rmorris

Thanks. Yes the braided shield will be stiffer than the 'usual' helical wound lapped / double lapped construction but, all else being equal, offers superior screening if not flexed too much / often. And the polyethylene insulation and largish diameter allows for lower capacitance. Do like you say excellent for static studio situations but not for long stage leads. Enjoy.

Do you happen to know the type of screening ? Eg braid / lapped etc.

Well I wouldn't term it a rebroadcast station as that implies some sort of active amplification. But yes the human body is a factor in the environmental noise being picked up by the bass. Whether you regard it as rf depends on what you call rf. In this case it's primarily mains related frequencies that are 'everywhere' that are detected by a High Impedance magnetic pickup. So 50/60 Hz depending and associated harmonics. It's relatively simple to show that a hand near an inductive pickup induced a signal in that transducer. Also bear in mind that the bass bridge/strings are already grounded. It doesn't matter whether you ground yourself by touching the strings or another bit of grounded metal eg a chassis screw on a rack unit or mixer. In either case the noise will be reduced. Depending on your own skin dryness / conductivity you may get better results with a dampened finger 🙂

Ok. As you please. I'm not coming out with anything original here. There's no real mystery.

No. This is well known and demonstrable stuff. Transmitting antennae are clearly not in contact with the receiving device. The receiving antenna in this case is the bass pickup etc.

Basically yes. Because when the player (of any sex or gender !) contacts the grounded metal then they are held at the same electrical potential as the "Ground" potential. If the question is why the player is held very near to "ground" rather than than the rf voltage then you have to look at the relevant impedances. It does get a bit technical 😳 But bear in mind that these concepts and models are well understood in electronics in general. There is no special branch of electronics for basses (or even guitars 😄)

Okay. The discussion on this topic has become ridiculous. No need to talk of "pseudo-science" and people evolving. So - shielding - Copper/Aluminium (as commonly used) shielding is effective in rejecting "rf mush" when it is held at a low impedance voltage. In practice this means connecting it to "Ground". More precisely the "0V reference" of the system. If using an "Earthed" amp etc (ie it has a three wire mains cord) then this is also "Earth". But it isn't always the case - consider battery powered systems or electronic systems on an aeroplane... Ideally the shield is continuous. In practice it never is (well those wires need to get in/out 🙂) but the more complete the better the shielding (basically - there are other considerations when you really get into it !) Grounding the bridge - and hence the strings if they are metal - has a different, though associated, purpose. That purpose is to "ground" YOU - the player. Yes - you are being "Grounded" by the bass/amp setup. You are NOT grounding the bass - since you are (generally) not grounded yourself. And the shielding on the bass is already "grounded". What is happening is that you are acting as a great big antennae and picking up / transmitting rf noise to the bass. Shielding will help with this but it will still be picked up from the pickups in general. Now, when you touch the grounded metalwork then you are being held at a fixed potential and the transmission is effectively halted. It can be demonstrated in the right circumstances - get a situation where you are picking up significant rf noise. Moving your hand(s) nearer the pickups will increase the noise level until you actually touch the string. To put it another way - if you (ie the player) were not near the electronics then the noise would essentially not be there !

Fair point. But I have noticed more discussion of them last few years. On a related note - ime there was a good deal of discussion / debate some years ago on 'Pressure Wound' and 'Ground Wound' options. But I don't see them discussed much these days ?

btw - I asked about the schematic source rather than just trawl the web because IIRC the OP said they worked from "factory schematics". Nice work though.

A 'Drive' pedal is indeed reducing the dynamic range of the signal (Compression). But it doesn't have time based envelope controls ie attack / release times. So it's arguably more like a Limiter. The results really depend on how you use your compressor. If it's to maintain a 'solid' level in the mix then it's probably good for that task. But if you use it to get eighth notes 'pumping' then it probably won't replace the compressor.

Another vote for Peterson Stroboclip HD (although it's oddly difficult to find the dedicated case for it - lots of places sell the tuner but not the case). Had one for Christmas and it seems very good. Obviously will have to see how it lasts. With cheaper clip ons previously I found they sort of dropped off in sensitivity (regardless of battery change) - probably to do with wear/tear on the 'hinge' bit ???

Impressed ? Where did you get the schematics ?

Link to schematic / service info. Note that there are two versions of the power amp (Bipolar and MOSFET). https://www.freestompboxes.org/download/file.php?id=7186&sid=c6fb8545ee36a61fbad7c8ad3ddcc8da GP7 150.300watt SM series Trace Elliot.pdf

I'm guessing that the £130 was for a tech' repair bod to diagnose / source transistors / replace / test. If you're happy to source transistors yourself and fit them - or get someone you know to do it - then it should only cost a few pounds (and maybe a couple of drinks) so might be worth a go if the effects option isn't successful.

