Outfitting New Home Studio - Interference Question

Discussion in 'Recording Studio' started by vintage_goldtop, May 30, 2017.

  1. vintage_goldtop

    vintage_goldtop Junior Member

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    I'm hoping someone can help me out. Long time lurker here and this forum has offered so much good advice but I have finally had a reason to signup and get some expert opinions.

    A little background...I am about set up my home studio and will soon be purchasing all of the cables to wire it up. My problem is I am smack dab in the middle of some major interference sources. There is a huge communications tower as well as a power substation (or whatever they are called) both within a quarter mile in opposite directions...huge bummer.

    I'm setting up in a basement and there is a noticeable difference from playing upstairs and down but I still get some noise through my mogami golds and some lava cables with braided shield. I've read just about every guitar cable guide (most are crap and thin) I can find on google and most forums I'm a member of but never stumble upon anyone experience the shit storm I'm in the middle of.

    Now, recently I found a guide for best guitar cables a few pages deep in google and it specifically referenced "twisted pair" conductors being superior for blocking emi. I was not previously familiar with this type of cable but Lava and a company Evidence Audio makes them.

    I'm considering investing in some of these (or others suggested in this thread) to eliminate the noise issue but was looking to see anyone has experienced such high interference and used a high end cable specifically one with twisted pair conductors. It's a steep investment and I don't want to just throw money at a problem that I can't be solved.


    TLDR; Big problems with interference...is there a magic cable that blocks it better than others?
     
  2. DarrellV

    DarrellV Almost 1 Year old this month! Premium Member

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    Paging @Freddy G and @John Scrip @yeti

    Someone in here will know, so I'm gonna get some of the big guns in here first

    Oh, and :welcome: to the club! :cheers2:
     
  3. vintage_goldtop

    vintage_goldtop Junior Member

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    Many thanks...anxiously awaiting to empty out my bank account! :fingersx:
     
  4. DarrellV

    DarrellV Almost 1 Year old this month! Premium Member

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    Not always, That's the beauty of this place. if there is a cheaper mod or substitute, someone here has prolly found it.
     
  5. vintage_goldtop

    vintage_goldtop Junior Member

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    Well then I came to the right place! That is what I'm hoping to find out...whether the cost is justified as its my only option or is there a better solution.
     
  6. yeti

    yeti Senior Member

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    Hm, so are you asking about guitar cables only or about studio wiring in general?
    As far as spending big bucks on boutique guitar cable to suppress interference I'd only explore that route after you have verified that the cable is indeed the problem. This is a bit outside my expertise but IIRC current based interference/ hum (like running audio lines in close proximity and parallel to power lines drawing lots of current) is largely immune to shielding (even braided shield balanced lines are suseptible) but responds well to changes in cable layout relative to the source of the interference (hence the practice of audio lines crossing power lines at 90 degree angles) while voltage based interference can be suppressed by shielding. I probably remember this wrong, sorry about that in advance, maybe Freddy or John can chime in. The point being: not all EMI/ RFI is created equal.
    But poorly shielded guitar electronics can be the problem also, and no cable or path layout is going to fix that. Same for mic cables, many times the interference enters the audio path at the mic, (especially cheap condenser mics) , not the cable. If the mic cable is the problem StarQuad cable (2 twisted pairs for + and -) offers better RF rejection but at a price, usually the capacitance is higher causing more HF roll off, although that's not really an issue at normal mic cable length. (guitar cables are a different issue with regards to capacitance)
     
    Last edited: Jun 1, 2017
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  7. Norton

    Norton Senior Member

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    There's nothing special about a mogami cable outside of the rubber jacket. There are PLENTY of great wire makers out there… gepco, chicago wire…redco etc. and on and on that have the exect same specs for 1/2 the price.

    That being said… mic lines and guitar cables aren't going to offer much in the way of solving any problems. Good mic/line cables are great mainly because they tend to be more durable…and have a little less high end loss due to lower capacitance (yeti's right on the money!)

    If you're having noise issues…. I'd say Yeti's post is filled with good info. RE: running signal lines away from and/or not parallel to power wire runs etc.

    It would also be wise to be 100% certain that some other internal issue wasn't the culprit, or at least contributing to the problem.

    I've got a tricked out studio space that's close to some radio and TV arrays… they've never been a problem. I've also solved studio noise issues for clients by cleaning up power routing, and using dedicated breaker runs.

