Would you be concerned if you had a 25' cable into a 75' sub snake into a 100M (328') main snake?
Maximum analog snake length
- Thread starter Jason Raboin
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Re: Maximum analog snake length
No. I have done quite a few installs with snakes that long or longer and never noticed any issues.
Technically-until you get to about 10 times that length-you should not have an issue.
ASSUMING a good quality input stage with a lot of Common Mode Rejection. If you have a poor input stage-then all bets are off.
A transformer input is your friend for really long distances.
No. I have done quite a few installs with snakes that long or longer and never noticed any issues.
Technically-until you get to about 10 times that length-you should not have an issue.
ASSUMING a good quality input stage with a lot of Common Mode Rejection. If you have a poor input stage-then all bets are off.
A transformer input is your friend for really long distances.
Re: Maximum analog snake length
I've run audio lines of 1000 feet with no issues at all. As long as it's good quality cable, it shouldn't be an issue.
With really long cables, you may have to turn your trim up a little more to compensate for the loss in the cable, but the difference should be quite minimal. The other thing you can see is with cables that have high capacitance, you will start to lose some high frequency response. Again, with good quality cable, this will be extremely minimal.
I've run audio lines of 1000 feet with no issues at all. As long as it's good quality cable, it shouldn't be an issue.
With really long cables, you may have to turn your trim up a little more to compensate for the loss in the cable, but the difference should be quite minimal. The other thing you can see is with cables that have high capacitance, you will start to lose some high frequency response. Again, with good quality cable, this will be extremely minimal.
Re: Maximum analog snake length
If all of your connections are balanced, you'll be able to run thousands of feet. The radio station I work with has analog multipair run from our studios on one side of campus connected to our transmitter facility on the other, and up 5 floors. Easily over 1000ft and no problems what-so-ever.
If all of your connections are balanced, you'll be able to run thousands of feet. The radio station I work with has analog multipair run from our studios on one side of campus connected to our transmitter facility on the other, and up 5 floors. Easily over 1000ft and no problems what-so-ever.
Re: Maximum analog snake length
Jason,
There are a few issues here, none of which are likely to be significant at that snake length.
1) Transmission line reflections from unterminated cabling that approaches or exceeds 1/4 wavelength at the highest frequency of interest. However, in baseband audio this is easily a kilometer so unlikely to be a problem.
2) Increased loading from the resistance of that much cable making preamps behave funny, but a few hundred feet still shouldn't be an issue at the impedances likely present.
3) Capacitance acting as a LPF - this is the most likely problem. Easy to compensate for. While this length (430') is getting pretty long even in the arena audio world, it will depend on the actual capacitance of the cable used. Better cable has lower capacitance, and in fact AES digital rated cable will probably not care about that distance at all.
Jason,
There are a few issues here, none of which are likely to be significant at that snake length.
1) Transmission line reflections from unterminated cabling that approaches or exceeds 1/4 wavelength at the highest frequency of interest. However, in baseband audio this is easily a kilometer so unlikely to be a problem.
2) Increased loading from the resistance of that much cable making preamps behave funny, but a few hundred feet still shouldn't be an issue at the impedances likely present.
3) Capacitance acting as a LPF - this is the most likely problem. Easy to compensate for. While this length (430') is getting pretty long even in the arena audio world, it will depend on the actual capacitance of the cable used. Better cable has lower capacitance, and in fact AES digital rated cable will probably not care about that distance at all.
Re: Maximum analog snake length
You'll start seeing the LPF start in as a factor around 100' or so, but how much depends on the capacitance and distance of the cable.
You just end up loosing some high end off the signal, so if that's ok...
Yep, digital snakes do not have that problem, and they also eliminate ground loops for the most part also.
You'll start seeing the LPF start in as a factor around 100' or so, but how much depends on the capacitance and distance of the cable.
You just end up loosing some high end off the signal, so if that's ok...
Yep, digital snakes do not have that problem, and they also eliminate ground loops for the most part also.
Re: Maximum analog snake length
FWIW back before they had wireless mics, film location engineers used low impedance mics (50 ohms?) to deal with the capacitance from extremely long snake runs (thousands of feet long).
