Hobner Strato

[ plain ]

On 4th of March, 2018, I inherited this guitar from my father.  The
Hobner Strato with an HSS pickup configuration and 4 switches and two
volume knobs to dial in the perfect tone, is truly the most iconic
guitar I've ever played with the most unique tone I've ever heard.  Not
because the pickups are the best pickups in the whole world, but
because it's the one guitar I've spent most of the time playing as my
first guitar.

The humbucking (bridge) pickup hums more than the two single coil (neck
and middle) pickups, but it definitely has a much graver and heavier
tone than the other two pickups.  The middle pickup is probably in its
best shape since it is loud and crisp.  However it fails to give that
recognizable stratty tone which the neck pickup is able to deliver
which is very quiet, probably because it hangs in place by a single
strand of copper.  I tried adjusting the height of the pickup to the
point where I was practically muting the 22nd fret of the strings but
it didn't become any louder or sharper.  Probably it's time for her to
see a luthier.

The most ridiculous and frustrating thing was figuring out what the 4
pickup selection switches do which for the most part was unknown to us.
I'm not sure if a manual came with her, since if it wasn't in the box
then it's probably lost forever.  The internet seemed to never have met
such a configuration of pickup switches before.

So one day, I screwed off her back cover and tried to make a diagram of
the circuit.  If you were to hold the guitar in a playing position,
you'll find the following arrangement of volume knobs and toggle
Both of the above are volume knobs.  SHE DOESN'T HAVE A TONE KNOB.  Let
us consider the down position of the toggle switch as '1' and the up
position as '0'.  Let us also name the switches in certain way:

    NS      BS      NM      BB

The meaning of the above are as follows:

    NS - Neck / Middle Selector
    BS - Bridge Left / Right Selector
    NM - Neck / Middle Select [0] or series [1]
    BB - Bridge Select [0] or series [1]

Let's try to understand what the different switches do, when BB = 0,
both the coils of the bridge humbucker gets wired in series.  Thus it
is in a state where it can ``buck the hum''.  If BB = 1, the BS switch
is responsible for selecting whether the signal from the left XOR the
right coil of the humbucker is to be taken to the signal output.

As you might have guessed from the similarity of the above switch
description that the Neck and the Middle pickups are also wired as if
they are the two coils of a single humbucker.  When NM = 0, the pickups
are in series and when (NM, NS) = (1, 0), the middle pickup is selected
and when (NM, NS) = (1, 1), the Neck pickup is selected.

It is a good idea to put this in a truth table to look like we're
discussing digital logic circuits.  This is for the bridge pickup:

        BB      BS      |   FUNCTION
        0       X       |   Bridge humbucker in series.
        1       0       |   Right coil of bridge humbucker.
        1       1       |   Left coil of bridge humbucker.

And for the Neck / Middle pickups:

        BB      BS      |   FUNCTION
        0       X       |   Neck and Middle pickups in series.
        1       0       |   Middle pickup.
        1       1       |   Neck pickup.

The 'X' means don't care and flipping that switch between 1 and 0 only
changes the direction of the signal flowing through it and nothing

Now consider the above two as two independent pickup banks.  The bridge
pickup configuration doesn't affect the configuration of the neck and
middle pickups and vice versa.  Each bank has its own volume knob.  The
knob towards the bridge is for the bridge pickup and the other one is
for the neck and the middle pickups.  This allows you to blend together
two different tones (one from the bridge pickup and the other from the
neck and middle pickups combined) in any proportion you desire.  This
alone is a major advantage in using this kind of a circuit and I only
realized it after I drew out the circuit.  (I'll attach a picture here
later if I find it someday.)

I mostly prefer leaving the guitar alone in the following
configuration since I think the neck and the bridge pickups are

    Rhythm or Lead,
    Distorted or clean,
    The following makes her sing.

        NS=0        BS=X        NM=1        BB=1

    Neck / Middle Pot   = 0
    Bridge Pot          = max.

The above selects one of the bridge pickup only.  If you were to
gradually dial the NM Pot towards max, you get a much fuller tone.
While I chug or play a heavily distorted riff, I don't really like the
sound of the middle pickup + the bridge pickup.  Hence I tend to stick
with the bridge pickup only (not in the humbucking position).

All the toggle switches are ``Break Before Make'' type switches and
hence it is possible to switch of a bank by putting either NS or BS in
the absolutely unstable middle position.

And now as long as this document exists, we have a written manual of
the absurd, weird but interesting pickup selection circuit of the
Hobner Strato HSS.

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