rmorris

What are the chances 😊 So there are actually four gangs there - 2x20K and 2x100K. I guess that you can just use one of each as long as it fits mechanically.

Yes - as it says : "different standards uses the same letters which can be confusing" so you need to consult the datasheet or manufacturer / distributor.

Interesting - although it comes to 48 Euro for a pot inc shipping (I'm assuming OP is in UK). I see they offer three tapers - although need to check what they are as letters to denote can be inconsistent. I guess for tone it's linear but you never know. There's no 20K option but there is 25K - maybe that's close enough for the OP ? Also - it doesn't mention the track composition - so I guess Carbon. It might be worth contactin OMEG in the UK to see if any response ?

+1. I doubt whether 20K / 100K is a readily available combination. I reckon the only realistic way to get what you want on a one off (or even small / moderate basis) without spending "mortgage money" is to build it from existing potentiometer component parts.

Unless you're keeping it as an historic artifact then I say rewire it.

Well there's a lot to remember / forget 😊 Anyway, we can probably agree that it's not a great circuit idea when you lose volume with tone. Personally I don't really use passive tone control much at all.

Me too + the rest. Still am. Cheers.

With those values of capacitance they will almost certainly (never say never - I once disputed the existence of tantalum resistors only to be proved wrong :-) not be electrolytics (or tantalum). As it happens Aluminium Electrolytics are usually marked on the negative leg (making the other +ve by implication while Tantalum Caps are maked at the positive leg / terminal. There are also Non-Polarised Electrolytics usually marked 'NP'). Yes - I deal with capacitors a lot :-) It wouldn't be strictly a good idea to use polarised capacitors in a passive tone / vol circuit in any case simply because you don't know what any dc bias will be - it's basically down to the following stage / amp input etc. However, in reality they are fine with a few volts 'the wrong way' as might occur in a typical audio circuit. As for the 'form of DC' - no :-) Although if I can work out a way to do that I might be in the money !

You're right that the circuits aren't separate. But the coupling capacitors don't do away with interaction apart for blocking dc - and that isn't an issue here. Although they will affect the degree of interaction depending on frequency and pot' settings.

I don't think that's true anymore wrt 1% cf 5% resistors. 1% has become the norm for standard small resistors - thru hole or SMT. (I design with these things and while I'm sure Behringer get better prices than myself that sort of means that the cost of the resistors becomes tiny.) Cost / Reliability issues are much more associated with mechanical elements - pots / sockets / switches / connectors etc as that's where more of the money goes. The footswitch on the BDI is a funny sort of thing. I have two of these - one I intend to mod - and no issues although light use only. I don't know if the casing is shielded internally ?

There is a 12V (and a 9V) voltage regulator inside so yes you do need around 15V for proper operation.

Since you're slackening off then you can't over-tighten. I don't see the big problem with using a powered driver that others do - but I'd go for my small 'pistol type' rather than the larger drill / driver type option. And I'd still loosen the first turn or two by hand - the screw may have binded a little and need a short strong action to 'snap' it off and allow it to be screwed out easily. Similarly when refitting I'd make the final couple of turns manually in order to 'feel' it. Do, of course, protect the area around the screws / plate. Screwdrivers can slip whether powered or manual.

Previously I've added (steel) rack ears to equipment - not specifically designed for the particular unit but with the apertures for the rack screws in place and maybe a few of predrilled holes in the sides for attaching the unit - but you might have to improvise there depending on the material / construction of the amp.

Good question. Could open up a 'can of worms'. Well I reckon it would on Talkbass anyway 😏

Interesting post. A few points come out of it for myself. re Phantom Power and the "Sound Guy" - some desks do indeed have 'global' Phantom Power switching. But it's typically only on Mic inputs (or XLRs that can be switched Mic / Line) whilst there are separate 'Line Only' inputs on TRS Jack and these don't get Phantom. There would be an issue if Phantom were applied to the output of a piece of kit not 'expecting' it. If the PA runs with only Dynamics mics - say the workhorse SM 58 / SM57 - or back-electret mics then Phantom isn't required. Means can't use 'proper' externally polarised condenser mics - well not without dedicated power supplies for them - but probably not using those for live in a lot of situations. The '50k Ohm' input impedance figure is a nominal figure only - generally related to a load impedance on the secondary side of 600 Ohm. But 600 Ohm is just a 'standard' used for basically historical reasons from telecommunications. It indicates that the impedance is 'transformed' by x83 (to integer approximation). Along with an attenuation of approx 19dB. It really a bit more complicated due to winding impedances and stuff but it's in the ball park. Of course there may be some loading built into the DI already to suit the transformer. Typically you'd might feeding a Mic input with something like 2 kOhm Input Impedance so that would end up looking like 166k Ohm to your bass - not too bad but still significantly les than the usual 470 kOhm or 1 MOhm at the front of a bass / guitar amp. The 'problem' I see with the test set up is that the sources will all be relatively low impedance. The impedance of the source will affect the transformer response and a passive pickup has a very significant complex impedance from the Inductance and winding resistance. Yes - it's hard not to wonder about the bass response of a small transformer. It's essentially down to the inductance characteristics and it's not usual to find them properly stated even when the transformer is a known one. There are ways to get a flat response from some small transformers but that typically involves active circuitry on the secondary side. Anyway I guess the proof's in the playing 😊 Nice Photos btw.

Yeah - they brought out a range of 'specialist' products. I saw them in my local (to work) RS Trade Counter. I'd still opt for Caig DeOxit products tbh.

Sounds about right. A high output but Hi-Z pickup is only "High Output" when it isn't loaded down by a low impedance.

Do you know the thread sizes ? Potentiometer Nuts are often thinner than normal nuts and with a 0.75mm pitch unlike most 'standard' threads.

To make a proper comparison you need to compare the Air Volume figures. If you can see the make / model on the Trace fan then you may be able to look it up. If not I'd say it's likely to be fine.

Do you mean they are 'Flat' wrt the Fretboard because they have lifted at the fretboard edges ?

If I had to guess I'd say that neither of those are "Galvanically Isolated" (well maybe one of the outputs on the second one but not all). For minimum power / ground noise and ground loop susceptibility you need separate grounds. Lots of supplies that state "isolated" just really mean that the outputs are separately regulated / protected - eg you could shortt one out and it wouldn't damage the other outputs - but they are on the same ground. But you can probably get an answer direct from Thomman. They were helpful when I enquired whether this was the case with the PowerPlant Junior vs Powerplant. The 'Junior' is, as stated "Galvanically Isolated" (also means can 'stack voltages to give 18V using two outputs) whilst the Powerplant is not. Sounds wrong I know. They were able to confirm this prior to purchase. I do realise the Junior is likely too small too meet all your requirents in one unit.

What make and model is the guitar in question ? The OP said not a big name but any more detail ?

When did the sale take place ?

Last time I had something like this it was a loose winding.

Can you get the electronic board(s) out to work with them ? If so then examine wiring connections visually and resolder / reflow any solder joints that don't look right. If in doubt get the iron on there. Consider replacing any electrolytic capacitors. Pot related noise could be the pot itself - mechanical due to wear / corrosion - or could be due to failing DC blocking capacitors.