What’s on *YOUR* workbench?

My last JMK order was Nov 2024. But I just did a quick test with his shop and shipping to my part of the US looked reasonable.
 
Guardians of the analog said:
I don't know if he's even still selling, and with them being in Canada if they are worth paying for extra shipping. I remember a few years back he said he was taking a new job
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Yeah, he was going to be the pastor at a church or something. Been a while since he be heard from him as well. He had some IT questions a few years back.
 
owlexifry said:
once again I'm a bonehead and I've inadvertently found a mod I like from a breadboarding error. this time it's a Buzzaround.
View attachment 117264
so I turned a MkIII build into a Buzzaround with the same MP38A transistors.
tried it, really liked it.
sounds even better than the MkIII, i thought.
captured a demo, even spent time trying to get a good mic position with multiple takes, and then after packing up and uploading, i realized i’d made an error.
- pin 1 of ‘balance’ control, not connected to ground.
View attachment 117266
whoops.
so i checked this and compared.
with pin 1 disconnected, this makes for a heckin huge increase in output volume and some extra girth too.
i like it though. it seems a lot fatter.
could even make it switchable and call it doom mode or something silly like that.

so here’s a demo with this ‘mod’
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That sounds pretty killer to me! I actually have a Buzzaround (GNAT) on my desk right now next to a DAM FS77 from Sheepy Love (build report pending). The FZ77 is a basically a TB MKIII. It's a bit more polite than the GNAT but the DNA is there in both pedals.
 
Guardians of the analog said:
Best thing I ever built. Mine was purpose built to be an all in one box. I've always hoped someone would make my test rig on one board for everyone. Everything you could ever want: oscillator, headphone jack, audio probe, voltage selector and added side DC jack for powering my looper pedal off one power supply when I'm calibrating something like an analog delay or other BBD pedals. View attachment 117331View attachment 117332
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Now you're just showing off...... :rolleyes:
 
analog_bham said:
I actually have two PCBs from him. Some of us who ordered early got a PCB with a horizontal tone pot that was the wrong board. When they noticed it, they sent us replacement parts and a new board with the vertical tone pot. My son and I built both of them.
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So ... maybe you should try your hand at tracing it!



Hmm just checked and my last JMK order was... 2020! 🤯


JMK's store is still online, but the inventory says there's only one (1) TESTING RIG still in stock $15.


Hmmm all the more reason for Robert to develop a similar yet more fully featured product (and the JMK is already fully featured, but GOTA's additions look good.
 
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owlexifry said:
at last 🤟
View attachment 116787
funnily enough, this one was quite a troublemaker 🥵
View attachment 116785
this took me much longer to get a handle on and running properly than it took for a Boss HM-2 or even the MT-2 - both more than twice the size of this circuit.

didn't help that I initially started with a fake TA7136 (got my refund)
View attachment 116788
but that’s not the worst of it.

i’m kinda shocked the problems this bastard circuit has isn’t talked about more, particularly the DS-1A / post-1994 version with dual opamp. fortunately at least one person here posted a DIYSB link that covers this issue.
initially I was referring to the aionfx comet legacy schematic, which unfortunately suggests you can just plop in a 4558 or equivalent...

but you can't, unless you move this diode:
View attachment 116789
View attachment 116790
IME, with the diode in stock position (+/non-inverting input to ground), that spicy signal coming off Q2 absolutely slams the opamp, in a way that makes it sound like a HM-2 doing the chainsaw thing, and not in a good way - if you play gentle it doesn't happen, if you play normally it sorta swells in and out. fucking awful.

i also made an odd discovery that I'm still yet to understand:
- if you skip the input buffer, and hook up the guitar input directly to C2/47n, this problem disappears! wtf... cool! but that didn't sound like a reasonable solution, and i was convinced I had made an error somewhere..

before I had found this advice above, i was stumped.

noting the advice above about opamp selection, i confirmed this with an LM358 - works fine with stock configuration.
RC4580, 4558, LF353 -> absolutely fucked with the stock configuration, and all worked well with the diode between (+) & (-) inputs

little bit disappointed that aionfx has not corrected the comet legacy document with it's misleading advice. the updated/current comet document has corrected this but still, ffs..