    You can mitigate your noise issues in a couple ways. 1. would be to have an isolation transformer for your studio which is going to be spendy….
    2. at the very least make sure all your studio power is on dedicated breakers. Sharing your studio outlets with other parts of your house i.e. appliances etc… can really add to noise issues.
     
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  8. LPSGME

    LPSGME Senior Member

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    I would say you need to discover the source of the noise and just how it is getting into your system before assuming that better wires will block it. Process of elimination is probably the best approach. Test various pieces of equipment one at a time to see which, if any, are picking up any interference and try to determine if it is being radiated from the 'communication towers' or coming from your electrical lines. Start with one device and listen at the most immediate point to the device. Then make some assessment of your findings.

    If you hear noise I would think it would have to be coming from frequencies that are in the audible range.

    I've experiences several different episodes of noise being injected into my video and audio equipment due to external sources. In one instance a neighbor 1000 feet away had a leaf blower whose electric motor was generating spikes. The spikes were somehow back feeding into their electric lines and traveling down the street and feeing into my electric service or cable service - thereby causing interference with my cable TV.

    Another time, back in the days when broadcast TV was the norm, my TV screen would white out from some apparent source of radiated energy - obviously within the reception frequencies of the TV. What was odd was that it mostly happened less when the sun was shining. I asked my nearest neighbor if they were running into the problem and they replied saying they didn't have time for such trivial wastes of time [as watching TV] because they just had a baby. So I got my electric company involved but they failed to find the problem after spending about $30,000 looking for it. So I drove around the street with a portable TV and was able to triangulate on the source and discovered it was coming from that neighbor's home. I brought back the electric company and we traced the source to the baby's room where we found a 'baby wipe warmer' sitting near a window. Apparently the company who made it used some sort of 'fish tank heater thermostat' that had a relay with spark arching problems. Being it was in the window, the sunlight kept it from turning on as much as it did at night. So after 3 months of not being able to watch TV the mystery was solved.
     
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  9. Dick Banks

    Dick Banks Senior Member

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    Also a great first step is to lift all of the grounds. Please realize though that this does not provide the permanent solution, as it creates a shock hazard. But it will tell you if the noise is propagating through the ground. In the US, there are three prong to two-prong adapters to do this. They are illegal in other countries, like Canada.
     
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  10. vintage_goldtop

    vintage_goldtop Junior Member

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    Wow...everyone's response has provided a ton of good info for me. My first thought was try to clear up any low hanging fruit, but my idea of low hanging fruit (the cable) was off. I figured since Mogami is just a quality spiral shielded cable and the noise diminished a good bit from upstairs to down, maybe I could clear it up with a better cables.

    My first order of business is going to evaluate all of the shielding in the guitars. Next I will try different cable layouts, which I hadn't thought about before. My space is pretty open so I should have no issue experimenting with different runs and layouts. I hadn't even thought of the other causes of noise mentioned by others, although I am mostly at work late night and I would think activity would be lower but I certainly wont rule it out.

    Again, I have a ton of good info now and I can get to work troubleshooting! I will sure to give an update as to what I find works best for my situation.
     
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  11. DarrellV

    DarrellV Almost 1 Year old this month! Premium Member

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    Told ya they're good! LOL! :h5:
    Keep us posted on what you find!
    Never know, someone else might find it useful....:hmm:
     
  12. yeti

    yeti Senior Member

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    I'm not sure that's what I meant to say. For mic cable I use Gotham GAC 3 at home. It has an additional 3rd conductor that, when tied to ground, increases RF rejection significantly. To say that using cable like that is mostly about durability and minute HF differences gives an incomplete picture. What I did mean to say was that if (and that's a big if) the interference can be traced to poor cable then investing in premium cable makes sense under certain conditions.
    I hope this makes sense.
     
  13. yeti

    yeti Senior Member

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    Like I said, I'm no expert on this, but this statement is incorrect. For example a guitar amp or stomp box can easily become a detector for AM signals , the interference signal is clearly outside of the audible range but you still hear it.
     
  14. LPSGME

    LPSGME Senior Member

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    True. But I was sort of saying that in the context of the OP saying that he was near a "huge communications tower". And these days that generally means a microwave cell tower etc.
     
  15. Norton

    Norton Senior Member

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    My point re mic cable etc. was don't get caught up in brand name... sure star quad or extra shielding is useful.

