Brian May Series/Parallel Mod

[xeroks]

Hi All

Been a long time since I last posted here, great to see some familiar usernames still here, very sad to see others no longer with us.



I bought myself a BMG Red Special a while back. I've been familiarising myself with that switching system and found some things.

Firstly, the base sounds it gives are great, and provide sounds you just don't get on any other non-modded guitar.
Secondly, I've found that leaving the neck pup out-of-phase with the others gives a wide enough range of sounds using just the on/off switches to be usable live. The other phase positions are useful options for recording.

However, I do miss the parallel sounds that a normal SSS guitar provides. In particular the Bridge - Middle combo has some of that stratty quack, but is warmer and smoother. It would be great to brighten that up. So I've been cooking up plans to enhance it slightly.


The basis for these has been John H's diagram for a serial/parallel option (below). I found it on a 2009 article on Premier Guitar website

I didn't want to add a toggle switch to the cramped panel, so was planning to go down the route of using a Fender S1. The downside of that plan is that the BMG has some nice aluminium knobs on the vol and tone controls which I'd lose.
Then I discovered that Switchmaster do a 4PDT slider. I've now verified that it fits into the existing holes in the scratchplate.

My plan now is to do a mod of JohnH's mod: the same arrangement, but with the bridge phase switch removed. I'll post the diagram later today.

This will give me all the original sounds plus all the parallel versions, without changing the aesthetics of the guitar. (The colour of the sliders is changing from white to black, but I'm also swapping the scratchplate from black to white. The contrast works for me.)


Enough of the background, here we get to the questions.

I was following the wiring of JohnH's awesome diagram and saw that, in series mode, it switches the pups off by short-circuiting them. I'm sure I remember this method is suboptimal as it can dampen the strings, sucking the higher frequencies out.

1. has this design been improved in the last 8 years, to remove those short-circuits? Maybe by replacing the DPDT on/off switches with 4PDTs? I've started doodling some ideas, but my head's not back up to speed with this stuff yet. TBH it's a bit of a miracle that John's circuit is possible at all, but I thought it might be worth a try with you guys.

2. Or is not not really a problem?


3. not a wiring question, but, as supplied, the guitar comes with black screws for the scratchplates, truss rod cover, switches and pickups, to match the black scratchplate. There are a variety of types of screws. Any suggestions on how to source replacement nickel plated ones to go with the new white scratchplates?


many thanks in advance for your consideration.

Al





John H's original Brian May with series/parallel option.

[reTrEaD]

Jul 3, 2018 7:43:28 GMT -5 xeroks said:

I was following the wiring of JohnH's awesome diagram and saw that, in series mode, it switches the pups off by short-circuiting them. I'm sure I remember this method is suboptimal as it can dampen the strings, sucking the higher frequencies out.

1. has this design been improved in the last 8 years, to remove those short-circuits? Maybe by replacing the DPDT on/off switches with 4PDTs? I've started doodling some ideas, but my head's not back up to speed with this stuff yet. TBH it's a bit of a miracle that John's circuit is possible at all, but I thought it might be worth a try with you guys.

2. Or is not not really a problem?

I think it's a bit better to avoid shunting coils or leaving them hanging from hot whenever practical but I wouldn't lose much sleep over either one. In a scheme that has both parallel and series modes, there's a difference in what's necessary when a coil is removed from the circuit. In parallel mode, just disconnect it. In series mode, the omitted coil must be replaced with a path to complete the circuit. Managing both requirements tends to tie up more poles.

You might search through the posting history of ChrisK, Sumgai, and Unklmickey for Brian May variants. iirc, there were several schemes depending on which functions were combined. The business of separates for each function (on/off, phase, S/P) tends to be rather 'switchy'. In your current proposal, omitting the phase switch for one pickup does reduce your switch count from seven to six without losing any functionality. But that might be reduced to four if three-position switches can be used, combining on-off and phase for a single switch for each pickup. In any case, some searching might bear some fruit, depending on your goal.

Jul 3, 2018 7:43:28 GMT -5 xeroks said:

3. not a wiring question, but, as supplied, the guitar comes with black screws for the scratchplates, truss rod cover, switches and pickups, to match the black scratchplate. There are a variety of types of screws. Any suggestions on how to source replacement nickel plated ones to go with the new white scratchplates?

Idk. Stew Mac sells pickguard screws for about half a buck each. I've seen them on Amazon for about five dollars per two dozen (less than a two bits each).

Perhaps another member will have a better source.

[xeroks]

Thanks reTrEaD!

I tried having a look for some other suggestions in the forums, but there’s a big archive here, I’ll have another look.

I’ve considered that 3 position switch idea when I was considering modding my old SSS to brian may wiring. Now i’ve tried it for real over the period of months, I can say that having separate on off switches from phases is better.

In the meantime though, I think I have worked out how to do it without shunted coils, using an extra pole on the B and N on/off switch and two extra poles on the M on/off. I’ll draw it up tonight.


Thanks for the tip about Stewmac, I’ll check it out. Sometime minor things like screws can screw you up, I guess!

