Swapping Pickup Magnets

Funkfingers · June 2020

Are you certain that the push-pull tone pot on your Chapman ML2 is a phase reversal rather than, say, a coil split?

Used in isolation, phase reversal of a single pickup will make no discernible difference to the tone produced. It would make a difference in multi-track recording situations if signals of both phase polarities were combined.

If activating the push-pull switch noticeably changes the tone, it is either engaging a filter or, more likely, shunting some or all of the output of one coil to ground.

I strongly suspect that the stock Chapman control circuit involves simultaneous coil split of both humbuckers. Adding phase reversal would require an additional switch or push-pull pot.

IMO, the neatest way to have all of these smartass switching options without new drilling holes in your guitar is to use the Freeway 3X3-03 six-way toggle selector switch.

ICBM · June 2020

A phase switch appears to change the tone when you reverse it while playing. It’s mostly an illusion though - if you do it while you’re *not* playing you will find it much harder to convince yourself there is one.

But it does change the relationship between the guitar and the amp, if you’re playing loud enough or standing close enough - it can affect the onset/frequency of feedback. (In the case of acoustic guitars, to help stop it.)

barnsleyboy · June 2020

Funkfingers said:

Are you certain that the push-pull tone pot on your Chapman ML2 is a phase reversal rather than, say, a coil split?

The stock ML-2's were fitted with a coil split. The classic (the gold top one) has phase reversal switch and SD SH-1 Blues humbucker set.

ICBM said:

A phase switch appears to change the tone when you reverse it while playing. It’s mostly an illusion though - if you do it while you’re *not* playing you will find it much harder to convince yourself there is one.

It's a very subtle difference, I've listened intently to both situations - playing, and "not" playing. I might try the Freeway switch at some point in the future and replace the tone push pull pot with a decent CTS one. The quality is a bit cr*p and you have to get your finger nails right under the edge to pull it up. I'll carry on tinkering with the magnets on the HB-35 for now and get that sorted before I embark on any more guitar based surgery!

BTW for the price, I have been really impressed with the Harley Benton. I had a few issues with the first one they sent me and the one I have now has some light scratches where it shouldn't have (remedied in part by them offering me a partial refund of 20 euros), but it's a bit of a dark horse!

ICBM · June 2020

barnsleyboy said:

It's a very subtle difference, I've listened intently to both situations - playing, and "not" playing.

I think it's also possible that there's a difference with a humbucker - the capacitance relationship between the coils and the baseplate/cover will change slightly when you flip the phase electrically, although it will be very minor.

I did some experiments on phase using a Fender Mustang, since it has the switches as stock - that showed no genuine difference, and it was inaudible if you weren't switching while playing, but those pickups are pure single coils with no baseplate.

I tend to put these sorts of differences at the level of "you can hear something change when you directly compare the two sounds together, but if you hear either of them in isolation you would not be able to tell which it was".

It is a bit OCD I know

, but I do like to find out about this sort of thing - I've found some that don't matter when popular opinion says they should, and a few the other way round.

barnsleyboy · June 2020

Nothing wrong with a bit of guitar related OCD!

"you can hear something change when you directly compare the two sounds together, but if you hear either of them in isolation you would not be able to tell which it was".

As an impressionable 18 year old and after reading Adrian Legg's book on customising your electric guitar I foolishly thought "I'll have some of that". I took my beautiful Fender Flame Master Series guitar to Andy's guitar workshop in Denmark Street to get some magical switching options installed. To say that it was butchered is an understatement (I'll post some pictures later if anyone is interested), and I only discovered quite a few years later when I took it to the excellent Martyn Booth that the numpty that worked on it originally hadn't even wired it up correctly!!

