention....hence my original question... Is there anyone already doing this who can make some recommendations about the type/model no. of cable they use for this purpose ? I was thinking that a length of the 'tail cable' at least as long as the stand + boom would bring the tail to star quad XLR connection down to floor level, which might be better than having to tape a pair of joined XLRs to the stand itself ?

Ray

[John Willett]

Originally Posted by studer58

<snip. ..... A neat (but pricey and perhaps fiddly) solution is provided by Rycote with their Connbox....see: Modular Suspension Connbox

and I'm intending to buy some of their Invision suspensions, so I'm wondering if I can home make a similar version to this, minus the box ? The main issue with the thinner cables available is their strength and their sreening, which tends to be served (spiral wrapped) rather than braided like the star quad...and I have concerns about it's longer term reliability with flexing. Anyway, I hope I've described the dilemma well enough...and thank you in advance for your advice.
Ray

No problem - Rycote do the S-series cable to go with the InVision mounts.

This is what I use - the S-series cable is a short, thin and flexible XLR cable that goes from the mic. through the cable grip of the InVision mount. - you then connect your normal cable to this.

I use this S-series tail with all my InVision mounts.

The price of the cable is the same as the InVision mount.

You can see the size of the cable in these pictures of the INV-3:-

[RickZ]

A word of caution on 'thin' cables . . I had purchased the 'remote' cable for the 8040, the 3 meter one, and got hammered with cell phone noise on a live concert recording. I've now gone back to the Klaus Heyne recommended GAC-3 cable all the way to the mic. I too use the INV mic suspensions. GAC-3 fits into the clip. On a previous post, with a clip of the noise, the consensus from fellow slutz was cell phone noise, most likely getting in through bad cable.

FWIW,
Rick Z

[Audiop]

RickZ,

what about the shells of the conectors? Was any of them connected to the shield?

Otherwise you end up with a non screened/shielded part that is like a door open with a welcome sign to RF.

I tie off the GAC-4 to the mic stand with velcro wrap and if that is done on two places I doubt that any significant amount of vibration will reach the mic via the cable... allthough I'm not sure and I have not done serious tests.


/Peter

[LX3]

A lot of "patch" cables (typically 4.5mm diameter) are exactly the same construction as ordinary twisted pair from the same manufacturer, only with a thinner outer jacket. So the shielding is much the same as the chunkier cable, it's just trickier to wrap.

I would have thought that 4m - enough to reach all the way up most medium-height mic stand - would work (although much longer than that and it becomes a pain to handle). Patch cables always seem to be the softest and most flexible around... apart from some of the even thinner cables for lavaliers etc. And I would say that combatting vibration is more important that the ultimate in shielding.

(Although, having said that, try Sommer "Goblin" - it's a patch cable that has the same construction as their "Source" cable. It has a lap screen over a metallised fleece, so remains very flexible, but with excellent screening. I'm a big fan of Source, it's my go-to mic cable.)

I agree, if you're picking up RF from a fairly short length of plain balanced cable, I would suspect something is wired wrong. Even in the horrible environments of rock and pop, I've never had RF leak into an ordinary twisted pair mic cable that was properly built. Into instruments, amplifiers, etc, yes, but never into a cable.

[RickZ]

I've attached the mp3 of the noise, along with a pic from Rycote's web site, and a pic from the concert, showing the mics.

The 'thin' cable is part of Sennheiser's 'remote' cable option for the 8000 series, I don't know what the termination is or type of cable.

All of my mic cables have shell of xlr connected to green wire and shield, and I've never had any RF problems, until this concert, one of my first with the 'remote' cable. As the concert pic shows, there were people all around, and if I remember a few youngsters off to the right.

Based upon this bad luck with 'remote' cable, I've discontinued its use. Will see how things go the old way. I don't do a lot of recording, and I won't be back to this venue til Christmas.

Hope any of this helps,
Rick Z

[studer58]

Thanks for all the input so far, it's pointing a direction for resolving this
My reservation about the Rycote S series short patch cable would be that it has a helical wrapped screen....which I'd expect might 'unwrap' itself over time and lead to reduced screening (not to challenge Rycote's wisdom in using this...I'm sure they've done extensive testing and are satisfied that it's not an issue ?) Rycote obviously have a lengthy background in supplying the broadcast and boom pole market, where vibration elimination is paramount, so my questioning here could be verging on the heretical .However I'm sure they have opted for the flexibility and ruggedness factor over the RF screening abiity...and of course there's ultimately a compromise to be made ! I'm not sure I'd want 4 metres or so of this dangling down from a tall stand, so maybe 24-36 inches would be enough. My impression is that the 'rubberized' or teflon coated cabling would lend more flexibility/strength than an equivalent PVC sheathing. If anyone has some specific recommendations apart from the Rycote S or GAC3/4 wires I's be keen to hear of that. Thanks again for your contributions here....love to hear more.
Ray

[Matti]

In my time I made thin tails from dead lavarier mic´s cables. That was
before conbox or similiar. And it worked even in winter temperatures like -25c !

