How I modified my Aria Pro 2 Elite 2 (late model) to include a varitone filter.

Introduction.
Over the past year I have collected a number of Aria Pro2 bass guitars including 2 SB2 Elite 2 models and an SB-1000 with active varitone.
The 2 Elite's are different models, a white one made in the Matsumoku factory in Japan. The other a padauk red grain. This is one of my favorites. It has a fast action neck and is easy to play. The padauk is a later model around 1988 or 1989 I think and was probably made either at another factory in Japan . The workmanship is the same quality as the earlier white Elite2 but the tone controls were simplified to Vol Neck,Vol Bridge and Tone. The earlier one has a separate tone for each pickup.

At first I thought about making giving the red one the same electrics as the white one. However, dual concentric, dual ganged miniature guitar pots with a long enough neck to fit through the body proved quite hard to find at first. I played my white Elite a bit more and pretty well convinced myself that there wasn't much overall effect from the passive tone controls. They are just treble cut. What I really wanted was a true filter such as in the SB-1000 giving several different tones rather than the treble roll-off with a normal passive tone control. Another requirement of this project was that I did not want to drill any more holes or modify the bass beyond the ability to return it to its original condition.

After researching passive tone filters I learned that the inclusion of an inductor is necessary to make a notch filter effect. Just a capacitor and a resistor or potentiometer are just treble cut devices with a coil of the right inductance other frequencies can be kept while the frequency band of the notch is attenuated. I didn't want to make this an active affair with a pre-amp and active controls because for me that would change the nature of the guitar. What I wanted to do was to give the SB Elite2 a similar sound pallet to the SB-1000. I think I was relatively successful and although the project is still open to modifying some capacitor values, I'm pretty happy with it the way it is. The birth of a new Aria Pro model. SB-2000 Elite ;-)

After researching the original SB-1000 capacitor values I went to work making a test rig outside the bass. One of my most useful tools is the Vox Amplug headphone amps. I have 2 now one is the bass model and has a clean channel. Its great for testing these kind of experiments as well as my main practice amp at home. The audio files at the end of this project were recorded through the Amplug into the audio in of my PC. There was a good deal of latency from playing to hearing myself in the headphones.
Anyway the tests were based on part of the bass line in Duran Duran's "Save a Prayer". John Taylor typically used Aria Pro SB-1000 basses during the era of the song giving that flat "nasally"sound that is so typical of their songs from that era.  I make no excuses for my poor playing. I started bass again last year at the age of 53 after playing nothing for more than 30 years. I can actually play this track better than this. Its one of the songs I rehearse with my band. I didn't want the recording process to be about how well I could perfect the line, the recordings are to give examples of some of the tone combinations available after the mods. Using the volume controls and the coil switches can give even more variation.

I live in Tokyo, Japan and a couple of trips to Akihabara (The electrical town) and to Ochanomizu (The music shop town) were necessary over several weekends. I try and make shopping lists and always forget things. The most difficult thing to find was a coil or choke. Research showed that for a bass guitar the inductance needed to be ideally around 1.5 Henry. (Henry is the measurement of inductance). This is quite a large value to have in a small package. After discussing the problem with a colleague who is a telephone engineer in my company we found that a small audio transformer about 1cm cubed had a primary wiring on 1.45 Henry, ideal for this project. After spending a very hot afternoon wandering around the old electronic stalls I finally found a transformer specialist. After giving him the part number he went of to rummage for a while and came back with the part. Well worth 450 yen.

