Hi Frequency hum on SKB 3006

[Jenkins101]

Hi All,

So I went by Guitar Center today to check out some combo amps and plugged into a MarkBass 210 and 15" cab and noticed a really high pitched hum. It definitely sounds like a ground hum. The volume of the hum would change as I rotated from very loud to almost gone. I had the tech there take a look to see if anything was loose and we did find a wire (pink wire that goes to the pickup blend pot) that seemed to have a bad solder so he re-soldered it but the hum was still there. I replaced the batteries, tried different cables, amps (an Ampeg B115 combo) and yet the hum was still there though it was much less noticeable on the Ampeg. But I am guessing that is because the MarkBass had a piezo and the Ampeg didn't.

It has the Bart NTMB 918 pre and Bart pickups. Could this be bad shielding or an early symptom of the preamp going bad? Any ideas on what could be causing it? I never noticed it before at home because I have an Ampeg rig there as well and also don't play it at very high volume.

Any advice would be greatly appreciated. Also if any of you guys have played much through a MarkBass rig let me know what you think. I liked it. Not as clean as a straight power amp/Bergantino setup but I've always liked things a little dirty!

[lwrthnwhalepoop]

I've had the same problem with a couple of my Roscoes, and have tried the same diagnostic steps you have with the same results you got. Hopefully somebody can lead us to a solution. I'm willing to send some or all of them back to Roscoe if need be. This can't be the way everybody's Roscoes sound, as there's no way I could record with them as they currently are.

[Darkstrike]

Originally Posted by lwrthnwhalepoop

This can't be the way everybody's Roscoes sound, as there's no way I could record with them as they currently are.

Definitely not, both mine are silent 100% of the time, besides the notes I'm playing.

Sounds like a grounding issue....

[Ryan L.]

I have never had any sort of problems like that with any of the Roscoes I have owned or currently own.

[Gard]

There can be all kinds of issues that cause noise like this, from a shielding issue within a bass to the wiring in a building - poorly grounded wiring can act like an antenna for stray electronic noise.

I'm guessing that both Jenkins and Mr. Whale Poop are suffering from an internal shielding issue, based on the directional component of the problem.

We would be happy to address the issue for both of you - however, it may be more cost-effective to find a good tech locally to do this kind of work, as it is fairly straight-forward and any competent electronics guy can do the job well.

Let me know if there is anything I can do to help out though!

[lwrthnwhalepoop]

Originally Posted by Gard

There can be all kinds of issues that cause noise like this, from a shielding issue within a bass to the wiring in a building - poorly grounded wiring can act like an antenna for stray electronic noise.

I'm guessing that both Jenkins and Mr. Whale Poop are suffering from an internal shielding issue, based on the directional component of the problem.

We would be happy to address the issue for both of you - however, it may be more cost-effective to find a good tech locally to do this kind of work, as it is fairly straight-forward and any competent electronics guy can do the job well.

Let me know if there is anything I can do to help out though!

Thanks for the offer, and I accept. Point me to someone local to the St. Paul/Minneapolis area that knows their way around Bartolini active bass innards. Results are more important than cost (within reason, of course). If they can cure my beloved Roscoes I'll be eternally grateful. I'm sure it's something straightforward and which I could probably diagnose and fix myself if I had the time but I've given a couple shops a shot at the problem and had no resolution thus far.

Had a great time showing the gf around n'awlins, BTW. Hadn't been there in many years myself, and it was her first time in the Crescent City. Had a mind-blowing dinner at Dooky Chase's and good grub all over town. We'll be back again in the fall, schedules permitting. It's a city like no other, anywhere, period.

[Gard]

Originally Posted by lwrthnwhalepoop

Thanks for the offer, and I accept. Point me to someone local to the St. Paul/Minneapolis area that knows their way around Bartolini active bass innards. Results are more important than cost (within reason, of course). If they can cure my beloved Roscoes I'll be eternally grateful. I'm sure it's something straightforward and which I could probably diagnose and fix myself if I had the time but I've given a couple shops a shot at the problem and had no resolution thus far.

