Guitar Gear Forum

Tortuga wrote:

Hipster Salad wrote:Just putting this out there, the Jet City JCA800 is wedged in the JCA20 chassis

Oddly enough, I have more room to work with in regards to the JCA800 than my Ceriatone 2204. It was a super tight fit to put in another 12ax7 socket and effects loop on my Ceriatone, but I have plenty of ample space if I want to do the same with the JCA800.

Yeah - that Ceriatone looks like it's a tight squeeze.


The Mojotone layout on their small box chassis looks workable, though:



Should be plenty of room for me to locate the loop board above V1 & V2... might just pull the board and mock it up, since I can't really do much more until the transformer reaches Mojotone (Monday, according to the tracking I have) and we determine course of action from there.

Hell... I might get a right bug up my ass and start pulling everything so I can start building into the new chassis as soon as it arrives.

Gonna be ordering some things I'll be needing if I do this (in addition to the chassis, cage nuts, and chassis screws from Mojotone): wire (seriously considering solid core stuff this time), grounding lugs, tube sockets (don't want something breaking on me after the solder/resolder work), and more fuses, for starters.




BTW - thanks for the pics, Cale - that really helps me keep things clear in my mind.

Already cooking up a future amp build using the perf board and turrets like JCA did - love that kind of construction

No prob! I will say, the Ceriatone gut shot is outdated by 2 days . I have since moved the loop board to right behind the loop jacks, as it created a shit ton of squeal near V1 and V2 (since I added another gain stage to it at least). I just drilled a hole in the board and used a standoff to secure the loop board there, and it's great now.

I really, really wanted to do a 2204 ground up build, but then the Jet City thing landed and couldn't pass it up. Maybe if I offload some of my amps I'll order a kit, but that might be a while. Scary saying this, but I'm at a point where I have too many amps.

Are you thinking I may have an issue with noise having the Metro board right above V1 & 2?

Tortuga wrote:Are you thinking I may have an issue with noise having the Metro board right above V1 & 2?

If you aren't adding another gain stage, then no it should be fine. You also have more room to separate the loop board from interfering with the voltages going through V1/V2. It's crazy what you can hear when simply moving wires with a plastic pick when you have live voltage running. Then you'll get paranoid about your ground scheme and want to rip everything out and do it another way

Hipster Salad wrote:

Tortuga wrote:Are you thinking I may have an issue with noise having the Metro board right above V1 & 2?

If you aren't adding another gain stage, then no it should be fine. You also have more room to separate the loop board from interfering with the voltages going through V1/V2. It's crazy what you can hear when simply moving wires with a plastic pick when you have live voltage running. Then you'll get paranoid about your ground scheme and want to rip everything out and do it another way

Good to hear, and definitely not looking to add another gain stage - got plenty of pedals for that

Lead dress is HUGE! It can make all the difference between a noisy amp and a quiet one.

Mojotone sent me the sales info for the replacement transformer, chassis, faceplates, and other hardware I need. Just gotta get some more wire and possibly a few tube sockets, and this second build is on!

Got the word Friday that Mojotone was shipping me the parts they have (transformer, chassis, hardware) and that the faceplates will need another week. So cool of them to move forward without even having seen/inspected the transformer I returned (should be arriving tomorrow, according to the tracking info I have).

Purchased wire, tube sockets, and some other stuff from Antique Electronic Supply.

Mojo amp v.2 coming soon!

Something wicked this way comes...

Progress has been made since last postings...

I have ordered and received everything I need to rebuild the amp into the new short box chassis, and will be installing it into the JTM cabinet I hinted above (story on that to come...) for now. I'll be doing a phase II (or really III) version of it later, but I think that'll be pretty damn cool to start.

I did some test measuring (coil resistances) of the replacement PT that they sent me, and I'm a bit concerned about one of the windings. They tell me to hook it up to power and check again before worrying about it, so I'll try doing that this weekend.

