BAJA boss PH-1 phaser build

bajaman · Post by **bajaman** » 20 Sep 2019, 01:31

Hi folks
A good friend asked me to build a replica of the BOSS PH-1 phaser recently - he had one of these back in the 70s and always regretted selling it. It is only a four stage phaser similar to the MXR Phase 45 and consequently is a very subtle effect and similar to a mild tremolo, but this is exactly what he was looking for. I set to work by resizing the Boss pcb layout to enable it to fit inside a 1590B enclosure. Here are some pictures of the finished product including schematic and board layout etc.
I used OPA4134 for the quad opamps and BC547B for the flip flop switching circuit. I used multi layer ceramic capacitors for most of the electrolytics - and low noise metal film resistors.
My friend was very pleased with how it sounded.
If anyone would like to build one of these i do have a few spare printed circuit boards available - PM me for details.
cheers
bajaman

bajaman · Post by **bajaman** » 20 Sep 2019, 07:09

As I built this to run off a regulated 9v power supply D5, and R45 were not required - they are replaced by shorting links. Also the 5.1v zener (D2) in series with the status led was not required because no battery was fitted - a shorting link is fitted here as well.
cheers
bajaman

aion · Post by **aion** » 20 Sep 2019, 11:23

This is awesome, great work!

Do you ever have any misfires with the footswitch? In my experience, the Boss/Ibanez flip-flop works best with non-bouncy tactile switches so that minimum debouncing is needed. I've tried it with those soft-touch momentaries before, but they didn't reliably trigger the flip-flop. It may have just been the brand of switch I was using, I don't know. But I've avoided trying to implement the Boss bypass since then.

bajaman · Post by **bajaman** » 04 Oct 2019, 09:26

PH-1-Schem.pdf: (305.62 KiB) Downloaded 719 times

rockola · Post by **rockola** » 10 Oct 2019, 13:06

bajaman wrote:
PH-1-Schem.pdf

I'm putting a BOM together for this. Q1-Q6 are 2SK30ATM GR/Y/O on the schematic. Is there another JFET that would work? These seem to be a bit thin on the ground.

bajaman · Post by **bajaman** » 10 Oct 2019, 20:08

2SK117 or 2SK118 should work as substitute for 2SK30ATM - pin outs may be different though

Gypsy Roadie · Post by **Gypsy Roadie** » 23 Oct 2024, 04:22

WOW this is amazing work! Came across this looking for schematic to aid in fixing an old PH1. I think i have a slightly different schematic but looks like just some value changes. Would it be ok to reach out for some tech help?

BAJA boss PH-1 phaser build [documentation]