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Kiwi

The "Clean Machine"

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I've been a little obsessed with guitarist Alan Murphy in Go West for a number of years.  The quality of my playing is a borderline insult to his legacy of talent but hasn't stopped me from a bit of a dive into 80's sounds.

So to scratch the itch, I'm working on a new build which is a bit of a mish mash of some of the instruments he played in the late 80's.  The primary mission is to recreate the cleans from his Aria RS Esprit. 

The Esprit is a very interesting guitar technically because it not only featured active electronics (which runs against the tide of prevailing opinion these days) but the circuitry was actually licensed from Alembic, a company whose reputation is founded on bass guitars.  Alan was quoted in a Home Recording Studio article, published a month after he passed, that the Aria sounded like nothing else on the market for cleans.  

So that was the starting point for this build - crisp, shimmery cleans with not much bottom end. 

But, as previous builds will attest, I have a habit of making things far more complicated than they need to be.   The Esprit has only two pickups - neck and bridge and both pickups are single coils with that middle 'pickup' a dummy hum cancelling coil.  The neck and bridge together are where it shines (or shimmers if you will) but just having a guitar for that setting seemed like a wasted opportunity.  So I felt the need to build in more options.  

See the source image

The controls are volume (pull = active circuit on, activates a flashing red LED), Lo pass sweep neck pickup,  bridge pickup boost switch at shelving point, lo pass sweep bridge pickup, neck pick up boost switch at shelving point and 3 way pickup selector switch.  The alder body and 1 piece bolt maple neck are nothing remarkable and neither is the Floyd inspired fulcrum vibrato.

That middle coil was at the centre of my concerns about 'waste'.  Firstly because hum cancelling can be achieved more effectively through other means these days (stacked coils for example).  Secondly because arguably the positions 2 and 4 on a strat are arguably some of the most evocative, conventional clean sounds.  So it would be nice to have them as well but that wouldn't be possible if the middle position was just a coil.  So I wanted to find a way to re-utilised that middle position for a pickup but without compromising what the Esprit does best.

This means having to use pickups that don't need a dummy coil and that also throws into the air questions about wiring direction, phase and inductance.  As it so happens, Aria commissioned Kent Armstrong to make the pickups for the RS Esprit based on information supplied by Alembic so after an exchange of emails with Aaron, we had a short chat on Skype about what Aria were up to.  Aaron makes almost all my new pickups since Andy at Wizard retired.  He can tap into all of the work that his father did for major boutique brands like Celinder, Ken Smith and others (as well as Aria).  Aaron advised that most of the clean sound of an Aria probably came from the filters and that to get traditional strat sounds from positions 2 and 4,  it was more phased on the phase relationship between the pickups than on the wiring.  This meant that doing the RS Esprit thing AND the Fender 2 and 4 thing could be technically feasible.

Aaron kindly offered to dust off the plans for the Aria pickups and wire up a set of improved coils when I was ready.  I also did a bit of research on Alan's signal chain and found that he ran a clean and dirty channels separately.  For overdriven sounds with Go West, the Aria was shunted into Alan's cherished Fender Super Champs and then into a Session power and JBL cab.  But for clean sounds, he went straight into the PA to preserve that crystal high end.  Here's a clip of Alan playing cleans into a Roland Dimension D and then direct through the PA at a shared billing gig in Japan with Go West, (or should I say 'Go Wet' given the inclement weather conditions.)

The next trick was the filters and there are a few options available.  First option was to use Alembic's Activator preamp.  I happen to have one in my Pedulla fretless which I wanted to replace so I just needed to find another.  But they're not cheap and the second option, replacement lo-pass filter circuits by Boogieman on Ebay are on the pricey side as well, now.   I also caught wind of a low volume manufacturer called Lustihand who were making circuits for Wal and Alembic basses and contacted them through Facebook.  A new double circuit was going to cost the same as a single, used Alembic Activator and Lustihand offered to tailor it for guitar frequencies so that might mean filtering anything out below 80Hz and above 8KHz.  I'm not sure yet, will have to think about it some more.