The first thing I did the first afternoon was to gut the innards of the SB Elite, taking care not to damage the wood or finish. I had always found this bass one of the most sensitive to pick up ambient noise and interference. So the first job was to fill the empty cavity with copper tape. This tape is only just over an inch wide and so therefore I layered the tape to fill the bottom and sides with a little to overlap the top. Since the self adhesive glue on this tape is conductive the whole cavity becomes one piece of circuit so long as you overlap say 1/8 of an inch when laying the next strip. I tested point to point with an ohm meter and there was zero ohms across all points in the cavity.
The advantage of this copper tape is that it is easy to solder to, and you can pick up an earthing point from anywhere. Many people favor star point earthing, taking every earth connector back to the same point. This works for me. My SB-2000 Elite is the quietest passive bass I have. I can play it with the florescent lights on and in front of my computer monitor and its dead quiet. You may notice some hiss or background noise in the recording, I am pretty sure this is not from the guitar but the Jerry rigged set-up I used to record. The recording software I used was Audacity.
Splendid, time for a beer!

Start of the project.

This is how it was before I started.
This is how the Elite looked at the start. I love the Paddak wood colour but on mine its a little too deep red, however I love the grain.


The reverse side. It is overall good condition for its age which I am guessing around 22 - 23 years. A couple of minor "dings" and that's about it.

Inside the control cavity before starting any work.

This is what the emptied cavity looks like. The brown wires are the multicore pickup cables.
This is the inside of the control cavity before laying the copper screening tape. Notice a very marginal attempt at the factory to use tape
to link the earth side of some of the controls together. Why didn't they at least do them all?

AfterCopperTape
This is after laying the tape. I wasn't too fussy or precise over this so long as there was sufficient overlap and there was conductivity
from any point to any point which I checked with an ohm meter. The black wires you can see are the earths or the two pickups and the
the bridge. My next move was to bare the ends and solder them to the copper tape making a good connection.

MatsumokuElite2
By comparison,you can see the neater, cleaner work in the cavity of my white Matsumoku built Elite2. Notice in particular the better
cleaner solder joints. A good solder joint should be shiny. If its matt, then its most probably a "dry"joint and is going to cause a problem
as some stage in the future. Soldering is an art. The rotary switch you can see here is not a varitone its merely a 3 way pickup selector.
<Neck,Both,Bridge>

ExternalTests
Here you can see part of the construction outside the guitar. This was my original idea to copy the Matsumoku Elite with dual concentric
dual ganged potentiometers. These were regualr electronics types and would not fit inside the guitar but were sufficient for testing. In the
background you can see the wiring diagram for the Elite 2 available on the web.

Halfin-Halfout
This next stage was "Proof of Concept" (POC), also could be piece of crap! The rotary switch in the picture is only a 4 way so I could
only test 3 filter capacitors. Notice the little green thing with metal edges, this is the audio transformer that is providing the function of
our inductor just using the primary winding. I played around with it now. I wasn't particularly careful about the solder joints and I did
suffer some crackles. Heed my own warnings!

Rewired
Here we are not with a new 6 way rotary switch and 5 tone capacitors (brown bulges around the rotary switch).
The capacitor values I chose are in the next section together with the circuit diagram.

Circuit
Sorry for the shoddy drawn and hastily photographed circuit. My scanner is down and this was meant to be a quick write-up ;-)

The capacitor values I chose are as follows: (Those marked * are values chosen in the original 1980's SB-1000 varitone)
C1 0.1uf
C2 0.047uf
C3 0.033uf *
C4 0.022uf *
C5 0.01uf *
C6 0.0068uf (I chose to use a blank terminal on the switch instead of C6. This effectively leaves no filter on the pickups. If I have a switch in the future
                     with more rotary positions, I'll add more capacitors)

So here we are completed.
As you can see it doesn't look much different externally. I kind of like the idea of gold knobs for this project, but not these ones, these
are just what I found laying around. The shops don't seem to have much of a selection these days so its web shopping for me.

Done!

Testing.

And now the bit you've all been waiting for. The sound tests. Once again it was a very quick and dirty test in my living room so apologies.
I also seem to have wired one of the caps in the wrong order so the position 6 really should to be position 2 and the others all one position lower.
I can live with that until such time I find another rotary with more positions.


