Upgrading a Squier J. Mascis Jazzmaster

FullSizeRender_1As you can imagine, I get asked about mods all the time. Recently, my new friend Brent brought his Squier J. Mascis model to me to hear my impressions of it and the many potential upgrades he was looking to have done. As-is, the JMJM is such a good guitar that many players don’t see the need for new pickups or hardware, but given the cheap price he paid and his needs, it totally made sense to do the work.

As I said before, the JMJM is a pretty cool guitar for the money. The neck feels great in your hand, the stock pickups are alright, and it has all of the right electronic appointments a Jazzmaster should have. Still, there’s room for improvement. Let’s jump in, shall we?

Tuners: Actually, these are good enough that I don’t see the need for a swap. As long as know how to string a slotted post correctly (string goes in the hole, 3-5 wraps) they work just fine. Great, actually. Even on my Squier VI!

Pickups: The stock units are pretty decent, but they are indeed P90s instead of Jazzmaster pickups, with big bar magnets and adjustable poles, with a tall coil that’s wound hot. If you want a real Jazzmaster sound, you’re not going to get it from those. Plus, as far as P90s go, I just feel there are better ones out there. I recommend a swap.

Electronics: On this particular instrument, I didn’t totally rewire the guitar. Generally, the one area where the current Squier builds fall short is the dependability of the electronics, which often develop shorts due to sloppy wiring or inferior parts. Instead, I went through and checked every wire and re-flowed some particularly bad connections. I do, however, recommend gutting the electronics and starting fresh with better components.

AOM/TOM Bridge: If you’re familiar with us, you’ll know that the AOM/TOM is the bridge we least recommend for offset guitars, both for sound and setup. Adjust-O-Matic/Tune-O-Matic bridges generally aren’t the correct radius for the most common Fender necks (7.25” and 9.5”) and even with heavy re-slotting of the saddles, it’s not always possible to totally correct that. As a result, the E strings will always feel more stiff than the others.

Additionally, even these bridges don’t always address the most common complaints with the original style bridges: buzzing and stability. This bridge already had some pretty nasty buzzing going on, which was mostly cured by re-seating the saddles. A shallow slot on the low E saddle meant that string impulsively jumped out with heavy picking as well. 

I recommend a change here, but obviously, your mileage will vary.

A Mastery bridge is almost always my first pick here, which does indeed require pulling the old AOM/TOM inserts, filling the holes, then re-drilling. Staytrem also makes a drop-in thimble replacement for these, so do keep that in mind if you’re looking for something less, well, surgical. They also used to make a drop-in replacement, but I can’t seem to find it on their site. I may be interneting improperly.

The Vibrato: I won’t totally rehash my arguments from our prior blog post on the quality issues of import vibrato units, but suffice it to say, if you’re a heavy trem user––hell, even a pedestrian––you should consider an upgrade here. Tuning stability is key, and the sloppy fit of the internals on these can be a nightmare.

In this case, we went with an American Vintage Reissue trem from eBay user trickedoutguitar, which came with the correct AVRI arm with the ever-so-lovely, gentle bend. Mastery also makes a delightful trem of their own, which I recommend highly for truly intense users.

IMG_8439So, when we finished our assessment meeting, I made my list of recommendations known. With Duncan Antiquity Is, a Mastery M1 kit, and an AVRI trem, I felt we’d pretty much covered everything. Obviously, the Mastery and pickups can be a significant investment for such an affordable guitar, but Brent wanted a guitar that would meet his needs without having to think about it ever again. Good call, says I.

After doing all of that and a proper setup by Yours Truly, I really believe we made a good instrument great. The difference in tone, unplugged and amplified, was immediately apparent. Whereas the guitar sounded pretty good plugged-in but was rather dead acoustically, the superior fit of the Mastery bridge and thimbles really made the thing come alive. And the trem? Smooth and immediate, and of course, stable as hell.

When I’m asked about my favorite Jazzmaster pickups, I always recommend Lollar, Novak, and Duncan Antiquity Is, the latter of which I feel does an excellent job of approximating the sound and response a 60+ year old black-bobbin pickup. In the case of this JMJM, we ended up with a brand new guitar, the sound of which belied its youth. Really a stunning pickup set. It has so much of the warmth and midrange complexity that’s associated with the best old pickups, woody and natural as can be.


Brent’s finished Squier J. Mascis pictured with Artoo and Pancake

We came so close to that sound that I decided to do a comparison video of the J.Mascis  Squier up against my 1961 Jazzmaster “Pancake”, which is the greatest guitar I’ve ever played. This was all rather last minute and I didn’t yet have a proper microphone, but the iPhone did a good job showing some of the more overt differences between them. I even threw in “Artoo”, my 2007 Thin Skin with Lollars for fun. Check the video below!