In the meantime, a set of Alembic Activator stratocaster pickups popped up on Reverb. 

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Normally they'd be about 400 quid for a used set but the seller was asking for less than half that.  So I snagged them after confirming with Mica at Alembic that they were indeed stacked humbuckers and therefore independently hum cancelling.  While not quite as shimmery as the Series instruments, I bore Aaron's advice on the role played by the pickups in the RS Esprit in mind along with a few clips on Youtube that suggested they'd be good enough. 

All the while this was happening, I also had in mind a guitar neck that I'd commissioned for thirty quid in April...

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Originally I'd had in mind something that was a bit more Yamaha SG-ish but set in rather than through neck.  But that never got off the ground because the manufacturer's sales representative decided that I wasn't going to buy enough from them.  So the neck is a five piece laminate made from maple and mahogany with an ebony fingerboard.  It's not the one piece maple job on the Aria because I prefer laminated necks for strength and wanted a bit of mahogany in the mix just for the mid range definition and slightly sweeter attack.  

IMG_20210122_144835.jpg

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The hardware will consist of locking tuners as you might expect and for the bridge, I'm going to dive into my stash of stuff opportunistically collected over many years and use a Wilkinson VS100C convertible fulcrum vibrato.   These haven't been made since the late 90's due to a patent claim by Gotoh but I happened to stumble across a stash of them being sold by Trevor Wilkinson's daughter on Ebay and bought three for my own personal use, one in gold and two in chrome.  The other option was a Kahler 2300 series.IMG_20210122_144735.thumb.jpg.49fe4c4565f015af49b42a8589e88f2a.jpg

Although this vibrato should fit a standard strat 2 post and rout, one can never been too sure, especially when commissioned from a Chinese supplier.  The other thing I discovered when measuring the neck is that the scale length is 321mm nut-to-12th-fret which makes it around 25.2".  Les Pauls are normally 24.75", PRS is 25" and Fenders are 25.5".  The scale length will have a slight impact on pickup locations so this necessitates putting something together in CAD in order to remove as much potential for misunderstanding as possible.

Luckily I'm a seasoned AutoCAD user.  But it does impose a level of precision on things which is above and beyond what someone might work to in person.   It also introduces more risk around areas where high precision is already needed, for example the neck pocket and bridge routs.  This is because the measurements can specified and milled with tenths of a millimetre in tolerance but the measurements themselves are based on measurements with fractions of a millimetre.  While it might not seem like much, that can make the difference between an acoustically coupled neck and something that just relies on glue to stop it moving about too much.  And, to top it all off, if someone is going to commit to that level of precision by virtue of using CAD, then that level of precision can potentially be assumed by the manufacturer across the whole drawing, not just the bits that are measured carefully.  So the whole process of manufacture still needs allowance for human fettling for some tolerances after carving.  Assuming I'm doing the fettling, that means no finish as part of the fabrication process.

 

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For the body I kept changing my mind for things beyond selecting alder for the wood.  I started off wanting to do a body shape inspired by my Yamaha MSG deluxes (which Alan Murphy also played while with Level 42).  Then reason grabbed hold and I started to ask myself what was wrong with just going with a stratocaster body. 

But I figured it might as well CAD the MSG body shape up and see what it looked like with the RS Esprit pickup layout.

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I was quite pleased with how it looked.  OK so the dimensions here are all over the place, the scale is wrong and the spacing and size of the pickups is wrong, the bridge is slightly out and the Gibson ES346 inspired headstock is going to be at a 13 degree angle in this view.  But it reminded me a bit of the PRS 305.  While I was drawing the control layout, I started to think about the pickup selection and realised that a toggle switch wasn't going to be up to the job if phase switching in addition to neck+bridge was necessary.  Another option was to use a rotary pickup selector like PRS.  Exploring that that bought me onto reviewing the electronics package in more detail.

