Understanding the ’72 Fender Mustang Bass Pickup Design

 

The ’72 Fender Mustang Bass Pickup may appear to be a budget model but Leo Fender cared about his products and everything was thoroughly thought out.

Table of Contents

A bit of history

What makes the Mustang Bass Pickup great

So back to the Mustang Bass Pickup repair

A bit of history

I get to repair old pickups as well as make new ones so when I was sent this old Mustang Bass Pickup I thought it was worth taking a few pics and writing about it.

This was the last bass designed by Leo Fender before he sold Fender to CBS in ’65. This pickup shows all the thought and consideration you would expect from the great man. It’s easy to dismiss pickups on ‘budget’ guitars but there’s a lot more to this one than meets the eye.

The later version of this instrument, the Musicmaster Bass had a single coil pickup straight out of a Stratocaster – yes really. Here is more on the Musicmaster bass pickup. I make my own version of the Musicmaster bass pickup in two flavours.

The original Mustang bass pickup that I have here is a split pair, like a precision bass pickup but with a few essential design differences.

What makes the Mustang Bass Pickup great

The obvious thing is that it’s smaller, but there’s a good reason for that.

The Mustang is a short scale bass, 30″. With a shorter scale comes less string tension and a much boomier sound with less percussive highs and a fatter bottom end.

So why didn’t he just use P Bass pickup?

It’s obvious from the design of the Mustang Bass Pickup that the intention was not to just knock out a cheap student model but to make a great instrument only with a shorter scale.

You can see that the magnets are protruding out of the bottom of the base plate – they’re 24mm long alnico 5 magnets. P Bass magnets are around half that length. Bigger magnets means more pull on the string and more punch to the attack of the note.

The distance between top and bottom plates is greater on the Mustang than the P Bass. This gives a much taller pickup. With a taller pickup more of the windings are closer to the magnet. A P Bass’ windings can get a lot further away from that magnetic field by the time you get to the outside turns.

Windings closer to the magnet gives a sharper, more percussive mote than the mellower P Bass.

With roughly the same turn count between P Bass and mustang this means the Mustang’s footprint is smaller.

Both those factors – coil geometry and magnetic pull are specifically designed to offset the lack of definition you can hear in a short scale bass.

This was not the easiest path to take. The magnets would have to have been specially made and the flatwork (top and bottom plates) would have been made specifically for this model. Not least there would have been molds made to injection mold the covers.

It was all about getting the best possible sound from a short scale bass while make the price accessible to more musicians.

It’s a clever design.

Five years later when CBS were running Fender they introduced the same bass but with a Stratocaster (yes, 6 pole) pickup. Now that was taking the easy route. Leo Fender always did things the best way he could, working up to a standard rather than down to a price.

If you’re interested in Leo Fender read Forrest White’s book, he was there.

So back to the Mustang Bass Pickup repair

As you can see from the colour of the windings the wire has plain enamel insulation. The insulation does make a difference. Not all insulation is the same thickness. Thicker insulation means windings are further away from each other. This changes the pickups capacitance and to an extent inductance and dc resistance. Remember, we’re multiplying small differences by how many turns there are, in this case over 10,000.

It appears this coil failed due to corrosion of the magnetic pole

You can see the corrosion in this pic.

In the 70’s Fender pickups were potted in lacquer rather than wax in both earlier and later periods. The lacquer didn’t penetrate all the way to the core of the pickup and this is the result.

Before I re-wound this coil it was rust proofed and insulated – I want this repair to outlive me.

Pickup String Spacing – choosing a humbucker

 

Pickup string spacing is something you need to be aware of when you’re buying guitar pickups, particularly humbuckers. Guitar bridges come with different string widths so pickups need to match that. In this blog post I’m going to explain what It’s all about and how to measure it.

Table of Contents

What is a Pole Piece?

What you don’t need to know

Pickup String spacing – what you need to know

How to measure string spacing

What is F spacing?

What is a Pole Piece?