Test1. Neck Volume 0, Bridge Volume 10, Coil switch Single, Varitone position 1 = No Filter.
http://www.youtube.com/watch?v=ac1YLphpNVw
Test1. Neck Volume 0, Bridge Volume 10, Coil switch Single, Varitone position 2.
http://www.youtube.com/watch?v=QrLlFFXbstk
Test1. Neck Volume 0, Bridge Volume 10, Coil switch Single, Varitone position 3.
http://www.youtube.com/watch?v=8r8NiYGcYaQ
Test1. Neck Volume 0, Bridge Volume 10, Coil switch Single, Varitone position 4.
http://www.youtube.com/watch?v=INgrvzdUPfc
Test1. Neck Volume 0, Bridge Volume 10, Coil switch Single, Varitone position 5.
http://www.youtube.com/watch?v=XFrEbOiEtCA
Test1. Neck Volume 0, Bridge Volume 10, Coil switch Single, Varitone position 6.
http://www.youtube.com/watch?v=GRQXv2zR6Gg

-----------------------------------------------------------------------------------------------------
Test2. Neck Volume 10, Bridge Volume 0, Coil switch Single, Varitone position 1 = No Filter
http://www.youtube.com/watch/?v=KaMo0RjIXRU
Test2. Neck Volume 10, Bridge Volume 0, Coil switch Single, Varitone position 2
http://www.youtube.com/watch/?v=oCQI-i_NMxg
Test2. Neck Volume 10, Bridge Volume 0, Coil switch Single, Varitone position 3
http://www.youtube.com/watch/?v=8dVK3bQ4Qlg
Test2. Neck Volume 10, Bridge Volume 0, Coil switch Single, Varitone position 4
http://www.youtube.com/watch/?v=O0KMlBHdb34
Test2. Neck Volume 10, Bridge Volume 0, Coil switch Single, Varitone position 5
http://www.youtube.com/watch/?v=gWvFHvWXfKE
Test2. Neck Volume 10, Bridge Volume 0, Coil switch Single, Varitone position 6
http://www.youtube.com/watch/?v=Mj08j0I2T98

-----------------------------------------------------------------------------------------------------
Test3. Neck Volume 10, Bridge Volume 10, Coil switch Dual, Varitone position 1 = No Filter
http://www.youtube.com/watch/?v=Ilq9e0BQUHg
Test3. Neck Volume 10, Bridge Volume 10, Coil switch Dual, Varitone position 2
http://www.youtube.com/watch/?v=1sobkItvg_c
Test3. Neck Volume 10, Bridge Volume 10, Coil switch Dual, Varitone position 3
http://www.youtube.com/watch/?v=zMdZtw1GqvI
Test3. Neck Volume 10, Bridge Volume 10, Coil switch Dual, Varitone position 4
http://www.youtube.com/watch/?v=7BrnfTxHv24
Test3. Neck Volume 10, Bridge Volume 10, Coil switch Dual, Varitone position 5
http://www.youtube.com/watch/?v=uJwp5lGrJ0M
Test3. Neck Volume 10, Bridge Volume 10, Coil switch Dual, Varitone position 6
http://www.youtube.com/watch/?v=xz_mGIoMu9c




Finally, here are some links that you might find useful if you chose to do this for yourself.
http://ariabasses.blogspot.com/2010/11/aria-pro-ii-sb-1000-wiring-schematics.html
http://guitarnuts2.proboards.com/index.cgi?board=wiring&action=print&thread=644
http://www.tdpri.com/forum/archive/index.php/t-175216.html
http://www.talkbass.com/forum/f38/simple-varitone-circuit-your-bass-596256/
http://www.guitar-mod.com/wiring/ctimages/ctbass_wiring.gif
http://www.prog.rockers.co.uk/elite2circuit.gif (Like my early white Elite2)
http://www.prog.rockers.co.uk/sb900circuit.gif (like my pre modded late Elite2)

If you like this project check out my index page for others.
https://sites.google.com/site/teesprojects/

Should anyone wish to contact me about this project or old Japanese bass guitars in general my contact addy is:
teesquared at gmail dot com.




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