[JohnH]

Hi xeroks, thanks for posting that diagram.

PG lifted it from our thread, here:
guitarnuts2.proboards.com/thread/4855/brian-series-parallel-switching-sss

(PG didnt ask, and neatly chopped off my copyright symbol. I was a bit annoyed, because mods on PG are usually full of mistakes! They also described me as an 'Australian guitar tech', and I'm neither! But now Im happy that it helped you find it)

You'll see some links to other versions there too. I first figured out the switching on the Tonemonster2 (see link in above thread). I built that one, as did a few orhers. I didnt find any problems with the shunting. I think its better to have that than the complexity of more complicated wiring.

But theres one linked there that Id also recommwnd, by newey. This uses only the existing switches, with one dpdt phase switch doing the series/parallel, though not with all the options. But its simple and an easy wire-up to test it before you decide if you want to go more complex.

[xeroks]

Thanks for the link, John, I’ll have a look just now.

I mean what do you expect from a journalist?

I’ve drawn up a first go at the shuntless version I was thinking of.



I’ve not checked it thoroughly yet, and haven’t included the grounding cable from the pups. It looks simpler than i thought it would in the end.

Edit: just noticed the crossover in one of the phase switches got deleted, oops.

[reTrEaD]

Jul 3, 2018 16:22:30 GMT -5 JohnH said:

(PG didnt ask, and neatly chopped off my copyright symbol. I was a bit annoyed, because mods on PG are usually full of mistakes! They also described me as an 'Australian guitar tech', and I'm neither! But now Im happy that it helped you find it)

They did attempt to credit you in the text below the drawing. But it would appear they may have botched that too.

Wiring diagram courtesy of John Hewitt (guitarnuts.com)

They don't seem to understand the difference that always existed between the now-defunct website and our forum.

There are a lot of mods out on the web for Red Special replicas and clones, mostly designed to coax more sounds out of the guitar. My favorite (Image 2) is by John Hewitt, an Australian guitar tech and the mastermind behind the GuitarNuts website.

At least they got the mastermind part right, even if it's in reference to the wrong location.

[reTrEaD]

Jul 3, 2018 17:12:18 GMT -5 xeroks said:

Edit: just noticed the crossover in one of the phase switches got deleted, oops.

I wouldn't worry much about that omission in the working copy. Anyone proofreading it will know that it's implied. The little jumpers drawn straight across the grey areas of the switch present a rather tidy appearance. I might make an attempt at verifying that it should work as-advertised.

[newey]

Here's my version, as referenced by JohnH above. It's only done in schematic form, but I can do a diagram of it if anyone ever wants to build it.

This gives the N + M and B + M combos for some Strat "quack", and has the advantage of not requiring any new hardware. The downside is that it has another dead switch position (the BM guitar already has a dead position with all pickups switched off). Here, with the mid pup set to parallel, one must have either the B or N selected as well, or a dead spot results.

guitarnuts2.proboards.com/thread/4650/parallel-tones-brian-guitar

I was following the wiring of JohnH's awesome diagram and saw that, in series mode, it switches the pups off by short-circuiting them. I'm sure I remember this method is suboptimal as it can dampen the strings, sucking the higher frequencies out.

We've discussed this effect in the past, and the consensus was that, while true in theory, any difference would not likely be audible.

[xeroks]

Thanks newey,
I had a look at your version this morning. I love that it gives a whole new range of useful sounds without removing any of the old sounds, and without requiring any new hardware. Very clever!

[xeroks]

So I had a check of my circuit.

It seems to be ok, but one thing I’m not sure about is the parallel/off/off/off layout. In that configuration, the ground and live don’t meet in the middle (unlike the series/off/off/off)
Is that OK?

[JohnH]

A fully shorted-out 'off' setting is dead quiet, while if it is not shorted,you may get a little noise picked up by wiring, but not much. Doesnt seem like a big issue, since most guitars dont even have an 'off'. It'll be fine for doing stutter effects and if you want a zero-output setting for set breaks etc, you have series off, or just turn volume to zero.

But if you can wrangle your design to get both modes fully shunted when off, then its a puzzle worth solving if it stays within the scope of switches that you are using.

I think if I remember right, I got a fully shorted 'off' setting in both modes on my versions, but Id need to check.(EDIT: yes I did)

ps. I havnt fully checked your wiring, but I did confirm one thing that I hoped it would have beyond my one: When a pickup is off, it is fully disconnected at both ends. That will give you the absolute quietest performance in terms of minimal interference picked up from unused pickups hanging on the circuit So 'tick' on that!

[xeroks]

Hmm I think i can see how to fully short that out by adding a couple of extra connections. But it looks too easy, I’ll have to do a lot of checking.


EDIT: Nope, it was wrong. However, I have another version, will post this evening AFTER I've checked it.

[xeroks]

Ok, I’m pretty confident this one works.





Interestingly I spotted a variant of this which has the bridge and neck on/off switches as DPDTs. When they’re switched off, one coil connection is left attached to the circuit. So it’s not so clean as the diagram above but it’s better (to my mind) than having them shunted.