santellan
Meter Reader 1st Class
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Post by santellan on Oct 21, 2011 11:10:27 GMT -5
Hi guys, I am working on a tele concept where I need to simplified this circuit. I know this in not the typical way to wire this mod but will this work as an alternate method? Image disappeared heres the link to circuit santellansounds.com/images/tele_2v_no_tone_sch.jpg
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Post by JohnH on Oct 21, 2011 14:18:12 GMT -5
Hi and welcome back.
Those volume pot wirings using just two lugs may be not so good. There probably wont be much volume reduction until the pot is turned down to a low setting, comparable with the pickup impedance, and when it does it will be accompanied by a loss of treble tone. Why do you need to do it like that?
cheers
John
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Post by ashcatlt on Oct 21, 2011 14:41:56 GMT -5
Yeah, it's more like 2 Tones no Volume. On top of that they'll be interactive - acting as dual masters in the middle switch position.
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santellan
Meter Reader 1st Class
Posts: 63
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Post by santellan on Oct 21, 2011 17:48:19 GMT -5
First this is going on a tele with emg pickups. The reason behind this circuit is I will re purpose the master volume and tone pot to become two volume pots. The number of dip switches required to do this the typical manner requires 6 switches while this possible method requires 3. It's less intimidating to deal with less switches. Here's a link to what I am trying to accomplish. santellansounds.com/ElekTrixTele3way.aspx
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Post by newey on Oct 21, 2011 20:02:08 GMT -5
I agree with JohnH and ashcatlt, you won't be happy with 2-wire rheostat-style wiring in this application. Consumers will expect their volume pots to work just like a normal Tele volume control.
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santellan
Meter Reader 1st Class
Posts: 63
Likes: 0
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Post by santellan on Oct 22, 2011 10:31:21 GMT -5
Thanks for the input. I agree with all your comments and will try to find another way if possible.
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Post by ashcatlt on Oct 22, 2011 11:32:13 GMT -5
Thinking about this led me to the question:
Is there any reason not to wire a Tone control as an actual potentiometer? Lug 3 to hot output, cap from hot output to 2, and ground on 1?
Don't know if that helps in this situation, but...
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Post by asmith on Oct 22, 2011 13:25:01 GMT -5
Ash: you'd be putting the whole of the resistance of the pot in parallel with the pickups, loading them down.
This piece of information is Copyright A. Smith 2011, and may not be used in commercial ventures without my expressed written signed permission.
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Post by ashcatlt on Oct 22, 2011 13:53:30 GMT -5
No more than with a standard tone pot. When it's at 10 it's exactly like a normal Tone. Turning down a Tone pot purposely "loads" the pickup anyway. I should punch it into 5spice and see what happens.
And nothing in your post is anything but basic theory and general knowledge. santellan has always been pretty upfront about the fact that he's working on stuff for sale, and pretty good about giving credit where it's due.
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Post by asmith on Oct 22, 2011 14:12:58 GMT -5
No more than with a standard tone pot. When it's at 10 it's exactly like a normal Tone. Turning down a Tone pot purposely "loads" the pickup anyway. I should punch it into 5spice and see what happens. I thought "Pickup + 250k Volume Pot + (250k Tone pot * Cap)" is different than "Pickup + 250k Volume Pot + 250k Tone pot + Cap. In the former, without the inclusion of the third lug in the circuit, the cap would "block" all but a certain portion of frequencies from heading through the 250k pot. There's 250k in constant parallel with the pickup with some (frequency-dependent) impedance being varied. In the latter, one's effectively got only 125k in parallel with the pickup at all times, at the same time as varying the resistance in series with the cap. That's what I figured. I'm looking forward to your 5Spice results though. Increasing the resistance in parallel with the cap at the same time as decreasing the resistance in series could make for some funky effects.decreasing That's why I think I'm being funny; I can't copyright what I regurgitate from ad-hoc self-tuition off Wikipedia. I wouldn't post in Santellan's thread if I wasn't comfortable with him using any input from me in his projects.
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Post by ashcatlt on Oct 22, 2011 14:50:27 GMT -5
The difference is minimal, and worst when the tone is at 0. Here it shows a damping of the resonant peak in the 3 lug version. With 250K pots, it's about 1.5 db down right at the peak. This really is just barely audible. As the pot gets bigger the difference gets smaller. With the pot at 10 the difference is negligible. Edit - Noticed I was using a 10nF tone cap. With 22nF the difference is about .7 or so. Bigger tone caps make for smaller differences. Also - Sorry, missed the sarcasm.
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Post by asmith on Oct 22, 2011 15:21:56 GMT -5
No need to apologise, I'm sorry for being so vague in my intent.
I thought halving the total non-frequency-dependent resistance in parallel with the pickups would have massive consequences. Hence the noticeable difference between 250k and 500k.
Hummm.
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Post by ashcatlt on Oct 22, 2011 18:09:17 GMT -5
I'm kinda surprised, too, since your argument makes sense. Went back and ran the analysis again with the same results.
It's worth noting that my test was with a passive pickup. santellan is talking about using low-Z, non-inductive active pickups here. I was going to check this, but didn't. I'd expect that the difference becomes even smaller, assuming the pots stay the same.
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Post by sumgai on Oct 24, 2011 11:44:32 GMT -5
Ace/ash,
The "half-this should result in half-that" differences don't occur because you're actually changing only one variable within the whole equation. Don't forget to consider the overall effect of having inductance and capacitance, as well as resistance, within your circuit(s).
Also, you might have forgotten that when you're speaking of "dB's of difference", you're looking at an amalgmation of the entire frequency spectrum.... a generalized picture, if you will. Those same inductance and capacitance values will definitely give much greater "swing" readings if you pinpoint specific frequencies toward the ends of the audible range.
HTH
sumgai
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