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SurfGuitar101 Forums » Gear »

Permalink Modifying MIJ Jazzmaster

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I have a MIJ Jazzmaster (2012) that I have spent a fair bit on to get it sounding more like my American Vintage Jazzmaster (2012).

So far I have replaced the pickups with Fender American Vintage ones, replaced the vibrato with a genuine American Fender one and the Bridge with a mastery.
Even with the new pickups, the guitar still sounds pretty thin and brittle.

Would anyone know how big a difference replacing the caps/pots would make to the overall sound?

Would anything else help?

The feel of this is nowhere near my American Vintage and I might be asking too much but it is still a great guitar to play plus I've spent too much to stop now!

Any advice would be greatly appreciated.

See Rapt In Blue:

There's a few players here who have recommended changing out the loom on Japanese export Jazz/Jags. They say it's a cheap worthwhile upgrade but I have never thought to ask if the loom is an off the shelf Fender part.

A poorly cut nut can soak the life out of tone especially if you've moved up a couple of size of strings - string strangulation!

Beware the sunk costs fallacy.

But yeah, get some fresh CTS or Alpha pots and decent caps in there (Sprague Poly ones are good quality, and should last a couple of decades), and some decent cloth wire. Make sure the cavity is well lined with grounded shielding, too. You're talking maybe £30 for all the materials, so it's silly not to - I do this on any £150 Squier I'm asked to tidy up. Switchcraft jack socket as well, while you're at it. Do that, and the nut as Crumble says, and you've basically done everything that can be done. Anything else that could affect tone is wood or frets.

Tweaking and mixing parts is a crap shoot.

One may be overlooking the fact that the wood may be different and the issue for both body and neck on the MIJ vs an American Standard or vintage Leo made guitar.

That's not to say that there isn't a good MIJ guitar. I found a great sounding MIJ Fender P-bass. Plays/sounds better than my MIA P-bass ever did. But this was the MIJ bass made for Japan-only consumption, not the "export" model that was an agreement with Fender USA to not clobber their American market, that Japan only sells those Japan-only issues in Japan.

The MIJ bass I purchased as 3rd owner was purchased from a seller who bought it from a Japanese gentleman friend that was in essence gifted to the seller.

One can try to find parts that may enhance the sonics of the wood of the MIJ whatever that might be, rather than buying parts nilly willy because they are deemed "better parts." It's hit and miss if it will make it sound better off the bat..

It doesn't work in a linear way.

It's like trying to photograph someone's face who has moles and scars with too good of an HD camera when a lower-rez camera would be more flattering, if you can follow this analogy.

"Better" parts will tend to enhance certain undesirable overtones that may detract from the sound rather than enhance it.

It's a balancing act.

Another issue is if one is willing to spend time and money finding the magic combination, of any parts, for that matter, with so many do-overs.

Reason that when buying a guitar, some go through many guitars at the store to find the one in the bunch that has their mojo. Or go to several stores until we find something that has an inherent sound that sends us. If not, keep looking.

Not every store will allow us to do that, open boxes of new guitars, only what's hanging on the racks.

If the guitar is ordered online we're facing the luck of the draw.

And this can be said for no matter where the guitar is made.

Sometimes better suited strings is a good start.

I find D'Addario's to add life over other brands.

Replacing the neck plate screws with better grade stainless screws helps in the sustain department and is also a good start.

And then changing the jack to a Switchcraft on an MIJ guitar adds better connectivity with the better cable plugs.

Per Dragon

Reason that when buying a guitar, some go through many guitars at the store to find the one in the bunch that has their mojo. Or go to several stores until we find something that has an inherent sound that sends us. If not, keep looking.

Dead on and best method-what I used to do before I bought my last Jazzmaster Lacquer online. Piece of junk compared to my other guitars I played first. Won't buy guitar online again.

Will continue to follow this post for suggestions to "fix" Jazzmaster. Thanks all!

Agent Surfcat Cool

Agent Octopus
Reverb Galaxy
Reverb Galaxy at CD Baby

I'll weigh in here.

Most pots will have little resistance when at 10, so caps and pots shouldn't have much effect at full volume and tone. To confirm this, measure the resistance between the pots' lugs. If your issue with tone is not there with pots at 10, but it is there at other positions, then new pots and caps might be in order.

Unless there was a noise or hum issue, I don't see how changing the wire should matter much. Likewise with a new jack, unless yours is dirty or doesn't make a good connection.

As far as the nut, wouldn't that only affect the tone of open strings? You didn't mention tuning stability, so binding strings at the nut doesn't seem to be an issue.

If it were me, I'd run a pickup directly to the jack to see what it sounds like. My guess is that it will sound a lot like what you have now.

Are any of the strings fretting out? This will certainly rob volume and tone. Strings not seating well at the bridge will do that, too. I assume a mastery bridge will not have this problem, but I don't know. Have you tried shimming the neck to get a greater break angle to the tail piece?

I'd consider how I'd feel after putting more time and money in this guitar and still not liking the tone. You might consider putting it back to stock and selling it. When you A/B it versus your other JM, you are disappointed, but it might be just the sound a new buyer is looking for.

Good luck, and keep us posted

Wow, thanks so much everyone for the fantastic response to my question.

The advice in regards to the wood rings pretty true in this case I'd say. Even when the guitar is not plugged in you can just FEEL something is missing compared to my American Vintage.

The fit and finish and playability are all fantastic but there is just something lacking. I guess in most cases you get what you pay for...