Matti

[Rick Sutton]

I make small "jumper" cables by using the inner cable runs of Mogami snakes. Never had any problems.

[LX3]

Originally Posted by studer58

However I'm sure they have opted for the flexibility and ruggedness factor over the RF screening abiity...and of course there's ultimately a compromise to be made ! I'm not sure I'd want 4 metres or so of this dangling down from a tall stand, so maybe 24-36 inches would be enough.

When I was in a rush a couple of years ago, I made a 20m mic cable out of some Sommer Goblin I had hanging around. While I wouldn't recommend it because it's a bitch to lay and coil (it's too flexible) I do occasionally still use it. It works just fine. It's 4.5mm diameter, with a lap screen and the metallised fleece underneath.

I think you're worrying too much about cable type. There are 150-foot-plus runs of lap screen cable installed at venues all over the world without a problem. Disassemble the problem cable, check it visually for shorts and busted solder joints, condition of the sleeving, etc. Get a multimeter out and check that it's wired properly. Check the screen is on pin 1 at both ends, 2 connects to 2, 3 to 3, and nothing is connected to the shell of either XLR.

Have you thought about making your own cables? That way you know what you're getting, how it's been wired, etc. I haven't bought a commercially-made mic cable.... ever, as far as I'm aware.

[Matti]

I buy ready made cables of quality, but for a location film/video set of equiptment I tend to make my own -especially for over the shoulder stuff, there the cable lenghts matter...

Matti

[John Willett]

Originally Posted by studer58

My reservation about the Rycote S series short patch cable would be that it has a helical wrapped screen....which I'd expect might 'unwrap' itself over time and lead to reduced screening (not to challenge Rycote's wisdom in using this...I'm sure they've done extensive testing and are satisfied that it's not an issue ?) Rycote obviously have a lengthy background in supplying the broadcast and boom pole market, where vibration elimination is paramount, so my questioning here could be verging on the heretical .However I'm sure they have opted for the flexibility and ruggedness factor over the RF screening abiity...and of course there's ultimately a compromise to be made ! I'm not sure I'd want 4 metres or so of this dangling down from a tall stand, so maybe 24-36 inches would be enough.

The Rycote S-series tail is very short - the idea is that it just decouples the cable and is *not* used as the main cable. The S-series tail is only about half a metre long.

You can see the whole length in the attached picture.

The helical wrap is to keep it flexible -the whole point in being to prevent mechanical noise getting to the mic. via the cable - a different screen could make the cable stiffer and therefore no good as stopping this handling noise.

So - I use the tail only through the shockmount and use starquad cable after that.

[studer58]

Originally Posted by LX3

Have you thought about making your own cables? That way you know what you're getting, how it's been wired, etc. I haven't bought a commercially-made mic cable.... ever, as far as I'm aware.

Thanks Paul,

Yes, perhaps I hadn't made that clear enough initially...I'm planning on making up my own sets of tails from thin gauge flexible cabling exactly as you and other posters are outlining here, as (for example) the Rycote tails don't seem to be made from anything too esoteric, and I know I can do so more cheaply as well ! That's the reason I'm asking if there are any specific makes/models of raw cable that might be more suitable than others ? I'm simply keen not to compromise the good RF rejection of my main star quad mic cables and multicores with a 12" tail that 'opens the gate' to that sort of hash....but maybe that's a rare occurrence anyway, judging by the majority of replies here so far ?
Ray

[RickZ]

Here's a link to a sticky from Klaus Heyne, regarding termination. There seem to be a number of thoughts on this subject.

PSW Recording Forums: Klaus Heyne's Mic Lab Stickies => Radio Frequency Interference (RFI) in Mics

FWIW,
Rick Z

[John Willett]

THIS is the spec. of the cable used in the Rycote tails.

[Audiop]

Originally Posted by RickZ

Here's a link to a sticky from Klaus Heyne, regarding termination. There seem to be a number of thoughts on this subject.

PSW Recording Forums: Klaus Heyne's Mic Lab Stickies => Radio Frequency Interference (RFI) in Mics

FWIW,
Rick Z

I skimmed thru that and will return to read the whole thread.

Some thoughts though..

