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The Boost is a feature brought over from the original Blackstone circuit. In fact, the Blackstone has TWO internal trimpots for boost! One is a straight boost (more gain) and the other is frequency dependent. For the Mysterioso, I reduced this to one trimpot which has a switch that can be used for full frequency or frequency specific boost. You do not have to have either installed, if you don't want to. Simply leave off the switch, C6 and jumper pads 3&2 of the boost trimpot.

If you don't want to have the 'buffer/reactive" feature, I suggest leaving off the "buffer" part. This means you can leave out C1, R2, Q1, R3 and C4. Also, you will need to jumper pads 1&2 of the "B/R" switch.

Thanks for the replies, Boom and Brian; much obliged. I was planning on wiring the boost to an external pot as shown in the PDF layout; presumably I could then leave off the trimpot, no? I'll be keeping the switch for fullfrequency/mid selection on the boost to see which I like better as time goes on. 

Looks like removing the volume pot from the circuit is just a matter of jumpering the relevant pads, ya?

That's exactly what I needed to know about the B/R switch and related components, thanks!

Mysterioso layout, for reference:

Good times, the PCBs arrived yesterday. Really nice work, Brian!



It's funny, for some reason the PDF versions seemed larger, on the same scale as my GGG PCB (yes, I set to 100%  ). 1/4 watt and 1/8 watt resistors it is! I'm going to build the Neutrino according to plan; no funny business for that pedal. But the Mysterioso...I'm good enuff with a soldering iron and diligent enuff in following layouts to build the pedal as is, but I'd rather dispense with one of the knobs...and a switch, too. Can yall help me sort that out? Here's my preliminary questions (should I post a layout on the thread?):

1. I don't want the B/R switch; this will be the first pedal in the chain. Besides the switch, which other components does that eliminate, and will I need to jumper any connections or what have you?

2. Why is there a BOOST and a VOL pot? I know I want the boost on at all times, isn't the volume working against that to begin with? What changes to components and the circuit does eliminating the volume control entail?

Thanks, guys.

Box caps offer uniformity in size. That's the main advantage for me. And, as I said, they "sound" very good, too.

Ah, gotcha.  Thanks!

Enclosures, meter, and wire are now on hand; I'm thinking that I'll want to snag a few different brands of certain components to hear the differences...what's the best way to setup a particular component for swapping? I've seen turrets and those IC heatsink things, but I have no idea on the merits of one method over another, or if there are other methods that might be even better, what do yall think?

No bulk buys for me; just wanna put my fabrication skills to use on a handful of pedals, then stick to playin. 

After doing a preliminary check on prices, I think I will go with Vishay to the extent possible; I'm also really digging Sozo caps, but those are spec'd for use in amps.

I'm seeing that quite a few 1/2 watt and 2 watt Vishay resistors will fit on Brian's PCBs, btw. Actually gonna wait on the PCBs to arrive before I order parts.

What IS the functional purpose of using box/drop caps in certain positions, is there a dissipation factor that I'm missing?

That's what I've been reading; the larger resistors...larger anything, really, dissipate heat more effectively due to increased surface area, thus lowering the thermal noise floor. Not all noise is thermal, tho, so there may be other considerations, like component separation, for example.

I'll stick with the 1/4 watt metal film units, and just use those throughout all 3 builds. I'm thinking of going with Vishay for ALL the caps in my compressor build, and get enough to swap in and out of the Mysterioso and Neutrino. Sometimes, "lesser" caps just sound better in a particular circuit.

I'll be using 22ga stranded and solid pushback for the lead dress, and I also have a supply of vintage type braided shield, which I was thinking of putting on the DC power supply to the board. I did not enjoy my experience working with whatever plastic was on the leads in my GGG kit, and I really dislike teflon, as well. Seems to me many pedal designs could benefit from better shielding inside the enclosure, e.g. between the pots and the PCB.

Is there any reason to insist on mylar/mica/etc for particular cap values, or is it just a matter of those materials being common for caps of certain values? From what I've read, film caps are much quieter and more transparent than the other options, no? I can see from the layouts which caps are electrolytic (I think...they're the ones with a defined polarity, right?), but I can't differentiate between any of the other types, which...from what I'm reading, are functionally equivalent? Thanks again for takin the time.

I've got a couple of Brian's PCBs on the way, the Mysterioso and Neutrino. I'm also going to build a Ross-type compressor; being a rabid hater of noise in audio circuits, I've been researching components with low noise floors, and it's led to some questions.

First, just to confirm...metal film resistors seem to be a common suggestion for those looking to reduce the noise floor thru component selection. 1/4 watt seems to be the standard recommendation, all reasonable and sensible. How much larger are the 1 watt resistors, and would they not reduce thermal noise?

Second, I've always heard good things about Vishay capacitors, their and their effect on guitar audio circuits. But, they're spendy, and some folks say they're irrelevant outside of the signal path. There's no good reason to just use Vishays throughout? Any good reason NOT to, outside of price?

Third, thermal noise being one of those issues that can only be defeated with blunt force/size...wouldn't 24mm pots be quieter than 16mm pots, all else being equal? I have plenty of room in my enclosures to use the larger pots, any good reason not to?

Thanks for takin the time!

Been playin to the pay the bills for over 20 years now, but there's been some side jobs too. Up until a few months ago, I would never have considered doing the builds I've done recently, like modding my vintage amp, building a TS clone, engineering a 4-coil humbucker; it's something I've always thrown money at, or known someone who could do it for me.

All the while, I was repairing and modifying vintage jeeps as a hobby, and applying that knowledge to my music gear over the past few months has been a great experience so far; no more wondering about the quality of someone else's work, and no more substandard parts in my signal chain.

Plus I end up with "handcrafted, American-made" stuff when I'm all done! 

All the jack contacts are clean? sometimes oxidation will give off a funky sound, especially when the SNR is real low.

I've only got the one TS Clone on my board right now, but that's going to be joined by a Mysterioso Jr. and a Neutrino very soon. I really like the sound of two Tube Screamers in series for the wild, wailing stuff, can't wait to have that back.

The Blackstone is a different animal; if I could have just one OD pedal, it would be that one, even over the TS variants.

Just wanted to introduce myself, my name is Lefty Phillips. I'm a working blues musician, just finishing up a months-long effort to gear up for electric after playing acoustic gigs for the past few years. Most of my adventure is documented over at Mylespaul.com under the same nickname.

In the past 6 months I've done alot of things I never imagined doing, like repairing and modding my vintage Deluxe Reverb, engineering a 4-coil humbucker, and building a TS clone, the GGG ITS8; at this point, my rig is functional, and I've been in rehearsals for the past few weeks, but I'd like to get things set up just right to my liking, so at least couple more pedal builds are in the works: The Mysterioso Jr., and a Neutrino to interact with my ITS8.

I'll be posting both builds here on Brian's forums for yall's entertainment, and asking alot of fundamental questions along the way; over 20 years of building, repairing, and modifying vintage jeeps has left me with plenty of fabrication skills, but I still can't read a schematic! I also like to think outside the box, which tends to make for some unusual ideas. Looking forward to lotsa fun here, and much respect to Brian for doing what he does!