Particle Accelerator - Alembic F-2B clone

In my never-ending quest to tinker with the Particle Accelerator I harken back to @vigilante398's tutorial on Tubes 101 (https://forum.pedalpcb.com/threads/tubes-101-intro-to-tube-preamp-design.10625/) re: the relationship btw the cathode bypass cap and coupling cap in affecting bass response. If we're using a smaller coupling cap to moderate bass freq why do we care about the size of the bypass cap? The Kingsley Page, for example, has these itty bitty cathode bypass AND coupling caps. If he's thrashing out all of the bass with his coupling cap is he just beating a dead horse with the bypass caps?
 
Would there be any issue sticking a di transformer in the same box as a PA? I don't see any reason there would be.

A PA would be a great replacement for my MXR m81 at the end of my board
 
matmonster58 said:
Would there be any issue sticking a di transformer in the same box as a PA? I don't see any reason there would be.

A PA would be a great replacement for my MXR m81 at the end of my board
Click to expand...
You would need to find one that fits, but electrically shouldn't be an issue. Throw the transformer at the end of the signal path and you have a tube D.I.
 
vigilante398 said:
You would need to find one that fits, but electrically shouldn't be an issue. Throw the transformer at the end of the signal path and you have a tube D.I.
Click to expand...
Any recommendations? I'm thinking cinemag but I don't have any particular reason for that choice besides their reputation
 
matmonster58 said:
Any recommendations? I'm thinking cinemag but I don't have any particular reason for that choice besides their reputation
Click to expand...
I have a grudge against Cinemag because a couple years ago I tried to place an order, they took my money and ghosted me for 4 months until I filed a paypal claim to get it back. They cited the pandemic supply chain issues, but supply chain issues don't prevent you from replying to emails. Anyway. I hear they're good which is why I placed the order initially, but never tried them because of that. Maybe they've gotten better about things and are easy to deal with now.

I've had good luck in the past with Jensen JT-DB-E, I use the -EPC version when I want to mount it to a PCB.

But lately I've been using Lightning Boy for all of my D.I. stuff. They're not cheap (though nothing is these days), but they're hand-made in New York by one dude, and he's great to deal with, and I love the sound quality. You don't feel like you're missing anything over the Jensen, and it feels like there's a little extra "something", some mild coloration that's very pleasing. I buy enough of these that he knows who I am, so you can tell him Sushi Box sent you. He won't give you a discount or anything, but he'll probably say "oh yeah, that guy."

lightningboyaudio.com

LBA-MC15 microphone input transformer

The LBA-MC15 microphone input transformer is a 1.4k:15k audio transformer designed for vacuum tube mic preamp input stages. It comes mounted in a MuMetal shielding can and provides PC Pins for termination. Crafted in small batches and assembled by hand in the USA.
lightningboyaudio.com

He also has a daughterboard specifically designed for mounting the transformer inside a build that doesn't already have a spot for it on the PCB. Optional of course, but not a bad idea if you're trying to add it to an existing build.

lightningboyaudio.com

LBA audio transformer mounting kit

A circuit board with adhesive standoffs for LBA audio input transformers.
lightningboyaudio.com
 
I won the 2020 he gave away recently. It sounds good but I haven't really put it though it's paces yet. I think I'm going to stick it after my Deep Dish.

LBA looks like the right choice
 
matmonster58 said:
I won the 2020 he gave away recently. It sounds good but I haven't really put it though it's paces yet. I think I'm going to stick it after my Deep Dish.

LBA looks like the right choice
Click to expand...
Just make sure if you're using the MC15 you wire it "backwards" as he mentions on the product page. As-designed it can take a balanced signal from a microphone and send it into a tube preamp, but we want to take an unbalanced signal from the preamp output and turn it into balanced to send into a mixer/console/etc.

So pins 4 and 5 should be your input (one goes to the circuit output, the other to ground) and pins 1 and 8 are your output (XLR pins 2 and 3, XLR pin 1 goes to ground/ground lift).

I think I still have a 2020 somewhere, I wonder where I put that.
 
