Splitting JB with 250k pot

[Baby Evil]

It's supposed to be 500k, but I have a 250k. How will that affect the sound?
Overall, I'd like it to be brighter.

thanks

Jan

 

[Marcel]

Re: Splitting JB with 250k pot

JB is build for 250K but if you like it brighter you might use a 500k pot

 

[Aceman]

Re: Splitting JB with 250k pot

Most people seem to prefer 500k's to open things up. For soemthing hot though, I like the Gibson stock 300k's. Keeps the harshness down in the bridge. I like 500k in the neck though.

 

[Amateur]

Re: Splitting JB with 250k pot

JB is build for 250K but if you like it brighter you might use a 500k pot

Correct me if I'm worng. I thought the 500k pot will give you a darker sound.

 

[Dave Z]

Re: Splitting JB with 250k pot

well, the pot resistance is resistance to ground...in other words, you are gonna lose some signal to ground even with the pot on 10.

since resistance filters highs more than lows you'd think a high value pot would let more lows go to ground, thus a brighter sound, but everything I have seen shows the circuit has a higher resonant peak with higher value pots. Go figure...

 

[Amateur]

Re: Splitting JB with 250k pot

well, the pot resistance is resistance to ground...in other words, you are gonna lose some signal to ground even with the pot on 10.

since resistance filters highs more than lows you'd think a high value pot would let more lows go to ground, thus a brighter sound, but everything I have seen shows the circuit has a higher resonant peak with higher value pots. Go figure...

Isn't that the RC circuit a high-cut circuit which lets the high frequencies to go to ground?

 

[Baby Evil]

Re: Splitting JB with 250k pot

Just did the soldering, and it sounds just fine. I'm amazed how good it sounds split, makes the guitar much more suitable for songs with clean picking and od'd power chords; the JB was just too much too get a really nice clean. Fixed.

thanks,

Jan

 

[Marcel]

Re: Splitting JB with 250k pot

Correct me if I'm worng. I thought the 500k pot will give you a darker sound.

your wrong

well, the pot resistance is resistance to ground...in other words, you are gonna lose some signal to ground even with the pot on 10.

since resistance filters highs more than lows you'd think a high value pot would let more lows go to ground, thus a brighter sound, but everything I have seen shows the circuit has a higher resonant peak with higher value pots. Go figure...

The resistance filters (ideal) all frequences the same. It's the interaction between the Capacity C, Induction L and Resistance R of the Pickup and the Resistance of the pot which build a resonance circuit.
Snaller load leads to a smaller resonant peak...

 

[Amateur]

Re: Splitting JB with 250k pot

your wrong


The resistance filters (ideal) all frequences the same. It's the interaction between the Capacity C, Induction L and Resistance R of the Pickup and the Resistance of the pot which build a resonance circuit.
Snaller load leads to a smaller resonant peak...

First of all, the pickup is not considered part of the circuit. The tone control circuit consists of the pot, which is a variable resistor (250k, 300k or 500k etc.) and a capacitor connected to ground, together they form the RC circuit. There is no inductance L. The capacitor in the circuit allows the high frquencies to escape to ground more easily than the lower frequencies. That is what we call a high-cut circuit because it gets rid of the high frequencies but keeps the lower frequencies and thus give you a darker tone. The higher the resistance, the darker will be the tone. If you think I'm wrong and it's the other way around, may be you can explain it to me how does the circuit work and I would appreciate it.

 

[Marcel]

Re: Splitting JB with 250k pot

I was using another model for the pickup to describe it:
You took the pub as a AC source and the RC as first order low pass. But the pickup is influenced by the other elements... you can see the pub as a second order lowpass or as a resonant circuit. It's much more complicated in reality coz the whole thing is nonlinear ... but that would lead much too far...

It's well described in this article:
http://www.buildyourguitar.com/resources/lemme/index.htm

 

[Amateur]

Re: Splitting JB with 250k pot

I was using another model for the pickup to describe it:
You took the pub as a AC source and the RC as first order low pass. But the pickup is influenced by the other elements... you can see the pub as a second order lowpass or as a resonant circuit. It's much more complicated in reality coz the whole thing is nonlinear ... but that would lead much too far...

It's well described in this article:
http://www.buildyourguitar.com/resources/lemme/index.htm

According to the article, you can change the tone of the guitar if
1. You install new pickups.
2. Change the coil configuration of the pickup.
3. Change the external load of the pickup which is RC circuit in this case.
4. Install an active electronic circuit.
However it does not tell you anything about the effect of the pot. It mealy touches on the capacitor and it does not exactly tells how the circuit works. The RC circuit will change the tone of the pickup regardless what its internal load is. According to what I had learned, when you keep everything other than the R constant in the circuit, the higher the resistance, the more high frequencies you will cut. I have not seen anything in that article that can convince me otherwise.

 

[Marcel]

Re: Splitting JB with 250k pot

then I can't help you...

The height of the peak of most available pickups ranges between 1 and 4 (0 to 12 dB), it is dependent on the magnetic material in the coil, on the external resistive load , and on the metal case (without casing it is higher; many guitarists prefer this).