question about guitar capacitor wiring

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question about guitar capacitor wiring

Post by heavenorlasvegas »

hello all,

I'm looking to add a capacitor to the signal path of my pickup for my teisco bass. i'm not using a volume or tone pot, just the pickup wired to a 1/4 ts jack.

So then, would I just wire the capacitor somewhere in the hot path and leave the ground as it is? I'm assuming this is the correct way to go. Just wanted to make sure.

Thanks

Roger
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Re: question about guitar capacitor wiring

Post by Wonks »

What is it you want to do? Do you want to use it as a high pass filter and roll off a fixed amount of bass, or as a low pass filter and roll off a fixed amount of treble?

If a high pass, then yes, it goes directly in the ‘hot’ signal path, nothing in the ground path or with any added connection between the capacitor to ground.

If a low pass, to simulate the effect of a tone pot on 10 and not have the sound quite so bright, then you need a capacitor and resistor in series between the ‘hot’ signal and ground, the way a tone pot is fitted.

A high pass capacitor would typically have around 1/10 of the value of a low pass capacitor, so maybe 0.0022uF or less for a high pass filter as opposed to 0.022uF, 0.033uF or 0.047uF capacitor and a 250k or 500k resistor for a low pass filter, depending on how much bass or treble you want to roll off.
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Re: question about guitar capacitor wiring

Post by heavenorlasvegas »

hi @wonks, thanks for your reply.

I plan to be using it as a "thru" component to see if it imparts any character on the signal, in neither a high or low pass capacity.

Thanks again.
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Re: question about guitar capacitor wiring

Post by resistorman »

heavenorlasvegas wrote: Sat Apr 01, 2023 3:59 am hi @wonks, thanks for your reply.

I plan to be using it as a "thru" component to see if it imparts any character on the signal, in neither a high or low pass capacity.

Thanks again.

Maybe a 1 Farad non polarized cap in series with the hot lead would impart some time delay? :bouncy:
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Re: question about guitar capacitor wiring

Post by Wonks »

It will act as a high pass filter then. So you’ll get less bass. I’ve just realised the typical value of 0.0022uF I gave above was with a volume pot after it and as you don’t have one, you’ll probably want a smaller value as the filter resistor becomes the amps input impedance.

I’d wire in some temporary terminals so you can try out various capacitor values.
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Re: question about guitar capacitor wiring

Post by Wonks »

resistorman wrote: Sat Apr 01, 2023 4:39 am
heavenorlasvegas wrote: Sat Apr 01, 2023 3:59 am hi @wonks, thanks for your reply.

I plan to be using it as a "thru" component to see if it imparts any character on the signal, in neither a high or low pass capacity.

Thanks again.

Maybe a 1 Farad non polarized cap in series with the hot lead would impart some time delay? :bouncy:

Well, if you’ve got two pickups, then a cap on one output lead before the two pickup outputs connect can give a phase shift, so you get a slightly different character to the mixed sound. Not necessarily something you’d want permanently wired in but you can make it switchable.

A friend made up a test rig on a Tele with a selection of phase shift caps. I didn’t prefer any of the shifted sounds myself over the standard parallel arrangement but YMMV.

But with a single pickup, you’ll just get bass roll-off.
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Re: question about guitar capacitor wiring

Post by ef37a »

"
I’d wire in some temporary terminals so you can try out various capacitor values."
I agree with Wonks ^ In fact Roger, buy a small diecast box and couple of jacks* so you can experiment with various capacitor values, maybe fit a couple of SPDT switches so you can make rapid comparisons? PITA to have to strip off the scratch plate for each try!

Be aware that without tone and volume pots the response will be solely at the mercy of the input impedance of the gear you plug the bass into so it might for instance sound OK into an amp with 1meg but not so good into a DI input with a lower impedance. This problem is of course always present with passive guitars/basses but the normal pot loads reduce it to some extent.

*As you have two pups maybe bring them out on a stereo, TRS jack and cable? You will need to parallel the two sources post caps of course. That cable should be as short as possible. No more than a mtr say.

Dave.
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Re: question about guitar capacitor wiring

Post by Wonks »

Teisco did a large range of basses over time, some with one pickup, some with two.

Roger’s first post only mentioned ‘pickup’ rather than ‘pickups’, so I expect there’s only one pickup, but you never know (at least until he tells us ;) ).
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Re: question about guitar capacitor wiring

Post by Wonks »

Without any volume control, If you use the bass live, I would suggest at least an on/off switch so you can put the bass down without having to turn the amp down first to avoid noise and feedback.

Best to connect the output signal to ground rather than just break the output connection. It won’t affect the sound at all.

To avoid drilling into the body or an original scratchplate, you can fit a rotary switch to replace an unused volume or tone pot.
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Re: question about guitar capacitor wiring

Post by ef37a »

Wonks wrote: Sun Apr 02, 2023 8:42 am Teisco did a large range of basses over time, some with one pickup, some with two.

Roger’s first post only mentioned ‘pickup’ rather than ‘pickups’, so I expect there’s only one pickup, but you never know (at least until he tells us ;) ).

Oh, it was you Wonks that mentioned two pickups! I knew I had read it somewhere. And yes, I would say some form of 'kill' switch is vital as well.

Dave.
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Re: question about guitar capacitor wiring

Post by Wonks »

Yes, but I did say 'if there are two pickups'.

I'm not sure why you'd want a permanent bass roll-off on a bass. An adjustable one would give you some tonal options, but then you really could do with a volume control to provide a known resistance from the signal to ground for the capacitor to work with.

This is the G&L passive treble and bass control circuit

Image

Though you could leave out VR3 and C2 if you didn't want any treble roll-off. and VR2 could be made 500k for a brighter sound (and closer to the no volume pot at all sound), though you'd probably want to halve the value of C1 to keep the cut-off point the same. That value's something you could experiment with.

With the bass roll-off pot on 10, the capacitor is fully bypassed for maximum bass.
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Re: question about guitar capacitor wiring

Post by Martin Walker »

Wonks wrote: Sat Apr 01, 2023 4:53 am Well, if you’ve got two pickups, then a cap on one output lead before the two pickup outputs connect can give a phase shift, so you get a slightly different character to the mixed sound. Not necessarily something you’d want permanently wired in but you can make it switchable.

A friend made up a test rig on a Tele with a selection of phase shift caps. I didn’t prefer any of the shifted sounds myself over the standard parallel arrangement but YMMV.

That's exactly what I did with my fretless bass, and I achieved a good variety of different tones overall, with three switched values of treble rolloff caps (plus none at all as the 4th option) on the neck pickup, and one switched cap for bass rolloff on the bridge pickup.
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