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Active Pickups with Luthier Kit, is it possible?


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#1 cags12

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Posted 17 July 2017 - 04:51 PM

Hi - well the tittle says it all. - Can we use active pickups with Luthier Kit?

As I understand all the pots used by the Kit are matched for high impedance pickups 500K (Passive). However, Active pickups use 25K. That is the reason for this question.

As for the Tone pot, I have come up with a workaround. Since it is a dual pot, a resistor in parallel can be added to the part that controls the regular pickups and thus matching the impedance.

The issue I have is with the Volume pot, which is even more important than the tone for me. This pot is not dual and it is shared by the ATG system and regular pickups. If it were dual I could do the same as with the Pot.

Is there any official solution (custom component) or is there any DIY alternative?

#2 GuitarBuilder

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Posted 18 July 2017 - 10:16 PM

I'll defer to Henrik as the final authority on this; my opinion is that it shouldn't matter what the potentiometer values are when using active pickups.  In fact, it's the other way around: passive pickups are very sensitive to any impedance that is connected, as it will determine the final voltage output.  In contrast, an active circuit will tend to deliver the same output over a wide range of load resistances.

Check page 55 in the Luthier Kit Installation Manual for an example of interfacing an RMC PolyDrive (which is active) with ATG.  The main considerations are power supply compatibility and hex signal levels.  Other than that, it should be quite straight forward.

#3 cags12

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Posted 19 July 2017 - 10:28 AM

Thank you for your input, however. Based on the article below and quoting:

http://www.seymourdu...-can-it-be-done

"Active pickups are used with 25K pots. Passive humbuckers use 500K pots (or maybe 250k but that’s much less common). First, I tried using a 500K pot as the master volume. This worked fine when the volume was on full. And switching to the passive pickup and rolling off the volume worked fine too. But switching to the active pickup, the master volume acted like a switch. The signal was either on or off. So that was no good. And when I tried a 25K pot, the neck pickup sounded horrendous – a completely unusable muddy mess. So it became obvious at this point that I would need to give each pickup its own volume control."

I am no electronics savy, but my take is that it really does not matter if something is Active (powered) or Passive (unpowered), the importance is the impedance. If I am not mistaken, the RMC Polydrive preamp takes super high piezo impedance down. Also, the Polydrive seem is designed to work with regular Passive pickups (no idea if Active would also be supported).

Hopefully Henrik can shed some light.

#4 Henrik

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Posted 19 July 2017 - 05:08 PM

I have not tested the ATG kit in combination with active pickups.  I have certainly used a lot of active pickups with 25k pots.  If you are serious about using active pickups on the same guitar, you may want to consider wiring the two systems separately.

#5 GuitarBuilder

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Posted 22 July 2017 - 02:45 AM

View Postcags12, on 19 July 2017 - 10:28 AM, said:

Thank you for your input, however. Based on the article below and quoting:

http://www.seymourdu...-can-it-be-done

"Active pickups are used with 25K pots. Passive humbuckers use 500K pots (or maybe 250k but that’s much less common). First, I tried using a 500K pot as the master volume. This worked fine when the volume was on full. And switching to the passive pickup and rolling off the volume worked fine too. But switching to the active pickup, the master volume acted like a switch. The signal was either on or off. So that was no good. And when I tried a 25K pot, the neck pickup sounded horrendous – a completely unusable muddy mess. So it became obvious at this point that I would need to give each pickup its own volume control."

I am no electronics savy, but my take is that it really does not matter if something is Active (powered) or Passive (unpowered), the importance is the impedance. If I am not mistaken, the RMC Polydrive preamp takes super high piezo impedance down. Also, the Polydrive seem is designed to work with regular Passive pickups (no idea if Active would also be supported).

Hopefully Henrik can shed some light.

That post was made by someone who doesn't understand electronics.  Mixing active and passive pickups with the same selector switch is a no-no, unless you know how to wire them as separate circuits using a Schaller Megaswitch.  Does not apply to what you want to do.

#6 cags12

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Posted 24 July 2017 - 12:47 PM

View PostHenrik, on 19 July 2017 - 05:08 PM, said:

I have not tested the ATG kit in combination with active pickups.  I have certainly used a lot of active pickups with 25k pots.  If you are serious about using active pickups on the same guitar, you may want to consider wiring the two systems separately.

Thank you Henrik. I will make some tests and also see if I can find a dual pot with momentary switch (tough). I may have to email support with some queries about the considerations of non-standard installations outlined on the Installation manual. Specifically, the on/off considerations and the "soft" power-on control.


View PostGuitarBuilder, on 22 July 2017 - 02:45 AM, said:

That post was made by someone who doesn't understand electronics.  Mixing active and passive pickups with the same selector switch is a no-no, unless you know how to wire them as separate circuits using a Schaller Megaswitch.  Does not apply to what you want to do.

Thank you for pointing that out. Since I do not consider myself  electronics expert I will give it a try then. I am going to test wire some Active pickups I have to a 500K pot and report the results. I have the feeling (based on several posts online and what I understand how pots work) that the Pot will act as an on/off switch due the increased resistance. In other words, the 25K threshold that would mute the signal gets quickly reached on a 500K pot.

#7 GuitarBuilder

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Posted 25 July 2017 - 07:27 PM

View Postcags12, on 24 July 2017 - 12:47 PM, said:

Thank you for pointing that out. Since I do not consider myself  electronics expert I will give it a try then. I am going to test wire some Active pickups I have to a 500K pot and report the results. I have the feeling (based on several posts online and what I understand how pots work) that the Pot will act as an on/off switch due the increased resistance. In other words, the 25K threshold that would mute the signal gets quickly reached on a 500K pot.

No - the 500K pot will simple produce a lower current signal than the 25K pot.  The range of control should be the same; audio vs linear taper (A vs B pot) will determine the ease of control.  It will not be an on/off switch due to resistance.




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