Particle Accelerator - Alembic F-2B clone

[vigilante398]

Thanks for the cool project, @vigilante398 !

Have you tried running clean preamps like this with submini tubes, e.g. 6n16b and 6n17b? If so, have you noticed any sonic difference compared to a 12ax7?

When I was first getting into tubes a few years back I had originally designed Particle Accelerator for 6N17B/6N21B. It sounded great and a lot of people liked it, but the submini tubes are more difficult to source, more difficult to swap, pull more current, and are much more likely to go microphonic. That's why I started moving over to 12AX7.

6N21B is also interesting because its gain factor (mu) is 82, putting it nicely in between 12AX7 at 100 and 12AT7 at 60. It has a great-sounding breakup and does well in tube overdrives. I also used it in a Hiwatt preamp, Ampeg preamp, Soldano preamp, and even Mesa preamp.

 

[Mike McLane]

I've been working on taking a Particle Accelerator into a Class D amp to drive a conventional speaker cab. Have gotten less than stellar results. The output was muddy. . . . workable, but muddy. I even bought a Milkman Amp 100 to find out what his secret was. . . no secret, his output directly into Class D was muddy, too. Finally thought to place a buffer to lower the output impedance of the PA into the Class D and VOILA the sparkle appeared . . . and a stronger signal as well! I A/B'd it against my Deluxe Reverb into the same speaker cab and got very favorable results. So now I want to test the PA in tandem with a Vampire Slayer. Any problem putting the PA output into a VS? Can I put them both in the same box and power them both from the same DC jack as long as I've got sufficient current (1A +/-)?

 

[vigilante398]

Any problem putting the PA output into a VS? Can I put them both in the same box and power them both from the same DC jack as long as I've got sufficient current (1A +/-)?

Nope, seems like a good idea.

 

[AlphaMoose]

I've been working on taking a Particle Accelerator into a Class D amp to drive a conventional speaker cab. Have gotten less than stellar results. The output was muddy. . . . workable, but muddy. I even bought a Milkman Amp 100 to find out what his secret was. . . no secret, his output directly into Class D was muddy, too. Finally thought to place a buffer to lower the output impedance of the PA into the Class D and VOILA the sparkle appeared . . . and a stronger signal as well! I A/B'd it against my Deluxe Reverb into the same speaker cab and got very favorable results. So now I want to test the PA in tandem with a Vampire Slayer. Any problem putting the PA output into a VS? Can I put them both in the same box and power them both from the same DC jack as long as I've got sufficient current (1A +/-)?

Thank you for this. I’m currently having much the same issue, wherein my imagined idea of “box up a class d supply to plug preamps into” has resulted in nothing but uninspired muddy signal. I believe a tube buffer is in the works now.

 

[Sono]

I've been working on taking a Particle Accelerator into a Class D amp to drive a conventional speaker cab. Have gotten less than stellar results. The output was muddy. . . . workable, but muddy. I even bought a Milkman Amp 100 to find out what his secret was. . . no secret, his output directly into Class D was muddy, too. Finally thought to place a buffer to lower the output impedance of the PA into the Class D and VOILA the sparkle appeared . . . and a stronger signal as well! I A/B'd it against my Deluxe Reverb into the same speaker cab and got very favorable results. So now I want to test the PA in tandem with a Vampire Slayer. Any problem putting the PA output into a VS? Can I put them both in the same box and power them both from the same DC jack as long as I've got sufficient current (1A +/-)?

Could please share what buffer and what class D amp did you use?
Cheers
Sono

 

[Passinwind]

Could please share what buffer and what class D amp did you use?
Cheers
Sono

The Tubecad Aikido line driver designs work fantastically for this sort of application, IME. In my case using the ICEpower 500ASP and 700AS1 modules. I usually transformer couple with various Jensen trafos too, but that’s certainly not strictly necessary and I also plan on trying one of Nathan’s Unagis sooner than later.

Convection cooled 700 watt Class D amp at bottom, below a SS preamp in this case:

 

[Sono]

The Tubecad Aikido line driver designs work fantastically for this sort of application, IME. In my case using the ICEpower 500ASP and 700AS1 modules. I usually transformer couple with various Jensen trafos too, but that’s certainly not strictly necessary and I also plan on trying one of Nathan’s Unagis sooner than later.

Convection cooled 700 watt Class D amp at bottom, below a SS preamp in this case:

View attachment 121391

Do you mean using the Aikido as a poweramp like so?
Particle Accelerator -> Aikido -> speaker

 

[Passinwind]

Do you mean using the Aikido as a poweramp like so?
Particle Accelerator -> Aikido -> speaker

Nope, as a super low noise buffer stage between the PA and whatever SS power amp. Most of them are essentially just variations on the cathode follower theme, although some are robust enough to drive headphones directly.

And of course there’s nothing wrong with a simple solid state solution either.

 

[Sono]

Nope, as a super low noise buffer stage between the PA and whatever SS power amp. Most of them are essentially just variations on the cathode follower theme, although some are robust enough to drive headphones directly.

And of course there’s nothing wrong with a simple solid state solution either.

Thanks for your suggestion but I'm a bit lost. I apologize for my ignorance. I'm looking for a schematic to build a circuit that does what Mike described, to allow me to connect the Particle Accelerator output into an SS poweramp with a speaker...also I'd like to keep size to a minimum...