Bumping the thread to let everyone know that Particle Accelerator PCBs are no longer be available from Sushi Box, from now on they will be sold by Conspiracy to Commit Electronics (@C2C Electronics). I'm still involved, but trying to be less in charge.

c2celectronics.com

Particle Accelerator PCB Set

This is a PCB set for building your own Particle Accelerator preamp. This is not a beginner project, so if you’ve never built a pedal before, then this isn’t for you. I’ve tried to make this as aff…
c2celectronics.com c2celectronics.com

Enclosures are still available, but listed separately.

c2celectronics.com

Pre-Drilled Enclosure

This option is to include a pre-milled enclosure for your PCB project. Enclosures are bare aluminum, no finish, CNC-milled. I try to get these done as quickly as possible, but please allow up to 3 …
c2celectronics.com c2celectronics.com
 
Just finished my latest Particle Accel. Turned it on and only got a faint audible output. After a couple of minutes. . . POP! . . . and
C1 blew. Almost positive it was high voltage cap, but if not would the pedal have at least worked for the duration until it blew? Any ideas?

PS - Went back and examined the "body". It was a fairly small diameter cap as compared to the HV cap I have in the power supply of the Ambassador I'm building so maybe I did inadvertently put in a LV cap. Question still holds though, would it have worked prior to meltdown if that was the only issue?
 
Last edited:
Mike McLane said:
Just finished my latest Particle Accel. Turned it on and only got a faint audible output. After a couple of minutes. . . POP! . . . and
C1 blew. Almost positive it was high voltage cap, but if not would the pedal have at least worked for the duration until it blew? Any ideas?

PS - Went back and examined the "body". It was a fairly small diameter cap as compared to the HV cap I have in the power supply of the Ambassador I'm building so maybe I did inadvertently put in a LV cap. Question still holds though, would it have worked prior to meltdown if that was the only issue?
Click to expand...
If you inadvertently used a low voltage cap instead of a 250V+ cap for the power supply bulk cap, it would have worked for a short period of time (the actual duration would depend on the voltage rating and tolerance/actual value of the cap) before failing. I've gotten away with 300V through a 250V cap for a couple seconds without damaging anything, and I've gotten away with 110V through a 100V cap for a couple years (didn't realize it) without damaging anything.
 
So my problem's got to be somewhere else. Dbl checked all of the component values and they appear OK. But I did find that two of the pins on the Treb Pot were left unsoldered. Could that have caused electro-constipation????
PA.jpg
 
Mike McLane said:
So my problem's got to be somewhere else. Dbl checked all of the component values and they appear OK. But I did find that two of the pins on the Treb Pot were left unsoldered. Could that have caused electro-constipation????
View attachment 58109
Click to expand...
No, leaving treble pot pins unsoldered wouldn't cause anything like that. The most likely causes would be a capacitor that wasn't rated for the voltage, or a capacitor that was put in backwards. Either of those would do it.
 
vigilante398 said:
No, leaving treble pot pins unsoldered wouldn't cause anything like that. The most likely causes would be a capacitor that wasn't rated for the voltage, or a capacitor that was put in backwards. Either of those would do it.
Click to expand...
We’ll, I’m up to the challenge. I can do either of those!!! Seriously, thx. It’s not a tough build. It’s got to be something stupid simple. I was trying to finish it up for a friend so I could concentrate on the Ambassador-DC30 mod.
 
vigilante398 said:
No, leaving treble pot pins unsoldered wouldn't cause anything like that. The most likely causes would be a capacitor that wasn't rated for the voltage, or a capacitor that was put in backwards. Either of those would do it.
Click to expand...
He was just testing to see if it is real 230v in this pedal & not that 12v starved plate malarky that most tube pedals are built on! ;)
 
Hi everybody,
I have been looking at the PA schem and have a question please: what is the direction of the pots pinout? There's a little black arrow on each one pointing at the wiper. Is the back of the arrow pin 1 or pin 3?
Thanks :)
 
Sono said:
Hi everybody,
I have been looking at the PA schem and have a question please: what is the direction of the pots pinout? There's a little black arrow on each one pointing at the wiper. Is the back of the arrow pin 1 or pin 3?
Thanks :)
Click to expand...
My potentiometer symbol is backwards from convention, the arrow is at pin 3.
 
vigilante398 said:
My potentiometer symbol is backwards from convention, the arrow is at pin 3.
Click to expand...
Excuse my language barrier but what do you mean by "from convention"? Why would you want to draw it backwards? Or do you mean that it actually works CCW in reality?

Cheers
Sono
 
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