noting comments about the redundancy of this 1st opamp/buffer stage in the dual opamp version, i was curious to try out a single opamp version with a KR140UD708 (soviet LM741 equivalent) and set up the breadboard to accommodate both 741 and 4558 for direct swap/comparison.

and then after finding this service manual with schematics for the x2 versions, I had to explore both.

honestly, the OG/pre-1994 version kinda sucks (for me). the larger cap values (1U v 470n; 470n v 68n) make for a flubby response.
yes, im not using the correct TA7136 opamp to assess it properly, but I'm not convinced it would rectify those issues.
I'm going to assume folks that prefer the early version are single coil players.

with the DS-1A values, comparing KR140UD708/LM741 to 4558, i wanted to like the 741, but the 4558 had more volume, punch, and high end detail, where the 741 was smoother, more polite, and a smidge less gain.
with this information, I would probably recommend the 741 for those that prefer a more 'vintage-inspired' DS-1, and the 4558 for those that like a more modern/full spectrum response.

here's my demo (DS-1A version w/ 4558)
surprisingly beefy. gain is cranked up to about 80-90% on the trimpot, so there is a touch of 'sag' going on..

next steps - will have to try some of CDB's mods --> particularly the one with 470R/2U2 for Q2s emitter.. (im not really into the sag)
View attachment 116795
Click to expand...
update:

so i finally got around to it and tried mods #2 and #3 (470R/2U2) as described below. i already tried red LED clipping earlier on, and it is good.
1778200252395.png
glad to finally be done with this DS-1 thing so I can free up the breadboard for something else.

here's how it sounds

sadly I'm not heaps excited about this one.
I'm not sure if I'm getting something wrong or if it just kinda sucks. even with those mods from CDB, it's still got this weird woofy low end that blows under big signal (chugs / power chords etc.). perhaps the transistor and/or opamp selection really does matter to some degree.
 
Feral Feline said:
So ... maybe you should try your hand at tracing it!



Hmm just checked and my last JMK order was... 2020! 🤯


JMK's store is still online, but the inventory says there's only one (1) TESTING RIG still in stock $15.


Hmmm all the more reason for Robert to develop a similar yet more fully featured product (and the JMK is already fully featured, but GOTA's additions look good.
Click to expand...
The schematic is there if you wanted to create your own pcb. Just a thought.
 
You are referring to the Testing Rig in the second half of my post rather than the first half which pertains to the Fuzz Remains, or do you have the Fuzz Remains schematic? I couldn't find a copy of the FR.

However, I've got two JMK Test Rig PCBs; one for me the other for a friend. Me needs to finish populating the second one.
I just think a similar project in Robert's oeuvre would be a great offering for many PedalPCB customers.


I'm indeed working (slowly) on creating a PCB, a utility thingy, but not based on anything else I've seen in the market... yet.

Cheers,
FF
 
Feral Feline said:
You are referring to the Testing Rig in the second half of my post rather than the first half which pertains to the Fuzz Remains, or do you have the Fuzz Remains schematic? I couldn't find a copy of the FR.

However, I've got two JMK Test Rig PCBs; one for me the other for a friend. Me needs to finish populating the second one.
I just think a similar project in Robert's oeuvre would be a great offering for many PedalPCB customers.


I'm indeed working (slowly) on creating a PCB, a utility thingy, but not based on anything else I've seen in the market... yet.

Cheers,
FF
Click to expand...
Test rig.
 
So much nonsense / conflicting junk online about annealing (95% by rifle owners reusing casings). Had to check for myself; just some 650 celcius for a minute or two. Didn't even see the faint glow that I had to wait for, and it bends easier than aluminum.

Time to save up for that finger brake. 100kg. Upstairs. Ugh..
29476.jpg
 
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You'd think a twelve string would take twice as long to intonate and set up, but it's actually more like three or four times! The original saddle screws weren't long enough, so I had to replace those. This meant the springs weren't long enough either, so those have been replaced with mechanical keyboard springs of all things. Also, the octave saddles didn't have enough forward adjustment, so I had to machine those a little bit. It plays in tune now...at least as much as any twelve string does. Once I solder the electronics—it's done!
 

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