 

[Passinwind]

Thanks for your suggestion but I'm a bit lost. I apologize for my ignorance. I'm looking for a schematic to build a circuit that does what Mike described, to allow me to connect the Particle Accelerator output into an SS poweramp with a speaker...also I'd like to keep size to a minimum...

Did you look at the website I mentioned? There are dozens of workable circuits detailed there, and he sells PCBs for several as well. But since that seems move involved than you need or want, how about something simple from here: https://www.pedalpcb.com/product-category/buffers-line-drivers/ ?

Have you settled on a power amp yet? A bit hard to give a specific recommendation without that info.

 

[Sono]

Hey thanks a lot for the links and suggestions
I'll take a look
Will any of those buffers serve my purpose though?
Thanks again

 

[Passinwind]

Hey thanks a lot for the links and suggestions
I'll take a look
Will any of those buffers serve my purpose though?
Thanks again

First you have to define your exact purpose, the most important specs to assure best results are power amp input impedance and input sensitivity. I do have a great deal of direct experience with this stuff and sometimes assume too much, so let’s examine your specific use case, OK ?

Taking a quick look at the PPCB offerings, the Skeptical Buffer is probably going to be your safest bet, as it runs internally at +/- 15 volts and should have tons of headroom.

 

[Sono]

Ok
So what I'd like to be able to do is to connect my Particle Accelerator to a SS amp without sounding muddy. Since I read Mike's post I was curious to know how he had sorted that problem... that's basically it

 

[Passinwind]

Ok
So what I'd like to be able to do is to connect my Particle Accelerator to a SS amp without sounding muddy. Since I read Mike's post I was curious to know how he had sorted that problem... that's basically it

Cool. With some Class D amps you won’t need to add anything and with others that have an input impedance below around 50k-100k ohms you will benefit from using a buffer or possibly a stepdown transformer. If you use any of the ubiquitous ICEpower amps (which are the industry gold standard) they will all benefit from the latter approaches. The Aikido tube or MOSFET circuits are next level beyond that, but at that point you may be better off just using an added or different Sushi pedal. Nathan can fill you in on which ones have the most suitable output sections.

 

[Sono]

Ok. Would any buffer circuit be ok then? Maybe I could build it on a really small board and add it to my Particle Accelerator...

 

[Passinwind]

Ok. Would any buffer circuit be ok then? Maybe I could build it on a really small board and add it to my Particle Accelerator...

You still haven’t said what amp you’re using, which is mission critical. But if you want a sure thing just build a Vampire Slayer or the Skeptical Buffer, or use some other pedal with a lower output impedance and a line level output level capability after the PA pedal.

 

[Sono]

You still haven’t said what amp you’re using, which is mission critical.

I apologize, I don't have a specific amp in mind TBH, I was just wondering about how to make this thing as "connectable" as possible. IU'm considering giving it a balanced output so when I read Mike's post I thought that being able to connect it to a SS poweramp without it sounding muddy would be great. If all there is to it is an impedance matter, then I guess the Vampirte Slayer or the Skeptical Buffer will do the job. I guess I can even tap from any of them into a balancing circuit for my XLR balanced output after an analog speaker sim
Thanks a lot for all the ideas and inspiration

 

[Passinwind]

You still haven’t said what amp you’re using, which is mission critical.

I apologize, I don't have a specific amp in mind TBH, I was just wondering about how to make this thing as "connectable" as possible. IU'm considering giving it a balanced output so when I read Mike's post I thought that being able to connect it to a SS poweramp without it sounding muddy would be great. If all there is to it is an impedance matter, then I guess the Vampirte Slayer or the Skeptical Buffer will do the job. I guess I can even tap from any of them into a balancing circuit for my XLR balanced output after an analog speaker sim
Thanks a lot for all the ideas and inspiration

No worries. Your active balancing circuit couold just be conigured to take care of the impedance issue too, if there even is one. I don't mind talking general cases, as I'm always hoping to learn something new myself along the way anyhow. BTW, there's a thread tangent on Talkbass right now about a potential similar issue with one of Josh Broughton's tube pedals, in the very long Broughton Club thread over there.

I owned an actual Alembic F-2B briefly and learned a lot by doing tone control mods to the second channel and throwing around ideas with other owners. There's a pretty common output mod that just adds a high voltage single MOSFET buffer, but I never got around to trying it since I had other stuff in my rack that already did the job. On that tangent, if you want to take the Alembic thing to the next level the Broughton RFE or this PPCB version : https://www.pedalpcb.com/product/pcb725/ would bring some of the Alembic SF-2 vibe, and there are a few recent commercial takes on the SF-2 as a pedal as well. My open source filter pedal modules can go there too but that's a whole other thread!

 

[blurphmagnifique]

If all there is to it is an impedance matter, then I guess the Vampirte Slayer or the Skeptical Buffer will do the job. I guess I can even tap from any of them into a balancing circuit for my XLR balanced output after an analog speaker sim

I would get the Vampire Slayer - it's a great circuit and will add some extra tube mojo to all that digital nasty in the Class D power amp. Besides the low impedance output, it really does have a softening and rounding, gentle soft clip thing that it seems to do which I really like. I've been using one in different parts of my digital recording chain to try to mitigate some of the harsher I/O and conversion points.