Need 500k and 25k Push Pull Pots

[Cjd262]

So here the idea of what i'm doing, i'm combining my active blackouts with my passive hotrails in my DK2 by seperating their circuits onto push pull pots. The Blackout will have the 25k volume in the down position and tone in up position. The hotrails will have the same setup except for a 500k push pull. Now what I need help with is finding push pull pots that will fit and work for my Jackson DK2, one in 500k and one in 25k.

Thanks for the help!

 

[Cjd262]

Re: Need 500k and 25k Push Pull Pots

Anyone got any ideas?

 

[octavedoctor]

Re: Need 500k and 25k Push Pull Pots

I don't understand how you think you can combine the two? you either have to have an active buffer preamp between the hi-Z side of the configuration and the low-Z side or you have to have separate outputs. Unless you have a stacked pot with a 500k track on one level and a 25k track on the other. Don't know anyone who makes such a thing.

Show me a circuit of what you plan and I'll tell you if it will work.

 

[Cjd262]

Re: Need 500k and 25k Push Pull Pots

Your correct I will be seperating the circuits, the Blackout will be attached to a 25k push/pull. Down it will act as the volume knob, up it will act as the tone knob. The two passive hotrails will be attached to the 500k push/pull, same thing for volume and tone. The two pots will not be connected like a typical tone volume two pot setup. This keeps both circuits completely seperate from each other untill they meet at the stereo jack after each leaves their pot. This way the 9 volt active system only affects the blackout. Pre-amps could work but it'd be pointless to turn two passives into actives, i'd loose the hotrails beautifull passive tone.

 

[octavedoctor]

Re: Need 500k and 25k Push Pull Pots

You can't do it.

When I say you must keep the two circuits separate I mean TOTALLY separate. You can't combine low impedance and high impedance without a buffer preamp.

You can switch between the two but the switching will have to be done at the output stage so you have an either/or option. The moment you combine the low and the high impedance output the low impedance pulls down the output of the high impedance side.

If you combine a 500k and a 25k pot at the output stage you don't isolate the pickups from each other you just get a combined impedance of 23.8k which the hotrails see as a small resistance between signal path and earth, effectively shorting them out.

You can keep the two circuits separate and switch between them using a a two way switch with the output of each circuit going to each side of the switch and the output going to the jack, or you can have two separate outputs.

What makes you think you would lose any tone from the Hotrails if you put them through a preamp? The EMG PA-2 is an impedance balancing preamp which is designed exactly for this purpose with a flat response curve. You won't change the tone of your hotrails any more than you do by plugging them into any amp.

 

[octavedoctor]

Re: Need 500k and 25k Push Pull Pots

Draw a circuit of what you plan and let's see if it will work.

 

[ratherdashing]

Re: Need 500k and 25k Push Pull Pots

You can't do it.

When I say you must keep the two circuits separate I mean TOTALLY separate. You can't combine low impedance and high impedance without a buffer preamp.

You can switch between the two but the switching will have to be done at the output stage so you have an either/or option. The moment you combine the low and the high impedance output the low impedance pulls down the output of the high impedance side.

If you combine a 500k and a 25k pot at the output stage you don't isolate the pickups from each other you just get a combined impedance of 23.8k which the hotrails see as a small resistance between signal path and earth, effectively shorting them out.

You can keep the two circuits separate and switch between them using a a two way switch with the output of each circuit going to each side of the switch and the output going to the jack, or you can have two separate outputs.

What makes you think you would lose any tone from the Hotrails if you put them through a preamp? The EMG PA-2 is an impedance balancing preamp which is designed exactly for this purpose with a flat response curve. You won't change the tone of your hotrails any more than you do by plugging them into any amp.

+1, excellent response.

 

[Zerberus]

Re: Need 500k and 25k Push Pull Pots

You can't do it.

When I say you must keep the two circuits separate I mean TOTALLY separate. You can't combine low impedance and high impedance without a buffer preamp.

