Maxon - PH-350 Rotary Phaser

idy · Post by **idy** » 30 Jun 2015, 20:19

This one has escaped the forums and layout sites. Switchable 4/6/10 stages, the feedback control is minimum at noon, one direction adds fb out of phase, the other in.
gut shot here:
http://www.modezero.com/maxon-ph350.htm

Dirk_Hendrik · Post by **Dirk_Hendrik** » 04 Jul 2015, 06:25

True. And I'd love to tackle this one.

But it's not going to happen without pictures of the trace sides of the boards.

andrej · Post by **andrej** » 14 Jul 2015, 11:32

How hard are these to find?

It's my holy grail of phasing, along with the Red Witch Moon Phase (also untraced).

idy · Post by **idy** » 14 Jul 2015, 16:43

One on Ebay for $220, one on Reverb for $300+...

idy · Post by **idy** » 04 Dec 2015, 21:22

without the back side mucho guess work amigo.

Post by **modman** » 04 Dec 2015, 21:25

http://www.thegearpage.net/board/index. ... or.254435/
Maybe check with our member Bucksears?

Please, attach pictures of guts to the thread. This way info gets collected and stays available for anyone wanting to work on this next week, next month, next year...

"The cause of the "vocal/wah" type sound of the PH350 comes from the fact that it uses photocouplers instead of FET's to create the phasing effect. Photocouplers are well known for their vocal-like audio quality, and they were used in all the original Mutron products as well as the original Univibe. Barely anyone designs around them anymore for several reasons - 1) They are expensive 2) They are hard to find 3) They are temperamental and have wide tolerance ranges so they generally must be matched for optimum sound quality. This is the reason the PH350 is somewhat expensive compared to other phasers."
http://www.maxonfx.com/article-better-guitar-2004

Dirk_Hendrik · Post by **Dirk_Hendrik** » 05 Dec 2015, 08:11

Looking at that photo I'm fairly sure I can draw up a schematic that is 98 or more percent correct. How?

By using the older brother:
http://dirk-hendrik.com/temp/ibanez_ph99.pdf

idy · Post by **idy** » 05 Dec 2015, 16:30

Thank you! Better than magic. The PH99 has the switchable stages and the +/- feedback.

k.kobain · Post by **k.kobain** » 24 May 2016, 19:47

Hi gays
Have any news? I need schematic for this magic pedal

Fender3D · Post by **Fender3D** » 25 May 2016, 08:44

I think this https://www.freestompboxes.org/viewtopic ... 93#p245607 is a good starting point, add an usual NE57x comp/exp circuit and you're close...

k.kobain · Post by **k.kobain** » 03 Aug 2016, 16:19

Hello. is there any news???

Dirk_Hendrik · Post by **Dirk_Hendrik** » 04 Aug 2016, 06:51

Hello,

Why you need a schematic?

k.kobain · Post by **k.kobain** » 04 Aug 2016, 08:09

Dirk_Hendrik wrote:Hello,

Why you need a schematic?

Hello
like everyone on this forum I want to solder the pedal for myself.
P.s. sorry for myself English. I am from Ukraine

Fender3D · Post by **Fender3D** » 04 Aug 2016, 10:12

Just guesses...

from picture posted it looks like it uses the schematic posted by Dirk. (10K filter resistors are there, 24k compressor feedback res too, and many other values on board seem coincide with schematic)
with 2 more static stages and 2 moving stages.
I can't say about LFO (it may be on the lower PCB with controls), but 1 more vactrol won't need further circuitry....

k.kobain · Post by **k.kobain** » 07 Aug 2016, 13:15

Does the owners of the pedal here? They might take a picture of both sides of the board.

roseblood11 · Post by **roseblood11** » 26 Sep 2018, 20:49

BUMP!!!

soulsonic · Post by **soulsonic** » 17 May 2023, 01:12

Sorry, I had taken these photos back in 2009 when I had worked on one of these to modify it for true bypass. Completely forgot about it.
I didn't take any photos of the board with the controls, sorry.

BMS1971 · Post by **BMS1971** » 26 Nov 2023, 17:25

Interesting beast... No schematic yet?

jimilee · Post by **jimilee** » 29 Nov 2023, 03:13

That’s freakin awesome.

ppluis0 · Post by **ppluis0** » 29 Nov 2023, 10:17

BMS1971 wrote: ↑26 Nov 2023, 17:25 Interesting beast... No schematic yet?

There is an image found after a brief search in the web

Cheers,
Jose