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Pups Polarity


Ulhuru

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Hi,

 

I just got my DF1483 back from service. And I am puzzled. To me it sounded good before, it sounds strange now. So here are my questions, if anybody has suggestions for me it would be just great:

 

a) With toggle switch on mid, both mics on 10, I have a polarity reversal between the 2 mics (twangy no lows sound unless I turn down a little one of the mics level). And I do have that on all banks.

 

Do you have similar behavior on your DFs?

 

:) Piezo's polarity is reversed too, compared to the pups, it behaves the following ways:

 

- Bridge + Piezo full = addition

- Bridge + Piezo 70% = cancellation

- Bridge + Piezo 30% = addition

 

- Neck + Piezo full = cancellation

- Neck + Piezo 70% = Addition

- Neck + Piezo 30% = cancellation

 

Well reading the B) above, it looks to me more Piezo / Mics phase relationship than straight 180° polarity reversal. And if you mention phase relationship, it means delay & expectedly digital stuff, but late, going on on the piezo.

 

I am mostly puzzled with a) because I remember DF before service sounding real good with the 2x Mics, and it also seem to me a regular LesPaul sounds huge with both mics on, usually???

 

 

I will do more testing tomorrow with my dealer, but if you have ideas in the meantime, thanks a many for sharing!

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Looks to me like your Neck PU is out of phase.

 

 

Gibson seems to be still playing with the right formula to get all Dark Fire pickups in phase. Unlike Godin, they have little prior experience with correct piezo + mag PU wiring to draw upon.

 

Dec 19 (pre RMA ) - on my Dark Fire, Both Mag PU's were in phase - while the Piezo was out of phase.

 

Then On Jan 16 (post RMA) I observed Gibson had rewired the whole guitar and now ALL pickups are now IN phase = Both Mag PU's and Piezo.

 

 

ON these type guitars - the Piezo PU dictates the polarity - you must change the Mag PU polarity to match the Piezo polarity.

 

 

 

You can tell two PUs are out of phase when both PUs under test have their volumes set at Vol "10" - yet the output level drops and the tone becomes "squawky" out of phase tone.

(unless you are on the Chamelon "Rock" setting - where "out of phase Neck vs Bridge Mag PU is intentional)

 

Set the Dark Fire Chameleon Mode to "Stock Gibson" put the PU toggle in the middle and turn up both Mag PU volume and tone controls to "10" and you should hear the classic sound of Neck and Bridge Mag PU in phase as an "Allman Brothers" Dickie Betts type tone.

 

 

I'm shocked that at this date -Gibson is still confused regarding the proper polarity wiring of the Dark Fire PUs.

 

No two Dark Fires I have played (at NAMM) were the same in this regard.

That is, one would be OK - then the next one I played was out of phase.

 

and even today - I have never played a Dark Fire with a fully functional Neck Humbucking PU. Instead the P90H always hums like a single coil - no matter what chameleon mode setting I try.

 

 

 

I should post pics of removing the PCB boards and gaining access to the Mag PU connectors - so a home repair could be performed. Its absurd that your guitar is still not right.

 

 

There are two methods to change the MAg PU phase polarity .

 

1) Reverse the electrical connections ( difficult)

 

or

 

2) Disassemble the Mag PU and flip the Magnets ( easy)

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One more question though: on your DF you do have the same wiring scheme (all in phase) regardless of your connection type, with RIP and with Analog Jack?

 

 

Correct! - All is now in phase - regardless of output connection method.

 

1/4" mono cord into amp = I can mix both Mag PUs and all are in phase - no volume drops as I enable one of the pickups.

 

 

TRS RIP into Guitar Rig = I can mix both Mag PUs and all are in phase - no volume drops as I enable one of the pickups.

 

 

 

 

 

 

If it were me - 6000 miles from Nashville

 

I would

 

** Verify I'm not in Chameleon "Rock" mode ***

 

as a test - enable the Chamelon Rock Mode and see if both Mag PUs now sound "In phase" - like a stock Les paul.

 

if the neck PU is deemed to be out of phase with respect to the Bridge PU in "Gibson Mode" - then :

 

 

1) get a protective cloth towel

 

2) remove the strings

 

3) carefully loosen the two Neck PU mounting screws

 

4) take apart the neck P90H PU ( take pictures)

 

5) prior to disassembly - mark the Magnets.

 

6) flip both magnets - that is make it so the edges of each magnet facing the center of the PU are now facing the outside.

 

7) reassemble the P90H PU

 

8) re mount it to the guitar and restring.

 

 

 

OR

 

 

 

just play it as is - and contact Gibson European Service and explain the situation.