You can switch between the two but the switching will have to be done at the output stage so you have an either/or option. The moment you combine the low and the high impedance output the low impedance pulls down the output of the high impedance side.

If you combine a 500k and a 25k pot at the output stage you don't isolate the pickups from each other you just get a combined impedance of 23.8k which the hotrails see as a small resistance between signal path and earth, effectively shorting them out.

You can keep the two circuits separate and switch between them using a a two way switch with the output of each circuit going to each side of the switch and the output going to the jack, or you can have two separate outputs.

What makes you think you would lose any tone from the Hotrails if you put them through a preamp? The EMG PA-2 is an impedance balancing preamp which is designed exactly for this purpose with a flat response curve. You won't change the tone of your hotrails any more than you do by plugging them into any amp.

I agree on all points. What you currently wish to accomplish is not technically possible with today´s methods and materials.

 

[Cjd262]

Re: Need 500k and 25k Push Pull Pots

I see what you're saying, I know ill be losing the ability to play the passives and the actives at the same time. For example the bridge, center, center neck, and neck should work fine but at bridge center the blackout will eat up the hotrails. So i'm sacrificing one pickup combination. Am I correct on this? Two out put jacks would mean I'd completely remove the blackout from the selector switch and give it its own output while giving the 5 way blade to the hotrails. Only problem is this isn't a very convient way to change pickups on stage. I looked at the emg pre-amp you were talking about, could you give me a little more info on it? Preferably I'd like to find one that was permanently on rather than having to drill a hole for a new switch.

Thanks for the help everyone.

I'm havin a few electrical engineer friends of mine help me work on this, they told me to buy these parts and theyd do the rest. Were gonna start tomorrow so we'll see how things work out.

Ill have them draw up a circuit for you so u guys can check it out. These guys build competition robots so i'm trusting they know what they're talkin about.

 

[octavedoctor]

Re: Need 500k and 25k Push Pull Pots

I see what you're saying, I know ill be losing the ability to play the passives and the actives at the same time. For example the bridge, center, center neck, and neck should work fine but at bridge center the blackout will eat up the hotrails. So i'm sacrificing one pickup combination. Am I correct on this? Two out put jacks would mean I'd completely remove the blackout from the selector switch and give it its own output while giving the 5 way blade to the hotrails. Only problem is this isn't a very convient way to change pickups on stage. I looked at the emg pre-amp you were talking about, could you give me a little more info on it? Preferably I'd like to find one that was permanently on rather than having to drill a hole for a new switch.

Thanks for the help everyone.

you can disconnect the switch and just connect the pre-amp so it's on permanently. Drive from the same battery as the Blackout

I'm havin a few electrical engineer friends of mine help me work on this, they told me to buy these parts and theyd do the rest. Were gonna start tomorrow so we'll see how things work out.

Ill have them draw up a circuit for you so u guys can check it out. These guys build competition robots so i'm trusting they know what they're talkin about.

Good. But remember that you cannot combine the output of a 25k pot and that of a 500k pot in a passive audio circuit. It sounds to me as though you think its going to be OK to do that as long as the pickups themselves are not in circuit together but the different pot values are a huge problem. The 25k works with the Blackout, the 500k with the Hotrails, no blending or mixing of the two is advisable.

I'll post some photos of a PA-2 later.

 

[Zerberus]

Re: Need 500k and 25k Push Pull Pots

you can disconnect the switch and just connect the pre-amp so it's on permanently. Drive from the same battery as the Blackout

Yep, remove the switch, jumper the leads for "always on" or "always off" (more likely always off, as you´re not looking for a gain boost but rather using the board as a buffer preamp), and stuff the board inside the cavity.

Then hook up the hotrails to the preamp, and from the board output you go to the switch (or to 25k pots and then to the switch)

From then on it´s standard guitar wiring just with 25k pots.