So I moved into my new place recently and while moving I threw my power cable to my markbass combo into my pile of other wires (mixed with computer cables)...I'm just wondering will any of those thick 18awg wires used for computer PSUs and monitors work with my amp? I plugged one in and theres a slight humming (but i think that might be related to my back pickups tbh). I am playing a small gig for my church this weekend and just wanted to make sure the amp wouldn't start smoking from a short or something. Thanks in advance!
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Question about different Wire Gauges for my Markbass CMD 102p
- Thread starter Shinku443
- Start date
- Feb 12, 2006
- 61,047
- 5
- 221,002
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- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Alright cool, Just wanted to make sure. Is there a way to determine what's causing the humming from my amp as well?
I was going to buy a new 14AWG power cable anyway cause I need something a little longer. Would that be fine?
- Feb 12, 2006
- 61,047
- 5
- 221,002
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Does the amp make the noise with the instrument cable unplugged from the input? If it doesn't, it's almost surely your bass (or a poorly shielded cable).
You can certainly use a longer cable, 14 gauge isn't going to make any difference though. It won't hurt either, provided the connector fits snugly into the amp.
You can certainly use a longer cable, 14 gauge isn't going to make any difference though. It won't hurt either, provided the connector fits snugly into the amp.
it only makes a noise when i turn up the blend + back pickups. it looks like this has PJ style "Select by EMG". If flip my switch to just use my neck pickups then the humming is gone, but when I flip the switch to the bridge pickups and turn that up, then it hums. I opened up the back but can't really tell what should be going on. when I lift the bass and point it straight in the air the humming also disappears.
- Feb 12, 2006
- 61,047
- 5
- 221,002
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
The noise is environmental EMC, it's being picked up by the pickups. When you change the orientation of your bass, you are changing the direction of the pickup's magnetic field relative to that of the EMC. Possibly there is a problem with the wiring or grounding or shielding of your bass, but it could be that there's no hum cancellation built in.
Your symptoms are pretty definitive IME.
Your symptoms are pretty definitive IME.
ah okay, so is that fixable then wiring wise? i just called guitarcenter and they said they could take a look for free...and he said it might cost anywhere from like 40 to however much depending on the issue. If it's a shielding issue what could I do to fix it either through a tech or by myself. Thanks for all the help by the way.
OH also. I just figured out that it doesn't hum when I'm actually facing toward or away the amp itself. when I'm perpendicular it hums alot!
OH also. I just figured out that it doesn't hum when I'm actually facing toward or away the amp itself. when I'm perpendicular it hums alot!
Al Kraft
Supporting Member
- May 2, 2016
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- Mesa Boogie beta product tester and player support
Wires will not change your situation in my opinion. As agedhorse suggested this is an electromagnetic interference/compatibility (EMI or EMC) issue. There are some techniques that can be applied to the bass itself (shielding and grounding) and even the pick-ups (like adding a dummy coil wired with reverse polarity) that might make improvements to some frequencies and sources. However, if just changing position does the trick, you have both diagnosed your problem with a high degree of confidence and developed an effective mitigating strategy.
EMI has a way of finding its way into even the best protected equipment/components and IME a bass guitar with exposed magnetic pick-ups is about as far from that definition as one can get. If positioning yourself to play in a way that doesn't involve only standing in only one spot all the time or contortions that resemble circus acrobatics solves the problem, you might have the best solution. Even additional shielding in the bass control cavity or better grounding of the bass components might not do much more than lighten your wallet.
Many of us have the same issues and we simply stand where the hum goes away. Almost any amp, power supply or even a cell phone held in the right (wrong) way can transmit EMI into most instruments.
- Feb 12, 2006
- 61,047
- 5
- 221,002
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
If the noise varies with the position of the bass to the amp, it's likely that the noise is being induced into the bass from the amp's power supply. Generally there's not much you can do other than increase the distance between your bass and the amp. IF it's low frequency hum or noise, this is very difficult to shield against.
Be sure the service tech is familiar with managing EMC into your bass and understands how this works. Otherwise you will be paying your money without much confidence that it will get fixed. You will also need to bring your amp in so that he can test with your known noise source. I would also suggest that if the tech can't fix your problem, you agree on a (reasonable) price in advance so you don't end up paying for somebody making a bunch of bad guesses.
