Secret Invasion Preamp

thewintersoldier

Well-known member
Heres my Secret Invasion Preamp, the clandestine. Comparing it to my Aion Ares which is a clinchfx ep-pre I much prefer the clandestine. Thanks to @caiofilipini for this one and answering all my questions. According to his original unit the jfet was biased at 12.46v. The silkscreen also called for a 2n5457. I always like to do my due diligence when I get ready to build a pedal and google was my friend as usual. The original jfets used in an echoplex are pretty much unobtanium and the general consensus on the web seems to be the obsolete j202 as the best substitute for all the specs of the original part. Other great subs would be 2n5484 2N5256 2N5952 2N5953 2SK30A-Y 2SK30A-GR. I had a bunch of 2n5484 and 2n5952. Looking at the preamp section of the original schematic, the drain has a voltage of 14,4v and the source has a voltage of 1.1v I started plugging in jfets and testing. Went with a 2n5484 and got the exact voltages. Its subtle, but its definitely making things sound different in n each eq position, in a really good way. I like this one and am going to be spending a lot of time with each eq position on each of my guitars/amps. Tayda uv print on dark matte gray enclosure with simple secret invasion logo from one of my favorite series in comics.
PXL-20211016-201830372-2.jpg

PXL-20211016-201849330-2.jpg


New-P3-with-FIlters.jpg
 

Big Monk

Well-known member
Heres my Secret Invasion Preamp, the clandestine. Comparing it to my Aion Ares which is a clinchfx ep-pre I much prefer the clandestine. Thanks to @caiofilipini for this one and answering all my questions. According to his original unit the jfet was biased at 12.46v. The silkscreen also called for a 2n5457. I always like to do my due diligence when I get ready to build a pedal and google was my friend as usual. The original jfets used in an echoplex are pretty much unobtanium and the general consensus on the web seems to be the obsolete j202 as the best substitute for all the specs of the original part. Other great subs would be 2n5484 2N5256 2N5952 2N5953 2SK30A-Y 2SK30A-GR. I had a bunch of 2n5484 and 2n5952. Looking at the preamp section of the original schematic, the drain has a voltage of 14,4v and the source has a voltage of 1.1v I started plugging in jfets and testing. Went with a 2n5484 and got the exact voltages. Its subtle, but its definitely making things sound different in n each eq position, in a really good way. I like this one and am going to be spending a lot of time with each eq position on each of my guitars/amps. Tayda uv print on dark matte gray enclosure with simple secret invasion logo from one of my favorite series in comics.
PXL-20211016-201830372-2.jpg

PXL-20211016-201849330-2.jpg


New-P3-with-FIlters.jpg

Timely. I’m considering switching to the Clandestine from the Area as well. I hate the huge boost of the Fat position on the Ares.
 

thewintersoldier

Well-known member
Timely. I’m considering switching to the Clandestine from the Area as well. I hate the huge boost of the Fat position on the Ares.
you can also do what I did with the fat position and use a smaller value cap. I ended up splitting the difference between the other two values and came up with something similar to what chase tone did with this pedal.
 

Big Monk

Well-known member
you can also do what I did with the fat position and use a smaller value cap. I ended up splitting the difference between the other two values and came up with something similar to what chase tone did with this pedal.

I may do that. I like the other two positions quite a bit.

What cap did you use for the Fat position?
 

Boba7

Active member

Excellent work as usual!
But what’s that schematic you put in your message? It’s not the Clandestine preamp.

In my Aion build, or in previous Madbean Fatpants builds I always used 22n-off-12n, it sounds like the perfect combination to my ears.

I find that J202 sound great in that circuit, and are very close to the jfet Clinch Fx uses for Q1 in his circuit. 2n5457 tend to not sound great to my ears (and to not bias properly)

I like the Clinch Fx output buffer, as it makes sure the pedal interacts well with anything after it, contrary to the Chase tone / Madbean ones, that can occasionally have dull interactions due to their higher output impedance.

In my own pcb (that runs at around 22/24v too), I now add a pseudo bias pot, inspired by Catalinbread: its a gain pot for the transistor. At minimum position it’s the Echoplex value, and at maximum position its way less, thus bumping the gain if needed.

Anyways, I love those preamps, congrats on building a beautiful one! :)
 
Last edited:

Big Monk

Well-known member
@thewintersoldier

I don’t want to be an opportunist dick and sidetrack your thread but this seems like a perfect place for this.

Can you or anyone else shed some light on the switched cap setup in the Ares? I’ve got the iron out for a few other parts changes today in other pedals and wanted to tweak the caps for the fat section but am I sure what’s doing what…

D5C39378-CE95-40E9-A77D-022E62A50B9A.png

It seems the 47uf is the cap to reduce but I’m unsure.
 
Last edited:
  • Haha
Reactions: fig

thewintersoldier

Well-known member
@thewintersoldier

I don’t want to be an opportunist dick and sidetrack your thread but this seems like a perfect place for this.

Can you or anyone else shed some light on the switched cap setup in the Ares? I’ve got the iron out for a few other parts changes today in other pedals and wanted to tweak the caps for the fat section but am I sure what’s doing what…

View attachment 17124

It seems the 47uf is the cap to reduce but I’m unsure.
If you look at the complete schematic above the difference between late and early models in tone was the 22n cap. On the ares the center off position is without the 22n and the late model. The 47uf cap is the one with huge boost and full range. I used 10n because it was pretty much half the value of 22n and would represent a middle ground between late and early models.
 

Big Monk

Well-known member
If you look at the complete schematic above the difference between late and early models in tone was the 22n cap. On the ares the center off position is without the 22n and the late model. The 47uf cap is the one with huge boost and full range. I used 10n because it was pretty much half the value of 22n and would represent a middle ground between late and early models.

I reduced it to 3.3 uf this morning and it’s still overpowering!

I have to go in an redo a bunch of the wiring as I’m embarrassed by it so I’ll tweak this cap down a bit further and see how I like it.
 

Big Monk

Well-known member
As is often the case here at the forum, @thewintersoldier and his build thread have inspired me to clean up my Ares and play with the caps.

I tore it down before, tweaked the LEDR so I can put the LED on board again, and removed the off board wires to clean up the pads and start fresh.

Going to rewire and change the 3.3 uf cap in a little bit.

Thanks man!
 

Big Monk

Well-known member
Having gone down a Chase Tone Secret Pre rabbit hole today and fixing up my Ares, I can definitely say I’ll likely be pursuing the Clandestine when it’s back in stock.
 

thewintersoldier

Well-known member
Are people just ordering parts based on the existing schematics or was there a BOM posted at some point? (There is no build document currently)
I have a pretty good stocking most parts and had everything on hand already. Also the board has all the values on the silkscreen so I went off of that.
 
Top