© 2017 by  The Tone Geek.  Donations are appreciated via Amazon wish list. (Thank you in advance!!)

Building John Mayer/Brad Paisley's Tone

AQUA-PUSS MKII MN3005 Conversion

Forever, the original Aqua-Puss has been on John Mayer's board and continues to be on his boards. Before the 2010 flood in Nashville, Brad Paisley rocked the original Aqua-Puss as well. I've built a few MK1 circuits using Madbean's AquaBoy PCBs. NOW I've finally cracked the code taking a MK2 MN3205-based circuit and modifying it to MK1 MN3005-based specifications. DISCLAIMER: I am not responsible for bricking your awesome pedal. Please proceed with caution. (I'm not sure why folks put disclaimers out there like that, but it feels right to do so as I don't want to lose any friends)

A few notes about what I find better about the MK1 specs:

  • Repeats are "warmer" (less treble-ly)

  • Repeats are longer

  • A lot more bottom end preserved in the mix

    • The Mk2 always sounded sterile to me.. The Mk1 is way better at preserving the original signal​

  • Overall, this analog delay adds slapback without sterilizing the original signal. (A++)

Overview of the modifications

The conversion of the MN3205/MN3102 to MN3005/MN3101 requires a change in voltage to the ICs and a VB/Ground pin swap. It's important to bend out the VB and ground pins so they do not go in the sockets because of the pin swaps on the chips. I found that the Way Huge daughter board supplies a very clean 9.00v signal to the AP board for us to use.

Q5 and D2 was setup originally as a 5v regulator for MN3205/MN3102 so we can eliminate that as part of this mod and reclaim those pads for VB taps. R5 and R28 need to be converted to a "pull-up" resistor. We are reusing R5 & R28's original ground pads for grounding the chups. Be sure to read everything three times and check your work.

There is an undocumented presence trim pot! Even if you don't perform the MN3005 mod, play with TR2! Turning it off (all the way to the left) is MK1 style. This makes a HUGE difference in tone. 

Here is my soldering station gear list:
http://amzn.to/2eFxEfj PCB Holder
http://amzn.to/2upePRL red lead forming tool
http://amzn.to/2un7nrQ 60/40 solder
http://amzn.to/2upj6Ez solder tip cleaning
http://amzn.to/2uMRE6n recommended soldering iron

 

Electronic Parts List
 

Instructions
  • Replace R33 with 22 Ohm resistor. This creates the VB tap.

  • Replace C26 with 100uf electrolytic.

  • Replace clear blue LED with 5mm green diffused LED (All the mojo is in the LED hehe)​.

  • Remove Q5.

    • Jump pads 1 & 2 of Q5.

    • Pads 1 and 2 is now a aux VB tap. 

  • Remove D2.

    • Cathode pad of D2 is now connected to VB​.

      • Jump cathode pad of D2 to MN3005 pin 1​ using hookup wire.

        • ​Bend the pin out so it does not go in the socket and directly solder to the pin.​ VB and GND is swapped in this conversion.

  • Unsolder ground end of R28 & connect R28 to Q5 VB tap.

    • Jump R28 ground pad to MN3005 pin 5 using hookup wire.

      • Bend the pin out so it does not go in the socket and directly solder to the pin.​ VB and GND is swapped in this conversion.

  • ​Unsolder ground end of R5 & connect R5 to Q5 VB tap.

    • Jump R5 gound pad to MN3101 pin 3 using hookup wire.

      • ​Bend the pin out so it does not go in the socket and directly solder to the pin.​ VB and GND is swapped in this conversion.

  • Using hookup wire, jump from Q5 VB tap to near the top of MN3101.

    • Solder anode of 1N4148 to VB and cathode to MN3101 pin 1 (creating a slight voltage drop for MN3101)​

      • ​Bend the pin out so it does not go in the socket and directly solder to the pin.​ VB and GND is swapped in this conversion.

    • Solder .1uf film capacitor (not polarized) to MN3101 pins 1 and 3.

      • ​Bend the pins out so it does not go in the socket and directly solder to the pins.​ VB and GND is swapped in this conversion.

  • Replace SA571 IC with the NE570N compandor chip. Direct 1:1 swap. 

 

Calibration (Source: Madbeanpedals.com)

​Make the following adjustments before beginning:

  • Mix control at center.

  • Delay at max position.

  • FDBK at about 1/3 up.

  • BIAS and Cancel trimpots to their center position.

 

If you have frequency measurement on your DMM, adjust the Clock trimmer to about 6.5kHz while probing either pin2 or pin4 of IC5. If you don’t have this feature set the Clock trim half-way up (note: this is when using a 9v supply).

  • Audio probe pin3 of IC3 while either strumming the guitar or send some audio through the input of the circuit.

  • Adjust the BIAS trimmer until you get delay passing. The range over which the trimmer will result in delay is usually about 1/4 to 1/6 of its entire rotation.

  • Continue refining the position of BIAS until you get the smallest amount of distortion on the delay signal. Now probe pin4 of IC3 to confirm it is also passing delay. If it does not, make sure that you have clock frequency on both pins 2 and 6.

  • Now finely adjust the CLOCK trimmer until just before you hear any high pitch whine in the audio path. This is the maximum delay setting. The clock frequency should land somewhere between 6 and 7 kHz.

  • Unless you are using an oscilloscope to calibrate the delay, leave the Cancel trim in the center position.

Conclusion

Enjoy your enhanced Aqua-Puss and let me know how you like it! I offer a mod service for $150 which includes parts, labor, and shipping back to you (lower 48 states). All you have to do is ship me your donor (working) pedal. Contact me to arrange the order.