Help with a Doubleneck

[nowonmai1999]

Hello everyone.

I am posting here hopefully to gain insight on a wiring issue with a double neck guitar that I have. 

Objective - I am looking to have consistent volume when in the neck selector/main toggle has all 4 pickups activated.

In the 12 string position I have Seymore Duncans (Hot Rodded Humbucker set). Volume and Tone operate correctly when main toggle switch is in 12 string position. 

In the 6 string position I have Dimarzio Pickups. (Super Distortion in Bridge, and a PAF Anniversary in Neck) When main toggle switch is in Down position activating this set of pick ups, volume and tone function correctly.

HOWEVER... When main toggle (which selects neck, or all 4 pickups) is in MIDDLE position, Volume and Tone for each neck becomes precarious and very sensitive. Also, the volume remains consistent for the 6 string neck. for example, if i strum on the 6 string neck and switch neck selector to MIDDLE position there is no loss of signal power. However if I go from 12 string neck to middle position of neck selector toggle then the 12 string neck power/volume seems to be greatly reduced.

What is noteworthy here is that when neck selector is in middle position, should I lower the volume even slightly on the 6string neck, then my 12 string neck is on full volume and power.


PIckups are wired properly, so is there somehow an out of phase happening somewhere when all 4 pickups are activated? if so, how can I correct this!

[JohnH]

Welcome to GN2. Maybe we can figure it out.

What model of guitar is it? and also, can you list all the controls and switches that are on it? eg, is there separate volume and tone for each neck? etc.

cheers

[nowonmai1999]

hello JohnH, and thanks for your reply.

Make is a "Wolf" guitar. Made in Korea. (Sold by All in One Guitars off Reverb)

Guitar has 3 toggle switches.

1 three way toggle for 6 string neck.
1 three way toggle for 12 String neck,
1 three way for Neck selection. 

two volume & two tone knobs.

[JohnH]

Ok thanks. So I assume that it works quite well if just one neck is selected? but gets finicky with both necks?.

It sounds like it may have the same issues between necks as guitars with two volumes (such as Les Pauls) have between pickups. Everything full-on is fine, but if you have one full and try to turn the other down, it quickly disappears instead of fading down smoothly. is it anything like that? (it is to do with impedances btw)

If so, its kind of implied by the system, and fixes to it can compromise in other ways. One thing to try if you want to set an in-between mix of necks is to turn both down to about 9, and then reduce one a bit more. Is that any better?

There are other possibilities to discuss though.

[nowonmai1999]

Feb 24, 2018 16:41:05 GMT -5 JohnH said:

Ok thanks. So I assume that it works quite well if just one neck is selected? but gets finicky with both necks?.

It sounds like it may have the same issues between necks as guitars with two volumes (such as Les Pauls) have between pickups. Everything full-on is fine, but if you have one full and try to turn the other down, it quickly disappears instead of fading down smoothly. is it anything like that? (it is to do with impedances btw)

If so, its kind of implied by the system, and fixes to it can compromise in other ways. One thing to try if you want to set an in-between mix of necks is to turn both down to about 9, and then reduce one a bit more. Is that any better?

There are other possibilities to discuss though.

* Yes & Yes to your first two questions. your asesment of my situation is Spot on. 

And yes if I turn down to 9 i can find a nice balance somewhat, but in a live situation it can't be very reliable. Here's why.. I play this instrument with both necks on for a sympathetic vibration on the 12string neck and s.jordan touch technique on the 6 string neck. when this is executed properly is quite beautiful. I would like to be able to have both necks work as i envision and bring one up fuller or down as i need to. I'm open to hearing how to overcome this. 

[JohnH]

The main effect is likely to be due to impedances (similar term: resistance).

When you directly combine signals of two different impedances, the one with lower impedance will dominate. At full volumes, both signals have impedance determined by the pickups, which are a few thousand ohms each. So they combine reasonably well. But when one is turned down, its impedance rises very quickly due to its volume pot, so it gets overcome by the other one. If both are turned down though, tbey balance better.

So ways to adjust this involve either changing the rate at which tbe pots turn down (adding parts or changing pots), or adding some resistance to each (can affect tone slightly)

Can you find out the type and value of your pots? Need to open up the guitar. The pots hopefully have 250 or 500 on them (resistance value in kiloohms) and A or B for audio taper or linear taper.

