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Chassis Comparison: Mojotone vs. Zachmdhunter (Princeton Reverb)

Discussion in 'Shock Brother's DIY Amps' started by Phrygian77, Sep 5, 2020.

  1. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    I've been wanting to do this side by side comparison for a while. Even though I've built three Princeton Reverbs with the zachmdhunter chassis, this is the first Mojotone PR chassis that I've had my hands on.

    The first in each of these pictures is the zachmdhunter chassis from eBay. The second one, with the welded corners, is from Mojotone. The former is supposed to be a copy of the latter.

    IMG_20200905_140959.jpg
    IMG_20200905_141023.jpg
    IMG_20200905_141104.jpg
    IMG_20200905_141213.jpg
    IMG_20200905_141050.jpg
    IMG_20200905_141036.jpg

    More to come!

    Now I know why the 1.5" can capacitor clamp from Mojotone wouldn't fit. FYI, the two piece clamp that AES (Amplified Parts) sells fits the former chassis.
     
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  2. King Fan

    King Fan Poster Extraordinaire

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    Thanks. Look forward to your reports. Any other holes different in spacing or size? IIRC, some years back I had to drill two new mounting holes for the cap can clamp (Mojo provided the JJ cap can) in my Mojotone chassis, and maybe also a new hole or two for the OT mounts; can't recall if it was spacing or I just wanted to get it out from under the board or something. But despite that I really liked the Mojo chassis at that time -- super solid, easy to work, only a couple holes to drill or move. I wonder if they've changed suppliers? I'm impressed here with the finish on the zachmdhunter.
     
  3. mjcyates

    mjcyates Tele-Meister

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    I have purchased 2 vibro champ chassis's from zachmdhunter. I am a fan.
     
  4. BigDaddy23

    BigDaddy23 Tele-Holic

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    ^ditto

    I've used 3 of them and they're super. Only mods I've had to do was drill 2 new holes for the cap can on a Princeton Reverb build, elongate PT mounting holes to suit my trannies and couple for my home build board mounting screws in all. Really well made and robust.
     
  5. SKEsq

    SKEsq TDPRI Member Silver Supporter

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    I have used the zachmdhunter chassis to house the RobRob JCM800 Micro. I chopped into it to fit a different transformer, but overall it seemed pretty comparable to the Mojotone version which I have as part of their Princeton Reverb Kit.
     
  6. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    I'll be measuring everything. I'm actually planing to have some custom chassis made. I had approached zachmdhunter about a run of chassis. All I wanted was some minor tweaks. One of the main things that I wanted was the board mounting holes reduced to .154" (#23). They told me that their fabricator was behind, and they couldn't do it for the foreseeable future. Okay, whatever, I'm sure someone else will take my money.

    As far as the finish (or cleanliness rather), the Mojotone just has some remnants from welding that weren't cleaned up. This zachmdhunter chassis is one of the cleanest I've gotten from them. I've had a few that I really had to clean up with mineral spirits. They also usually have some scratches here and there.

    I've done a total of 6 builds with zachmdhunter chassis (3 Princeton Reverbs, 2 Vibro Champs, and 1 blackface Bassman). Every one of each chassis type has been exactly the same, but there are odd differences between the chassis models. I've noted this in some of my other posts. The Vibro Champ chassis, for example, has shorter mounting centers for the 9-pin sockets than the other chassis. I had to elongate them to fit. There's a photo here in my last VC build thread...

    https://www.tdpri.com/threads/vibro-champ-build-2.973955/#post-9344299

    Another difference is that the Bassman chassis had keyways for the switches (power, ground, and standby). The Princeton Reverb chassis does not. One difference that I really don't understand, is that the VC and PR chassis have a slightly different PT cutout, and different sized PT mounting holes. What sense does that make? In all, I had to make a lot more corrections to the Vibro Champ chassis than I did the Princeton Reverb chassis.
     
    Last edited: Sep 6, 2020
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  7. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    Mounting holes for the board and the output transformer are different.

    This is my board template that I crated to match the zachmdhunter chassis. It includes the OT hole locations (and my own for a DR OT).

    IMG_20200906_140245.jpg


    Matched up with the zachmdhunter chassis...

    IMG_20200906_140226.jpg

    IMG_20200906_140233.jpg


    This is the Mojotone chassis...

    IMG_20200906_140602.jpg

    IMG_20200906_140551.jpg
     
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  8. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    This is the zachmdhunter chassis, turned over. Tape measure from the rear of the chassis...

    IMG_20200906_153852.jpg

    IMG_20200906_153923.jpg


    And the Mojotone chassis...

    IMG_20200906_153711.jpg

    IMG_20200906_153723.jpg
     
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  9. theprofessor

    theprofessor Poster Extraordinaire

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    Thanks for doing this. I have used both with good results. I always end up having to drill several new holes in the chassis, anyway.