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With the rotary pickup selector, I needed to check what the specification needed to be.  At the least, the following settings were going to be needed:

  1. Bridge only
  2. Bridge + middle (maybe out of phase)
  3. Bridge + neck
  4. Neck + middle (maybe out of phase)
  5. Neck only

Normally for a three pickup strat style layout, a 2 pole rotary switch is enough.  The neck and bridge pickups can share a pole because they aren't in use at the same time.  But in my set up above, I would need at least a 3 pole switch, one for each pickup because I was combining bridge and neck.  However, when the low pass filters were taken into consideration, there was also the challenge of how to sum three pickups into two channel eq.  

Luckily, a four pole rotary switch would probably work, if I summed the four poles into two sides.  Each pair of poles into one of the two filters.  But there was still the challenge of how to manage the middle pickup in the settings.  Again that would be possible if I assigned two of the four poles to it and had the middle pickup switch from one channel to the other, depending on whether it was summed with the neck or bridge pickup.

This arrangement does have the disadvantage of upsetting the filter settings with a pickup shift from position 2 to 4 but that would only really be felt if I was playing it live and I have no plans to do that.  This is a proof of concept, a prototype which I'll use almost exclusively at home and it's main trick is going to be position 3 anyway so I put together a circuit diagram (without phase switching for positions 2 and 4) as proof of concept where position 1 was now just the piezo and all the others were moved forward by one.   Lustihand also advised that in their latest edition circuits, separate boost switches were no longer needed, the boost was activated by push pull pots so there was a welcome visual simplicity and logic to the layout despite despite it being pretty versatile.

But while I was browsing on the Stewmac website, I noted they offered 6 position rotary switches with four poles and I started to wonder whether that might be useful.  Then I remembered I had a spare Graphtec acoustiphonic preamp left over from my Shuker Headless bass and a quick search of the Graphtec website revealed they offered piezo saddles for the Wilkinson VS100 series bridges.

804073801_circuitdiagram.thumb.JPG.e19f9463536bbcd8d6caef4a45f5c193.JPG

That got me thinking about a clean piezo/acoustic type sound for one of the six positions so I threw it into the diagram and it seemed to work.  It would sit with the overall mission of the guitar for cleans. 

And I also had a spare hexaphonic PCB which opened up the possibilities of pitch-to-MIDI.

Hmmm.

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3 hours ago, ezbass said:

OK, I’m going to be following this. Bring it on. I really like that body shape.

It's one of three builds that are planned.  The second one is a "Sustain Machine" which is going to include using a Fernandes Sustainer from my Kleinberger copy, a laminated through body mahogany and maple neck and probably a Kahler 2300 series bridge for effortless divebombing harmonics.  The third one is more along the lines of an MSG V2.0 with laminated mahogany/maple neck, another Wilkinson VS100C bridge and PRS Mira pickups (medium gain, much like Pearly Gates) maybe with a single coil if I can find one that matches.  

I know Martin Booth still makes the MSG for discerning clients. But his skills are in a different league to mine and he's resistant to the idea of three pickup guitars so I'd like to think I'm not treading on his toes here.

Now I've put together a drawing specifically for the body fabricators and, in doing so, have been double checking and measuring (where possible) all the critical dimensions.  It turns out that the Wilkinson bridge DXF block that I was using is out by a few millimetres in critical places, so I really need to nail the distance between the posts and the edge of the bridge rout. The pickup blocks I'd been using were fractions of a mm out as well which impacts on tolerances.  It kind of goes to show that third party CAD blocks can't be trusted in most shapes and forms.  It also means I'm going to have to partly disassemble my strat, which has a VS100C already installed, in order to measure the clearances. 

I also borrowed body dimensions from a Les Paul drawing to begin with but the body depth was too thick  (56mm vs 44mm for MSG/43mm for strat) and the neck angle was wrong.  Putting it right has taken more work than if I'd taken measurements off the MSG.  Serves me right for taking short cuts, I guess.

