P90 single mag / narrowfield mod

[eclecticsynergy]

Has anybody here tried running a P90 with just one mag?

Last week I found this article whose author describes the result as sounding somewhat Gretsch-like.

http://www.award-session.com/pdfs/P90 Hidden Talents.pdf

Have been thinking about giving it a shot, maybe on a neck pickup first.

Would like to hear from anyone who's done this. I'm curious to learn how satisfying the result was, also how much output was lost in exchange for the tighter tone. And whether perhaps using an A8 could make some of that up, or if it might make the tone so fat that it'd pretty much defeat the purpose of the mod.

Reviews? Comments?

 

[freefrog]

Re: P90 single mag / narrowfield mod

Hello,

I've done a quick test...

Pickup involved: a home brew P90 with a modern poly insulated coil but also with vintage correct magnetic circuit: proper baseplate, keeper bar and poles pieces. Rough cast long A4 AlNiCo bars.

DCR: 9k. Inductance @200hz: 7.4H.

Once one of the mag has been pulled off, the inductance drops to 7.2H.

Ain't got the time to measure Gauss levels: I've not our lab teslameter here.

Guitar used: my test bed partcaster, basswood body, Kahler bridge, with a hole through the body allowing to swap the bridge pickup... 500k controls. Plugged direct to the board.

I've tried the pickup with its two mags (spectrum in red) then with a single mag, towards the neck and towards the bridge (spectrum in blue, two times). Frequency charts below.



FWIW.

 

[VinceT]

Re: P90 single mag / narrowfield mod

Hey, freefrog - interesting stuff. If you don't mind, could you describe how you play the guitar for the two tests - i.e. "Single notes along all strings & frets", "chords, unfretted strings > 12 fret" - to arrive at a single image - I'd like to replicate for a couple of amps so that I can see what's happening in the EQ curve.

As an aside, I recently fitted some Nuevo-90 P90s by Railhammer into one of my guitars, and to my ears they achieve similar to this mod (tightening the bass, etc.)


Sent from my iPad using Tapatalk

 

[freefrog]

Re: P90 single mag / narrowfield mod

Hey, freefrog - interesting stuff. If you don't mind, could you describe how you play the guitar for the two tests - i.e. "Single notes along all strings & frets", "chords, unfretted strings > 12 fret" - to arrive at a single image - I'd like to replicate for a couple of amps so that I can see what's happening in the EQ curve.

As an aside, I recently fitted some Nuevo-90 P90s by Railhammer into one of my guitars, and to my ears they achieve similar to this mod (tightening the bass, etc.)


Sent from my iPad using Tapatalk

Hello,

Single notes and chords are just that: I play separately all the single notes available on the fretboard... Then I fret the six strings altogether and my index slides from unfretted strings to 12th fret. I try to pluck the strings in the same way each time.

I record these sounds in short Ableton tracks, played directly through a 1M input.

Then, I use the "SPAN" linked to a VST plugin named "Voxengo" and set it on "inf" (infinite) in such a way that any peak produced in the soundtrack stays printed on the screen. These frequency peaks stack upon each others and it finally gives a fixed curve.

If you want to test the frequency response of an amp, don't hesitate to try one of the freewares found on the Net (like this one:http://audio.rightmark.org/products/rmaa.shtml) : several of them produce polyphonic and monophonic signals, able to feed an amp and to be recorded in return, in order to produce a spectrum analysis... I often do that and for me, it's an essential part of the process when I modify an amp or a stompbox.

 

[eclecticsynergy]

Re: P90 single mag / narrowfield mod

Freefrog- Interesting that the inductance only dropped by so small a bit; was there a pretty significant loss in volume? I see some interesting peaks in the bridge-mag-only single note trace, especially considered in relation to the lower overall level. Would you say it was much brighter overall, or do the peaks just reflect a brighter, snappier attack? How did the modded pickup sound and feel to you?

VinceT- I like the Railhammer humbuckers; have a couple of them. The rail makes a real difference on the low strings. The Chisel bridge is one of the few ceramic pickups that I've ever really been able to bond with. Had thought about trying their P90 models when they were Gnarly90s. Am interested in the new dual-half-coil design that makes them noise cancelling. Would you say they still have characteristic P90 growl & bark and singlecoily highs, just with tightened lows? Or do you feel the mids and highs are different too?

 

[freefrog]

Re: P90 single mag / narrowfield mod

Freefrog- Interesting that the inductance only dropped by so small a bit; was there a pretty significant loss in volume? I see some interesting peaks in the bridge-mag-only single note trace, especially considered in relation to the lower overall level. Would you say it was much brighter overall, or do the peaks just reflect a brighter, snappier attack? How did the modded pickup sound and feel to you?

I've also been surprised to see the inductance almost unchanged.

The loss of volume was comparable to the difference between typical humbuckers and single coils. It affected the fundamentals more than the harmonics, making the sound brighter, as you said: I've not the feeling that this brightness was due only to a snappier attack but remember that I was not plugged in a guitar amp...

That said, I can share another testimonial with you: I've played once a guitar with an "experimental" mid pickup, that I had made with a single coil over a single alnico bar mag, itself perpendicular to six steel pole pieces (and without baseplate). It sounded like a fat Strat pickup, with more of a bell-like tone...But it squealed terribly under high gain.

 

[eclecticsynergy]

Re: P90 single mag / narrowfield mod

I've played once a guitar with an "experimental" mid pickup, that I had made with a single coil over a single alnico bar mag, itself perpendicular to six steel pole pieces (and without baseplate). It sounded like a fat Strat pickup, with more of a bell-like tone...But it squealed terribly under high gain.

I know some Squiers and inexpensive Strat copies have single coils which look like Strat pickups but actually use nonmagnetic slugs with a powerful ceramic bar magnet underneath. I think this was originally conceived as a cost-cutting measure. But there have been posts from people who like the tone of these cheap pickups a lot. Their feedback resistance at volume is another question; I'm not sure how they perform at volume.

 

[freefrog]

Re: P90 single mag / narrowfield mod

I know some Squiers and inexpensive Strat copies have single coils which look like Strat pickups but actually use nonmagnetic slugs with a powerful ceramic bar magnet underneath. I think this was originally conceived as a cost-cutting measure.

Yes, I've still a bunch of these things here. Some have a single mag, others feature a dual magnet "sandwich" with steel slugs in between. When it's possible, I unglue their ceramic mag(s) and use their coils for something else (as dummy coils, most of the time).

That said, my "experimental" mid PU was based on a rough cast alnico bar and the result was slightly different.

But there have been posts from people who like the tone of these cheap pickups a lot

Yes; some of them sound pretty good. There's even boutique PU's whose design relies on this principle. Example: http://www.skguitar.com/SKGS/sk/Images/pickups/T-90.jpg

 

[eclecticsynergy]

Re: P90 single mag / narrowfield mod

Hadn't realized that the P90 Strat/Tele types fell into the same general category; I'd sort of considered them a different animal because of the adjustable poles and dual mags. One if my partscasters has VintageVibe SP-90s and I like 'em. Pete Biltoft makes good pickups; the PAF types I have of his are nice too, and he makes a humbucker set that uses dual SP-90 coils which looks interesting- probably too hot for my taste right now though. I've heard very good things about the Harmonic Design Super 90s also.

I have a $25 set of Dragonfire singlecoils sitting around somewhere, with oversize slugs and a ceramic bar underneath. I've sometimes wondered whether it'd be worth trying to remove the ceramics and give them A5 or A8 bars. Felt they probably wouldn't be worth the effort but now I wonder. They could become dummy coils at least if it doesn't work out, that's a good idea.