I'll let you guys know if I decide to continue down the money pit!

See Rapt In Blue:

I have a 90s Japanese Jazzmaster (heavily modified, of course) and a Thinskin American Jazzmaster.

Both make insanely great tones. Both resonate differently: the JP JM is heavier with a deeper resonation, and the nitro thinskin resonates wildly and freely like its a living thing! Both have Mastery bridges, both have similar pickups, and both have American wiring. Yet they feel and sound different.

Its possible you got some bunk pickups. But its also possible that you got some "void wood" that just sucks up the tone rather than resonate it out. Of course, some people say that wood doesn't matter so much. I am not an expert, but I've had some cheap wood Jazzmasters that I've modded with the exact same components and the guitars didn't sound nearly as good. And like my paragraph above, two electronically similar guitars sound and feel different.

The only way to really tell is to try new pickups and wiring. But that's another investment in what might be a dead end.

Keep us posted on your findings, and good luck in your tone search!

This would be an interesting experiment, but would take time and motivation on your part.

Swap the electrical components between the guitars--pickups, pots, wiring. If the holes in the pickguards and control cavity cover match, this would be relatively easy. If not, well, a little harder.

Record all four configurations and post the results here.

You are looking for differences between the two guitars that you did not recognize. Here is a possibility--the thickness and material of the vibrato plate. By the vibrato plate I am referring to the metal plate that holds the ball end of the strings. I have greatly improved sustain and tone of guitars with jazzmaster-jaguar type vibrato by gluing 2 to 4 ounces of lead weights onto the vibrato plate. See my discussion about gluing lead weights onto strat vibrato blocks for how to do this

In my opinion, this is the most likely explanation. Another reasonably possible explanation is that one or more connections between the volume pot and the output jack are weak and need more solder.

The Insanitizers!

Last edited: Apr 17, 2018 16:17:07

I bought a late-80s MIJ Strat in the early 90s primarily because I loved the neck on it. I used the guitar extensively for live and recording but always felt that it lacked the definition, clarity and punch that it should have. Flipped pick-up sets - tried different strings etc. To cut a long story short, in the end I bit the bullet and ordered a light weight swamp ash body from Warmoth and the difference is unbelievable. Considered upgrading a couple of times but never found anything with a neck like that MIJ Strat neck. In the end I worked out what I liked and didn't like about the guitar, did a bit of research buy way of trying different guitars, looked at the costs involved and made a decision based on that. In the end buying a new body was way cheaper than forking out on a new guitar.

Thanks again to everyone who has posted. Some great ideas and thoughts here.
I think I might order the electric componants and slowly change things out and see how that sounds. Nothing much to lose except time I guess and it would be a good chance to work on my soldering skills or lack there of...

See Rapt In Blue:

What are the values of the pots in the two guitars ?

ldk wrote:

I'll weigh in here.

Most pots will have little resistance when at 10,

They have maximum resistance at 10.

ldk wrote:

pots shouldn't have much effect at full volume and tone.

They have much effect at full volume and tone because their value determines the amplitude/height (Q) of the resonance peak of the pickups.
They are made with pretty big tolerances (compared to resistors and capacitors). A 1M Ohm pot can measure 800kOhm or 1,2M Ohm.
A lower value pot will give a less thin or darker tone.

ldk wrote:

Unless there was a noise or hum issue, I don't see how changing the wire should matter much.

Wire has capacitance. Capacitance determines the frequency of the resonance peak of the pickups. Crappy (higher) capacitance wire, if there's a lot, will make the pickups sound darker because it will shift the resonance peak of the pickups downwards (to a lower frequency).

ldk wrote:

If it were me, I'd run a pickup directly to the jack to see what it sounds like. My guess is that it will sound a lot like what you have now.

It won't.
Running it directly, the pickup sees a resistive load of 1 M Ohm, namely the input impedance of your amp or first active stompbox.
Running it with both volume and tone pots in circuit it will see a resistive load of 333kOhm (1M Ohm vol, 1M Ohm tone and 1M Ohm amp input impedance in parallel).
As previously explained, the resistive load determines the amplitude/height/Q of the resonance peak.
The higher the resistive load the taller the peak, the brighter the sound, because the frequency of the peak is in the treble range.

baddbear wrote:

Would anyone know how big a difference replacing the caps/pots would make to the overall sound?

If they are of the same value, the sound will be identical. You change them for more reliability not for their sound.

baddbear wrote:

Would anything else help?

True Jazzmaster pickups are low inductance, low capacitance and have no eddy currents. That by itself makes for a bright sounding pickup.

Usually you'd mellow down such pickups with lower resistance pots (like the 250k Ohm pots in a Strat for example) but in this case 'they' did quite the opposite and used 1M Ohm pots. This greatly amplifies their bright character.
It can also make pickups with fairly similar specs sound very different. With lower value pots on the other hand, the peaks in the frequency spectrum are almost flattened out and differences between different pickups become much less apparent.

Jazzmasters can be very bright and thin sounding. I like that sound in some cases and the times I don't I turn down the volume to around 7 (unless there's a treble bleed cap) or the tone to 3. That will remove the huge resonance frequency peak and will give a more flat frequency response.

The great thing about pickups that start out with a very tall peak that is also in the very high frequencies, is that there is a lot of room in tuning these pickups to your liking by adding resistive or capacitive loads. This way you can lower the amplitude/height of the peak and/or lower the frequency of the peak.

Last edited: Apr 25, 2018 02:58:53

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