Secret Preamp (effectslayout)

spi

spi

Well-known member
Build Rating
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I already own a Chase Tone Secret Pre-amp, so building this was redundant. I got the PCB because when I ordered a flanger from effectslayout.com, I wanted to get something more to justify the shipping cost, and couldn't decide on anything else. My plan was to build this and sell off the Chase Tone.

I use the Chase Tone as a unity-buffer, tone-sweetener. It isn't even essential, but is a nice to have.

The first blooper: For the 2nd time ever I soldered the 3PDT PCB upside down. Last time it happened it was also an effectslayout board. Now I'm not saying effectslayouts is to blame because it's my own damn fault both times, but is it a coincidence that it only ever happens with their boards? Just saying.

Now I'm not going to waste a perfectly good switch just because it's upside down--I had to unsolder all my offboard connections and then rewire them to the opposite sides. I had to unsolder the power lines multiple times (don't ask) and ended up having a hard time clearing the pad that was tightly spaced so I ran the negative (ground) signal from the bias test.

Now the second blooper: Something is not right with the volume control. On my commercial Chase Tone the volume has a smooth taper from 0 to unity at about 9 or 10 o'clock. On this one, the volume is off at 0, but a slight nudge and it's full-on boost. I think I gotta remove it all and see if there's another mistake (I may have to unsolder the power yet again to get the pcb out).

Lastly, tonewise it does sound good but also seems slightly boomier than my original. Although this could also just be due to the volume issue.

For now it's definitely not board-worthy until I can straighten out the volume issue. If I can't, I will scrap it and find another use for the enclosure.


IMG_20230820_165904549_HDR.jpg IMG_20230820_165837143.jpg
 
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And not Effects Layout, but Moonn does indeed have the ins and outs switched because of his preferred method of wiring 3PDT and I think his breakout boards also match up with the reversed layout.
 
comradehoser said:
If it helps as a mnemonic, you want to see the effects layout white "circuity" logo if the switch is installed correctly.
Click to expand...
I've done it twice with these boards. He really should mark it with a more explicit "do not put this side up" marking. Or I should just be more cautious. Although I've never had this issue with other vendors.
 
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linjor said:
@spi sorry to bump an old thread, but did you ever figure out the volume issue? I built one and am experiencing the same thing. Thanks!
Click to expand...
It's not a big. It's a feature
mkstewartesq said:
That volume drop is exactly how the original Chase tone pedal works. From the documentation for that pedal, you’ll see that the last portion of the knob turn actually decreases in volume.:

  • VOLUME CONTROL- Wired just like an original EP3 for Amazing Versatility!
    • FULL COUNTER-CLOCKWISE = NO SIGNAL
    • 10 to 11 0’clock = UNITY GAIN (Depends upon EQ Setting)
    • 1 to 2 o’clock = 3dBs+ MAXIMUM OUTPUT BOOST
    • 3 to 5 o’clock = 1dB or 2dBs with FLAT EQ just like a worn, vintage Echoplex
  • Chase Tone® Exclusive 3-Way EQ 1970s Era EP3 Mini-Toggle Switch!
  • Early 1970s = BRIGHT
  • Late 1970s = DARK
  • Hybrid Early & Late = MID”
As far as your voltage, normally people shoot for around 12 V (although that is normally around the middle of the trim in my experience) but if you’re hitting 12 V, you should be just about right.

Mike

EDIT to add – I can tell a difference between the three EQ settings, although it’s not super dramatic. But note that when you turn the knob all the way up, in addition to the volume drop, the EQ becomes flat and so the switch isn’t going to function or make any difference during that last part of the turn.
Click to expand...
If you want a more traditional control, lift one leg of R9 or just remove it (Ro on effectslayouts schem refdes, R8 on PPCB), snip the connection off leg 2 on the level pot near the PCB and temporarily bridge legs 2 and 3 of the pot.
If it seems to sweep in reverse, I screwed up and you should bridge 1 and 2.
You could possibly leave R9 and just snip leg 2 and bridge the legs. It won't turn all the way down but should have a hotter max output.

If you snip the center leg cleanly, you should be able to reverse this pretty easily. No idea how good/bad it will work beyond it will at least kinda work.
If you weren't already populated, I'd go about it differently but I'm taking the path of least resistance that's easily reversible here.
If you do this and are happy with the results, I'd bend leg 2 up away from the pcb a little
 
spi said:
I've done it twice with these boards. He really should mark it with a more explicit "do not put this side up" marking. Or I should just be more cautious. Although I've never had this issue with other vendors.
Click to expand...
I mean, there is a footprint there. :p
He does have a note on other switch boards but generally, put the component inside the footprint and cover up the note(in your case, about the LED) should work. :)
 
jwin615 said:
It's not a big. It's a feature
Click to expand...
I don't think you read my original post then :). I have the original chase tone too.

On the original, if you start at off (7 o'clock), you get a gradual increase as you turn it up, reaching unity around 9-10 o'clock.

On the one I built, it's off at 7 o'clock, and then above unity at 7:15. There's no unity and no gradual ascent.
 
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