While grounding the shell to the cable shield may help sometimes I also believe most mic's and preamps actually ground the shells when you insert the connectors and in such case it won't really matter if the connector shell is grounded inside the connector itself.

If you daisy chain two such cables you will get a couple of inches that is open to RF though.

Heyne also mentions ground loops. If the connector is grounded both internally and via the preamp chassis you may actually have created a groundloop (inside the pre) that wouldn't be there if you had not made the internal connection of the shell and cable shield or ground wire.

I'm glad if someone could correct my thinking if I'm totally off. :-) I left the shell unconnected in my latest bunch of cables and I'm thinking of a reason for connecting the shells to the ground/shield.

To check if your shells are grounded to the chassis of the mic and pre you can use an ohm meter.


/Peter

[nosebleedaudio]

Not sure if this was mentioned already but the Mogami snake cable is perfect for this, use it all the time for small spaces, inside mic pres ect... great cable

[John Willett]

Originally Posted by Audiop

While grounding the shell to the cable shield may help sometimes I also believe most mic's and preamps actually ground the shells when you insert the connectors and in such case it won't really matter if the connector shell is grounded inside the connector itself.

If you daisy chain two such cables you will get a couple of inches that is open to RF though.

Heyne also mentions ground loops. If the connector is grounded both internally and via the preamp chassis you may actually have created a groundloop (inside the pre) that wouldn't be there if you had not made the internal connection of the shell and cable shield or ground wire.

I'm glad if someone could correct my thinking if I'm totally off. :-) I left the shell unconnected in my latest bunch of cables and I'm thinking of a reason for connecting the shells to the ground/shield.

I like to use the new Neutrik EMC-XLR connectors - these bond pin 1 to the shell via mini capacitors and there is also a ferrite bead on pin 1. They also have a toothed ring on the female to make a full and proper contact.

The EMC-XLR Series is a specifically designed version of the XX series to give enhanced RF screening for critical applications in live performance and recording where there are particular problems with radio transmission or mobile phones. The design guarantees a continuous RF shield connection from the cable to the chassis connector housing via a circular capacitor around the cable shield. An EMI suppression ferrite bead between pin 1 and the cable screen provides a low-pass filter for improved RF rejection.

[Audiop]

Aaaargh! Hmphffrrp!! :-(

And this I found out a couple of weeks after a purchase (and many painful hours of soldering and stripping cables) of 30 standard XX connectors.

Grrrr!




/Peter

[studer58]

Originally Posted by John Willett

THIS is the spec. of the cable used in the Rycote tails.

Thanks for that background John...interestingly I also received correspondence from Simon Davies at Rycote regarding the cabling used in the Connbox (see link in my original post at the head of thread) He says:

"The choice of both Mogami cables for the
Connbox is primarily due to the softness & flexibility of the
insulation jacket - to aid the suspension. As you'll see from the wire/
pin combinations we use the star quad pair as twisted pairs on the
mono connbox, but for stereo 5-pin O/P we use each conductor, the thin
cable is just a twin conductor cable.
As far as the RF rejection goes, we've now linked Pin-1 and the shell
ground on both XLR's, but as you say it'll always find the weakest
link. So either the thin cable or the mid-connection point will
probably allow some RFI. We have considered using Neutrik's EMC
Series, but for the time being we'll stick with the gold pin X or XX
series.
Connbox (CB1) Cable Spec.
Thin Cable - (fitted with Neutrik NC3FX-B or NC3FXX-B)
Description: Mogami W2697
Exposed length: 130mm
Jacket: Black Flexible PVC (OD - 2.5mm)
Conductors: 2 (16/0.08 A - 28 AWG)
Insulation: PVC (Red / White)
Web: MOGAMI - Miniature Balanced Mic. Cables / Lavalier Mic. Cables
Thick cable - (fitted with Neutrik NC3MX-B or NC3MXX-B)
Description: Mogami W2893
Exposed length: 450mm
Jacket: Black Flexible PVC (OD - 4.8mm)
Conductors: 4 - (30/0.08 - 26 AWG)
Insulation: XLCPE ( Black / Red / Blue / Clear)
Web: http://www.mogamicable.com/Bulk/micr...micr.htmMogami
W2893
Pin connections:
Pin 1/Male XLR - Mogami 2893 (Screen)/Female XLR Mogami 2697 (Screen)
Pin 2/Male XLR - Mogami 2893 (Red & Clear)/Female XLR Mogami 2697 (Red)
Pin 3/Male XLR - Mogami 2893 (Blue & Black)/Female XLR Mogami 2697
(White)
Link Pin 1 and the shell ground in the NC3MX-B and NC3FX-B"