 

Welcome to the bleeding edge of technology.

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See if you can get your Gibson dealer to compare your Dark Fire to a Stock Les Paul - plug each guitars into a clean amp and compare the sound of:

 

* A stock Les Paul with both Mag PUs on and all controls on "10". Focus on this PU combinations sonic characteristics, it should sound very Allman Brothers type southern rock.

 

then try the Dark Fire.

 

* Dark Fire with MCK pushed in - no LED lights on - and both Mag PUs on and all controls on "10"

 

 

The Dark Fire should sound very similar to the Les Paul.

 

If not - then your Dark Fire needs servicing to check its Mag PU phase.

 

 

Based on the information in your first post in this thread- - I have determined your Neck PU is out of phase.

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Yes,

 

All the above make sense & sounds pretty clear to me. (if I may say so!)

 

I can probably manage reversing the polarity of the Neck PU, according to your explanations.

 

But it seems my piezo is still out of phase, and there is not much I can do about that.

 

We'll see...

 

Elantric, thanks for all your help, it was efficient & quick!

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Yep, reading my first post, you must be right!

 

:-)

 

... But I am not too sure yet about the cancellation at 50 to 70% of piezo level compared to Bridge PU. Why would that be?

 

I no longer think clearly for tonight... to be re-tested tomorrow,

 

Thanks again.

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Yes- during some mix level combinations of mag and Piezo - you may experience the drop outs you describe.

 

Use a mono guitar cord - feed a clean channel of an amplifier

 

1) Enable the piezo. To activate the Piezo signal output, pull the MCK, turn it to Letter “I” LED (Blue Bank) and gently press & release. The guitar symbol on the MCK will turn green and the acoustic tone of your Piezo will mix with your regular Mag PU signal as you ramp up your toggle Sw Piezo Blend pot. With a mono guitar cable, your piezo signal will blend with your regular Mag PU output at the tip of the cable’s plug.

 

 

2) Rotate the PU toggle SW Piezo Blend pot full clockwise = full piezo output. You should hear the "acoustic like" piezo sound.

 

3) Turn both Mag PUs Vol Off ="0" You will still hear the "acoustic like" piezo sound only.

Use the Piezo Blend to control the Piezo volume, for now turn piezo to full output = full clockwise.

 

 

4) Test the Piezo vs Bridge Mag PU phase - switch the PU toggle SW down to "Bridge PU". Since the Bridge Mag PU volume is on "0", you will still only hear the piezo PU. Slowly rotate the Bridge Mag PU volume Up to "10" - and note if there are certain ranges of the Bridge PU volume pot where perceived audio signal level is lowered due to phase cancellation.

If the Bridge PU is in phase with the Piezo PU, at a Bridge PU Volume Pot setting of "10" you should have a good full frequency response signal. * Now turn the Bridge Volume Pot to zero as proceed with test #5

 

 

5) Test the Piezo vs Neck Mag PU phase - switch the PU toggle SW up to "Neck PU". Since the Neck Mag PU volume is on "0", you will still only hear the piezo PU (step3) . Slowly rotate the Neck Mag PU volume Up to "10" - and note if there are certain ranges of the Neck PU volume pot where perceived audio signal level is lowered due to phase cancellation.

If the Neck PU is in phase with the Piezo PU, at a Neck PU Volume Pot setting of "10" you should have a good full frequency response signal. Now turn the Neck Volume Pot to zero as proceed with test #6

 

 

6) Test the Neck Mag PU and Bridge Mag are in phase. Switch the PU toggle SW up the middle position = both Mag PUs. Use the Piezo Blend to control the Piezo volume, turn piezo PU to full OFF = full counter-clockwise.

You should have both Neck Mag PU Volume on zero, and Bridge Mag PU Volume on zero, and Piezo Blend full counterclockwise, and hear No sound.

 

7) Slowly rotate the Neck Mag PU volume Up to "10". Due to traditional Gibson Les Paul Wiring, and with the PU toggle switch in the middle position = both Mag PUs , if either Mag PU Volume control is on "0", you will not hear any sound.

 

8) Slowly rotate the Bridge Mag PU volume Up to "10" - and note if there are certain ranges of the Bridge PU volume pot where perceived audio signal level is lowered due to phase cancellation.

If the Bridge PU is in phase with the Neck PU, at a Bridge PU Volume Pot setting of "10" you should have a good full frequency response signal.

 

Report your results.

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Elantric,

 

Thank you sooo much for this info! The earlier discussion was waaay over my head, but you've just provided absolutely clear test instructions; I'm all over it. I'll report back. You have a tremendous wealth of technical knowledge, hard-earned, I'm sure; thank you for sharing!!!

