allmektig
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Post by allmektig on Feb 13, 2010 11:11:04 GMT -5
Is that possible?
I'm experimenting a bit on my fender jazz bass, and I've found that both pickups in series, with one of them out of phase, is a very interesting sound. But is there any way for me to be able to adjust the volume of the pickups individually? That way I can control how much of the phase-turned pickup I want to include in the sound.
Any ideas?
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Post by wolf on Feb 13, 2010 14:56:56 GMT -5
Hello allmektigI've got an idea. How about connecting variable resistors in series with each of the pickups? I'll leave it up to the more knowledgeable folks here to comment on what problems may arise from doing this such as impedance mismatches. At least this offers a solution so that even if you turned down the volume on the neck pickup to zero, the bridge pickup would still be at full volume. Now that I think of it, you may only need one variable resistor because you said that you wanted to control the out of phase pickup's volume.
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Post by JohnH on Feb 13, 2010 14:59:52 GMT -5
Hi allmetig - there are a few possibilities, either with a blender knob that makes the transition between pickups by progressively cutting one out, or with two volume knobs. Are you thinking to hard-wire your bass so it is always in series and out of phase?, or are you thinking of a series/prallel switch plus a phase switch to keep the standard options? I have these features on some of my guitars. The swutching is not a problem if you want to keep all the options. I just keep the whole pickup/volume/tone assembly for each pickup intact and put the switching after that. This is my latest Les Paul build: guitarnuts2.proboards.com/index.cgi?board=schem&action=display&thread=4571This one, based in Jimmy page wiring is similar, with the phase switch before the volume pot: guitarnuts2.proboards.com/index.cgi?board=schem&action=display&thread=3159I find these schmes work very well for mixing pups in series, with a smooth combination as you adjust each one. If a single volume and a blender is more what you need, we have examples of that too. cheers John
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allmektig
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Post by allmektig on Feb 14, 2010 14:19:55 GMT -5
I'm thinking to hard wire it in series, with a DPDT switch to turn the phase of one of the pickups. I don't really think I need two seperate volume controls. What I'm after, I think, is a way to blend the phase turned pickup into the signal so I can get a various degree of phase cancelation.
I had a look at the schematics you posted, but they are a bit complex.
Edit: I also want to use the original control plate, wich has three holes.
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Post by JohnH on Feb 14, 2010 14:42:22 GMT -5
OK, so you could have Master volume, Master tone and blender. The phase switch can be a push/pull on the master tone.
For series blending like that, I have used a single linear pot, with one end to hot, one to ground and the centre lug to the connection between pickups. The diagram is a bit like Wolfs above, but as if the two variable resistors are part of the same pot. Then I do one more thing, which is to open up the pot and remove a small section of track in the centre. This means theres no overall connection from one end to the other, and only one pickup is bypassed, or none in the central position. 100k and 250 are good values.
John
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Post by newey on Feb 14, 2010 15:03:36 GMT -5
Yes, have 2 volume pots. Or, use a concentric pot so it only takes up one hole. Well, if you want to adjust the volume of the pickups individually . . . You could also use a blend pot, but you need to be sure it's a true blend pot: Blend vs. Pan PotsI'm not sure how that would be wired for series blending, but I'm sure there's a diagram around here somewheres . . . If that's the route you want to go, we'll get it figured out for you. EDIT: Ninja'd by JohnH. Or, you could make your own like John suggests!
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Post by JohnH on Feb 14, 2010 20:34:59 GMT -5
the next step is to figure out how you want to control the pickups, and you can have two volumes and a tone pot, plus a phase switch as a push pull, or master volume, blender and tone/phase switch. Either way, if it is all series wired, you are heading towards a simple scheme that will work very well and, aprt from the ability to set those phased blends, wil allow you to get any mix in or out of phase at any volume.