It seems the OD (outer diameter) of the Connbox 'thin tail' cable is a little less than that of the Mic D you linked to above, but understandable for a captive or attached cable compared with perhaps a more free-standing tail in the case you describe. I'll be using them with the Invision 3 suspension and Sennheiser 8020 mics, which are a pretty low mass mic/xlr combination, so I'm looking for a quite flexible tail link to avoid vibrational coupling

[John Willett]

Originally Posted by RickZ

A word of caution on 'thin' cables . . I had purchased the 'remote' cable for the 8040, the 3 meter one, and got hammered with cell phone noise on a live concert recording. I've now gone back to the Klaus Heyne recommended GAC-3 cable all the way to the mic. I too use the INV mic suspensions. GAC-3 fits into the clip. On a previous post, with a clip of the noise, the consensus from fellow slutz was cell phone noise, most likely getting in through bad cable.

Originally Posted by RickZ

I've attached the mp3 of the noise, along with a pic from Rycote's web site, and a pic from the concert, showing the mics.

The 'thin' cable is part of Sennheiser's 'remote' cable option for the 8000 series, I don't know what the termination is or type of cable.

All of my mic cables have shell of xlr connected to green wire and shield, and I've never had any RF problems, until this concert, one of my first with the 'remote' cable. As the concert pic shows, there were people all around, and if I remember a few youngsters off to the right.

Based upon this bad luck with 'remote' cable, I've discontinued its use. Will see how things go the old way. I don't do a lot of recording, and I won't be back to this venue til Christmas.

Hope any of this helps,
Rick Z

I was extremely concerned when I read these posts from Rick and sent all the information to the Product Manager and Microphone Designer at Sennheiser Germany.

Their reply said that the remote cables were very robust against RF interference.

So I decided to run some tests myself:

I connected a pair of MKH 8020 to my Nagra VI and waved my mobile all around (ringing my landline number at the office, so it was fully transmitting and as we are in a building that is metal clad, probably ramping up the power as well). Not even a hint of RF interference - clean as a whistle.

I then attached the 3-metre remote cable to the mics and repeated the test, even sitting the mobile on the cables. Again - not a peep - nothing - no RF interference at all.

I then took the rig down to the Service Dept. and repeated the test with an RF test generator with sweep signals across a wide frequency range at a high transmit level. I even had the remote cables touching the transmit antenna - again no RF interference at all - not a single peep.

I can safely say that the MKH 8000 remote cables are *not* prone to picking up RF interference, even in nasty RF environments with a mobile phone actually touching the cable.

The interference you had, Rick, must have been getting in by another route and you should check other areas - or - your remote cables may be faulty and should be checked by your local Sennheiser agent.

As a result of my tests I am extremely happy with the RF rejection of the MKH 8000 remote cables (and, yes, I do use these myself).

[studer58]

Originally Posted by John Willett

I was extremely concerned when I read these posts from Rick and sent all the information to the Product Manager and Microphone Designer at Sennheiser Germany.

Their reply said that the remote cables were very robust against RF interference.

So I decided to run some tests myself:

I connected a pair of MKH 8020 to my Nagra VI and waved my mobile all around (ringing my landline number at the office, so it was fully transmitting and as we are in a building that is metal clad, probably ramping up the power as well). Not even a hint of RF interference - clean as a whistle.

I then attached the 3-metre remote cable to the mics and repeated the test, even sitting the mobile on the cables. Again - not a peep - nothing - no RF interference at all.

I then took the rig down to the Service Dept. and repeated the test with an RF test generator with sweep signals across a wide frequency range at a high transmit level. I even had the remote cables touching the transmit antenna - again no RF interference at all - not a single peep.

I can safely say that the MKH 8000 remote cables are *not* prone to picking up RF interference, even in nasty RF environments with a mobile phone actually touching the cable.

The interference you had, Rick, must have been getting in by another route and you should check other areas - or - your remote cables may be faulty and should be checked by your local Sennheiser agent.

As a result of my tests I am extremely happy with the RF rejection of the MKH 8000 remote cables (and, yes, I do use these myself).

John,
On the face of it you seem to have run a pretty convincing test...although maybe the RF Rick experienced was from a source other than cellphones, or of a different frequency ? However, a damaged cable seems a more likely scenario, as you mention. Returning to the original thread, they seem as if they'd be excellent candidates for 1 metre mic tails...do you happen to know what cable Sennheiser employs for these remote extenders ?
I use the 8020's also...so it likely would be a good match !
Ray

[John Willett]

Originally Posted by studer58

John,
On the face of it you seem to have run a pretty convincing test...although maybe the RF Rick experienced was from a source other than cellphones, or of a different frequency ? However, a damaged cable seems a more likely scenario, as you mention.

