Electric ukulele produces helicopter-like sound

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stian

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Hello all. First off the bat: I'm a beginner with both ukuleles and string instruments in general, so in order to practice quietly, I bought a Vorson electric ukulele in addition to an acoustic one.

However, the ukulele produces a flapping, helicopter-like sound that is driving me nuts. What's more, the helicopter sound varies with the position of the ukulele.

If it's on my lap in playing position with the front perpendicular to the floor, the helicopter sound is low, but still very annoying. If it's slanting or laying flat, the sound is just unbearable.

It produces the sound both hooked up to an amp and with headphones connected directly.

Any ideas what can be causing this, and how it can be fixed?

If you'd like I could post a clip of the actual sound?

Thanks,
Stian
 
A clip would definitely help, but my first guess is that the instrument is not properly shielded, and you're getting all sorts of ground loops, depending on the position of the ukulele.

It's a relatively easy thing to remedy. I buy copper shielding tape off of eBay for around $6-8, and it covers 3-4 guitars or electric basses easily, so you'll be fine with just the ukulele. There are a number of how-tos online to walk you through the process of shielding it.
 
Thanks, will definitely try that! Uploaded a link to a sound clip if you could be so kind as to check it out.

Cheers,
Stian
 
One Bad Monkey said:
A clip would definitely help, but my first guess is that the instrument is not properly shielded, and you're getting all sorts of ground loops, depending on the position of the ukulele.

It's a relatively easy thing to remedy. I buy copper shielding tape off of eBay for around $6-8, and it covers 3-4 guitars or electric basses easily, so you'll be fine with just the ukulele. There are a number of how-tos online to walk you through the process of shielding it.
Click to expand...

I agree with OBM. Sounds like you are getting either electromagnetic or radio frequency interference, also know as EMI/RFI.

The magnetic pickups will act like an antenna, and if there are any stray radio waves in your home, it will catch them and amplify them.

Stray radio waves can be caused by poor grounds in anything plugged in to the wall, fluorescent light bulbs, AD-to-DC power supplies, your microwave, cordless phone, cel phone, TV, computer monitor, nearby power lines (yes even a mile away).

You could take the Vorson in the car with your headphone amp unit and try it somewhere a few miles from your house and see if the sound is still there.

Also, failing batteries can cause a sort of heterodyne pulsing sound, so check the voltage on, or replace the battery in your headphone amp.

Another thing is that the Vorson has 2 single-coil pickups, which unless all body cavities inside the instrument are shielded with the foil tape as OBM has mentioned, will produce hum. Fender stratocaster guitars are almost famous for the hum.

One solution is to have humbucker pickups, which have 2 magnetic coils in them, which are 180 degrees out of phase, and by doing so what is called 'phase cancellation' takes place and most, if not all of the hum is gone.

I too have a Vorson, the LP version, and each of these ukes has a 3-position switch, neck pickup, both, and bridge pickup. I thought I read somewhere that in the middle position the pickups act as humbuckers since they are wired opposite to each other with the way the the signal and ground wires are soldered to the switch. What this means is that, if the wiring is as humbuckers with the middle switch position, is that it should cancel or eliminate most of not all of the hum. I have not traced the wiring on mine to verify this, but if you are handy with a soldering iron, it would take maybe 5-10 mins to set this up as humbuckers.

There are lots of guitar pickup wiring diagrams online, and I dont have a schematic handy, but you can find the easily enough. Stewmac has lots of info about this stuff.

Also, as OBM said, if your ground wires in the guitar and all connected equipment are not with solid connections, you will get hum.

One last thing, the metal bridge of the Vorson should have single wire that connects to the ground circuit inside the wiring cavity, this makes sure that when you touch the strings, that YOU act as the Earth, i.e., the 'ground' and this cancels the hum because your body absorbs the capacitance generated by the lost/disconnected ground.

Hope this helps...:)
 
Booli said:
I agree with OBM. Sounds like you are getting either electromagnetic or radio frequency interference, also know as EMI/RFI.

The magnetic pickups will act like an antenna, and if there are any stray radio waves in your home, it will catch them and amplify them.

Stray radio waves can be caused by poor grounds in anything plugged in to the wall, fluorescent light bulbs, AD-to-DC power supplies, your microwave, cordless phone, cel phone, TV, computer monitor, nearby power lines (yes even a mile away).

You could take the Vorson in the car with your headphone amp unit and try it somewhere a few miles from your house and see if the sound is still there.

Also, failing batteries can cause a sort of heterodyne pulsing sound, so check the voltage on, or replace the battery in your headphone amp.

Another thing is that the Vorson has 2 single-coil pickups, which unless all body cavities inside the instrument are shielded with the foil tape as OBM has mentioned, will produce hum. Fender stratocaster guitars are almost famous for the hum.