For 400' probably ok. How does it sound?
JR
FWIW back before they had wireless mics, film location engineers used low impedance mics (50 ohms?) to deal with the capacitance from extremely long snake runs (thousands of feet long).
For 400' probably ok. How does it sound?
JR
Re: Maximum analog snake length
Fun fact: Due to this phenomenon, the AC that trains run off of is at 33,3 cycles. If you're ever on a train with old-fashined lightbulbs in the reading lights, try staring really hard and you'll actually see them "strobe". It's kinda cool that signal transmission laws apply to AC Power transmitting mega wattages!
Re: Maximum analog snake length
Maybe, but most electric trains run of 50hz (or 60 min America) it's only Germany really that stuck for 16.7Hz (not 33.3) (due to the use of dc motors with ac current and the inefficiencies when used at 50 hz) and it was only due to interoperability issues that anyone else used 16.7hz. Modern high speed lies use 25kv at 50hz as the newer motors can handle it better.
Re: Maximum analog snake length
Due to high conversion costs and little advantages it is unlikely that existing 15 kV, 16.7 Hz systems will be converted to 25 kV, 50 Hz.
" SORRY GUYS I REALLY AM TRYING BUT THIS BROWSER HAS SO MANNY CARRIAGE (NO PUN INTENDER) RETURN ISSUES IT'S NOT EVEN FUNNY!
You're right, it was 16,7Hz! And it is what they use all over Norway. I was taught in school that this was introduced specifically to hinder line reflections in very, very, very, very long cables. Edit: Might very well be there were some urban ledgends going around school? I could not find info on the line reflection topic in this article, but lots of other neat stuff! http://en.wikipedia.org/wiki/15_kV_AC_railway_electrification This also from the article: "The 15 kV, 16.7 Hz AC railway electrification system is used in Germany, Austria, Switzerland, Sweden and Norway. The high voltage enables high power transmission with low losses powering traction motors available since the beginning of the 20th century. Railway electrification in late 20th century tended to use 25 kV, 50 Hz AC systems which has become the preferred standard for new railway electrifications but extensions of the existing 15 kV networks are not completely unlikely.
Due to high conversion costs and little advantages it is unlikely that existing 15 kV, 16.7 Hz systems will be converted to 25 kV, 50 Hz.
" SORRY GUYS I REALLY AM TRYING BUT THIS BROWSER HAS SO MANNY CARRIAGE (NO PUN INTENDER) RETURN ISSUES IT'S NOT EVEN FUNNY!
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Re: Maximum analog snake length
Use Opera or Firefox. And if you have any issues with Opera, they're in your own country...
Use Opera or Firefox. And if you have any issues with Opera, they're in your own country...
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Re: Maximum analog snake length
Thank's, I'll try and see if there is some "home field advantage"
Re: Maximum analog snake length
I haven't ordered it yet. We play a lot of unconventional venues in Europe which often require unconventionally long cable runs. So a few years ago I bought a 100M LK85 from Link. I was, at the time, using outboard mic preamps on stage, so most of my inputs were traveling at line level. I was also only using 50' sub snakes. It was very clean. I should also mention that there is no monitor split.
For our upcoming tour we are doing co-bills which will require quick changeovers. I want to and need to simplify our on stage setup, so I am going to get rid of most of the outboard mic preamps. I will still use an A Designs Pacifica for the lead vocal and an Avalon U5 for her guitar. We will also be playing on shed sized stages, so am moving to 75' sub snakes, also from Link. Losing a bit of top end from all of my inputs except the main vocal would be fine.
I haven't ordered it yet. We play a lot of unconventional venues in Europe which often require unconventionally long cable runs. So a few years ago I bought a 100M LK85 from Link. I was, at the time, using outboard mic preamps on stage, so most of my inputs were traveling at line level. I was also only using 50' sub snakes. It was very clean. I should also mention that there is no monitor split.
For our upcoming tour we are doing co-bills which will require quick changeovers. I want to and need to simplify our on stage setup, so I am going to get rid of most of the outboard mic preamps. I will still use an A Designs Pacifica for the lead vocal and an Avalon U5 for her guitar. We will also be playing on shed sized stages, so am moving to 75' sub snakes, also from Link. Losing a bit of top end from all of my inputs except the main vocal would be fine.