Rick *did* say that it was cellphone interference.

On all remote recordings I do, I use mains blocks with decent RF filters:

• Triple level surge protection - reduces transient surges up to IEC 610000-4-4 level 2 and suppresses all transients above 0.8kV
• Each socket individually filtered and isolated from interference and surges

As each mains socket is RF filtered from all the others any equipment I have can't stuff cr*p down the mains to be picked up by anything else.

I also have some Canford Audio XLR in-line RF filters in the kit to plug in-line if I have a real problem.

Originally Posted by studer58

Returning to the original thread, they seem as if they'd be excellent candidates for 1 metre mic tails...do you happen to know what cable Sennheiser employs for these remote extenders ?
I use the 8020's also...so it likely would be a good match !

I don't actually know what cable Sennheiser use for the MKH 8000 remote cables - but it *is* stereo enabled so you can run two mics down the same cable. I'm just waiting for the Y-cable so I can run an ORTF pair of heads down the one cable.

[iluvatar]

Originally Posted by John Willett

I was extremely concerned when I read these posts from Rick and sent all the information to the Product Manager and Microphone Designer at Sennheiser Germany.

Their reply said that the remote cables were very robust against RF interference.

So I decided to run some tests myself:

I connected a pair of MKH 8020 to my Nagra VI and waved my mobile all around (ringing my landline number at the office, so it was fully transmitting and as we are in a building that is metal clad, probably ramping up the power as well). Not even a hint of RF interference - clean as a whistle.

I then attached the 3-metre remote cable to the mics and repeated the test, even sitting the mobile on the cables. Again - not a peep - nothing - no RF interference at all.

I then took the rig down to the Service Dept. and repeated the test with an RF test generator with sweep signals across a wide frequency range at a high transmit level. I even had the remote cables touching the transmit antenna - again no RF interference at all - not a single peep.

I can safely say that the MKH 8000 remote cables are *not* prone to picking up RF interference, even in nasty RF environments with a mobile phone actually touching the cable.

The interference you had, Rick, must have been getting in by another route and you should check other areas - or - your remote cables may be faulty and should be checked by your local Sennheiser agent.

As a result of my tests I am extremely happy with the RF rejection of the MKH 8000 remote cables (and, yes, I do use these myself).

Hopefully, somebody with more knowledge than me can chime in, but from what I understand, cell phone interference isn't necessarily the same as regular RF interference. It's some sort of broadband pulse around 200 Hz as the thing communicates with the tower and it only comes from phones on certain carriers that use one of two competing technologies. I forget what they're called, but I know that Verizon phones do not cause these problems.

-Dan.

[John Willett]

Originally Posted by iluvatar

Hopefully, somebody with more knowledge than me can chime in, but from what I understand, cell phone interference isn't necessarily the same as regular RF interference. It's some sort of broadband pulse around 200 Hz as the thing communicates with the tower and it only comes from phones on certain carriers that use one of two competing technologies. I forget what they're called, but I know that Verizon phones do not cause these problems.

That's why I did the test with two different cell phones and had them very close - even touching the cables - to try and make it the worst possible case - and not a hint of a problem at all.

Sometimes it's easy to blame what you *think* may be the weakest link; when, in fact, it's something else.

For example - not bonding XLR pin-1 to the shell can let in RF. Was it coming up the mains? Was it coming in your long XLR runs? Was it getting directly into the mixer? Etc.......

Blaming the wrong thing is very easy to do, especially if you had not had the problem before and this was the first time out with these cables - but it could be a venue thing and getting in elsewhere.

[RickZ]

I should clarify that fellow slutz identified my noise as cell phone, as I had no idea what it was. I believe one person thought it was iPhone, saying it was the most powerful. Again I have no expertise in that area, that's why I posted the noise clip the first time in the hope that someone might know. Unfortunately, this may remain a mystery, as the chances of having the same person with the same phone sitting in the same place . . etc. is unlikely to happen again. I've retired the remote cables for now.

This morning on NPR, during a report from London, I could have sworn I heard exactly the same buzzing noise.

FWIW,
Rick Z

[mohthom]

John, your mobile is quad band isn't it - about 50% of mobiles in the UK are tri-band and this may be why you couldn't pick up the fault .

For reference, Tri-band mobile phones run on

900 MHz,
950 MHz and
1800 MHz

The additional band for American handsets runs on 1900 MHz.

I'm pretty convinced from what John says that it ain't the design of the cable though.