 

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Last night I decided to tackle the matter of whether phase switching was needed for positions involving two pickups.  I did a bit of research on the sound of reverse phased pickups and found one vid where the vlogger had switched the phase of pickups in his telecaster and it sounded damn close to the Aria Esprit.  So then the challenge was to adapt the original circuit diagram, but the more I looked into it, the more it seemed like a separate pole was needed to handle the earth/neg side...and I didn't have one spare because of the need to connect the middle pickup to two different poles.  

By late this morning I'd more or less given up and was in the process of typing an email to someone asking for help when it occured to me that instead of making the middle pickup switch from one side of the preamp to the other, why not make the neck and bridge swap from one side to the other and have the mid stay on the same channel while it's connected.  I did a bit of mucking about with connections and found that not only could it work but it actually freed up one pole for use as an earth so it was possible to switch phasing for the bridge pickup in position 4 by swapping neg and positive around.  I also had to wire up the neg side for all the other pickups to run through pole 2 as well but the point was it's possible.

This also means I can go back to the plan to have a push pull vol pot to switch the preamp in and out.  I have also found a supplier on Made-in-China who does 6 position 4 pole pots and they don't cost anywhere near the same as those made by Stewmac.

image.thumb.png.3de7c017267a1ad77e1f080a605255ca.pngThis is subject to further tweaks, for example, I suspect pole 4 won't be needed either if I make better use of the vacant positions on pole 1.

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11 hours ago, Kiwi said:

Last night I decided to tackle the matter of whether phase switching was needed for positions involving two pickups.  I did a bit of research on the sound of reverse phased pickups and found one vid where the vlogger had switched the phase of pickups in his telecaster and it sounded damn close to the Aria Esprit.  So then the challenge was to adapt the original circuit diagram, but the more I looked into it, the more it seemed like a separate pole was needed to handle the earth/neg side...and I didn't have one spare because of the need to connect the middle pickup to two different poles.  

By late this morning I'd more or less given up and was in the process of typing an email to someone asking for help when it occured to me that instead of making the middle pickup switch from one side of the preamp to the other, why not make the neck and bridge swap from one side to the other and have the mid stay on the same channel while it's connected.  I did a bit of mucking about with connections and found that not only could it work but it actually freed up one pole for use as an earth so it was possible to switch phasing for the bridge pickup in position 4 by swapping neg and positive around.  I also had to wire up the neg side for all the other pickups to run through pole 2 as well but the point was it's possible.

This also means I can go back to the plan to have a push pull vol pot to switch the preamp in and out.  I have also found a supplier on Made-in-China who does 6 position 4 pole pots and they don't cost anywhere near the same as those made by Stewmac.

image.thumb.png.3de7c017267a1ad77e1f080a605255ca.pngThis is subject to further tweaks, for example, I suspect pole 4 won't be needed either if I make better use of the vacant positions on pole 1.

Good Work, well done. It's a pity that it's illegible, though. Run out of black ink..? 9_9

...

xD :P

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It's legible but...well, funny you should mention the black ink...I can do any colour your heart desires though.  Fuchsia perhaps?  

I was working on the schematic up until midnight and made some major changes that means (thankfully) I may only need 2 pole not 4 pole and I'm probably going to ditch the reverse phasing for now as it might not be needed.  The whole point of doing this was to get my head around the switching arrangement as a form of escapism over CNY to stave off boredom.  It worked.  I've also been tweaking the body a little more and worked up two alternative designs using a Kahler 4200 X trem bridge, one has a glue in neck and the other is through.  However there aren't any CAD blocks out there of the X trem so it seems like I'm going to have to buy one and work it up myself just like I did with the Wilkinson VS100.  But Kahler's installation instructions are a whole load more helpful than Wilkinson's and drawn up in CAD.

 

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