At the time I thought that a 3 way micro switch installed for each pickup giving series/ single coil/ parallel option, and a third switch which phase reversed one of the pickups would give me every sound that I could ever dream of!. The phase reversal switch has since been removed during the corrective works as I've been told that it is just too complicated to wire and retain the 3 options for each pickup. In reality, there is such a small difference between the single coil and parallel positions that in the future I might get it changed to a 2 way series/ parallel switch for each pickup and try to get the 3rd phase switch reinstated. But hey, you live and learn.

ICBM · June 2020

barnsleyboy said:

At the time I thought that a 3 way micro switch installed for each pickup giving series/ single coil/ parallel option, and a third switch which phase reversed one of the pickups would give me every sound that I could ever dream of!. The phase reversal switch has since been removed during the corrective works as I've been told that it is just too complicated to wire and retain the 3 options for each pickup.

It can be done, but it's a little bit more complex than without it. It's when you start wanting to be able to switch the pickups in series - with each other, not just each one - as well that it becomes a real faff... but any of the options can be done if you remember to keep the grounds and the pickup 'cold' coil connections separate.

I used to do all this sort of stuff too, and you can end up with the control cavity looking like the inside of a BT street box if you're not careful

.

normula1 · June 2020

I quite often do a partial out of phase by introducing a series capacitor in the out of phase mode. This does sound different when the pickup is solo'd as the cap removes some bass.

barnsleyboy · June 2020

To say that it was butchered is an understatement (I'll post some pictures later if anyone is interested), and I only discovered quite a few years later when I took it to the

Not for the squeamish!

Image: https://live.staticflickr.com/65535/50023473967_733e70fddb_c.jpg

Image: https://live.staticflickr.com/65535/50022675013_6c93270fa4_b.jpg

Image: https://live.staticflickr.com/65535/50022675043_615f0b7786_b.jpg

Image: https://live.staticflickr.com/65535/50023216796_e1736486b9_c.jpg

As you can see, he really f*cked it up! Even to the extent that the black cover plate that he used was off-set to one side. This has since been corrected with a newly made cover and the cheap micro switches replaced with something a bit more durable.

normula1 · June 2020

Ouch !!

Funkfingers · June 2020

Whoever did that work should commit seppuku.

ICBM · June 2020

That’s one of the worst bodges I’ve ever seen

. Did he try to rout the top of the cavity from the inside and go right through the top?

Not a lot of things are completely beyond repair, but that’s pretty close. To make a clean job you’d basically have to re-top it.

barnsleyboy · June 2020

The 2 things that are most galling about the whole thing is when I took it into the workshop (I'm having a Nam style flashback here) him and his colleagues were dissing the guitar finish, having a laugh and getting sniffy about the wood grain on the back of the guitar. And the second thing is that he completely messed up the wiring anyway. I only found out when I took it to Mr. Booth to get some advice and a price to change the pickups for some Seymour Duncans! All those years I had the guitar it never functioned properly ...... I'll never get that time back again. Seppuku is too good for him!!!!

PeteC · June 2020

Desecration .......such a lovely geetar to start with ! I feel your pain. Worth recapping at some point by someone skilled ?

barnsleyboy · June 2020

I've toyed with a recap, but I'm guessing that it would cost me an arm and a leg to get done (I don't mind the leg, but the arm will make it tricky to play!). Do I really trust that a luthier could get it back to something resembling it's original state? Would I be prepared to go through the stress? What if I don't like the grain pattern on the new top? What if the paint job and the burst doesn't come out right?

Anything that gets done to a guitar, good or bad is part of it's history and the journey it has been on. It's my history, warts and all. Some people love relic-ed guitars, but to me the dings and scratches after the pain over the first one or two belong to you and your 6 string buddy. I don't like the idea of having a new guitar that someone (no matter how skillfully) has beaten up with a wire brush, some paint stripper and a bottle of acid in the factory. Anyway Steve at Guitar Lodge in Felixstowe fashioned a new more central cover plate and with the larger switches it is a definite improvement in looks.

