New bass but PC static problems

[David Houldworth]

Hi all,

Received great advice from my last question about bass tuition - wonder if you can help with this.

 

I have a small music room/workroom 10 ft by 7'5 feet. I have my PC/desk and 3 basses, a small amp, a sort of worktable, 2 floor standing shelving units for Hifi, music books/odds and ends etc.

(so the 10 x 7.5 is the bare room size, it's a fair bit smaller with the above in it). The relevance of this will become clear.

 

My 5 string Sadowsky Metro Express bass arrived this morning (YAAYY!), checked it, played it for a few hours - love it (came with a very nice gig bag too)

 

Anyway, to play, I did as I usually do with my other basses and guitars - plug into the little desktop outboard Presonus sound unit which goes to my PC and comes out through my Pioneer Hifi.

Been doing it this way for more than 15+ yrs with various guitars and basses and never had an issue. It's more than loud enough for the size of the room.

The basses used have always been passive. No effects are used, the bass goes straight into the Presonus or practice amp.

 

When playing the Sadowsky in active mode I'm getting high pitched static which I believe is from the PC (I don't have fluorescent lighting). When I switch to passive mode, the static disappears. 

In active mode I tried playing through the small practice amp to check if plugging into the Presonus/PC that was the problem, but the interference/static is still there, coming through the amp.

 

I then used a longer lead and moved away from the PC - had to move slightly out of the room doorway before interference went away.

I tried this with bass (active on) plugged into the PC and then again plugged into the practice amp with the same result - the further the bass was away from PC, the less interference noise there was.

 

Unfortunately I cant get far enough away from the PC to reduce the static and still be in the room... (I know that my first ask would have been, 'can you move further away from the PC'). I could, but I'd be out on the landing  lol.

 

As a test, I switched off the PC and plugged into the practice amp - active on, there was no static, but when I switched the PC on, the static came back through the amp. The PC is the source, the active is picking it up.

I checked the battery/wiring compartment - it has shielding paint in it. I may put copper foil in there going forward. 

 

Unfortunately I can't borrow another active bass to check if it happens with others. I have my music programs and software on the PC along with play along files, study materials/PDF's etc - I also play through the PC with headphones too, so I really need to be playing in the same room as the PC.

 

Has anyone any ideas to suppress the static/interference ? I'm assuming others must have had a similar problem.

 

Apologies for the exhaustive post but wanted to provide the full picture 

 

Any help, gratefully appreciated

 

David

 

 

[asingardenof]

Is this one of the RSD MetroExpress basses, or the new SMX ones with the roasted necks? If the former they were notorious for having shielding and other electronic issues, which may or may not be contributing to your issue.

[David Houldworth]

Hi there,

Thanks for replying - It's one of the RSD ones. Didn't want to/couldn't pay SMX prices.

 

I'd read that Sadowsky had addressed the noise issue in subsequent runs of the RSD. 

 

Plugged into the PC If I can get 5+ feet away from the PC,  no issue - plugged into the amp 5+ feet away from the PC, no issue, but I need to be next to it.

 

I have an idea that any active bass in close proximity to a PC would generate interference. Unfortunately I don't know anyone with one I could borrow to test that idea. 

 

My little room isn't a box it's sort of 'L' shape, there's a walk in cupboard which is sort of built into the room so that also reduces how far I can get away from the PC.  

 

If I can find out soon that computer/PC proximity isn't an issue with other active basses, I'll be sending it back to Thomann.

 

Cheers.

[sandy_r]

hi David

Let's kick the word 'static' into touch ...unless you're prone to receiving small stinging discharges of electricity with an accompanying blue or white flash

 

Computers are very noisy creatures, unfortunately, and not usually well-designed to 'play nice' with analogue equipment

...Welcome to the world of ElectroMagnetic Interference (EMI)!

