Variax Conversion (W/ GK13 Pin Output)

Started by Elantric, May 09, 2008, 11:46:40 AM

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Elantric

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<Dave on the VG-8 Yahoo mail list wrote>

I recently got my Variax conversion guitar to the point where it's playable
and figured I would share some pics: http://www.sendspace.com/file/1jtdmc

As you will see from the photo's there is still some work to be done. Before
I even got started a friend offered to paint the guitar when it's done so I
didn't worry much about the original finish as I did the wood work. I still
have to fill the hole left over from the originals tone knob location. I
also have a lot of cleanup work to do in the areas where I routed. Right now
the general idea is to use the guitar some and sort out all of the details
before I hand it off to be painted.

Some notes on the guitar:

I used a Variax 300 for the donor. I did not use the electronics cage since
I wanted to keep the original pickups. I also didn't want to add a pickguard
which seems to be used in most Variax 300 conversions to cover the large
route the electronics cage dictates.

I used aluminum for the back plates so that they can be painted along with
the body to make the back look a little better. They also provide shielding
and on the control cavity cover provide support for the DIN-13 Roland GK HEX
style output connector.

My DSP board is much further away from the Volume/Tone/ Model PCB than it is
on a stock Variax 300 so I had to remove the stock ribbon cable connecting
the two and use a different setup. This worked out well since it gave me the
freedom to change around the locations of other things like the VDI
connector which is not shown but will go right next to the DSP board. I will
have to remove the DSP cover to get to the VDI connector but I don't expect
to use workbench all that often.

The GK up and down buttons are located in the trim ring for the neck
humbucker right below the pickup. I use a volume pedal to adjust GK volume
so I did not include a synth volume pot. I do not need a Guitar
Only/Guitar+ Synth/Synth Only switch so I did not include one.

For my hex output I tapped into the piezo signals at the point after they
are buffered by the Variax electronics and fed into the AtoD converters. The
upside of this approach is that I didn't have to do any additional (active)
buffering of the signals. I only had to add a 100 Ohm resistor to each
signal before
being fed to the 13 pin din connector. The downside to this approach is that
the signals going into the AtoD's have a 2.5V offset since the Variax
converters are not using a bipolar supply.

This setup forces some conditions to be met:

1) You must connect the Variax supply ground to the Hex device ground at
some point.

2) The input circuit of the Hex device must have some form of DC blocking to
get rid of the 2.5V offset so that the circuitry can work properly (and to
prevent damage).

The input circuitry on the GR-30 and GI-10 I use both use bipolar
electrolytic capacitors that keep condition 2 from being a problem. I have
no idea if similar circuitry is found on other devices but I would be
inclined to think that most of the Roland gear would use a similar
arrangement.

I arranged things to keep the unbuffered piezo signals between the saddles
and DSP board as short as possible.

The stock pickups are not wired yet, for now all of the wires are stuffed
into a piece of heat shrink tubing to prevent them from damaging anything. I
will eventually wire them to the 5 way switch. The real pickups will only be
used as an emergency backup so I will probably wire them to a connector
inside the control cavity that can be connected to the output jack if the
Variax electronics ever go down. They won't have a volume control but that
was an acceptable trade-off for me over adding another pot to the guitar.

I moved the volume and tone pots to the opposite side of the
Volume\Tone\ Select board so that they would operate left handed. I was not
able to figure out a decent method to mount the selector control so I
replaced that with a 12 position rotary switch and appropriate resistors.
Since I use workbench to do editing I also eliminated the push to store
function of the select knob. Since I was free to arrange resistors in any
order I wanted I took the opportunity to re-order the models in the order
that made the most sense to me. I know the same result can be achieved with
Workbench but I liked the idea of doing it in hardware. Since the

Eventually the guitar will also have a graphite Steinberger/ Moses neck. I
have the neck but I have to remove the existing inserts and fill the holes
before I can drill it for inserts that match the holes on the spirit body. I
also have to add the side dots since it was originally a right handed neck.

Thanks,
Dave

Elantric


abhijitnath

I know this is ancient, but do you happen to know where he got the piezo saddles from? I know of only one source- Jon Bondy. Perhaps there are others?

admin

#3
These appear to be L.R Baggs Piezo saddles on the Steinberger - perhaps modified Variax 300/600 Piezo Saddles

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abhijitnath

Oh, that's excellent. I won't have to spend more money on saddles when I do my transplant then- I can use my 500 saddles.
Thanks a ton.

abhijitnath

Does anyone have a clue as to how the saddles were hacked? Are they the existing Steiny saddles machined out to include the LR Baggs ones?

Elantric


vtgearhead


admin

#8



Its the ultra rare RMC VAR-01

It connects to old Variax bridge Piezo ribbon cable and provides active  buffererd dual outputs

Handy for adding an internal  GK-KIT- GT3 or RMC Polydrive I GK  Interface to Variax

HAMERMAN409

Quote from: abhijitnath on October 04, 2013, 12:26:23 AM
Does anyone have a clue as to how the saddles were hacked? Are they the existing Steiny saddles machined out to include the LR Baggs ones?
I am no machinist but I did have access to a machine shop at the time so if I recall correctly I did the following:

For each saddle:
Started with the Steinberger saddle.
Removed the round silver colored string contact section from middle of the Steinberger saddle.
Milled two thirds of one side of the Steinberger saddle flat.
Drilled and tapped a hole in the stock Steinberger saddle.
Drilled a hole in the center of the Steinberger saddle (clearance hole for the piezo wire to pass through)
Took the Line6 Saddle and cut off the back section
Drilled a hole in the Line6 saddles to allow access to the Steinberger height adjustment set screw.
Then using one of the height adjustment screws on the Line6 saddle screwed it down into the Steinberger saddle, holding the two together.

It sounds kludgy and is kludgy but it works and the final product worked pretty well. Besides the fact that the final saddles look a little funny I also had to do a good job of smoothing the areas on the line6 saddles where I made the cut to keep them from being a cut hazard.

A far cleaner approach would be to start with the one piece Steinberger saddles (that do not have the round insert) and just have the appropriate slot milled in them. I just did what I could with what I had. :-)

I have some pictures of the saddles I can share that might do a better job of showing what I said above if you want to PM me.

Thanks,
Dave