If thats not feasible or not clear, you can measure this info using a multimeter without opening the guitar.(more info needed to explain)

[nowonmai1999]

thanks for your response,

to answer your question, these are CTS Model:500k Short Split Shaft, Audio Taper Pots.

[JohnH]

Ok thats great. Im thinking a few small resistors and capacitors could help this. Very inexpensive if you can do a bit of soldering. Ill work something out....

[nowonmai1999]

soldering is no problem.

muchas gracias!

[JohnH]

This is my suggestion, to do this to both volume pots.

It combines two ideas that should help with the issue:

The 100k and 1nF are a treble-bleed network - usually for the purpose of maintaining treble at lower volume, without loss due to cable capacitance. They have a side effect of slowing down the rate at which volume is reduced, and I changed the usual 150k to 100k to increase this effect. You may notice a smoother slower volume taper even when one neck only is used. The other is the 10k resistor, creates more separation from the other pickup when both are on. There may be a very slight loss of high treble but probably not noticeable.

This probably wont totally fix the problem, and there will still be an apparent difference in how the volume pots work with one or both necks, but you may find it more workable (hopefully). Let us know! and if you don't like it, make sure you can put it all back again.

[nowonmai1999]

Many thanks for your help JohnH. Many thanks. i will give a try to your suggestions.

here is a quick demo of my musical style (where all of this is going) just for your reference. 

[JohnH]

Beautiful, and magical!

Fretting the 6 while plucking the 12 is very cool.

I hope this works. Delighted to try to help an artist.

[JohnH]

BTW, if you need more smoothing of the blend, there are two more things that can be tried, a bit more involved:

Assuming the idea above does not spoil the tone, then keep that idea but change all the pots to 250k linear pots for volumes and 250k audio no-load pots for tone. This will further slow down the pot taper, and also reduce the change in impedance as volume is reduced (for better blending), with no further change of tone when at max volume.

The 10k separating resistors could be increased, for more separation. With the diagram above, you could try 22k instead of 10k (a bit more treble loss). Or, you could increase them to 56k and add an active buffer just before the output. See this thread:

guitarnuts2.proboards.com/thread/3150/jfet-buffer-cable

The buffer separates the guitar from the cable capacitance which is what loses treble. You get a more hi-fi extended treble that you might like for your style, and allows those separating resistors to be larger for smoother blends.

[nowonmai1999]

thanks so much. will post next week or so and update. 

I appreciate your taking the time and offering these solutions.

[nowonmai1999]

Feb 24, 2018 21:58:22 GMT -5 JohnH said:

BTW, if you need more smoothing of the blend, there are two more things that can be tried, a bit more involved:

Assuming the idea above does not spoil the tone, then keep that idea but change all the pots to 250k linear pots for volumes and 250k audio no-load pots for tone. This will further slow down the pot taper, and also reduce the change in impedance as volume is reduced (for better blending), with no further change of tone when at max volume.

The 10k separating resistors could be increased, for more separation. With the diagram above, you could try 22k instead of 10k (a bit more treble loss). Or, you could increase them to 56k and add an active buffer just before the output. See this thread:

guitarnuts2.proboards.com/thread/3150/jfet-buffer-cable

The buffer separates the guitar from the cable capacitance which is what loses treble. You get a more hi-fi extended treble that you might like for your style, and allows those separating resistors to be larger for smoother blends.

Ok... so parts update.

*Two; Emerson Pro CTS Blender/No-load Pot for Tone
*Two; CTS Control Pots, Split shaft, 250K-ohm for Volumes
*Two; Golden Age Treble Bleed Circuit With .001uF ceramic capacitor
*Two; 22k resistors

also, i am attaching a photo of my current wiring situation as it stands now. From top to bottom/Left to Right, there is; 12 String Neck, Volume/Tone, followed below by 6 string Volume/Tone. The neck selector switch wires are color coded Red for 12string neck, and Green for 6 string neck.




The diagram you sent shows the Treble bleed circuit wired to the volume pot and the 22k going to the neck selector switch. My Neck selector switches are connected to the volume pots by the red & green wires.

Question: The green & Red wires have within them, a white wire and a bare wire. The white wire goes to the output on the pot, and the bare is soldered to the back of the pot. When I attach the 22k into the picture will they be soldered to the end of the green& red wires respectively and then connected to the output??

thanks for tolerating a noob!