Image: https://live.staticflickr.com/65535/50025559772_57814d397f_b.jpg

Image: https://live.staticflickr.com/65535/50025300521_4cfeea4068_b.jpg

Linking things back to the original post, while I was tinkering with magnets I thought I'd take a peak inside the Flame to see if there might be any mileage in warming up the tone with a magnet swap. The stock Schaller ones are quite aggressive and not as vintage sounding as they could be to match the look of the guitar.

Image: https://live.staticflickr.com/65535/50024766803_2615462f62_b.jpg

Image: https://live.staticflickr.com/65535/50025308016_47355a3d64_c.jpg

This looks like a bigger job than I anticipated as they seem to be glued to the base-plate. There were a set of the same pickups on flea-bay some time back which I missed out on which would have been ideal candidates to be re-wound/ rebuilt so I still had the option to put the originals back in. But having said all that, I could never part with the old girl!

Today's job is trying out the Alnico 4 in the HB-35 and checking that I put the magnet in the right way round. Thanks as always for your advice, guidance and shoulder to cry on!!!!

normula1 · June 2020

Is it glue or just wax?

barnsleyboy · June 2020

Hmm, I'm not sure now. At first glance it looked like glue - I didn't want to poke around too much just in case I broke something. I'll take another look this week. I didn't see any screws in the base plate connecting the bobbins so I assumed that it had all been glued in place.

ICBM · June 2020

I'm pretty sure these are glued, from memory - it is a long time since I've looked at one though.

Funkfingers · June 2020

I recall Schaller following the DiMarzio practice of bonding bar magnets with epoxy.

The bassist of a band I briefly joined had defretted his Kay “Austin Hatchet” travel bass and routed it for Schaller bass humbuckers. For reasons lost in the mists of time, he opened up one of the pickups. (Probably, an output cable repair job.) The bass limped on with just one working pickup and sounded rather good. I left the band before the repair was completed.

barnsleyboy · June 2020

That's settled it, too much room for me making a dogs dinner of it.

ICBM said:

barnsleyboy said:

At the time I thought that a 3 way micro switch installed for each pickup giving series/ single coil/ parallel option, and a third switch which phase reversed one of the pickups would give me every sound that I could ever dream of!. The phase reversal switch has since been removed during the corrective works as I've been told that it is just too complicated to wire and retain the 3 options for each pickup.

It can be done, but it's a little bit more complex than without it. It's when you start wanting to be able to switch the pickups in series - with each other, not just each one - as well that it becomes a real faff... but any of the options can be done if you remember to keep the grounds and the pickup 'cold' coil connections separate.

I used to do all this sort of stuff too, and you can end up with the control cavity looking like the inside of a BT street box if you're not careful .

I'm very tempted to get the phase reversal switch reinstated as in the original (incorrect) wiring I liked the tone option. I found a wiring circuit which looks hopeful albeit that there is an additional switch for neck+bridge series parallel!

https://guitarelectronics.com/2-humbuckers-3-way-lever-switch-2-volumes-2-tones-series-split-parallel-reverse-phase-master-series-parallel/

ICBM · June 2020

barnsleyboy said:

I'm very tempted to get the phase reversal switch reinstated as in the original (incorrect) wiring I liked the tone option. I found a wiring circuit which looks hopeful albeit that there is an additional switch for neck+bridge series parallel!

https://guitarelectronics.com/2-humbuckers-3-way-lever-switch-2-volumes-2-tones-series-split-parallel-reverse-phase-master-series-parallel/

That won't quite work correctly for series/parallel unless you have the main pickup selector set to the neck pickup, as it says.

You could use the second half of that switch to fix the problem - you would break the connection between the bridge pickup volume control and the main selector switch, connect the top terminal on the switch to the bridge pickup volume pot, the middle terminal to the bridge pickup connections on the selector switch (ie two two connections you've just separated), and the bottom terminal to the neck pickup volume pot output.

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Swapping Pickup Magnets

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