In the end, Brent was absolutely blown away by his guitar, and so was I.

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37 thoughts on “Upgrading a Squier J. Mascis Jazzmaster

  1. G. Case says:

    Thx for the new mail! Always enjoy hearing new about your guitar actions. I’m curious, what do you think about MojoTone Jazzmaster pickups? I have pair with their full electronics and wiring in my Starcaster and I love them. If you get a minute could you let me know your thinking or a URL that might have your line of thought. Ciao, G. Case

    Sent from my iPhone


  2. Will says:

    Love the comparison video, that’s really interesting. For my money, the Artoo comes across best. What pickups does that guitar have? For the record, I’m a ’93 MIJ man myself, with Antiquity IIs and StayTrem bridge and tremolo. Had it since new but the mods have all been done in the last year. Totally changed the guitar for the better. It’s never sounded so good.

    • I hear that! Staytrem stuff is pretty great.

      Artoo has the standard Lollar Jazzmaster pickups. I really love them.

      • Will says:

        Cool. Good to know. Shame I hadn’t seen this when shopping for my pickup upgrade two years ago. But it’s all good, I’ll stick with my Ant2s as they’re working really well in my set-up (and I’ve spent the money so there’s no going back now!). Recently played around with the pickup height and am really getting the full spectrum of jazzmaster tone now (incredible range and clarity through my Laney tube amp with GHS nickel .11s strings).

        I had some problems with the Staytrem and the dreaded buzz, but it was simple to remedy – the little plastic washers just needed tightening. Now it’s a peach. Been a long journey getting here (22 years!!!) but my JM is playing and sounding pretty much perfect right now. Wouldn’t change it for any other guitar. Well, except maybe a Montezuma Ricki 360 with toaster pups. But that’s another story.

  3. Pat Benson says:

    Can you use the replacement thimbles from staytrem with the mastery bridge?

    • HEY Pat! How’s it going?!

      I think you can, yeah. Haven’t had the chance to try it myself, but I’ve read about other people using those conversion thimbles with great success.

      • Pat Benson says:

        Hey Michael, Im great Man! Love the blog/instagram. Keep it up.

        I might try that, or instead just get the M1 kit like you suggested and do some surgery on the guitar if that doesn’t work out. Thanks for the response!

  4. Pat Benson says:

    One last question (i think!) is there a difference between the AVRI trem and the 62 Jag/JM that are made in Japan?

  5. Adrien says:

    Hey ! Great article for a cool guitar. One question though. You mention the AVRI tremolo, is this the one ? http://intl.fender.com/en-NL/guitar-bass-parts/bridge-assemblies-components/american-vintage-jaguarjazzmaster-tremolo-assembly-nickel/

    Living in France I’m having a hard time locating this particular part and I’ll probably have to buy it on ebay. Thus I’d like to know how to truly recognize the tremolo part… Is the patent number (PAT. #2,972,923″.) a good way to be sure ?
    Thanks for taking the time and documenting all your work on this guitar, it’ll be a huge help !


  6. ctonia says:

    Great article, thanks!
    Maybe my lovely Squier JmJm also needs identical job…!
    Greetings fron Italy

  7. Ricardo says:

    Hi! What about the nut? Did you find JMascis´ one good enough for the job (tuning stability specially)?

    • Sorry I missed this! The nut on the Mascis isn’t great, so I’d recommend having a good bone replacement cut by a qualified luthier. For this job, I opted to make it as good as it could be and it ended up working well enough, but I’m sure we’ll replace it down the road.

  8. Inspired me to start looking at upgrading my J Mascis JM.
    Once think I’m really wanting to do is change the pickguard, any ideas where to start ?

  9. Jason DeBack says:

    I have a Squier J Mascis…I have read and read numerous forums regarding the TOM bridge radius misalignment…HOWEVER, I look at mine and the TOM is NOT flat, the low and high E string posts are indeed lower than the rest, what I mean is that this TOM on mine does indeed seem to follow the actual radius of the neck….does anyone know if Fender adjusted this TOM issue to match the radius at some point? I haven’t come across anyone else talking about this, but I looked close and there certainly is a ‘curvature’ to my TOM that does seem to align with the actual 9.5 radius…am I missing something here??

    • Hey there, Jason! The TOM bridge isn’t flat, but a flatter 12″ than the 9.5″ radius of the neck. Sure, there’s a curve there, but it’s not matched at all. A visual inspection won’t tell you what radius you’re looking at, you’ll need gauges like the ones sold by Stew-Mac to see it.

      Fender has never addressed this issue.

      • Jason DeBack says:

        does the mastery bridge addition to the squier j mascis make a significant improved difference in regards to the radius issue of the stock TOM?