Re: Maximum analog snake length
I believe you'll lose the HF due to capacitive effects regardless of signal level, so going line level won't help you here.
I believe you'll lose the HF due to capacitive effects regardless of signal level, so going line level won't help you here.
Re: Maximum analog snake length
It depends... back in the day when pro interfaces were 600 ohm for line level, the capacitance would make more of a difference than modern gear that is generally designed to present lower source impedance.
There is not a firm standard for line level source impedance. Most professional (expensive) gear will generally drive 600 ohm loads to decent level which requires output impedances a modest fraction of 600 ohms (i generally used 50-100 ohms build-outs in pro designs). Some lower cost (MI, semi-pro) gear to save the cost of high current output drivers, or to improve effectiveness of turn on transient clamping can use hundreds of ohms. I've seen low cost gear with source impedances as high as 1k.
So the short answer is YMMV, and again "how does it sound?". With well designed professional gear, I would expect line level gear to deliver slightly better HF response than a simple microphone. Old legacy (600 ohm) or cheap semi-pro gear could deliver worse HF performance.
JR
It depends... back in the day when pro interfaces were 600 ohm for line level, the capacitance would make more of a difference than modern gear that is generally designed to present lower source impedance.
There is not a firm standard for line level source impedance. Most professional (expensive) gear will generally drive 600 ohm loads to decent level which requires output impedances a modest fraction of 600 ohms (i generally used 50-100 ohms build-outs in pro designs). Some lower cost (MI, semi-pro) gear to save the cost of high current output drivers, or to improve effectiveness of turn on transient clamping can use hundreds of ohms. I've seen low cost gear with source impedances as high as 1k.
So the short answer is YMMV, and again "how does it sound?". With well designed professional gear, I would expect line level gear to deliver slightly better HF response than a simple microphone. Old legacy (600 ohm) or cheap semi-pro gear could deliver worse HF performance.
JR
Re: Maximum analog snake length
If you do the math, 400 feet of 30 pF/ft. cable, and an output impedance of 600Ω, gives you a 3 dB down point of 22 kHz. And those numbers are sort of a worst case example. The old Belden 8773 snake cable was 30 pF/ft. Most of the new stuff is less than that, unless you're using quad cable, which is likely worse. As JR pointed out, 600Ω is also probably a worse case for output impedances too, unless you're using the cheap stuff. The real corner frequency should be much higher than my example.
As Bennett surmised, the level doesn't really enter into it, unless you get slew limiting distortion because of that extra capacitance. I'm skeptical about concerns about level loss too. The previously mentioned 8773 has a DC resistance of 50 Ω/km. So a round trip on Jason's 328m trunk is only about 30Ω, which isn't going to make much more than a fraction of a dB difference once it's terminated in 1200Ω or so.
GTD
If you do the math, 400 feet of 30 pF/ft. cable, and an output impedance of 600Ω, gives you a 3 dB down point of 22 kHz. And those numbers are sort of a worst case example. The old Belden 8773 snake cable was 30 pF/ft. Most of the new stuff is less than that, unless you're using quad cable, which is likely worse. As JR pointed out, 600Ω is also probably a worse case for output impedances too, unless you're using the cheap stuff. The real corner frequency should be much higher than my example.
As Bennett surmised, the level doesn't really enter into it, unless you get slew limiting distortion because of that extra capacitance. I'm skeptical about concerns about level loss too. The previously mentioned 8773 has a DC resistance of 50 Ω/km. So a round trip on Jason's 328m trunk is only about 30Ω, which isn't going to make much more than a fraction of a dB difference once it's terminated in 1200Ω or so.
GTD
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Re: Maximum analog snake length
Yes you will get HF rolloff-so many people just "assume" that it is a bad thing-and they never look a little bit further to see if it even matters! If you can hear 3dB rolloff at 22K through any normal PA speaker (or any speaker for that matter) you have MUCH better hearing than me. Yes it is happening-but I DON'T care.
Just like in speakers-A product may claim a 40° pattern, but the horn opening is only 8". So that means that the "40°" pattern can only be down to 3KHz or so. Below that is wider.
