Alumitone string balance issue.

[jtmuk]

Hi guys,

I recently installed some alumitone pickups and really like their tone and the ‘split’ sound that sounds close to single coils.
However I’m having an issue with string balance where the high E string sounds a lot weaker and duller than the rest.
If I raise the treble side as close as possible ( nearly touching ) then it’s better but still not 100% right.

The pickups are centred and the string firmly over the magnet so it’s not really clear why this would happen.
I’ve never had this issue with other pickups so I’m assuming it’s something with this particular design - I’m wondering if anyone has any insight ?

[ms]

Is it really the string volume that is less, or is it just lack of high frequencies, which affects the highest string the most?  Lace avoids the issue of the spectrum of the pickup by saying that it has more bass and more mids, which is a way of saying that it has relatively less highs.

You need to look at anything Lace writes with caution.  This is his basic "sell":
"This radical departure from pickup design is aluminum based, rather than copper. Result: less resistance, higher output coupled to a "current driven design" as opposed to conventional voltage based pickups.

The aluminum water jet cut exoskeleton is then matted to a micro winding using 90% less fine copper wire, a low impedance/high impedance pickup is then created."

Pure nonsense, right?  Aluminum has a higher resistivity than copper.  If he made that single turn coil out of copper, the pickup would have less AC resistance, not more.  "Current driven design" has no meaning in this context.  The coil has a very low output voltage because it has only one turn.  The voltage is raised with a transformer to be similar in performance to a regular high impedance pickup.  Whatever "voltage based" means, it is just like a conventional pickup in this sense.  That is, they all work because of Faraday's law of magnetic induction.

I believe that the resistance he gives is just the resistance of the transformer.  You need to add to this (for what counts, the total AC resistance) the resistance of the coil multiplied up by the square of the turns ratio.  If the transformer has 5000 turns (it could be more),  then the ratio is 25 million. So that very low resistance coil in effect is not so low.

[jtmuk]

Thanks for the reply ! I agree his writing is nonsense, though in practice the resistance is still lower than most other pickups including filtertrons.
Good point regarding the filtering, the pickups indeed could do with more highs, but the high E is still far below the cutoff frequency of the pickups.
It seems to be more an issue with the relative mass of the string compared to the others. 
Edit: either that or the magnetic field doesn't extend far enough but that would seem weird given that the magnet extends past the string by at least 1.5mm

[ms]

Nov 16, 2020 2:33:53 GMT -5 jtmuk said:

Thanks for the reply ! I agree his writing is nonsense, though in practice the resistance is still lower than most other pickups including filtertrons.
Good point regarding the filtering, the pickups indeed could do with more highs, but the high E is still far below the cutoff frequency of the pickups.
It seems to be more an issue with the relative mass of the string compared to the others. 
Edit: either that or the magnetic field doesn't extend far enough but that would seem weird given that the magnet extends past the string by at least 1.5mm

Perceived volume is to some extent a function of harmonic content.  Have you measured relative string volumes (with careful  picking), and compared to measurements made with your previous pickup?  Harmonics that are low in actual power can have a significant impact on the perceived level because the ear-brain combination is very sensitive in the 2-3 KHz, or so, range.

Pickup resistance is an easy measurement, but difficult to interpret.  For example, a typical humbucker has high enough eddy current losses to make a significant difference in the tone near the resonance, which has a big impact on the sound.  In the Lace AT you have some eddy losses, presumably, and the transformed up effect of the "coil" resistance.  It would take careful measurements to separate out these effects.

Edit: Antigua did his standard measurements and one conclusion was that when loaded as typical, they do not have much of a resonance peak, and thus they have quite a bit of loss.  It seems to me that the loss is much higher than you would expect from the dc resistance alone.

guitarnuts2.proboards.com/thread/7821/lace-alumitone-analysis-review

[jtmuk]

All good points, thanks !
That being said if you compare the measurements to say the chopper here:

guitarnuts2.proboards.com/thread/8502/dimarzio-chopper-analysis-review

than you can see the loaded alumitone still has a higher cutoff. I've used the chopper and it didn't have this issue at all.
Admittedly the alumitone test was for a single coil version, it's possible the humbucker size measures differently but I doubt it would be drastic enough to explain the problem.

[ms]

Nov 16, 2020 13:45:53 GMT -5 jtmuk said:

All good points, thanks !
That being said if you compare the measurements to say the chopper here:

guitarnuts2.proboards.com/thread/8502/dimarzio-chopper-analysis-review

than you can see the loaded alumitone still has a higher cutoff. I've used the chopper and it didn't have this issue at all.
Admittedly the alumitone test was for a single coil version, it's possible the humbucker size measures differently but I doubt it would be drastic enough to explain the problem.

Then this is a mystery!  I would check the magnetic field along its length with a meter.  Also measure the output from a tiny driver coil along the pickup (which should be the same even if the magnet varies).  Somehow, I do not expect that this will  be easy to find.

[jtmuk]

Good idea. I don't have a meter for this but have been thinking about getting one.