Pickups have pole pieces, think of these as magnets mounted in the pickup listening for string movement. Sometimes they are actual magnets, sometimes pieces of steel directing magnetism towards the strings. In this case they are steel screws.

This is what we mean by ‘pole spacing’ its the distance between the outer most poles, centre to centre.

What you don’t need to know

The way a pickup works is the string sitting inside the magnetic field actually becomes a temporary magnet and when it vibrates it disturbs this magnetic field and creates an electrical signal in the coil of wire around the magnet.

It’s a tiny signal but enough to get through your guitar’s on board circuit and down a cable to an amplifier. It’s hard to imagine that such a small amount of electricity can produce such a lot of sound. Have a think about it next time you’re at a big gig. What you’re hearing is just that small amount of electricity generated in a coil of wire. It’s really cool stuff and I find it fascinating. But you don’t really need to know all that.

Pickup String spacing – what you need to know

What you do need to know is that the string needs to align with the magnet to get the best signal. Magnets are, however, not lasers, they generate a magnetic field and not a precise beam. If the string isn’t in perfect alignment it’s fine. If the slightest misalignment made a difference then string bending would cause a drop in volume. Have a look next time you bend a string how far the string moves away from the pole.

As you can see, a little bit out of line makes no difference. Eddie Van Halen used a vintage PAF on Van Halen I with a Fender type bridge – the PAF ‘s were 49.2mm (1 15/16″) spacing and Fender bridges are usually 52mm. If there had been a problem he would have noticed.

Please remember that if a humbucker has 49.2mm spacing or 52mm spacing it’s outer dimensions are the same. The overall size of the pickup doesn’t change. So if you take out a 49.2mm humbucker and replace it with a 52mm it will still fit, it’s just the pole alignment to the strings that will be different.

Guitar bridges come in various sizes giving different string spacing. So if you have a Gibson ABR Tune-o-matic your string spacing will be narrower than a Fender Strat bridge, for instance.

By the time the strings get to the neck pickup the spacings are just about the same so neck pickups don’t vary in width. We’re just talking about bridge pickups here.

So we really want the strings to line up as best as possible with the pickup’s poles but we’re not getting too hung up on it.

How to measure string spacing

The measurement is the distance from the first to the sixth strings centre to centre at the bridge pickup. This diagram should help:

You can simply do this with a ruler, like I have.

As you can see this ’89 Strat bridge has 52mm string spacing. If you wanted to choose a bridge humbucker to make it a HSS Strat than choose the 52mm option.

If you’re buying a Mr Glyns Pickup and have any doubt just send me a pic of your bridge and I should be able to advise you.

What is F spacing?

F spacing simply means a wider spaced bridge humbucker – 52, 52.5 or 53mm. The F stands for either ‘Fender’ or ‘Floyd Rose’. It isn’t clear which and doesn’t really matter.

Why 49.2mm not just 49mm? You may well ask! It’s the metric equivalent of the pole spacing for a Gibson PAF which is the pickup most humbuckers are based on. The original measurement in imperial is 1 15/16″ – which if you ask me is no less silly a number that 49.2 but we’re stuck with it.

If this has given you a need for a new set of humbuckers you can find the Mr Glyns Pickup humbucker range here.

Here is a link to my YouTube playlist for humbucker demos.

Maxon humbucker?

 

I thought it was going to be a straightforward pickup repair but is this pickup actually a Maxon humbucker?

As part of my work I repair pickups for luthiers. Most guitar repairers don’t wind pickups and even the ones that do often send me pickups to repair, it saves them a lot of time. One such repairer is Auckland’s Ramsay Phillips.

For me repairing pickups is a really interesting part of my job. I enjoy seeing how the basic concept of a magnet and a coil of wire can be made in so many different ways. Back in the 1990’s I first learned about pickups by repairing them and I don’t think that instinct ever leaves. Most of my pickup repair work is very straight forward but occasionally something interesting comes along. This is one of those.

So Ramsay sent me a bridge humbucker from this 1970’s Antoria to repair. I was expecting something like the classic Maxon U-1000 but there was a surprise.