So do they REALLY think that having a rotatable horn is REALLY going to make that much of a difference? Only in the upper octaves-but down in the "meat" of the sound-NOTHING is going to change-yet people will talk about it all the time-"OH just rotate the horn so the cabinets will couple better" YEAH RIGHT! Have they EVER ACTUALLY LISTENED to it? or do they just "get part of it" and "think" that it carries all the way through------------------------
Sounds like a "good idea" except it DOESN'T work! Or it only works jsut a little bit-but then if you consider how far apart the drivers are-and all the combfiltering that is going on-how much of a difference did it REALLY make? What about the coverage of THE REST of the speaker system? It doesn't change when you "rotate the horn".
Just like skin effect on cables-SURE it has a VERY REAL effect and is easily measured BUT NOT AT AUDIO FREQ!!!!!!!!!!!!!!!!!!!!!!!!!!! So why bother if it does not make a difference in what you hear?
Or Damping factor- How any people (not you JR ) have ACTUALLY done the MATH on their SYSTEM in regards to damping factor?
If they would, they should quickly realize that the damping factor of the amp is completely washed out by that of the rest of the system-cable-connectors etc.
So yes damping factor matters-but NOT in the amp!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
At least for most cases in "normal" system.
Sorry to rant-but there needs to be a lot more "Audio 101" being taught and NOT about "the cool plugins" on a console.
We are missing THE BASICS so much these days. The FUNDAMENTALS are VERY important-if you want to have a REAL understanding on what is going on.
And once again-what the "theory" says 9or what people "think" it means) and what reality is are often VERY different things.
Yes you will get HF rolloff-so many people just "assume" that it is a bad thing-and they never look a little bit further to see if it even matters! If you can hear 3dB rolloff at 22K through any normal PA speaker (or any speaker for that matter) you have MUCH better hearing than me. Yes it is happening-but I DON'T care.
Just like in speakers-A product may claim a 40° pattern, but the horn opening is only 8". So that means that the "40°" pattern can only be down to 3KHz or so. Below that is wider.
So do they REALLY think that having a rotatable horn is REALLY going to make that much of a difference? Only in the upper octaves-but down in the "meat" of the sound-NOTHING is going to change-yet people will talk about it all the time-"OH just rotate the horn so the cabinets will couple better" YEAH RIGHT! Have they EVER ACTUALLY LISTENED to it? or do they just "get part of it" and "think" that it carries all the way through------------------------
Sounds like a "good idea" except it DOESN'T work! Or it only works jsut a little bit-but then if you consider how far apart the drivers are-and all the combfiltering that is going on-how much of a difference did it REALLY make? What about the coverage of THE REST of the speaker system? It doesn't change when you "rotate the horn".
Just like skin effect on cables-SURE it has a VERY REAL effect and is easily measured BUT NOT AT AUDIO FREQ!!!!!!!!!!!!!!!!!!!!!!!!!!! So why bother if it does not make a difference in what you hear?
Or Damping factor- How any people (not you JR
) have ACTUALLY done the MATH on their SYSTEM in regards to damping factor?If they would, they should quickly realize that the damping factor of the amp is completely washed out by that of the rest of the system-cable-connectors etc.
So yes damping factor matters-but NOT in the amp!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
At least for most cases in "normal" system.
Sorry to rant-but there needs to be a lot more "Audio 101" being taught and NOT about "the cool plugins" on a console.
We are missing THE BASICS so much these days. The FUNDAMENTALS are VERY important-if you want to have a REAL understanding on what is going on.
Re: Maximum analog snake length
To amplify Ivan's rant I draw a distinction between phenomenon that can actually make an audible difference in the margin, and phenomenon that while perhaps real do not ever make an audible difference.
This discussion of snake length correctly zero'd in on the real, lumped capacitance forming an RxC with products source impedance, issue and not the esoteric transmission line characteristic impedance and termination effects. It is the nature of internet forum discussions that people often post everything that they know on some subject, instead of just the pertinent information useful to the OP. This can get confusing when the real answer gets lost in the noise.