I'm building up some of my infrastructure to help me build this amp more efficiently and (hopefully) enjoyably. Working on improvements of my bench, tool storage, lighting, and other fixtures, like this amp cradle I just finished building:









Still needs sanding and finishing, and yeah - it's made from MDF, but it'll be serviceable for now. If I get a bunch of use out of it, I'll probably build a new one from better materials and implement some improvements I determined would be useful while building it.

...and probably paint FLAMES on it!!!!

The amp cradle is awesome!

Got stalled on a lot of other projects around the house for the last couple months, so no other amp building for me...

Decided to put the power transformer up on the bench Thursday night, and see if my concerns about no conductivity between the high-voltage secondary was justified... Yup - was just as I'd thought. Perfect voltages across the heaters and from one outer high-voltage to center tap, but there was little voltage leaking out between the two outer legs. Either that coil is fucked or something's up with the wiring inside the bell.

Called Mojotone, and described what I was seeing. They ordered a replacement for me on the spot. No questions... no shipping it back for analysis... nothing...

New shipment due in from Heyboyer on the 30th, and it'll ship to me immediately.

I'd say it sucks to be hit twice with the same component failing, but Mojotone is a phenomenal company to work with, and I'm completely happy about where this is going right now. I'm chalking the transformer issues up to Covid and leaving it there.

Will probably begin a new build thread when I start building the amp in the next week or two.

ledvedder and Hipster Salad have me looking seriously at a few mods (JEL-related), and I may put the main gain-related mods on a switch so that I can retain the stock 2204 sound.

Called Mojotone today. Product shipment came in just this week, and they've started the shipment. Tracking shows Monday. Fingers crossed this one works

Now I gotta find my meter... where the FUCK is my meter????!!?!?!

So you have a 3rd chassis that needs a head shell?

Going to be rebuilding the 2204 into a short chassis, Mort. I am after a proper 70's-style JMP, and decided I'd do a full rebuild, which lets me address the PT swap without worrying about all the work I did on wiring, as well as give me the equivalent of a second build for more experience.

I've got an actual Marshall Hendrix (plexi) dummy headshell that Mike hooked me up with (his brother-in-law actually found it and a JCM800 dummy shell sitting by the road, apparently) that I'm going to install the new short chassis into, to get me going, but have been thinking seriously about modifying and re-covering the JCM800 shell to make it closer to a JMP. Mods would be a new front baffle and removing the extra wood trim on the upper panel. I'll post more about that in the new thread I'll start when I get back to this build (hopefully in the next week, provided I can find MY FUCKING METER!!!!! ).

Tracking shows the new PT is due here tomorrow. Can't wait

New PT arrived safely (TRIPLE-boxed with layers of padding between each ).

Initial resistance testing of all coils looks good

Long time ago (pre-mortatone) I sloppily built a headshell for a JTM45 project that Slagle put a tobacco burst finish on. Sold the chassis a long long time ago but still have the headshell in my shop. It's dusty as hell and needs cleaned up but as whacky as it is, it needs another chassis someday. I'll be happy to mail it to anyone that could use it.

mortatone wrote:Long time ago (pre-mortatone) I sloppily built a headshell for a JTM45 project that Slagle put a tobacco burst finish on. Sold the chassis a long long time ago but still have the headshell in my shop. It's dusty as hell and needs cleaned up but as whacky as it is, it needs another chassis someday. I'll be happy to mail it to anyone that could use it.

I think I remember that one. I’d love to have it!

Tortuga wrote:

mortatone wrote:Long time ago (pre-mortatone) I sloppily built a headshell for a JTM45 project that Slagle put a tobacco burst finish on. Sold the chassis a long long time ago but still have the headshell in my shop. It's dusty as hell and needs cleaned up but as whacky as it is, it needs another chassis someday. I'll be happy to mail it to anyone that could use it.

I think I remember that one. I’d love to have it!

It's all yours. I'll dig it out and clean it up this weekend.

Dude...

If you have an old picture of it, I'd love to see what it looks like again. I could swear I remember seeing it on an old post of yours or Paul's somewhere, but I couldn't find it (not to mention so many photobucket/other hosted pics seem to be blank in old posts now )

Thanks man!

Hurry the fuck up with that pic !

Started the rebuild - new thread here:

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