Rickenbacker 330 Hum With Volume Completely Down

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daveseven7
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Rickenbacker 330 Hum With Volume Completely Down

Post by daveseven7 »

I recently bought a Rickenbacker 330 from a licensed dealer. I love the sound and feel of this guitar--it's as unique as my 4003 bass. I've noticed that I get substantial hum from this guitar with the volume turned all the way down. It's the only guitar in my collection that isn't silent when the volume is turned all the way down. It's the same in the bridge pickup position or the neck pickup--if I set it down on it's stand with the volume turned all the way down there is a surprising amount of hum. Could this be a disconnected ground wire in the guitar? Shouldn't there be zero signal (including hum) when the volume is turned all the way down? (even when both volumes and both tone pots are turned completely down).
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espidog
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by espidog »

Hi David,

Regarding your query, I need to ask you a question: do any of the other guitars you own have independent volume controls for each pickup, or do they rely on a single master volume control?

The reason I ask is that on a guitar such as the 330, which uses a separate volume control for each pickup, the "hot" signal wire from each pickup goes to the centre (wiper) lug of its dedicated volume control. Thus when you turn the control down to zero, it's the pickup you're shutting off (dumping to ground), not the connection to the amp. With the pickup turned down, the +ve signal wire to the amplifier (which is connected to the top lug of the pot track) is left "floating" above ground by the value of the pot (around 330k I believe) and consequently will be somewhat susceptible to picking up electromagnetic noise.

Schematic of a 330 here:
https://www.chanish.org/wp-content/uplo ... gram_4.jpg

On a guitar with a single master volume for everything, they're usually wired with the +ve signal wire from the pups going to the top of the pot track, and the connection to the amp going to the wiper, so when it's turned down, it's shutting off/grounding the input to the amp. Result: no hum pickup when it's turned down.

On a guitar like a 330, you can't wire the volume pots this way, because if you did, turning down one volume pot would silence both pickups - i.e. either volume pot would act like a master volume.

Given that you describe it as "substantial hum", I'd say that yes, it's possible a grounding wire has come adrift somewhere. OTOH, it may just be that something in your practice space is kicking out a lot of electromagnetic noise. Got any fluorescent lights in there?
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jdogric12
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by jdogric12 »

Not normal. Call dealer.
daveseven7
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by daveseven7 »

espidog wrote:Hi David,

Regarding your query, I need to ask you a question: do any of the other guitars you own have independent volume controls for each pickup, or do they rely on a single master volume control?

The reason I ask is that on a guitar such as the 330, which uses a separate volume control for each pickup, the "hot" signal wire from each pickup goes to the centre (wiper) lug of its dedicated volume control. Thus when you turn the control down to zero, it's the pickup you're shutting off (dumping to ground), not the connection to the amp. With the pickup turned down, the +ve signal wire to the amplifier (which is connected to the top lug of the pot track) is left "floating" above ground by the value of the pot (around 330k I believe) and consequently will be somewhat susceptible to picking up electromagnetic noise.
Ken,
Thanks for your input. I do have a D'Angelico semi hollowbody with separate volume controls for each pickup and a three-way switch. I just checked it, and when I turn the volume all the way down on that guitar, there is absolutely no hum (even when using a distortion pedal). When I put the three-way switch in the center position (engaging both pickups), turning down either volume control lowers the volume of that pickup, and does not seem to alter the volume of the other pickup. However, when I turn either volume control all the way down (with the switch in the center position), it silences both pickups (even if the volume on the other pickup is still turned all the way up)--so apparently it is wired differently than the Rickenbacker.

It turns out my Rickenbacker 4003 bass also has separate volume controls for each pickup. When I completely turn down both of those volume pots, I DO get noticeable hum-especially if I'm using distortion--which is not the case with the rest of my guitars which only have one volume control for both pickups. With those, as you described, when I turn the volume all the way down it silences any hum. So, the 4003 seems to be wired like the 330. When the volume is all the way down, hum is actually louder than when the volume is all the way up.

So, two more questions.
1) I guess this means the 330 is operating normally?