 

EMI can happen: by transmission (ie. without any connecting wires), by conduction (thro' connecting wires), and by induction (the magnetic interaction of nearby wires, usually coiled)

 

More likely to be a problem where low-level analogue signals are passing thro' either high-impedance circuits (found in parts of passive guitar wiring) or thro' high-amplification circuitry (eg active guitar circuitry in general)

 

As a simplification, EMI can be reduced by conductive shielding (usually around low-level signals needing amplification), or magnetic 'shielding' (eg. ferrite cores around wires carrying higher-frequency signals)

 

So for instance, it's a good idea, especially in the presence of digital noise EMI 'generators'/'transmitters' such as computers, to increase the effectiveness of any existing shielding in guitar signal paths:

 - ensure pickup/control wiring and cavities are completely enclosed by well-grounded conductive surfaces, all grounded back to a single point (usually the guitar jack shield lug);

 - experiment by adding ferrite rings, looping any wires connecting guitar to computer, and low-voltage power supply leads  thro a ferrite core a few times, to see if this reduces EMI transmission by the digital/swiitching devices

 - if you, or friends are handy with elec. tech., try fitting some small ferrite bead/capacitor filters on input paths of low-level analogue signals

 

Bit of a dark art for us mere mortals, unfortunately -good luck!

 

 

Edited November 17, 2023 by sandy_r

[velvetkevorkian]

If it's buzz from a flat screen monitor, sometimes turning the instrument so it's at right angles to the screen can help.

[David Houldworth]

Hi Velvet,

Thank you for the suggestion. I actually didn't think of that, so I unplugged the monitor, but the EMI (as Sandy corrected me) is still there. 

 

David

[David Houldworth]

Sandy - Thank you for a very comprehensive response. I now know more about EMI than I ever wanted  lol.

 

To follow up your suggestions - to start :

 

Foil the control cavity and underside of the cover and check with a meter for continuity.

Shield the underside of scratch plate too. Haven't checked that for shielding yet. I prefer the foil rather than paint for shielding anyway.

Make sure foil is grounded to one point.

Attach ferrite cores (I have them) on the guitar input lead to the Presonus and other low voltage leads (maybe the lead between the Presonus and the PC)

 

Thank you for your help sandy. I'll do the above and see how that goes.  

 

Cheers

 

David

 

 

 

[asingardenof]

7 hours ago, David Houldworth said:

I have an idea that any active bass in close proximity to a PC would generate interference. Unfortunately I don't know anyone with one I could borrow to test that idea. 

 

 

 

I've not come across any issues with my active bass running into my PC, but then my setup including the bass would be different to yours. If happily lend you my bass to test it but unfortunately we're not in close enough to just pop round sort of proximity.

[cocco]

I'm just here to investigate whether PC stood for Personal Computer or Politically Correct. 

[sandy_r]

11 hours ago, David Houldworth said:

... I now know more about EMI than I ever wanted  lol....

 

 

 

 

hah - me too - but as with fixing damp in a single room building, you need to know if the water is coming thro' the roof, floor or walls!

 

key points from your own tests so far:

 

 - the noise also happens when you use an amp (+ the guitar) near, but not connected, to the computer;

 - with guitar into Presonus into computer, the noise only significant when switching guitar into active mode

 

This info tells us that the noise is being transmitted, it's being picked up in the guitar, and it's not a ground-loop type issue

 

So, in addition to ensuring well-grounded and fully-enclosing shielding in the bass wiring cavities (and if so, don't bother initially with trying to ground pot cases, if they aren't already), it could also be helpful to add some simple resistor/cap filtering** at the input of the active pre in the bass (ie. between pickup(s) and their preamp wires - this would be the time to slip on a small ferrite bead over the wire from pickup, too)

 

** experiment with values, but try, say, a 5 kOhm resistor in series between each pickup 'hot' wire and its connection to active pre, and a 1n (1000pF) ceramic capacitor from the active pre end of the 5k, other end of 1n cap to ground (ferrite bead over pickup lead end of the 5k res - bead can be glued if you fix the noise issue)  NB. Increasing values of Res and/or Cap will improve filter action but eventually start to reduce the pickup signal

 

all the best!

 

Edited November 18, 2023 by sandy_r

[David Houldworth]

Hi all 

 

I've attached a sound sample of the suspected EMI. It was taken with my phone very near the speaker 

 

This sound changes with computer activity, eg if I open a program, click on something, change a window etc 

 

Enjoy 

 

 

[neepheid]

19 minutes ago, David Houldworth said:

Hi all 

 

I've attached a sound sample of the suspected EMI. It was taken with my phone very near the speaker 

 

This sound changes with computer activity, eg if I open a program, click on something, change a window etc 

 

Enjoy 

 

 

Don't think much of the new Doctor Who intro music... the BBC Radiophonic Workshop are really phoning it in here...

