Maestro PS-1 Phase Shifter - anyone tried to clone one?

[box]

In my project I used all DPDT as mentioned earlier.Switch OFF/Slow phase is working when is off  the signal is sent to the output( 3k and next to 4k7).
When is on position jfet(Q8)transistor carries the signal from IC3 pin no1 to the output.
Other switches are also DPDT and the diodes are connected as in the previous description

[jdub]

Hi- nice work on this, looks like you are using the layout I posted on here back in-whoa!-2013.  Haven't been around for a while, life gets in the way, etc.

So, this has always been my favorite phaser, but I've never been completely satisfied with the power supply for it- I have the GGG bipolar power board powered by an 18v AC supply.  I've recently been working on a reduced-size version of my earlier layout to fit in a BB-size box with built in power supply and buffer.  Got the board etched and populated, and used the Traco TMR3-1223 DC-DC converter to get +/-15V from a 9V DC supply.  That unit can do 100mA per rail, which I figured should be sufficient, and I put some basic filtering similar to Box's on the input and output.  It powered the board, but I got some nasty clipping on the output, similar to a mis-biased transistor. Swapped some parts around plus other tweaking, thinking it was something in the board, but could not get the harshness to go away. My original never had that problem, but it uses +15 and -15 LM regulators that put out like 1A each, so I thought maybe it was due to the Traco supply.

As a test, I tried using the Traco with my original board, and sure enough the clipping was present. Box, did you have any problems like this with your build? At this point, I'm not sure if it's noise on the output of the power supply or if it's clipping because that unit does not have quite enough juice for the Maestro (the 12V version puts out 125mA per rail, a little greater than the 15V version). I should mention that I have bypassed the isolation and connected the input ground to the isolated ground, because my build didn't work without it.  I haven't tried grounding the input and output jacks to the 0V- I'll give it a try. I'm also looking into some L-C filters on the input and output.

Box, any suggestions you might have about using the Traco supply would be appreciated- I'd love to get it working.  I'll be glad to post my modified layout if I can get the thing working properly. Many thanks!

[box]

 Box, did you have any problems like this with your build?

Please follow this reply:
« Reply #32 on: June 27, 2021, 07:28:34 AM »
my effect working without any issue.

[jdub]

Thanks Box- I also see that your Traco converter only puts out 80mA per rail, so it wouldn't seem that low current is my issue. Hmmm, I guess I'll try grounding to the isolated ground and see what happens.  The only other difference I can see between yours and mine is that I am also powering a Klon-type buffer from the supply, but that shouldn't draw more than 15mA tops- and I've also tried bypassing the buffer with no improvement.

From the datasheets of the 2 Traco products we are using, it seems the unit you used has internal filtering, but the noise specs are the same in both- 50mV p-p @ 20MHz, so I'm not sure if output noise is the issue with mine. Last night I tried it with an added L-C filter on the input (as recommended in the application notes for the TMR3), and there was no difference. I also have external filtering on the output.

Frustrating!

[jdub]

Success! Finally got the new layout working with the Traco supply. After some audio-probing and numerous hours peering over the board, turns out it wasn't the power supply after all, it was the op amps in the phase section- seems one or more wasn't making good contact in the (new) sockets on the board, or they were just faulty, I'm not totally sure which yet. Gonna do some more testing to make sure everything is solid then I'll post. I have some concerns about the heat generated by the converter- not a lot, but may move some caps a bit to get them further away. Basically the same layout from back when, but slightly rearranged to make it smaller, with on-board power converter and buffer, running off standard 9-18V DC center negative supply. Cheers!

[orangetones]

Success! Finally got the new layout working with the Traco supply. After some audio-probing and numerous hours peering over the board, turns out it wasn't the power supply after all, it was the op amps in the phase section- seems one or more wasn't making good contact in the (new) sockets on the board, or they were just faulty, I'm not totally sure which yet. Gonna do some more testing to make sure everything is solid then I'll post. I have some concerns about the heat generated by the converter- not a lot, but may move some caps a bit to get them further away. Basically the same layout from back when, but slightly rearranged to make it smaller, with on-board power converter and buffer, running off standard 9-18V DC center negative supply. Cheers!

Good news!  I had forgotten this project as I got busy with many others. 

Remind me again why you needed the buffer on this?

Also, using the Traco TMR1222, I have decided to do up a board like this.  Pretty simple, but could someone put eyes on it and make sure I haven't messed something up with the power supply?

[orangetones]

Anyone want to comment on this?

[MikeA]

Remind me again why you needed the buffer on this?

The original design has a relatively low input impedance, adding a decent input buffer will compensate for that.

[orangetones]

Actually, looking at your posted pics, it seems the jacks are grounded to the board.  It seems you added a pass to ground then with that grey wire.

Wondering about LED indicators.

If you are looking on the left side of the board-3 wires my power supply( is on the separated board) is connected only from isolated ( Orange+12V,Green 0V , Brown-12V). Do not connect GND from power supply from the socket power   ---only +9V and GND).
For LED indicators use DPDT switch and one section connect to +9V input power and GND , not from isolated power!!!!
On the my board input signal and output is grounded from 0V Grey( isolated ground).

Question.  If the input and output jacks are connected to 0v on the board, but are not supposed to connect to the 9v /ground of the power supply, do I not need to use a dedicated power supply?  If I was using a daisy chain power supply, wouldn't the ring on the input and output jacks connecting to the other pedals essentially connect the 0v on this board to that ground?  Am I confusing myself or making sense?

[box]

Actually, looking at your posted pics, it seems the jacks are grounded to the board.  It seems you added a pass to ground then with that grey wire.

Wondering about LED indicators.

If you are looking on the left side of the board-3 wires my power supply( is on the separated board) is connected only from isolated ( Orange+12V,Green 0V , Brown-12V). Do not connect GND from power supply from the socket power   ---only +9V and GND).
For LED indicators use DPDT switch and one section connect to +9V input power and GND , not from isolated power!!!!
On the my board input signal and output is grounded from 0V Grey( isolated ground).

Question.  If the input and output jacks are connected to 0v on the board, but are not supposed to connect to the 9v /ground of the power supply, do I not need to use a dedicated power supply?  If I was using a daisy chain power supply, wouldn't the ring on the input and output jacks connecting to the other pedals essentially connect the 0v on this board to that ground?  Am I confusing myself or making sense?

Hi,
if you read with the note, note that I did not connect the ground from the 9V power supply to the insulated ground. The isolated ground is the ground on the board, so the input and output of the ground is unchanged.
Regarding the LED power supply, because you use the + 9V and Negative (GND) power supply, you can connect to one section of the 3PDT diode.
Rgds,
box

[Paul Marossy]

I was actually turned onto the Maestro PS-1 while trying to find out which phaser Alex Lifeson used on the early Rush albums, and specifically on parts of "Lakeside Park".  Somewhere on the net it referred to his use of Maestro phasers, so I began to look into them. 

There has been a few times recently while playing my newly completed Ampeg Phazzer clone with a mix/depth control that I thought to myself that it sounded very much some of things I've heard on Rush's Caress Of Steel Album. Interesting things going on in the Maestro circuit. I don't recall seeing caps in the opamp feedback loops on any other of the popular phase shifting circuits. I wonder what affect that has on the sound.