SimpleMod-h - The Design

The next project in this current SimpleMod series - "SimpleMod-h".

This design is based on SimpleMod-g, which I thought was going to be the final experiment using a P-90 -style bridge pickup (a GFS Dream 90) combined with 'standard' Ceramic magnet single coil pickups.

However, on constructing the SimpleMod-g design, I found out a bit more about the noise cancelling characteristics of the arrangement; specifically, only the (middle + neck) combination was noise cancelling. Hence, I had to rectify that situation... and I was not very keen on the tone controls nor the "out-of-phase" switch arrangment, so I decided to change them as well.


Background

With the above-mentioned "problems" that needed to be rectified, as well as the addition of a couple of features, it was something of a "back to the future" design that was needed for this outing.

Specifically, here's what was required:-

• To get the (B+M) and (N+M) BOTH to be noise cancelling, I had to swap the neck and middle pickups, both in wiring and in physical location. After these changes, the neck pickup will be RW/RP, whilst the middle and bridge pickups will NOT be RW/RP). For some more background on the thinking behind this, please see this posting in the SimpleMod + ToneMod = ...thread.
  
  
• Replace the DPDT switch that changed the wiring of the bridge pickup so that it was "out-of-phase" (OOP) or "in-phase" with respect to the middle pickup. Whilst the OOP sound was Ok, I felt that I could achieve similar sounds with less complicated wiring (see next), so I decided to make the DPDT switch simply add the neck pickup signal (in parallel) with whatever sound was selected by the 5-way switch. NOTE: I'd tried this before with less than satisfying results but I thought the Dream 90 in combination with a slightly "better"(?) single coil pickup might yield something more interesting.
  
  
• Remove the "Master Tone" and "Bridge Pickup Tone" controls and install a modified "G&L Legacy Tone Control" (basically, a master "treble cut" pot, together with a master "bass cut" pot).
  

Schematic (864x644, 13kB):



Wiring Diagram (1024x724, 94kB) (added 22-May-2011) :



Wiring Layout (800x600, 280kB):



Pickup Combinations:


...where:
+ = pickups are combined in parallel
^* = traditionally missing combinations
^¤ = noise cancelling

NOTE: When I actually constructed this design, I used a SPDT switch, which is all that's really necessary to switch the neck pickup on/off.

When the SPDT is in the "Normal" position (toggle bat is upward), we have the 5 standard Stratocaster pickup combinations.

When the SPDT is switched to the "Neck On" position (toggle bat is downward), the neck pickup signal is added (in parallel) to the signal selected by the 5-way switch. This means the (B+N) and (B+M+N) combinations are added to the available sounds.


Sample Sounds

SimpleMod-h-P1.mp3 (128kbps, 872kB) - Some simple chord sounds when switching from 5-Way Position 1 (Bridge pickup only) through to Position 5 (Neck pickup only), with the "Neck On" switch turned off.

SimpleMod-h-T1.mp3 (128kbps, 724kB) - Here I've recorded some sounds available from this design when playing the "middle pickup only" combination but with variations in the Modified G&L Tone Control settings. The sounds in the MP3 file are (in order): 1. Treble Cut=10 & Bass Cut=10, 2. TC=10 & BC=1, 3. TC=1 & BC=10 and 4. TC=1 & BC=1. NOTE: each of the sounds has been normalized; when BC=1, the level is very much reduced and you need to bring the volume up a bit to hear the sound.

SimpleMod-h-N1.mp3 (128kbps, 728kB) - Some simple chords again that illustrate the following sound combinations: 1. Bridge alone 2. Bridge + Neck 3. Middle + Bridge 4. Middle + Bridge + Neck. The sounds have again been normalized in the recording.

SimpleMod-h-N2.mp3 (128kbps, 502kB) - That previous MP3 didn't really show the differences in the sounds off too well. Here's a few chords to show the difference a bit more. Bridge alone, then (Bridge + Neck).