    But mogami and monster are upcharging you in a hifi manner.

    There are just so many great options...that it's unnecessary to spend extra $$$ for the jacket.

    Hope your noise issue is a quick and easy fix
     
  16. spitfire

    spitfire Senior Member

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    Shielding is just one part of reducing interference. And proper layout is much more important than the quality of the cable. I'm not quite saying that shielding is shielding, but I'm close to that.

    Aside form just having basic shielding, it's extremely important to having proper layout. They key to this is eliminating ground loops.

    For those not familiar, a ground loop is any path through ground that allows you to return (loop) back to a point you have already been on.

    So start at the guitar, flowing the grounded shield. To your amp or first pedal etc. If you just go into the amp, and that's it, your done. No loop. But say you have a pedal board. You go to the first pedal. Of course the output of this pedal goes to the next and so on. Ultimately out the last pedal to the amp.

    However, each pedal is being powered form the pedal board power supply. These power inputs also have ground. Therefore you have another ground path that will form a loop. This loop goes through the pedal board power supply to the AC ground (wall socket ground). All AC ground are tied together somewhere, so once the ground path goes into one wall socket, the path comes back to the amp ground, through the amp, back to the last pedal in your pedal board chain.

    This can actually be a huge loop. It may go back all the way to your breaker box. Though if the amp and pedal board are plugged into the same wall outlet, or common power strip, the loop is much smaller.

    Also, there are small ground loops created by each pedal and the pedal board supply. For example, you have a loop form the first pedal's power ground to the pedal board supply, back to the second pedal, through the cable connecting pedal 1 & 2, and back to pedal 1.

    So why are ground loops a problem.

    There are two kinds of electrical interference, magnetic and electrostatic (think voltage). The thin shielding on cables, in guitars, and electronics in general, is much too thin, orders of magnitude to thin to block 60 Hz magnetic fields. I don't know the needed thickness for 60 Hz, but I think it may actually be feet thick.

    The shielding we have is only useful for blocking electrostatic fields (voltage fields). It forms a Faraday cage.

    There is no practical way to block 60 Hz magnetic fields in this application. What you have to do is avoid picking the up in the first place.

    Magnetic fields induce currents in wires. Specifically in loops of wire. The amount of interference is proportional to the size of the loop. Think of it like a net, the bigger the net, the more you "catch"

    So any loop of wire is susceptible to magnetic fields. A ground loop is no different. Doesn't matter that it is ground. Ground does not have magic properties. It isn't a giant black hole for all things electrical. It is just a name we give to an electrical point (node) that is referenced to actual ground (the Earth).

    So okay, we have a ground loop, a 60 Hz magnetic field from a nearby substation or just your house wiring, creates currents in this loop. Here;s why that is a problem.

    The currents induced in the house wiring don't matter, but part of that loop is you cables that carry your guitar signal. All wires have some resistance. So when these currents flow through the shields of your guitar cables, voltages are generated over the length of the cables. These voltages add directly to your guitar signal. Therefore you hear them.

    So if you don't have a loop, you can't have these currents, and they won't create voltages that add to your signal. So get rid of these loops.

    In the example, above, with a pedal board, the best thing to do is get an optically coupled pedal board power supply. This is a supply where the power plugs going to each pedal, do not have a connection to ground. It's pretty much like each pedal is being powered by a battery. The pedal board supply itself still plugs into the AC ground, but DC outputs of the supply are all floating (not referenced to ground).

    These types of supplies are more expensive, but it's a great first step in avoiding ground loops.

    There are of course many other possible ways to create ground loops. Especially in a recording studio. But the same principle applies.

    This is also a reason for using XLR cables. These have two signal wires inside and a separate shield. The music signal doesn't go through the shield. So a ground loop through these is not as big of a problem. However, it is still best to avoid the ground loop. This is quite easy. Just lift the XLR shield at one end of the cable. It's actually best practice to only connect a shield at one end (assuming the gear at both ends is grounded). This is not possible with a guitar cord because the shield also completes the signal circuit.

    Proper layout and paying close attention to where the actual signals flow through the cables can make a huge difference in the interference you pickup. I think you should always be able to get to the point that it is the guitar pickup itself (or crappy amp etc.) that is the source of the most interference.

    Hopes this wall of words makes a bit of sense.
     
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