This is not the first Maxon Humbucker I’ve seen I’ve worked on a few old Maxon pickups in my time and they have always deserved their great reputation. So I had a good idea what to expect from this humbucker.

Maxon serial number dating

The number on the base plate of this pickup is a date stamp not a model number though it would be nice to have both.

So to translate the Maxon pickup dating code:

The first number is a production line code

second number is the year, so in this case 1974

third number, the month, so September

and the last 2 are the day, so the 17th

So that tells us its from Sept 17th 1974. I always wonder why manufacturers can’t just write the date plainly instead of a secret code but they all seem to do it.

Something unusual

But there’s something odd here. The pole piece screws don’t extend under the base plate. The 6 holes in the base where I expected to see the poles are blocked by something. Time to get the cover off and see what’s inside.

What’s Inside?

This is exactly what was inside – a single coil disguised as a humbucker! So Maxon humbucker? Well, it’s a Maxon but not a humbucker.

It has the typical floppy nylon bobbin I would expect to see in a Maxon but this one is sitting on top of a large ceramic magnet.

My job here is to fix this pickup so I remove the bobbin and start to carefully remove the sticky old tape.

I remove the hookup wires and try re-soldering them to the winding wire and the pickup comes to life. It was simply a dry joint. This one is showing me 8KOhms on the meter which is in the ballpark of a PAF though it would sound nothing like one.

You can see the metal plate mounted inside the bobbin that connects the short pole screws to the magnet.

So, Maxon humbucker? Well, certainly Maxon but not a humbucker. Beware – not all Maxon pickups are classics.

I’ve had a look on line and can’t find a model number for this pickup. It seems the only distinguishing feature from the outside is the lack of pole screws through the base plate.

If you are interested in vintage humbucker tones check out the Mr Glyn’s ‘Integrity’ humbucker. It comes in 4 flavours or both bridge and neck.

www.mrglynspickups.com

 

 

Precision Bass

Precision Bass split pair is based on the Fenders of the early/mid 60’s. Full and clear with that distinctive mid range that sits well in any mix. It is the essence of bass. It has the woody, full tones we all love. As a stand alone or used with my Jazz Bass bridge pickup as part of a PJ set.

 Alnico V - 10.9 kOhms

www.mrglynspickups.com

Arguably the most important instrument of all of Leo Fender’s creations the Precision bass changed music more than any other instrument. From James Jameson to Steve Harris, the P Bass is surprisingly versatile and has such a distinctive tone.

As with the early pickups this split pair is built to be hum cancelling – the two coils are electrically out of phase but also magnetically out of phase. Here’s an explanation: How Humbuckers Work

With fingers, with a pick and especially with flat wounds.

My Precision Bass pickups are designed to be used with 250 K Ohm pots.

For more P Bass fun: https://mrglynspickups.com/2021/04/06/bass-pickup-re-wind/

Cool 90

 

The Cool 90 is a P90 based pickup available in both Dogear and Soapbar. Designed with Jazz and Blues players in mind it produces a clear, full, well balanced tone. Never harsh, always full and musical.

The bridge pickup has an organic sound with a lower mid push ideally suited to dynamic lead lines and tight rhythm playing.

The neck pickup is clear and chiming with enough clarity to always be heard in the mix. It has that lovely woody tone especially in an archtop.

For the shop and more pickups -  www.mrglynspickups.com

For ‘full fat’ P90 tones have a look at our “Sassy” P90 pickup set.

The Cool 90 Story

Like many of my pickups the Cool 90 started with a repair job. A customer sent be a faulty Gibson P90 out of a 1955 Les Paul Junior. Naturally, I took measurements and completely analyzed every detail of it. Unlike the information in the books (and internet) it had less windings and Alnico II magnets instead of Alnico V.

And what a great sounding pickup it was.

I decided to make my own version of it to compliment the ‘Sassy” P90 pickup I was already making. The Sassy has the classic “full fat” P90 tone, plenty of growl and cut through.

The idea behind the “Cool 90” was to make a lower powered version for the cleaner player. Still keeping the classic P90 character but with less grunt.