2) Is there a way to wire the 330 (and 4003) like my D'Angelico (which also has two separate volume controls)? As I stated earlier in this reply regarding the D'Angelico " I just checked it, and when I turn the volume all the way down on that guitar, there is absolutely no hum (even when using a distortion pedal). When I put the three-way switch in the center position (engaging both pickups), turning down either volume control lowers the volume of that pickup, and does not seem to alter the volume of the other pickup. However, when I turn either volume control all the way down (with the switch in the center position), it silences both pickups (even if the volume on the other pickup is still turned all the way up)."
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by daveseven7 »

jdogric12 wrote:Not normal. Call dealer.
Thanks for your reply Jason. Do you think what I'm describing in my response to Ken means this is normal? Hum is actually louder when volume is turned all the way down than when volume is turned all the way up. Seems counter-intuitive but my 4003 bass is exhibiting the same "behavior" as my 330 when turned all the way down....
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jdogric12
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by jdogric12 »

Right, that's normal. Ricks (both guitars and basses) are wired so that when the switch is in the middle position, and you turn just one volume control down to 0, you still get the sound of the other pickup. Gibsons (and I guess your D'Angelico) are different. Turn down one knob and you kill the whole thing. (I prefer the Rick arrangement)

In many years and many Ricks, I've never had a problem. I even played a nasty (but fun) bar gig for about 2 years with an '85 4003 where during breaks I would put the switch in the treble position and turn treble volume to zero. Never had a problem.

I don't follow all the electrical talk, so I can't speak to that. A few thoughts:
-any dimmer switches in the house?
-is your guitar going through any compression that would amplify hum and noise?
-does the guitar have any other typical ground-issue symptoms, like buzzing when you do (or don't) touch the metal parts or strings?
-what amp, and what is the amp volume and drive set to?
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espidog
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by espidog »

Something I did with my 4003 (although I realise it's not practical on a hollowbody like a 330) is to shield all of the body cavities and the back of the pickguard with copper tape. Made a considerable difference to hum pickup, especially on the bridge pup. My 4003 never was noticeably hummy when the vols were turned down, though, so I still think you may have a grounding fault somewhere in your wiring. The trouble with hollowbodies is getting access to the wiring loom: unless there's a handy hatch in the back of the thing, it's a right PITA. :(

ADDED LATER: I'd love to see a schematic for that D'Angelico. :)
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daveseven7
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by daveseven7 »

UPDATE:

Since noticing that both my 4003 bass AND 330 guitar were having the same hum with all volume pots turned all the way down I (of course) concluded that both guitars function normally and the issue is with something electrical in my home. After reading your replies and doing some research I narrowed it down to a ground loop issue and/or EMI/RFI interference. I read up on those online--and came across an AV forum where a guy had a similar problem with his stereo system that turned out to be cause by his cable tv connection causing a ground loop issue. I recently switched from Satellite back to cable tv so I tried disconnecting every cable coax and cable box A.C. connection in the house ( I have three cable boxes/three TV's) and the Rick hum was much lower. So, I called the cable company and said there's a ground issue with my new cable setup--and they begrudgingly sent a guy over the next day (after first stating that as long as my cable picture is good it's not their problem). The guy came out and installed a ground loop isolator (that looks just like this one) between the cable connection coming in from the telephone pole and the splitter that sends the signal into my home. https://www.amazon.com/gp/product/B00B2 ... MFLQ&psc=1

That did reduce the hum when the volume was all the way down on the Ricks, but not completely so he checked by ground connection coming out of the electrical meter in my basement (something he said he's not supposed to do). The ground wire seemed slightly loose, and his readings fluctuated greatly when the wire moved as he pressed his meter against it. I called my utility company and reported a loose main ground wire--they considered it an emergency and sent someone out the same day who confirmed the ground connection was bad and re-attached/tightened it. The amperage reading on the ground wire went from over 2 amps to .2 amps and he was satisfied it was fixed. That lowered the hum even more, but I was convinced there was still room for improvement so I bought one of these and plugged my guitar amp into it (Furman Power Conditioner with EMI/RFI filter). https://www.amazon.com/gp/product/B0002 ... UTF8&psc=1

There is now no audible hum from either of my Ricks when their volume is turned all the way down. So, happy ending. I hope this thread helps anyone else with a similar issue. Thanks for your help guys!
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espidog
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by espidog »

David... what a fabulously thorough fault-finding regime - in the course of which you discovered and fixed a potentially lethal house wiring issue - and what a great outcome! :)

Now shield all the cavities on that 4003. You know you want to... :lol:
2004 4003 JetGlo
Epiphone Jack Casady
Ovation Magnum 1
Mania VTB-4BS
Dean Stylist w/ John Birch Magnum II pups
Yamaha BB414
Trace Elliot VA350/GP11 Mk1
Peavey TB-Raxx
2 BFM Omni 10.5 crossfire cabs
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jdogric12
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Re: Rickenbacker 330 Hum With Volume Completely Down

Post by jdogric12 »

RRF saves lives!
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