Had a great time showing the gf around n'awlins, BTW. Hadn't been there in many years myself, and it was her first time in the Crescent City. Had a mind-blowing dinner at Dooky Chase's and good grub all over town. We'll be back again in the fall, schedules permitting. It's a city like no other, anywhere, period.

Well, I'd suggest getting in touch with Tony @ Planet Bass to see if he can address it, or maybe recommend someone that could sort it out for you. That's my only contact in your area, right now.

Glad you guys enjoyed my hometown, I really need to make a trip down myself, but it won't be until fall at the earliest - it DARN sure won't be during the summer!

[JOME77]

As Gard stated it can be the shielding and really needs to be checked by a qualified tech.
That being said, something to check out prior to going to that extreme would be verifying that the output jack has heat shrink (or insulation tape) around all of the output jack. I've had Roscoe's get noise, and even totally short out in that area. Most of the earlier model Roscoes didn't get heat shrink around that area.
You can usually take off the control access plate and see if the jack is insulated. If not, just remove the 2 screws from the jack plate and insulate it well via either large shrink tubing or electrical tape. Also verify that there are no sharp corners of solder are sticking through any existing heat shrink or insulation tape. I had that happen on one Roscoe too. Any continuity from the output jack "+" connection to the shielding paint in the control area will cause noise and/or totally short out the electronics.

Good luck!

[Gard]

Originally Posted by JOME77

As Gard stated it can be the shielding and really needs to be checked by a qualified tech.
That being said, something to check out prior to going to that extreme would be verifying that the output jack has heat shrink (or insulation tape) around all of the output jack. I've had Roscoe's get noise, and even totally short out in that area. Most of the earlier model Roscoes didn't get heat shrink around that area.
You can usually take off the control access plate and see if the jack is insulated. If not, just remove the 2 screws from the jack plate and insulate it well via either large shrink tubing or electrical tape. Also verify that there are no sharp corners of solder are sticking through any existing heat shrink or insulation tape. I had that happen on one Roscoe too. Any continuity from the output jack "+" connection to the shielding paint in the control area will cause noise and/or totally short out the electronics.

Good luck!

Joe, thanks for pitching in!

[lwrthnwhalepoop]

Originally Posted by JOME77

As Gard stated it can be the shielding and really needs to be checked by a qualified tech.
That being said, something to check out prior to going to that extreme would be verifying that the output jack has heat shrink (or insulation tape) around all of the output jack. I've had Roscoe's get noise, and even totally short out in that area. Most of the earlier model Roscoes didn't get heat shrink around that area.
You can usually take off the control access plate and see if the jack is insulated. If not, just remove the 2 screws from the jack plate and insulate it well via either large shrink tubing or electrical tape. Also verify that there are no sharp corners of solder are sticking through any existing heat shrink or insulation tape. I had that happen on one Roscoe too. Any continuity from the output jack "+" connection to the shielding paint in the control area will cause noise and/or totally short out the electronics.

Good luck!

Joe, thanks so much. Great info, which I'll use as a check list with whatever tech I find to tackle the job. It won't be me, though, since my mollusk-like manual dexterity puts these sorts of delicate tasks out of reach.

[CrashClint]

The only noise issues I have had with Roscoe basses, once as stated by Joe, bad shrink tubing around the jack and the second was with an Audere preamp in a school auditorium. As soon as they hit the stage lights I got the 60 cycle hum from hell.

[lwrthnwhalepoop]

Originally Posted by CrashClint

...the second was with an Audere preamp in a school auditorium. As soon as they hit the stage lights I got the 60 cycle hum from hell.

So it suddenly became an "Oh dear!" preamp, if I'm reading you right.

Sorry, couldn't help myself.

Thanks for the input, Clint.

[CrashClint]

Originally Posted by lwrthnwhalepoop

So it suddenly became an "Oh dear!" preamp, if I'm reading you right.

Sorry, couldn't help myself.

Thanks for the input, Clint.

Well, you are lower than whale poop!