    One difference I noted with the chassis from Zach Hunter is that the faceplate I ordered does not exactly line up at the pilot lamp hole. I'm not sure if that's an issue with my source for the faceplate or with the chassis itself. At any rate, I had to use a Dremel to make them align properly so that the faceplate wouldn't bulge at the front. After that, no problems at all.

    For the quality of manufacturing and the price, the Zach Hunter chassis is unbeatable.
     
  10. mjcyates

    mjcyates Tele-Meister

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    I had the same issue with the pilot lamp hole.
     
  11. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    I originally assumed that the Hunter chassis were exact copies. They look almost exactly alike. In fact, I thought they may have even been made by the same fabricator. I later suspected there were differences between the two, especially after reading somewhere that the Mojotone has welded corners.

    I didn't have any issues with the Mojotone faceplates fitting on the zachmdhunter chassis. I did however have issues with vintage style reproduction faceplates.

    Here's the Mojotone plate on the Mojotone chassis...

    IMG_20200906_165010.jpg
    IMG_20200906_165020.jpg
    IMG_20200906_165026.jpg
    IMG_20200906_165035.jpg


    This is the same plate on the zachmdhunter chassis...

    IMG_20200906_165219.jpg
    IMG_20200906_165225.jpg
    IMG_20200906_165231.jpg
    IMG_20200906_165238.jpg
     
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  12. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    Now, here is a reproduction Princeton plate...

    IMG_20200906_165449.jpg
    IMG_20200906_165457.jpg
    IMG_20200906_165507.jpg
    IMG_20200906_165513.jpg


    You can see in these pictures that the Mojotone faceplate is considerably different from vintage style faceplates...

    IMG_20200906_165744.jpg
    IMG_20200906_170021.jpg
    00000IMG_00000_BURST20200906170126211_COVER.jpg
    00000IMG_00000_BURST20200906170105310_COVER.jpg
     
  13. CordovaNate

    CordovaNate TDPRI Member

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    I've used a ZackHunter chassis for a Princeton Reverb build. The only notable alteration I had to make was to enlarge the hole for the cap can. It was perfect for the CE brand but the JJ 4/20/20/20 cap can was too fat for existing opening.
     
  14. King Fan

    King Fan Poster Extraordinaire

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    This is good info throughout; thanks, @Phrygian77 .

    I'm under the impression that zachmdhunter basically creates carefully-measured repros of each Mojo chassis and maybe gives them a few small tweaks or fixes. The tweaks may vary from model to model, and Mojo may evolve a few things over time. Zach told me at one time that his 6G2 chassis reproduced the Mojo including a couple weird choices (mistakes?) Mojo featured then, like swapping the fuse hole with the power entry hole and a 'big' PT cutout. Likewise, IIRC, Mojo's PR chassis at one time had board mounts, OT mounts, and cap can mounts (for a can with a clamp) that were better off moved or enlarged -- zach may have 'fixed' or tweaked some of those and not others. Finally, if you're saying Mojo faceplates fit the Mojo *and* Zach chassis well, that goes along with my 'Mojo repro' idea.

    Can you add it all up for us, at least on the PR version? I'm getting the impression that the Zach version is less expensive and "at least as good if not better." Or am I missing something?
     
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  15. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    They are definitely not exact copies. The Zachmdhunter chassis is about 3/16" deeper than the Mojotone. The position of the first chassis strap hole from the rear of the chassis is exactly 1" on the Mojotone, and it's 1-1/32" on the Zachmdhunter. So, you can see right here where making the assumption that they are the same could get you into trouble. I've had issues with the Zachmdhunter chassis not sitting correctly (too far forward) in Princeton Reverb cabinets with predrilled chassis holes. And, I always felt like the RCA connectors were sticking out too far. Well, now I know why.

    You don't want this...

    IMG_20200510_111544.jpg
     
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  16. King Fan

    King Fan Poster Extraordinaire

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    Yeah, for sure, that's the kind of thing I overlooked despite all the detail above. Thanks!
     
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  17. sds1

    sds1 Tele-Afflicted

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  18. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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  19. sds1

    sds1 Tele-Afflicted

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    Not to be obvious but I reckon mojo and Zach have both revised their drawings over time, who knows which versions you have in front of you now are based on what since nothing including the dimensional drawing have versioning indicated.

    They made of the same gauge material? The mojo one is quite a bit more expensive! What's ideal, the mojo chassis at Zach price or something in between?
     
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  20. Phrygian77

    Phrygian77 Friend of Leo's Gold Supporter

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    The Zachmdhunter chassis hasn't changed at all, as far as I can tell, over the last 3 years. I'm saying this after going back and looking at my emails to Peter Mather with dimensional info, and they have all lined up, including this latest one, with the drill templates that I created from the original (the one I got 3 years ago).
     
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