Yes, Modulation Monday is back with the Ross Phaser. It's not for the feint of heart, but doesn't require any JFETs, matched or otherwise. Instead it uses OTAs with 3, LM13700N (one for the LFO, two for the audio path). Should fit nicely in a 125B with top mounted jacks. Schematic for reference.
It works! you can mark it verified. It does have a vibe and feel like a vintage pedal, and some great phasing sounds.
ReplyDeleteHow about Beetronics whoctahell? a nice simple one. https://docs.pedalpcb.com/project/DirtDauber-PedalPCB.pdf
DeleteThe 3.3 electro is 3.3uf
DeleteWas checking the comments exactly for this.Thanks
Deletehttps://docdro.id/4YhimFr
Deletecheck my post too!!
https://www.diystompboxes.com/smfforum/index.php?topic=130479.0
have fun!!
Hola a todos .. Funciona ! los integrados a 2024 todavia se consigen.. yo los compre desde china, Saludos.
ReplyDeleteI finally got around to putting this one together. Thank you!!! This layout is excellent work as always, my board is now swooshing and swirling like never before. I did follow Dee's advice from an earlier comment and used a 3.3uF cap for C11 as indicated in the schematic.
ReplyDeleteThe black Ross Phaser is an adaptation of the original "6-chip" Small Stone, that used two OTAs for its sweep generator. The "color" switch on the Small Stone made three changes at the same time. It selected between higher and low feedback, and between two different sweep waveforms. As it turned out, one of the sweep waveforms was also slightly faster than the other, which gives us three changes. One of the color settngs provided for slower sweep, with lots of feedback/emphasis, and what is termed a "hypertriangular waveform", that slows down as it sweeps downward, and speeds up at the "top" of the sweep cycle. This is optimized for long slow majestic sweeps. The other Color setting was faster, with less feedback, and a triangular waveform giving the more familiar up-down sweep, with a bit less sweep width. This was optimized for fast bubbly phasing.
ReplyDeleteI mention this because the black Ross Phaser only used the one hypertriangular sweep waveform. While its inclusion of continuously variable feedback/regeneration allows the user to "tone down" the sweep, the stock hypertriangular swep is irritating when you turn the speed up. Fortunately, the circuit can be modded to provide the two different sweep waveforms that the Small Stone included, making it optimized for BOTH very slow, and very fast sweeps.
The LM13700 in the upper right of the layout shows two 270k resistors, one of which is connected to pin 1 and the other to pin 3. Both of them are tied to V+ at the other end. Replace the 270k going to pin 1 with a 100k and 180k in series. The waveform switch is going to treat the three resistors (270k-100k-180k) as if they are a sort of "loop". The switch is going to make the connection to V+ EITHER from the junction of 270k and 100k, OR from the junction of 100k and 180k. In other words, pin is going to be connected to V+ through just the 180k resistor OR through 280k (100+180). When connected to V+ diretly from the junction of 180k and 100k, you'll get the slightly faster, triangular sweep, more suited to faster bubbly sounds.