Adding a wet/dry mix to the Ross phaser...has it been discussed?

[skiraly017]

I've done a light search on the topic but didn't see anything that jumped out at me. Has this topic been covered? If yes, I apologize and will dig deeper. Thanks.

[jmasciswannabe]

Yes, it has. Be sure to search under ropez as well. Mark Hammer has contributed loads of mods and options to this sucker. Most recently a step mod!

[Mark Hammer]

I'm biased in this regard, but a wet-dry mix control is really only useful in one direction, that of reducing the contribution of the wet signal below 50%.  Anything more than that, and you're really looking at shades of vibrato that aren't particularly useful.  I find it considerably more useful to have an effect intensity pot to dial back the wet side, and a simple toggle to lift the dry signal completely and go to vibrato.  YMMV.

[skiraly017]

I find it considerably more useful to have an effect intensity pot to dial back the wet side.

I suspect this is what I'm attempting to do, "wet/dry" was probably the wrong choice of words. Thanks for both repsonses, I'll keep looking.

[Mark Hammer]

For the Ross in particular, I'd recommend a 100k pot in series with a 24k fixed resistor.  A total series resistance of 124k will be more than sufficient to dial the notches into the background.  I suppose there might be instances where you might want to make it even subtler than that, but I haven't personally come across them yet.  The reason why I suggest 24k instead of 27k is because it allows you some overshoot and a little bit of leeway to dial in a "perfect" 50/50 blend in case there is some discrepancy in actual wet and dry levels resulting from component tolerances.

For actual physical construction, what I personally do is remove the wet mixing 27k resistor from the board and run a pair of leads from those solder pads to the pot.  I solder the fixed resistor directly to one of the lugs, and slip a piece of heat shrink over it and the solder lug to prevent shorts and add some strain relief.

[skiraly017]

Thanks. I'm very excited about this build. I have been looking for a particular phase sound for a long time and the samples I've heard of the Ross I think will get it.

[Mark Hammer]

1) Stick a 22-47uf cap between the point where the 10k current-limiting resistor feeds the four LM13600 sections and ground.  It will serve to smooth out the sweep at fastest speeds but have little or no audible effect at slower speeds.  The net result is that the fast-Leslie settings will sound more pleasingly bubbly and not as jarring.  This was part of the very first Small Stone.  I'm not sure where it disappeared to over the years.

2) The Ross can be made to sweep a little wider (higher) by reducing the value of that 10k resistor a bit, and made to sweep more narrowly (i.e., turn back around at a lower point in the sweep) by increasing it.  DO NOT go below 8k2 or you risk frying the 13600 with too much current.  At 8k2 resistance, the sweep is tantamount to that of an A/DA flanger.  In other words, just when you think it is going to stop and make the turnaround, it keeps on going in very dramatic fashion.  Not everyone's taste, but it's impressive in comparison to what you're accustomed to from most phasers.  You can opt for something like an 8k2 - 9k1 fixed resistor in series with a 10k-25k variable resistor, or simple a wide/medium/narrow 3-position toggle that selects between, say, 8k2-15k-27k.  Of course, the stock 10k is fine too, but since you seem to want variations....  Keep in mind that it is a common principle in modulation effects that as speed goes up sweep width needs to go down.  The Ross, and a great many others, provide no means of adjusting sweep width so they provide a compromise width that will work reasonably well for all speeds attainable.  Doesn't mean it's the "best" width for you at that speed.