Generally, I haven't found that the GC service guys are all that good with such issues (I'm sure there are some), so be sure you know what you are getting for your service dollar.
Be sure the service tech is familiar with managing EMC into your bass and understands how this works. Otherwise you will be paying your money without much confidence that it will get fixed. You will also need to bring your amp in so that he can test with your known noise source. I would also suggest that if the tech can't fix your problem, you agree on a (reasonable) price in advance so you don't end up paying for somebody making a bunch of bad guesses.
Generally, I haven't found that the GC service guys are all that good with such issues (I'm sure there are some), so be sure you know what you are getting for your service dollar.
When you pick a power cable from your pile, make sure that it fits snugly into the amp’s IEC socket. They vary a bit and you don’t want one that’s loose.
Pick the length that works for you as well.
Pick the length that works for you as well.
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The Guitar Center tech will be looking for ways to get you to spend money. They may start by saying that your bass needs shielding. Maybe some new instrument cables. How about their service tech taking a look at your amp. Maybe they do have issues but take what they say with a grain of salt.
Al Kraft
Supporting Member
- May 2, 2016
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IME having a connector that fits snugly and a sufficiently/properly sized power cable that is light enough in weight that it doesn't "pull down" on the connector is exactly what is needed. I've read ads about power cables as thick as welding cables that provide some type of electrical magic - IMO not only are they a worthless waste of money, but just place unnecessary mechanical stress on connectors.
To me this is also worth keeping mind with signal carrying cables as there is always a cable size beyond which you are accomplishing nothing useful for your system and often creating mechanical stress on mating connectors that may eventually lead to reliability issues.
To me this is also worth keeping mind with signal carrying cables as there is always a cable size beyond which you are accomplishing nothing useful for your system and often creating mechanical stress on mating connectors that may eventually lead to reliability issues.
Yeah I decided not to go into guitar center - I'll be facing away from the amp when I play so I should be fine. Is it weird that it only occurs when my bridge pickups are turned up vs neck pickups? Thanks for all the help though everyone! Really appreciate it!
There was a run of EMG Geezer Butler PJ pickup sets several years ago with a faulty J pickup.
In that set, running either the P alone or the J alone would be still be hum free. Both were designed to be hum cancelling on their own as each had two coils and were made to RWRP standards.
The J pup was made incorrectly (the D/G pole pieces were not reversed from the E/A, they were inserted with the same magnetic polarity as the E/A). As a result, they produced single coil noise that got less or worse depending on the orientation of the guitar, IE worn normal, or laid flat like a lap steel. EMG replaced them if you contacted them.
Perhaps another bad batch of J pups got out from EMG, or your J is not the hum cancelling design (RWRP) type of pickup.
In that set, running either the P alone or the J alone would be still be hum free. Both were designed to be hum cancelling on their own as each had two coils and were made to RWRP standards.
The J pup was made incorrectly (the D/G pole pieces were not reversed from the E/A, they were inserted with the same magnetic polarity as the E/A). As a result, they produced single coil noise that got less or worse depending on the orientation of the guitar, IE worn normal, or laid flat like a lap steel. EMG replaced them if you contacted them.
Perhaps another bad batch of J pups got out from EMG, or your J is not the hum cancelling design (RWRP) type of pickup.
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That's one of the problems with PJ-style pickup setup. Maybe that's why Leo didn't make it that way. I hope they can fix it at the shop. Happy playing!
In my opinion, save your money. From what you have described, this is normal for a J type pickup, and maybe more so for the EMG select model. They have been described as a passive bargain basement offering from EMG.
If the J pup is made to be hum cancelling AKA RWRP, it will be as dead quiet as the P pup.
But not all J pups are hum cancelling/RWRP. Seymour Duncan SJB-1 pickups for example. You’d have to check with EMG to see what those are designed as.
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If the J pickup is wound as a hum bucker, or anything other than a single wound coil, it's not really a J pickup, except maybe in appearance.
That’s debatable as the differences are slight depending on how they are made. If the coils are next to each other, one coil under the E/A, the other under the D/G, it can be hard to tell.
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