Single – “Cool 90” P90 NZ$189 for NZ customers, if you’re overseas it’s GST free; NZ$164.35

Pair – “Cool 90” P90 NZ$369 for NZ customers, if you’re overseas they’re GST free; NZ$320.87

Neck- 6.4 KOhms, 5.45H, Alnico II. Bridge 7.25 KOhms, 6.42H, Alnico II

 

 

 

I also make a humbucker size P90 set – the “Black Sand” if you need some P90 goodness in your humbucker guitar, here’s a link to them: https://mrglynspickups.com/2020/03/29/black-sand-humbucker-sized-p90-neck/

For a full range of demo videos of Mr Glyn’s pickups go to my YouTube channel https://www.youtube.com/c/MrGlynsPickups/featured

Kōkako Strat Pickup

 

The Kōkako Strat Pickup is is strongly influenced by the Fender Stratocaster pickups of the 60’s but with a little more. It has a full yet clear bottom end , smooth highs and clear mids. It’s aimed at players who love the sounds of Frusciante and Hendrix.

The Kōkako set was spawned by a few things coming together in November ’22.

For a while I’ve been offering my Bellbird Strat set with various winding options – 5% under, 5% over or 10% overwound. I’ve been playing with a 10% over wound set in one of my own Strats and for me they have ‘that’ vintage Strat tone that’s perfect with a little dirt be it fuzz or overdrive.

I was sent a Strat pickup to re-wind and the customer told me his ideal sound was Hendrix. I’d just read an article saying how Seymour Duncan had wound some pickups for Hendrix and the spec of those pickups looked very similar to the 10% overwound Bellbirds. 

That got me thinking.

The same day a customer contacted me wanting advice about my pickups and which one would be best for a John Frusciante sound. 

Well, it’s the Bellbird +10%.

Here are the numbers: 

Neck 6.15 KOhms, 2.79H, AlnicoV

Middle 6.15 KOhms,2.79H, AlnicoV

Bridge 6.64 KOhms, 3.08H, AlnicoV

For the shop and more pickups go to :  mrglynspickups.com

I thought this was too good to let go. 

I could have left the pickup as a version of the Bellbird but decided it needed its own life. 

 

My Strat pickups are named after native New Zealand birds like the Bellbird and the Tui; I chose the Kōkako because its song reflects the tonal characteristics of the pickups. I wanted a bird that has a song fatter and fuller sounding than the Bellbird but not as aggressive as the Tui – so Kōkako Strat Pickup it is.

 

 

Here’s the original Bellbird pickup https://mrglynspickups.com/2020/03/29/bellbird-vintage-strat-set/

 

 

And YouTube demos of all my Strat pickups https://www.youtube.com/playlist?list=PLOdXLT6XwMymw8-Kvl1fQi1wfkQ-iDg7z

Telecaster Bass

There is something so unbelievably cool about the Fender Telecaster Bass. 

The classic lines, that headstock, the pickguard, the association with great players and, of course, the tone. 

What ever it is we all love about this great instrument here’s a pickup to do it justice.

 

 

 https://mrglynspickups.com/2022/10/14... 

 Whether you play with fingers or a pick this classic pickup will deliver. 

More present in the mix than the Precision split pair but with that distinctive punch and clarity. This bass is also known as a '51Bass.

 

 Over the years I’ve re-wound a lot of old Fender pickups. I like to make notes to record what I find in these old pickups, wire gauge, insulation types, d.c. resistance, magnetic gauss, dimensions. 

My notebook is getting pretty full. 

This is my constant reference when I’m designing a new pickup, that and my ears. I’ve based these pickups on the best of the old Fenders I’ve come across over the years.

 Not all vintage pickups are great but when you see enough of the good ones patterns begin to form. 

 I still repair pickups and still add to my old notebook, always learning 😎. 

Thanks to Mark Hughes for his playing on this bass pickup demo, he is available for on line lessons http://www.markhughesbass.com/ Telecaster Bass Pickup - Mr Glyn's Pickups