Discussion

A few points of interest:-

• Swapping the neck and middle pickups has made a significant difference to the noise cancelling characteristics of this design. We now have the "notch" positions being noise cancelling (as is often the case in modern guitars) and it would seem the theory I explained in another thread (mentioned above) seems to hold true (in this case, anyway).
  
  One of the main things to learn from this, is that it's probably a good idea to gather as much info about your pickups if you're possibly able to.. and to write that info down somewhere. The things we're interested in would likely include:-
  
  - 'preferred' position (Bridge, Middle, Neck)
  - type (Single Coil, Humbucker, P-90, etc)
  - phase (check screwdriver pull-OFF => "+" or "-")
  - magnet type (ceramic, alnico, other)
  - magnetism (North pole up or South pole up)
  - wire resistance (eg 8.2k)
  - wiring direction (RW/RP or NORMAL - can be hard to determine without the pickup being in a circuit)
  - resonant frequency (from specs? from measurements?)
  - inductance (from specs? from calculations? from a bridge circuit?)
  - distance between poles (if not a rail p/u - important for string location, nut size, etc)
  
  
• The "Neck On" switch has been another curious addition with this design. In previous incarnations, I never heard too much difference when the neck pickup was switched on. Neither did I hear anything marvelous this time... until I played about with the pickup heights.
  
  I made some adjustments and, as I tend to think the sound is never bright enough [...Hmm... Maybe I should be looking at a Telecaster, y'think?...], I have some "interesting" alignments on the pickups. Here are a couple of photos of the installed pickups:-
  
  Photo 1 (850x262, 88kB), Photo 2 (850x369, 127kB)
  
  ...but I'd ask you to please listen to the sounds from this design first (see above) and not let the (possibly) strange look of the pickups bias your opinion of the sound
  
  Making these adjustments has sort-of changed my mind about including the "neck on" feature as a standard element in my designs.. as long as I can adjust the pickups to get the sound I want in the first place...! Still, I wonder how much the Dream 90 contributes to the (Bridge + Neck) combination sounding "good" to my ears..!?
  
  
• The "treble cut" and "bass cut" functions provided by the "Modified G&L Legacy Tone Control" affect the sound much the same as observed previously (see SimpleMod-d). Most of the tone control is done with the "treble cut", which is the same as a standard Stratocaster tone control. The "bass cut" is handy as it can "thin-out" the sound a bit, albeit with a decent volume drop.
  
  
• In this design, I used "log" taper pots for both of the tone controls (another experiment)... but the "action" of both of the tone pots is poor. Starting with both controls on "10", nothing happens with the "treble cut" until the knob is at "3" and then all the tone colour changes happen as the knob is turned from "3" to "1". Similarly, the "bass cut" changes tone colour a lot as the knob is turned from "10" until "7" but nothing else happens as the knob is turned from "7" through to "1".
  
  Now, this is peculiar, as I've used the same pots, from the same supplier and the "treble cut" design that worked well when originally installed in SimpleMod-b now exhibits the "poor action range" problem again. The "bass cut" would normally have used a "linear" pot... and the behaviour I'm seeing in the current design seems to confirm that a "linear" pot is required for that control... but why should the response of the "treble cut" have gone haywire!? Does this mean, to be sure, I will need to check the response of every pot before I install it in a guitar?! Pffft! Do techs DO that!? ...or is it as simple as the fact that I'm using pots from an electronics company and not from a guitar company!? (that is, I'm spending $1.75 on Alpha pots instead of $4.75 (or up to $12 in Australia or $33 for some Honeywell pots via online sellers) for CTS "guitar pots")
  
  In short, it seems the "design" side of the required pot taper remains unresolved... and you really need to test the pots before you install them.
  

Photo(s)

The actual external look of the guitar hasn't changed. To save you from flipping back and forth between web pages, here's a photo from SimpleMod-g that's still accurate (even though the labelling might not be):-



I think it would be best to post any further thoughts, comments, etc about this design in the SimpleMod + ToneMod = ... thread.

Hope this proves useful, everyone...


John

Edit: 22-May-2011: Added complete wiring diagram