One solution is to have humbucker pickups, which have 2 magnetic coils in them, which are 180 degrees out of phase, and by doing so what is called 'phase cancellation' takes place and most, if not all of the hum is gone.

I too have a Vorson, the LP version, and each of these ukes has a 3-position switch, neck pickup, both, and bridge pickup. I thought I read somewhere that in the middle position the pickups act as humbuckers since they are wired opposite to each other with the way the the signal and ground wires are soldered to the switch. What this means is that, if the wiring is as humbuckers with the middle switch position, is that it should cancel or eliminate most of not all of the hum. I have not traced the wiring on mine to verify this, but if you are handy with a soldering iron, it would take maybe 5-10 mins to set this up as humbuckers.

There are lots of guitar pickup wiring diagrams online, and I dont have a schematic handy, but you can find the easily enough. Stewmac has lots of info about this stuff.

Also, as OBM said, if your ground wires in the guitar and all connected equipment are not with solid connections, you will get hum.

One last thing, the metal bridge of the Vorson should have single wire that connects to the ground circuit inside the wiring cavity, this makes sure that when you touch the strings, that YOU act as the Earth, i.e., the 'ground' and this cancels the hum because your body absorbs the capacitance generated by the lost/disconnected ground.

Hope this helps...:)
Click to expand...

Thanks for good pointers! I actually also have the LP type (the maple quilt one). The noise is actually highest when the switch is in middle position..

As a small preliminary test for interference, I took a little walk around the house and the sound was pretty consistent as far as I could tell. Will definitely give it a more devoted approach tomorrow and drive a bit away from the house and see if it makes a difference. Will also inspect the instrument more closely for loose couplings.
 
stian said:
Thanks, will definitely try that! Uploaded a link to a sound clip if you could be so kind as to check it out.

Cheers,
Stian
Click to expand...
Ooo-err!!

Are you mains powered or running off batteries?

That noise sounds like a mains power adaptor that is either faulty or simply not up to the task and is continuously shutting down and re-starting.

You need to isolate whether the fault is inherent in your equipment or caused by external influences within the building. The latter may be improved by shielding with copper tape etc., but not the former.

If you are all-battery take the kit outside somewhere for five minutes, the local park, playing field or even an open-air car park and see if you've still got a problem. If you're "stuck" with mains power, try different rooms, maybe a different building if possible, even an extension lead out onto the balcony or to the garden or roof. Just any opportunity to try to establish if the problem is external influences or not. Basically you're trying to leave the fault behind thereby indicating external interference. If you've still got a similar problem in a different location, it's likely to be faulty gear.

BTW ... my Stratocasters (three single coil pickups) don't hum, but they have been re-wired using audio co-ax instead of the original hook-up wire ... a lot easier and quicker than fiddling copper or aluminium foil into all those nooks and crannies ;)
 
kypfer said:
Ooo-err!!

Are you mains powered or running off batteries?

That noise sounds like a mains power adaptor that is either faulty or simply not up to the task and is continuously shutting down and re-starting.

You need to isolate whether the fault is inherent in your equipment or caused by external influences within the building. The latter may be improved by shielding with copper tape etc., but not the former.

If you are all-battery take the kit outside somewhere for five minutes, the local park, playing field or even an open-air car park and see if you've still got a problem. If you're "stuck" with mains power, try different rooms, maybe a different building if possible, even an extension lead out onto the balcony or to the garden or roof. Just any opportunity to try to establish if the problem is external influences or not. Basically you're trying to leave the fault behind thereby indicating external interference. If you've still got a similar problem in a different location, it's likely to be faulty gear.

BTW ... my Stratocasters (three single coil pickups) don't hum, but they have been re-wired using audio co-ax instead of the original hook-up wire ... a lot easier and quicker than fiddling copper or aluminium foil into all those nooks and crannies ;)
Click to expand...

Good point about using coax. I have a bit of 75 ohm shielded coax laying about from a former project, is that what you're using? :)

Will take a drive tomorrow with the ukulele and my headphones and see how that goes.
 
stian said:
Good point about using coax. I have a bit of 75 ohm shielded coax laying about from a former project, is that what you're using? :)

Will take a drive tomorrow with the ukulele and my headphones and see how that goes.
Click to expand...

I wouldn’t use 75-ohm coax that is typically used for video. This kind of coax wire is going to massively thick for use in the Vorson, or any electric guitar (with such small body cavities), and bending it in an arc greater than 30 degrees is likely to snap the inner-core solid copper wire resulting in a shorted, i.e., broken connection that cannot be fixed without cutting the end at the break, stripping the end properly, and then crimping on a new F-connector.

This holds true for RG-6, RG-59 and RG-58 spec 75-ohm coax used to carry video and also cable internet signals.