Ivan is correct that even these real effects must be kept in perspective. How many signals in that snake need a >20kHz passband? That said, a 5kHz LPF could very easily be audible, so some worst case consumer VCR fed through the snake with high capacitance wiring "could" make an audible difference.
I thought this thread was mostly reasonable and constructive, but know what Ivan is ranting about. I'm afraid it is the nature of the WWW and lurkers need to be selective about what they take from most threads.
JR
PS: Note the receiving end's input impedance is in parallel with the source impedance for RxC HF pole calculation, so results will be slightly better than using source impedance alone.
To amplify Ivan's rant I draw a distinction between phenomenon that can actually make an audible difference in the margin, and phenomenon that while perhaps real do not ever make an audible difference.
This discussion of snake length correctly zero'd in on the real, lumped capacitance forming an RxC with products source impedance, issue and not the esoteric transmission line characteristic impedance and termination effects. It is the nature of internet forum discussions that people often post everything that they know on some subject, instead of just the pertinent information useful to the OP. This can get confusing when the real answer gets lost in the noise.
Ivan is correct that even these real effects must be kept in perspective. How many signals in that snake need a >20kHz passband? That said, a 5kHz LPF could very easily be audible, so some worst case consumer VCR fed through the snake with high capacitance wiring "could" make an audible difference.
I thought this thread was mostly reasonable and constructive, but know what Ivan is ranting about. I'm afraid it is the nature of the WWW and lurkers need to be selective about what they take from most threads.
JR
PS: Note the receiving end's input impedance is in parallel with the source impedance for RxC HF pole calculation, so results will be slightly better than using source impedance alone.
Re: Maximum analog snake length
[TMI] For an example of a TMI answer that has nothing to do with the OPs question.... skin effect in fact is real at audio frequencies while still not significant in the context of your audio snake.
Not to get too esoteric, skin effect is a kind of a self repulsion of current flow so it tends to aggregate on the outer surface of conductors. This effect is so pronounced on high current (but low audio frequency) power lines that they often use hollow wires, or steel core cables with more conductive aluminum conductors wrapped around the steel core to provide good conduction in the outer "skin" region.
This is absolutely not a consideration for general purpose audio applications, while there is a legacy "Litz" wire design using many small conductors braided together to optimally provide lots of surface area for a given cross section area for improved RF impedance and embraced by some misguided audio-phools.
[/TMI]
JR
[TMI] For an example of a TMI answer that has nothing to do with the OPs question.... skin effect in fact is real at audio frequencies while still not significant in the context of your audio snake.
Not to get too esoteric, skin effect is a kind of a self repulsion of current flow so it tends to aggregate on the outer surface of conductors. This effect is so pronounced on high current (but low audio frequency) power lines that they often use hollow wires, or steel core cables with more conductive aluminum conductors wrapped around the steel core to provide good conduction in the outer "skin" region.
This is absolutely not a consideration for general purpose audio applications, while there is a legacy "Litz" wire design using many small conductors braided together to optimally provide lots of surface area for a given cross section area for improved RF impedance and embraced by some misguided audio-phools.
[/TMI]
JR
Re: Maximum analog snake length
I use 350ft snakes all the time. Attached are often 100ft or more subsnakes and 25-50ft mic cables. If the levels of the source are very low, like an SM57 3ft away from the person talking softly, and you have 6 or 8 of them open at once, at times you can get quite a bit of rizz. For R&R it is not usually an issue because you just don't need that much gain for a singer eating a mic, or a drum, or a guitar speaker. If you can get things up to line levels, then it's totally fine. All that being said, getting rid of all the copper, or going digital with a really exceptional desk, makes a huge difference in the perceived quality. Your audience probably won't notice but you might.
I use 350ft snakes all the time. Attached are often 100ft or more subsnakes and 25-50ft mic cables. If the levels of the source are very low, like an SM57 3ft away from the person talking softly, and you have 6 or 8 of them open at once, at times you can get quite a bit of rizz. For R&R it is not usually an issue because you just don't need that much gain for a singer eating a mic, or a drum, or a guitar speaker. If you can get things up to line levels, then it's totally fine. All that being said, getting rid of all the copper, or going digital with a really exceptional desk, makes a huge difference in the perceived quality. Your audience probably won't notice but you might.