[JohnH]

ok

Are you getting linear pots for the volumes? Slower volume fall off and smoother blending if you do so, but its a free choice.

What resistor is in the treble bleed circuit that you noted?

The 22k resistors will smooth the blending more but will cause a little more high end loss. I suggest you try the 10k as well.

Whichever value, they should be soldered in line with the white inner wires of your red and green. Could be either at the pot end or the switch end.

Good luck

[nowonmai1999]

Feb 25, 2018 23:00:17 GMT -5 JohnH said:

ok

Are you getting linear pots for the volumes? Slower volume fall off and smoother blending if you do so, but its a free choice.

What resistor is in the treble bleed circuit that you noted?

The 22k resistors will smooth the blending more but will cause a little more high end loss. I suggest you try the 10k as well.

Whichever value, they should be soldered in line with the white inner wires of your red and green. Could be either at the pot end or the switch end.

Good luck

volumes are linear pots.

resistor in treble bleed circuit is 150K-ohm 1/4-watt resistor (1% tolerance) in parallel with a .001uF capacitor.

many thanks & will update when parts are installed.

[wolf]

I figured I'd redraw the graphic that John H posted.

[reTrEaD]

That was nice of you, Wolf.

It looks like imgbb doesn't handle images which are taller than they are wide, very well in the thumbnail.
You might want to use a square format (or maybe width greater than height might work) for images hosted by them.

It's a shame, too. Because the image wasn't very large in the first place.

[nowonmai1999]

Feb 27, 2018 23:28:06 GMT -5 wolf said:

I figured I'd redraw the graphic that John H posted.

Thanks wolf. Your time is much appreciated. The new parts arrived last night. Well Most of them did. Still waiting on the 10k resistors. But I'm so eager to try this out. 

[nowonmai1999]

Feb 28, 2018 1:02:47 GMT -5 reTrEaD said:

That was nice of you, Wolf.

It looks like imgbb doesn't handle images which are taller than they are wide, very well in the thumbnail.
You might want to use a square format (or maybe width greater than height might work) for images hosted by them.

It's a shame, too. Because the image wasn't very large in the first place.

Thank you too reTrEaD.Updates coming in the next day or two.

[JohnH]

Thanks from me too Wolf. I tend to dash off a quick doodle to show an idea during a discussion, and the hand sketch shows that its part of a thinking process rather than something to be set in stone. Maybe once its tested, and if successful, you could be invited to update it?

Nowonmai1999 - For the design, the parts that your are getting provide four ways to improve the neck mixing:

Lower value volume pots
Linear taper
Treble bleed circuit (but particularly the effect of the resistor)
Seperating resistors

I dont know if you can easily try it stage by stage (ie, if you can keep it strung while working on it). But if so, you might find the best version for you by putting the new pots in first, then maybe the treble bleed parts and then the seperating resistors. Listen for not just the mixing but also how the volume control feels with one neck at a time, and any changes to high treble. I'll be interested to know your opinion.

Potentially, this can apply to single-neck guitars too with twin volumes, as well as mixing double necks.

[nowonmai1999]

Been out of the loop with lots of work lately.

I wanted to return to the forum with a huge thanks to all who came to help with input for getting me through my wiring concern (you know who you are). Your knowledge, help and promptness in replying when everyone has busy lives is exemplary. 

The guitar works as I had originally envisioned now. I have an excellent blend of all 4 pickups.

Gratitude & Respect!!!!!

[reTrEaD]

It's always good to hear a success story. Thanks for taking the time to post.

We enjoyed your first visit with us. Drop a youtube into Sound Samples or the Coffee Shop any time you like, too.

[JohnH]

Thanks that's good to hear!

So for tbe record:
The final recipe was the 250k linear volumes with 150k//1nF treble bleed, no-load tone pots and the 10k seperating resistors?

[nowonmai1999]

You are correct!

[nowonmai1999]

Mar 11, 2018 14:52:22 GMT -5 reTrEaD said:

It's always good to hear a success story. Thanks for taking the time to post.

We enjoyed your first visit with us. Drop a youtube into Sound Samples or the Coffee Shop any time you like, too.

I will post vids at the right time. On Friday, I am performing a noonday concert at a Cathedral. 16th of March. I will be using the doubleneck for a few songs. hopefully someone will make a video recording of this performance and I will post any footage upon my review.