In a situation with no overall pickup selector switch, just the three knobs, I would personally favour Volume + Blender + Tone. As you turn the blender, it will go through a range such as:
100% Neck 100% Neck & 50% Bridge 100% Neck & 100% Bridge 50% Neck & 100% Bridge 100% Bridge
All phased or not, and then all under further control by master volume and tone
John
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allmektig
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Post by allmektig on Feb 15, 2010 11:30:34 GMT -5
Volume + blender + tone sounds just perfect.
What pots should I use? 250k log for master volume I guess. And a 250 linear with a piece of the track removed for the blend. But what kind of pot and what cap would you reccomend for the tone? And should I put the tone before or after the master volume? What are the pros/cons for the various options?
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Post by cynical1 on Feb 15, 2010 12:57:01 GMT -5
We had a similar discussion along these lines ages ago on a question I had on a similar design...or so I interpret it... Why no 3 volume pots in a design?Granted, this is for a bass with 3 pickups, but stripping the P-Bass pickup out may make it clearer. ChrisK was very helpful on this thread, and it does meander a bit...okay, it meanders a lot... Hope this helps
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Post by JohnH on Feb 15, 2010 14:50:10 GMT -5
Volume + blender + tone sounds just perfect. What pots should I use? 250k log for master volume I guess. And a 250 linear with a piece of the track removed for the blend. But what kind of pot and what cap would you reccomend for the tone? And should I put the tone before or after the master volume? What are the pros/cons for the various options? My thoughts are, for volume, tone and tone cap, use whatever are normal for a bass (I dont know what that would be), with tone before the volume, and a push/pull on one of them for your phase switch. The blender should be a full size (24mm) 250k linear - which is easy to open by bending up the lugs, and lifting out the track. Ive done this on several Alpha and CTS pots with never a problem. Its neat to connect a multimeter across the ends of the track as you start to scrape, and you can see the resistance rising, as you scrape gently with a small screwdriver tip. Its best to make two breaks at about 11 oclock and 1 oclock, so theres a disconnected zone between. Theres no risk by trying this beacuse you ar only investing in a very standard pot. Whats also good about it is at mid position, you get your full output with no loading from the blender. As an alternative, there is a more expensive way of doing this with a dual gang blend pot, and its also IMO not quite so pure electrically because it puts more load on the pickups - the advantage is that you can get a centre detent however. John
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allmektig
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Post by allmektig on Feb 15, 2010 15:26:13 GMT -5
Is there some way to get a center detent in a normal pot?
I'm thinking that since I have scraped off part of the track, will I feel it when I turn the pot past that point?
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allmektig
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Post by allmektig on Feb 15, 2010 15:34:31 GMT -5
But this has me kinda confused.
In the case of wiring a pot meter in parralell to one of the pickups... How would the pickup "know" when the potmeter is turned all the way up? Isn't a 250k linear pot the same as a 500k turned half way?
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allmektig
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Post by allmektig on Feb 15, 2010 16:21:23 GMT -5
I've been thinking a bit more. This is the stock wiring on a jazz bass: www.lacemusic.com/wiring/pdf/8.pdfTwo volume controls and a master tone. Would it be possible to have it wired that way, but to add two push-pulls for phase turning and series/parralell switching. The only difference between my bass and the one in that schematic is that my pickups only have two wires out. Edit: My first idea would be something like this: To blend the signal from the first pickup into the total signal. But as I turn the volume of the first pickup down, that would create a resistance from the other pickup to ground. And I guess that is a bad idea. I'm used to thinking of a volume controller as a simple voltage divider. I can understand the physics behind that. I don't really understand how the suggestions in this thread work.
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Post by JohnH on Feb 15, 2010 22:00:24 GMT -5
Wrote the following before seeing your edit, the blending idea with the single track cut pot just shunts one pickup with a resistance, until it is completely shorted out and only the signal fro teh other pup gets through.
The Jazz bass diagram is OK for mixing in parallel (reverse volume pot wiring) , but I don’t think there is a way to go from there to an effective series wiring with less than 3 switch poles and push/pull switches can only have 2 poles. (this is due to teh resistance issue you noted in your edit)
On the 250k track-cut blender, the action is fairly smooth, you don’t feel much or hear much as a step as you go through the centre, which is actually quite nice, just a smooth transition. Detent mechanisms have ball bearing devices in them, hard to add. But I did a couple of these with a dual gang detented 100k pot, and only used the back half for the series blending. I can’t find a new source of these, but if you can find a single or dual gang 24mm linear detented pot, I’d be interested to know!