  10. Indeed it does! Unlike the TOM, the Mastery isn’t a fixed-radius design, do you can adjust it from 7.25″ all the way to 12″ I believe, which is perfect for most instruments out there. Another one of my favorite features of that bridge.

  11. Alex says:

    Did you install an M1 and did it really require to drillnew holes in the guitar body?

  12. Alex says:

    PS I see there are M1 kits with a thimble, wouldn’t this avoid the drilling? Also, did you have to re-drill the pickguard?

  13. Brian says:

    Sorry, but I don’t quite understand your reply on Alex’s question regarding the M1 kit. If one uses the M1 kit is drilling necessary? What needs to happen to make the mastery bridge fit? Thank you!

    • Ah, Alex asked two questions, and I only approved one. Redrilling the pickguard isn’t necessary on the Squier JMJM, filling and re-drilling the body thimble holes IS required.

      • Brian Lee says:

        Thanks very much for the clarification. That’s what I was afraid of. I think I will soldier on with the TOA for the time being and refer the installation of the Mastery to a more qualified luthier than I in the future.

  14. Chad says:

    How does this upgrade compare to just buying a better guitar from the start? My calculations put this upgrade at about 500.00 in parts. I am just curious because I purchased a JMJM a while back and I like it but could see doing a similar build.

    • Billy says:

      Considering the cost of the guitar with upgrades, one could buy a used AVRI from CL, with patients, for a few hundred dollars more.

      Or same senerio, buy a new road worn or 60’s laquer for a few bucks more. Laquer finish, 7.25” neck radius, & AV65 pickups. Far better electronics & pickups than any of the MIJ / CIJ offerings.

      Not that some great upgrades weren’t done, one has to know when to draw the line when upgrading budget guitars. I’ve been there.

      • Oh yeah, I hear that. I mean, when you look at the value of the parts and work against just spending more for a “nicer” model, it may not make much sense. Still, there’s more to playing guitars than that, so if you flat-out adore your Mascis, then why not upgrade? The one I used for the subject of this post was truly an incredible guitar to begin with, super light weight and with a neck that’s uncharacteristically skinny for the model. Honestly, it blew away the one I bought to mod and never got around to, which I then sold.

        So yeah, you could buy a nicer guitar, but if lightning strikes, go for it. And that’s to say nothing of the fact that you could buy the nicer guitar and still have to do those upgrades. Road worn and Lacquer models still benefit from electronics and hardware upgrades, and if you find the AV65 pickups too bright (like I do) then you’ve got more cash to drop. Nice guitars, but not perfect.

  15. Thought I’d jump in with some of my recent findings. Doing some upgrades to my MIM Classic Player Jazzmaster. It comes with the made in Korea 007-6232-000 Tremolo with screw in arm. I have replaced with American (AV) 005-4466-000 which uses a pop in arm. Also note the threads on the bushing if replacing that (which I did with the staytrem arm/bushing. Metric threads on Korean and American on the AV. Both are stamped with the patent # and have the lockout. AV has the spun markings on the lockout button. I noticed the AV has a thinner top plate, but the tremolo plates inside are a bit thicker (which should perform better?) Either of these would be good for the Squier. But get the American if you have a little extra money.

  16. ..Also, I just ordered the “Staytrem bridge replacement for Adjusto-matic” which I am excited for. The stock Classic Player TOM has been a pain. Right off the shelf they all buzz. I flipped the whole bridge and all the saddles which helped, shimmed the neck, and was good for a while. used files and a radius guage to fix the bridge radius, but then the Buzzing was back! I will be glad to get rid of the TOM and hopefully not need neck shims either.

    • Andy K says:

      Bradley, was just wondering how your Staytrem worked out for you?

      I am considering buying a Staytrem bridge for my MIM Classic Player Jazzmaster (9.5″) to replace the standard (sigh) TOM bridge. I use 0.10 gauge strings, generally play quite hard but don’t use the tremolo bar too, too often. And if I do, not in any kind of extreme dive bombing kind of way, hehe.

      Did you install, by chance, the NON-rocking version of the Staytrem bridge with your CPJM? If so, what are you experiences with it like?

      And one more query. If you did buy the rocking Staytrem bridge and play quite hard, is the issue of the bridge shifting/leaning over time a problem?


  17. Dan says:

    Dumb question: Can I use the original Squier screws to put on the replacement AVRI trem?

    • Not a dumb question! You totally can, but in my experience they’re a bit short and not as robust as the US screws. This surely sounds like a silly complaint, yet I worry about string tension on the vibrato and it pulling off the body. However unlikely that is to happen, those holes do strip quite easily.

  18. james chapman says:

    Hey MJM,

    I’m trying to drop a mustang bridge into this JMJM, but I’ve never drilled and filled. I’m getting some help from my dad, who is a great carpenter but not a luthier. We are wondering what exactly is being used to FILL before the DRILL. Thanks.


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