Adding a passive tone control to EMG circuit

[iiipopes]

I have an EMG tone pot at the end of my active bass signal chain before the jack to cut any residual noise. Yes, even with EMG actives having an average noise floor of over -90dB and the pickups -100dB, I still like it. In this context, it is NOT a "passive" tone control like a 250kohm pot with a .047 capacitor on a P-bass. It is actually an treble cut pot designed to work with EMG actives and act the same way as a traditional passive tone pot. Link to EMG:
Invalid Link Removed

 

[sunbeast]

You can also use a resistor in series with the capacitor to do kinda the same thing. The parallel resistor (the first scheme you mentioned) has the side effect of robbing a bit of level from the signal when the tne control is "off", even above the cutoff frequency of the filter. The side effect of the series resistor circuit is that the rolloff curve of the filter isn't as steep once you get well above the cutoff frequency.

No what I suggested was a series connection (resistor between the capacitor and ground, not alongside it)

 

[micguy]

No what I suggested was a series connection (resistor between the capacitor and ground, not alongside it)

OK, but you can make it work either way - there are minor tradeoffs as I detailed, but either topology basically works.

 

[sunbeast]

I have an EMG tone pot at the end of my active bass signal chain before the jack to cut any residual noise. Yes, even with EMG actives having an average noise floor of over -90dB and the pickups -100dB, I still like it. In this context, it is NOT a "passive" tone control like a 250kohm pot with a .047 capacitor on a P-bass. It is actually an treble cut pot designed to work with EMG actives and act the same way as a traditional passive tone pot. Link to EMG:
Invalid Link Removed

All it is is a 25K pot with a .1uf smd capacitor though (identical to a standard passive tone control except with a much smaller sweep to accommodate a buffered signal). I’d still call it a “passive tone control” because it is not using an integrated amplifier circuit to manipulate the EQ (even if the signal being sent into it is amplified). Maybe semantics? You could plug that EMG tone control into a completely passive bass and it would still function as a passive tone control (just without the majority of the top end of the sweep when paired with passive pickups).

 

[sunbeast]

OK, but you can make it work either way - there are minor tradeoffs as I detailed, but either topology basically works.

A resistor in parallel with the capacitor would make your tone control work (somewhat) like a volume control too unless you used a larger resistor than the potentiometer value used (so we are talking MUCH different values)

 

[micguy]

A resistor in parallel with the capacitor would make your tone control work like a volume control too unless you used a larger resistor than the potentiometer value used (so we are talking MUCH different values)

At DC yes, but not at the frequencies we're talking. Trust me, I've done my homework on this - many times.