 

[sandy_r]

2 minutes ago, neepheid said:

 

Don't think much of the new Doctor Who intro music... the BBC Radiophonic Workshop are really phoning it in here...

 

 

...yeah, but you're not listening in 4D!

 

[David Houldworth]

Hi Sandy, 

 

Thank you for your help. My bass teacher tells me that he has an active Ibanez bass he can lend me to check against mine to see if the noise is still there. I'll be picking it up within the hour.

If there's no sound, or it's much reduced with the Ibanez, I'll be shipping the other one back to Thomann and then look at other options.

 

I see where your going with the resistors and ferrite beads and could do this myself, but having to do this on a brand new guitar is something I'd be reluctant to do. And with no 100% guarantee that it will work.

 

Cheers

[sandy_r]

1 hour ago, David Houldworth said:

Hi Sandy, 

 

Thank you for your help. My bass teacher tells me that he has an active Ibanez bass he can lend me to check against mine to see if the noise is still there. I'll be picking it up within the hour.

If there's no sound, or it's much reduced with the Ibanez, I'll be shipping the other one back to Thomann and then look at other options.

 

I see where your going with the resistors and ferrite beads and could do this myself, but having to do this on a brand new guitar is something I'd be reluctant to do. And with no 100% guarantee that it will work.

 

Cheers

 

Yes, no worries - only to be considered for out-of-warranty, or a definite keeper.

 

Thanks for the audio clip, it appears to be the usual suspects of a mix of mains-related, 2nd-harmonic (100Hz & multiples) and higher data-related noise (could be local, or broadband data-packets) - presumably transmitted as modulation of radio-length frequencies and then detected by the semiconductor devices in the preamp.  Too much info, i know!

 

Hopefully the active bass loaner will show the way ahead

 

Edited November 18, 2023 by sandy_r

[David Houldworth]

So, I managed to borrow a 5 string active bass - an Ibanez GSR205. Significantly cheaper than the Sadowsky.

 

Plugged it in to Presonus - completely silent in terms of noise, static, EMI, 50 cycle hum and whatever else. This is what the Sadowsky should be. 

 

Turned the HiFi volume up maybe to 70% (never play the HiFi at this volume - way too loud for my wee play room, even then I'm only getting the very faintest of hum.

 

The Sadowsky is now all re-boxed and have begun the returns process. No doubt it will take bloody weeks but, that's fine. A huge lesson learned. 

 

Thank you for your help and suggestions, they were much appreciated. 

 

Now, the hunt begins for left handed Ibanez. 

 

Cheers all

 

(ironically I looked at the Ibanez and by passed it thinking Sadowsky - more £ = better) Not in this case, although the fit and finish was excellent.

[ezbass]

4 minutes ago, David Houldworth said:

So, I managed to borrow a 5 string active bass - an Ibanez GSR205. Significantly cheaper than the Sadowsky.

 

Plugged it in to Presonus - completely silent in terms of noise, static, EMI, 50 cycle hum and whatever else. This is what the Sadowsky should be. 

 

The Ibanez pickups are humbuckers (as far as I can ascertain) so will be way quieter than the Sadowsky's single coils. I imagine that the pre amp is boosting the noise that the single coils will always make, thus the difference when you engage the preamp.

[David Houldworth]

Hi EZ,

 

Indeed they are HB's - I didn't even spot/consider that, thanks for pointing that significant factor out.

 

So I don't necessarily have to go for an Ibanez now that I know that (although I probably will)

 

My other basses are passive with SC's though and they're very quiet.

 

Ok the search for a 5 string left handed with HB's begins.

[ezbass]

3 minutes ago, David Houldworth said:

Ok the search for a 5 string left handed with HB's begins.

This Ibby 505 is at GG in Edinburgh if you want to do some hands on action. https://www.guitarguitar.co.uk/product/200325357674025--ibanez-sr505e-brown-mahogany-left-handed 

[David Houldworth]

Thanks EZ - That is a beautiful thing. Always like the natural wood look. 

 

The Sadowsky was just under the £500, so that's my budget, unfortunately.

 

I'll keep an eye out for a second handed sr505, which maybe more in my price range 

 

You know what the thing is ? - didn't even want an active bass. I only bought one because there were few, if any, options of a passive left handed 5 in the UK...and I looked. 

[asingardenof]

If you like the Sadowsky apart from the noise maybe check out a secondhand Sire V7 (or a V5 if you're not fussed about having an active bass)