From: META000 <META@UNB.CA>
Subject: RE: Ibanez pickups hum
Organization: The University of New Brunswick
Date: Sat, 26 Sep 1992 22:25:19 GMT

In article <1992Sep25.212442.25912@verdix.com> bill@verdix.com (William Spencer) writes:
>I recently bought an Ibanez RG-550. The excellent satin finish, maple
>fingerboard neck sold me on it. But I have one serious complaint: the
>humbucking pickups are not completely humbucking.
>
>Compared with the humbucker on a Fender Squier Bullet (which costs 1/3 as
>much), hum is appox. 3 times as loud. Furthermore, it includes a definite
>60 Hz fundamental component, indicating unbalanced construction. Compared,
>using measuring instruments, to the single-coil, hum is about 1/10th that of
>the single-coil. This indicates a 10% unbalance between the two coils, if I
>understand correctly.
>
>The guitar uses Ibanez "V1" and "V2" pickups plus an "S1" single coil. Hum
>is similar for both of the humbuckers, despite the fact
>that they are somewhat different
>from each other. Another guitar I tried in the store also hummed. I believe
>the inbalance is due not to different windings on the two coils, but due to
>the use of screws in one coil and slugs in the other. There may be also a
>problem due to the way the screws stick out of the bottom of the pickup
>(Don, anyone, care to comment?).
>
>The hum was not particularly bothersome when trying out the guitar at low
>volume at the store -- I wasn't sure if it was due to imperfection or higher
>gain than the guitar I was comparing it with. As I see it, the guitar is not
>broken and there lies my problem with repair. It is merely poorely designed.
>This is all the more surprising when you consider what they did right. Control
>cavities are shielded. Combinations using the single-coil middle pickup
>use one coil of either the bridge or neck pickup to result in partially
>hum cancelling operation  and single-coil sound
>(the bridge-middle combination is as quiet as the
>bridge pickup alone, despite the difficulty involved in matching). This latter
>feature will not work as well if I start replacing pickups. I will probably
>replace one or more pickups -- probably will sound better anyway.
>I was initially tempted to return the guitar
>when I discovered the problem, but after making the decision to get it it was
>hard to turn back.
>
>I have complained to Ibanez customer service both through the store and
>directly. They ask that I send it in to be checked out. I do not want to
>go without the guitar and doubt they would fix anything. I told them to try
>another guitar with the same pickups.
>
>I seem to recall a post or two about hum troubles -- same guitar maybe?
>(I probably dismissed it as "normal" hum.)
>Would like to hear from other Ibanez owners.
>
>Bill s
>bill@verdix.com
>Not the opinion of my employer.
>----------------------
>Please reply by email or cc: me if you follow up as I may temporarily lose news
>access very soon.
>.
>.
In the early 80's, Jeff "Skunk" Baxter used to write a column for
Guitar Player.  In one issue he explained how to improve the noise
and hum on humbuckers.

First, the theory.  Hum"buckers" provide a virtually hum-free sound
by providing two "antenna's" for 60-cycle hum and RF, which are
electrically opposite to each other.  When the hum and RF picked up
by one coil are combined with the hum and RF picked up by the other,
the two cancel each other out.  Fortunately, for us, the sounds
picked up from the strings themselves don't cancel out entirely, and
the result is a hum-free, meaty sound.

In order to be able to accomplish this, the two coils have to act as
equivalent "antenna's".  This means that the magnetic field in each
coil should be equivalent, and the coils themselves should also be
of equivalent impedance.

Althoughthe technology for producing pickup coils is pretty damn
good, there are sufficient differences that occasionally crop up,
such that the two coils in one "humbucker" are not matched enough to
buck the hum completely.  It's my understanding that the factory
folks often take coils off the line and sort them into bins with
specific impedance ranges.  Any two coils from the same bin will be
much more alike in impedance than two coils from separate bins.

Fine.  IF it happens that somebody ain't doing their job right, you
can end up with a pickup where the impedance of one coil is a bit
different from the other.  We're talking a few per cent here, but
not much more.  Let's give the folks who work for Larry and Seymour
a bit of credit!

If you are delicate and graceful with a soldering iron, you can
improve the tone and noise/hum of your humbucker in the following
manner:

1) Remove the pickup entirely from the guitar (sorry).

2) Detach all relevant leads so that you have exposed two contacts
for each pickup coil.

3) Get hold of a 4 1/2 digit ohm-meter (3 1/2 may not be precise
enough), and measure the electrical resistance of each coil.

4) If they are within 1% of each other (e.g., one coil is 5000 ohms,
and the other is 5050 ohms), then any annoyingly loud hum may not be
coming from your pickups (although there are exceptions to this).

5) If they are more than, say 0.5% different, take the coil with the
greater resistance, and GENTLY! lift the wire at the end of the coil
(i.e., on the outside) and unwind it approximately ONCE for each
ohm, until you have reduced the coil resistance by thedifference
between the two coils (e.g., if you needed to reduce the 5050-ohm
coil in the above example, take off about 46 turns) scrape the
insulation off at the appropriate part and measure the new
resistance.  When the two pickups are within 0.1% of each other,
you'll have done about the best that can conceivably be done.  I did
this with a home- brew "stacked humbucker" I made, and I can
practically stick this thing on the damn power transformer, and not
hear any hum.  We're talking VERY quiet.

6) Once the two coilsmatch, put the pickup back together, making
sure that the appropriate phase relationship between the two coils
is restored to its original state.  If the two coils are
electrically in phase, no hum-rejection will occur.

This is obviously delicate work, and time-consuming.  It is also one
of the reasons why pickupsof any quality cost big bucks.

Jeff Baxter was quite laudatory of this procedure, as am I.  We both
stress the delicate nature of this.  Pickup coils are easy destroy,
if you don't know what you are doing, so be careful.

Mark Hammer (aka META)

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