You might consider either series only wiring with the two volume pots, tone and phase switch or,
A dual gang detented blend pot – ie a specialist blend pot, with master volume and tone and a series/parallel switch and phase switch – as noted above, a bit more load on the pickups so use all 500k pots, but nice action with the detent.
Or the 250k linear track-cut series only, non-detented blend pot, master volume, tone and phase switch.
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allmektig
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Post by allmektig on Feb 16, 2010 10:29:32 GMT -5
Ok. So series only wiring it is. With a master volume, master tone and blend. And a push pull for phase turning. I'll try to draw up a schematic for it sometime later this evening.
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allmektig
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Post by allmektig on Feb 17, 2010 5:36:30 GMT -5
Does this look right? The DPDT switch would be a push-pull on one of the pots. I think I might have gotten the lugs on either the tone and master volume wrong. (Or even both) but I'm to sleep deprived now to sort that out. Would be nice if anyone could create a better looking wiring diagram. All I have is paint and mediocre skills with it. (BTW, is there some program that's good for making these kinds of things? I've seen some pretty nice looking wiring diagrams on this site) Edit: Another thing I'm wondering about. How would the blend pot behave when it went from center (no connection) to either side? When connection was made. How would that effect the volume?
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Post by JohnH on Feb 17, 2010 6:35:26 GMT -5
I think that is good, just swap the centre and left volume pot connections. Also, you should connect the blender so as you turn it towards one pup (looking down on it as you play), it fades out the other pup - that may mean reversing the outer lugs of the blend pot, depends where the pups really are physically.
For diagrams, some use paint, others have cad programs. I do mine on good old Microsoft Word, using the drawing functions. Then when they are all done, I make a screen capture, paste it into any free graphics program and crop it to suit, saving to a giff file.
I find with these blenders, as you move off the centre, the sound has hardly any jump, its fairly gradual, but see what you find. Its not expensive to try.
John
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allmektig
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Post by allmektig on Feb 17, 2010 17:46:43 GMT -5
"just swap the centre and left volume pot connections."
Why? I'm curious as to why the volume is wired like that, and not like a regular voltage controller.
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Post by ashcatlt on Feb 17, 2010 20:20:13 GMT -5
It will be a voltage divider either way. We like to wire the master volume in such a way that the output is shorted to ground when turned all the way down. Wired as you have it now, the cable becomes an antenna when the pickups are shorted, which can be quite noisy.
You'd usually want to wire a volume control that follows an active stage with the wiper to output as well, to avoid shorting the active stage. Guitar pickups can't provide enough current to hurt anything, even into a 0 Ω load, but an opamp might just burn itself up.
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allmektig
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Post by allmektig on Feb 18, 2010 0:26:20 GMT -5
But appart from that, it looks right?
I'll try to make a proper wiring diagram out of it then, and post in in the schematics subforum. If there aren't any objections.
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Post by sumgai on Feb 18, 2010 13:46:14 GMT -5
I'll try to make a proper wiring diagram out of it then, and post in in the schematics subforum. If there aren't any objections. Errr, we (The Admin Staff) ask that you hammer it all out here first, then when everyone has no more to say, there's nothing else to add to your project, then it would be time to post it in the General Guitar Schematics sub-forum. Not that we don't like questions and answers in that forum, but it makes things "less friendly" for new readers if the subject is spread out over two (or more!) threads. Best to try to keep all the discussion in one place, I'm sure you understand. The suggestion would be to post your images and descriptions in GGS, and finish your post by linking back to this thread as a reference. And yes, you do note that there are few topics over there that get a bit long-winded. Those are mainly from the days prior to newey and I coming aboard, and (hopefully!) giving the Forum a bit of structure.... all in the name of making the place easier to find things, you understand. HTH sumgai
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