Fixed Resistor for Knobless Bass?

Have you tried it with no resistor? The difference between the two is the equivalent to less than a 1/16th turn on the high or high mid EQ knob on your amp.

 

if you did want the exact same circuit load as a 25k volume and 25k tone both dimed then you'd want a resistor to simulate the two pots in parallel, not series.

that means about a 12k resistor between hot and ground.

+1 to it not making much difference with EMGs, though some argue that a 10k output impedance is actually rather high for an active pickup and you could in fact hear a slight darkening with 25k pots and straight-out might be slightly brighter.

 

Pot resistance really isn't a thing with active EMG pickups - that was one of the big reasons for EMG making the pickups active in the first place - they are buffered so the pot resistance won't affect them (much).

 

I like the absence of devices (knobs, switches, jacks) in the front of instruments; my only suggestion would be to add the pots inside the cavity, perhaps using some mini-potentiometers, as you may want to set it a the right spot and it could mean to have to adjust the controls at least once.

 

Tonally it shouldn't be necessary for an active pickup. Just wire it straight to the jack.

The tone of a passive pickup depends on the capacitive and impedance loads it feeds, but an active pickup has its coil(s) feeding a constant load - that tiny inbuilt buffer preamp.

Having said that, in some circuits, like the classic musicman preamps, the volume pot is also the earth reference for the (polarised) output coupling cap. But I'd be very surprised if EMG haven't thought of that already, and there's a resistor already in the pickup's buffer preamp that does this job.

 

I'm just here for the cool idea.

I love me some knobs, don't get me wrong, but there's something liberating about not even having the option to turn one: either balls to the wall or yank the plug.

Re: the internal trimpots with amputations, that reminds me of a custom Cog Effects pedal build someone had done wherein some of the pedal's pot shafts were hacked down to nubs, then flathead screwdriver grooves were cut into the nubs. That way, changes COULD be made, but not without premeditation and effort.

Seeing as a course has been decided upon, the prior is academic but it might be good to know it's an existing practice. Doing it inside a bass might actually be pioneering, even.

 

Something I feel confident to reply to!! The tone control simply cuts the upper frequencies. The thing is though, even set at its least effective, the capacitor is still in circuit so you still are cutting some of the upper frequencies, often what you want on a bass. On my homemade 6 string, I have a push/pull tone so I can remove the entire circuit to let all the upper frequencies through. The easiest way to test is to put a capacitor across the jack socket. You can try the original 0.01 MF everyone first but you could also try other values which raise or lower the cutoff frequency.

 

In the most technical sense of the word, you cannot wire EMG pickup elements straight to the jack. The actual pickup elements (magnet & wire) are wired straight to their own built-in preamp to create a pickup system within the pickup shell. You can wire THAT to the jack but the actual pickups are buffered, isolated, behind the preamp and will be unaffected by the switch from 20k pots to direct wire.

 

Well, yes you are right but there is a minor distinction you're missing. In a passive system the tone cap is not in the circuit by itself. It is in series with a tone pot. Signal must pass through the 250k pot then through the cap to ground. So doing a test by just adding a cap across the output does not duplicate the tone circuit.

Also with passive pickups, their tone is affected by the impedance of the wide-open volume pot. Even with no tone circuit, having different volume pot values (500k, 250k) will affect the sound of the pickups.

So it isn't just simply the presence of that capacitor.

 

Along with other suggestions, I'd encourage you to just try it. A resistor hardly costs anything.

That said, record yourself so you can compare between the two configurations.

 

You are right, the tone circuit comprises the whole inductance of the circuit, from the pickup (s), resistor and capacitor. What I meant though is that with no resistor the cap and pickup still remove some of the upper frequencies which some people like in a bass guitar. By adding back the cap you do get some low-pass filtering if that is what you like hearing. Personally, I like the all-frequency output but opinions vary.
Greg

 

Have you looked at @RobbieK's video on passive tone controls? It's pretty danged interesting and his conclusions were not exactly what many of us expected at first blush. Well worth a look IMO, perhaps Rob can post the link as I can't seem to find it right now.