Looks like nice work. On the noise / shielding front [ assuming that's what it looks like - aluminium Hammond type die cast box and its screwed together properly with the cable screens taken to the box - then screened wires inside are unlikely to make much difference to interference noise. It's putting a screen inside an enclosure that is already screened. It will reduce cross talk but I don't see that as an issue here. Maybe more effective to filter the incoming signal - suggest something like 100p caps straight from the T of the TRS or TS socket to the box. Possibly a series resistance, say 100R, although if source is a passive pickup then that won't make a difference. Is the noise broadband hiss or like mains interference. If mains type it could be due to the transformers and copper/aluminium screening may not be very effective.

I've noticed that a lot of prices on Reverb are well above 'reasonable' and seem to indicate quite a bit of "arm chancing". There's no "correct price" for anything used - music/bass related or otherwise - of course but something seemingly overpriced 'disappearing' does often mean that it's been withdrawn from sale rather than sold at that price. I see quite a lot of "high priced" items for sale but they tend to hang around for very long times and you never know what they actually sell for. Stuff may also circulate around shops/dealers with incremental price drops to stop it looking desperate/stale although this is more prevalent in something like used car sales (well it was - although in Covid/Supply Chain Issue times the cost of used cars has risen very significantly).

Plenty to look through here (no personal commercial interest in this business) https://shop.pedalparts.co.uk/Fuzz/cat847125_2465698.aspx

Is it a thru or set neck ? Or a Bolt On ?

Good point, and I'll generally change one string at a time (A/D/G/E) but it depends a lot on the neck itself. I have a Westone Thunder where the neck seems very very stable and doesn't seem to 'be bothered'. It's laminated (I can see as it's the natural finish) and I suspect that is related. And it's generally rock solid. Meanwhile other basses, and I'm looking at OLP Musicman copies here, seem to need constant truss rod attention on string changes and generally. Not laminated so I'll let you draw your own conclusions. Then you get into half sawn / quarter sawn timber etc. Carbon Fibre ? - above my budget !

Yes - it does sound odd if it is now working with the fuse replaces. Might it be that the output (that was not plugged into the brick) was inadvertently shorted ??? Sounds unlikely with that connector type but otoh something happened !

If the polarity is opposite to that required then simply cut off the connector and git a new one as required. Most supplies are centre positive. Guitar fx are the general exception.

Are we talking about 'mains' related hum here - '50Hz' noise + harmonics (100Hz is often the largest component due to rectification) ? Adjust frequencies for '60 Hz' territories of course ! That interference is primarily magnetic field related (H-field). It's always an electromagnetic field but the relative contributions of electric and magnetic field strengths vary. It's the reason why mains frequency transformers may need to be shielded with a suitable grade of mumetal rather than copper or aluminium. You need some ferrite element to shield against H-fields. Similarly microphone input transformers are typically fitted with mumetal shields.

So...it seems clear that your bridge/string grounding is fine. To reduce noise when you're not touching earthed metal - check the shielding. Not simply ground continuity - is the shielding complete and how it is implemented. And yes - SCR dimmers are a major source of noise so if you can avoid them then all the better. And don't ignore noise sources that may be in an adjoining room or building. Or, from experience, even further away. Note on this: Coated strings can be an issue with this.

Yes - low impedance pickups like EMG are less susceptible to interference as you say. And the associated controls are then lower impedance themselves eg 25K pots vs 500K or 1M0. But can we dispense with the idea that there is some problem with the earthing of the bridge in this particular case. The noise 'goes away' if the OP touches the strings. That indicates that the 'Earth' path is intact. When the player is near the bass but not touching any grounded metal - be it the bass strings / bridge or another piece of metal that is grounded eg a rack unit / chassis - the body acts as quite a good antennae for the 'emi soup' we are immersed in and causes this to be picked up by the (High Impedance) bass electrics. Screening is advised as it will attenuate the amount of interference getting through to the electrics. I'm an advocate of screening the rear of any plastic pickguard. It also reduces the problem of them "going static" where touching them causes a "brushing / rustling" noise in the output.

Not in general. Anyone near the bass but not at a fixed potential - practically this means not touching 'Earthed' metal acts as a source of radiated noise due to the RFI soup we are generally immersed in. So if there were no one near the bass there wouldn't be the buzz. But it's difficult to play it from a distance ! By 'Earthing' to the player it stops the antennae effect. Having said that I did once he ave a glitch at distinct one second intervals and I really should have realised it was my quartz movement watch causing it as it was synchronised with the movement of the seconds hand 🙄