There is a much thinner coax wire used for audio that that has a 16 AWG stranded or smaller inner core, then an insulation later of PVC, and that is over-wrapped with a braided wire that acts as both a shield and ground, and then this is covered with PVC, which is what you see on the outside. Such wire comes both in single-conductor, as well as multi-conductor varieties.

I'm pretty sure both StewMac and LMI sell this kind of wire.

Please report back what happens after your drive-test. Make sure to also test a new battery in your headphone amp while doing so to eliminate the battery as the source of the problem.
 
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I have one thing you may eliminate almost immediately:
Is there a cell phone nearby? Turn it off!
Cell phone radio interference often sounds "helicopter" like.
If you had a cell phone in your pocket while playing the ukulele on your lap, I would almost guarantee that is what is causing the sound. Especially when you say it happens in headphones too.

I get the same problem if I am taking on my work (desktop) phone and my cell phone is lying on the desk near my wired phone.
 
stian said:
Good point about using coax. I have a bit of 75 ohm shielded coax laying about from a former project, is that what you're using? :)
Click to expand...

The "audio co-ax" I used came from the lead of a "retired" set of earphones that had "gone intermittent" ... nothing special, but perfectly good for the job in the short lengths needed. Just be careful soldering it, the plastic insulation is thin and soft and melts easily ;)

Not sure about 75ohm co-ax for this job. If it's the small-diameter stuff used for the internal wiring of radio equipment it'd probably be OK in the short lengths we're talking about here. If it's the (approx.) 1/4" diameter stuff used for domestic wiring, then probably too thick to be easily manageable in a tight space.
 
Everything everybody else said, plus these:
Try a different cable. Instrument cables are usually single conductor with a shield. It's possible you have one with a poor shield connection, or just generally poor shielding. Also possible you're accidentally using a speaker cable instead of an instrument cable (you wouldn't believe how often I see these two mixed up). Try another amp. It's possible you've got an amp that has a poor or faulty grounding scheme. Lastly, is your cell phone in your pocket, right next to the uke? If so, try putting it some distance away. Modern electronics generate lots of noise, and unfortunately there are all sorts of ways for that noise to infiltrate your instrument/amp combo.
 
Thank you everybody for all your great help, I never expected so many great answers!

Took the instrument out for a drive earlier today, and the noise went away not far from where I live. After I came home, I dismantled the electronics (not de-soldered anything yet). Tried positioning the pickups 180 degrees at each other (one facing upwards and one downwards) to test phase cancellation (thanks Booli!), and this also made the noise go away.

Now that we have pretty much established that interference is the issue here, I've gone ahead and ordered some 16 awg coax (the outer diameter is pretty much the same as the existing wiring), which I think was a really good tip. Hopefully I'll be able to swap the existing wires with this and see how it goes. The coax I already had are leftovers from wiring s/pdif digital audio connections with my stereo, and you are indeed correct it would be unsuitable in this case.

Also ordered some copper tape in case I'm unsuccessful with the coax approach. I guess I'm a bit of a belt and suspenders guy sometimes :D

Will write more about the rebuild once I receive the parts, as well as post some pictures.
 
Or you could use it to your andvantage and play Charlie don't Surf. A very limited repertoire I know but.....

 
stian said:
Thank you everybody for all your great help, I never expected so many great answers!

Took the instrument out for a drive earlier today, and the noise went away not far from where I live. After I came home, I dismantled the electronics (not de-soldered anything yet). Tried positioning the pickups 180 degrees at each other (one facing upwards and one downwards) to test phase cancellation (thanks Booli!), and this also made the noise go away.

Now that we have pretty much established that interference is the issue here, I've gone ahead and ordered some 16 awg coax (the outer diameter is pretty much the same as the existing wiring), which I think was a really good tip. Hopefully I'll be able to swap the existing wires with this and see how it goes. The coax I already had are leftovers from wiring s/pdif digital audio connections with my stereo, and you are indeed correct it would be unsuitable in this case.

Also ordered some copper tape in case I'm unsuccessful with the coax approach. I guess I'm a bit of a belt and suspenders guy sometimes :D

Will write more about the rebuild once I receive the parts, as well as post some pictures.
Click to expand...


Glad you were able to make some progress with the troubleshooting and use the good info that your fellow UU members have offered.

That's great that you got the phase cancellation set up. Now, with the 3-way toggle switch in center position you will have BOTH pickups as intended, but they will be acting like a single humbucker, but with the two coils a few inches apart, but it still works any way :)

One more thing - before you de-solder anything, you might want to take LOTS of pictures of all the wiring, as well as manually write down the wiring, if not a full schematic.