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Hey, Steve! Good stuff!

Here are my results:

Step 2 - Good

Step 3 - Good

Step 4 - once volume for Bridge PU reaches about 50% the volume drops about 30%. Problem?

Step 5 - Same as in Step 4, but I hear distinct lows coming on. Normal / Problem?

Step 6 - Good

Step 7 - Good

Step 8 - Interesting...With toggle in the middle, piezo off - neither Bridge nor Neck volume increase produces any sound when turned up one by one. It only starts making sound if Bridge volume is more then zero and then Neck volume is increased from zero up. It is definitely blending both Bridge and Neck at that point, because if I move the toggle off fcenter either way - the sound changes as it should... Weird how Bridge volume does nothing by itself.

Problem?

 

Thanks!

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Step 4 - once volume for Bridge PU reaches about 50% the volume drops about 30%. Problem?

 

Not necessarily -

 

Question? With the Bridge PU Volume on "10" - do you have a full sound? Or does the signal level continue to degrade, and sound "squawky" with Bridge PU Volume on "10" ?

 

Out of PHASE = Squawky, low volume.

 

In Phase = full fidelity, and decent volume level.

 

 

RE: STEP 8

If this is your first Gibson, you may be very confused how the controls react with both Mag Pickups selected - it can be confusing - most newbies will swear that "things aren't right". If Either Neck or Bridge Volume control is at zero with both Mag Pickups selected- you get no sound. This is normal!

 

 

 

Easiest test for the Mag PU's both being in phase is:

 

* Disable the Piezo PU - easy to do, lift the MCK "OUT" - rotate to "D" or "G" or A" - any one of those will work. Push the MCK all the way "IN" . Verify no LEDs are lit on the MCK display.

 

* Rotate all 4 knobs to "10" - (Neck Vol, Bridge Vol, Neck Tone, Bridge Tone (MCK))

 

* Use the PU Selector Switch - move it to "Neck PU , and play - note the volume level.

* Use the PU Selector Switch - move it to "Bridge PU , and play - note the volume level.

* Use the PU Selector Switch - move it to Middle position = "Neck + Bridge mag PU , and play - If the volume level drops significantly in level here and you detect "squawk" , then the Mag PUs are out of phase.

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In step 4 as I wind up the bridge pu knob, the overall volume decreases until the bridge pu knob reaches 8 to 9 but quality is not lost.

 

In Step 5 as I do the same with neck pu the volume drop is maxed at around 5 and then as I keep winding it all the way to 10 volume is returned gradually to the normal level. Again no sound quality issue that I can detect.

 

Am I ok or just plain mad? Thanks for the diagnosis!

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RE: STEP 8

If this is your first Gibson' date=' you may be very confused how the controls react with both Mag Pickups selected - it can be confusing - most newbies will swear that "things aren't right". If Either Neck or Bridge Volume control is at zero with both Mag Pickups selected- you get no sound. This is normal!

 

[/quote']

 

Sorry for my earlier post. Had not read your question carefully. Elantric's statement above outlines the behavior very well.

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Sorry, but just to reconfirm - with toggle in the middle, Neck PU volume at zero, shouldn't increasing the volume on Bridge only produce a sound?

 

No , you will not get any sound.

 

With PU toggle SW in the middle - if either mag PU Volume control is on "0" , then no sound is possible.

 

So - with Both Mag PUs ON (MAg Pickup Switch in the Middle):

 

and

 

Bridge PU Volume on "0", Neck PU Volume on "10" = No Sound

 

also

 

Bridge PU Volume on "10", Neck PU Volume on "0" = No Sound

 

 

If you want to mix Mag PUs - start with both MAg PU Volume controls on "5" - adjust to taste.

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In step 4 as I wind up the bridge pu knob' date=' the overall volume decreases until the bridge pu knob reaches 8 to 9 but quality is not lost.

 

In Step 5 as I do the same with neck pu the volume drop is maxed at around 5 and then as I keep winding it all the way to 10 volume is returned gradually to the normal level. Again no sound quality issue that I can detect.

 

Am I ok or just plain mad? Thanks for the diagnosis![/quote']

 

Elantric, any thoughts about this condition? Thanks!

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Sounds OK

 

When mixing standard Mag PUs and Piezo bridge PU, There will be observed signal level drop off when the Mag PU volume control is at "5" - "7".

 

Just be certain that with Mag PU Volume on "10", and Piezo Blend full up, that you have a full signal, with full frequency response.

 

 

In actual playing situations, I prefer to blend the piezo with the Neck PU - sounds nice to my ears, for clean jazzy stuff.

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