At least something like:

jack plug has ground and signal,
-signal wire goes to X on toggle switch in Y position,
-ground wire goes to Z on toggle switch in W position​

tone pot has 3 lug connectors and the back metal plate acts as the ground
-with knob facing AWAY from me:
-left lug is wired to X
-middle lug is wired to Y
-right lug is wired to Z
-capacitor is orange rectangle (or teal blue disc) shaped 47uf (22uf, or any other value) and wired with one leg to ground and other leg to ??? lug on tone pot
​

etc....

for EACH and every wire including the capacitor that is on the tone potentiometer, AND that capacitor's value or markings on it in case one of the legs get broken off and you need to source a replacement.

This documentation of the existing configuration will be a lifesaver in the event that you cannot complete the rewiring all in one sitting. What if it is two weeks (or longer) from when you start before you come back to it, and it is half-desoldered? Will you remember how it was or supposed to be?

I've been burned by not doing this myself often enough with other projects when 'real life' distracts me, and coming back to it much later, I've often found that it's like starting over from scratch or that I have to go online and find another reference to look at if I cannot remember exactly how it's supposed to be set up.

Do yourself a big favor, and carry that 'belt-and-suspenders' idea forward with what most folks would call 'ridiculous' or 'overkill' documentation both with photos and DETAILED written description or schematic if so inclined.


Also, since you might be removing the knobs from the body to do the rewiring, it cannot hurt to put in the copper foil tape at that time. You might also want to solder a small wire length from one of the grounds to the copper tape somewhere as this can also help to provide another ''earth" connection.

As you can see, I too try the belt-and-suspenders approach if/when I can remember to do it at the time.

EDITED TO ADD: I am glad that you are confident with a soldering iron. Its use is a skill that will have many applications down the road. Many folks are afraid of it, but it takes a few minutes to learn how to use, and a lifetime of burned fingertips if you are not careful - LOL
 
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Thanks again, this is getting to be quite a learning experience for me :)

Tried making a schematic with the software downloaded from http://fritzing.org/home/, but it got a bit too involved for an amateur.

I imagine I will take a ton of pictures as well as make an amateur-friendly schematic using pen(s) and paper.
 
Booli said:
EDITED TO ADD: I am glad that you are confident with a soldering iron. Its use is a skill that will have many applications down the road. Many folks are afraid of it, but it takes a few minutes to learn how to use, and a lifetime of burned fingertips if you are not careful - LOL
Click to expand...

Yes, I have a soldering station and even though I'm no expert I dabble with some smaller electronics projects from time to time. In that respect I consider my fingertips to be pre-conditioned for playing with steel strings ;)
 
It is 100% easier to line the area under the pickup and under the controls with foil tape than to start rewiring a ukulele with better wires. For the record this stuff works fine and you can buy it at most any Home Depot or Lowes: http://www.homedepot.com/p/Nashua-T...ulti-Purpose-HVAC-Foil-Tape-1207792/100030120

Remember even with the best wire the solder joints, inexpensive pickups and cheap pots or switches will still leak interference.

I have had to do this with one Risa stick and a KonaBlaster I own. Cheap foil tape lining, no wire running from the bridge to anywhere and we went from hum city to silent night.

http://forum.ukuleleunderground.com/showthread.php?92068-Risa-electric-background-noise

http://forum.ukuleleunderground.com/showthread.php?72464-Risa-Stick-Amplifier-Buzz-Hum-Help-Plz

Sadly both used Risa sticks Ive bought have had the frets molested by uneducated attempts to stop the buzz.

Good luck
 
Inksplosive AL said:
It is 100% easier to line the area under the pickup and under the controls with foil tape than to start rewiring a ukulele with better wires. For the record this stuff works fine and you can buy it at most any Home Depot or Lowes: http://www.homedepot.com/p/Nashua-T...ulti-Purpose-HVAC-Foil-Tape-1207792/100030120

Remember even with the best wire the solder joints, inexpensive pickups and cheap pots or switches will still leak interference.

I have had to do this with one Risa stick and a KonaBlaster I own. Cheap foil tape lining, no wire running from the bridge to anywhere and we went from hum city to silent night.

http://forum.ukuleleunderground.com/showthread.php?92068-Risa-electric-background-noise

http://forum.ukuleleunderground.com/showthread.php?72464-Risa-Stick-Amplifier-Buzz-Hum-Help-Plz

Sadly both used Risa sticks Ive bought have had the frets molested by uneducated attempts to stop the buzz.

Good luck
Click to expand...

Thanks! This will be a bit of a trial and error exercise for me I guess, but hopefully without messing up completely. I actually initially didn't think it was interference at all because the noise can hardly be described as a sort of humming sound, which from what I've read is mostly what others complain about. Anyway, I have placed orders for both tape and wires and think I'll test both and see how it works out.
 
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