Boss RPH-10: What the hell is Mode II?

[Mark Hammer]

I managed to pick up a Boss RPH-10 that I had my eye on for a decent price last week: http://filters.muziq.be/model/boss/halfrack/rph10   http://www.modezero.com/boss-rph10.htm

It's a nice unit that uses 8 swept OTA-based phase-shift stages and 4 unswept stages, set up as a 6+6 configuration.  I have the schematic, but I have to say that the thing is difficult to read because of how packed it is and how many busses it shows running here and there.  The thing has 3 modes: a 6-stage mode, 12-stage mode, and a third mode (Mode II) that I honestly can't figure out.  None of the stuff I've found on-line gives any sort of technical explanation of what it does, and as close as I listen to it, I'm not hearing anything that jumps out at me and says "It's doing X".  Do any of you have any experience with this or information on it, such that you could describe what 0 technically - Mode II does?

There's a patch point on the back that appears to allow the LFO to be used outside the RPH-10 for syncing things or to be over-ridden or complemented by some other modulation source.  I think I'd like to stick an envelope follower in there, since there appears to be panel space for it.

EDIT:  Incidentally, for those of you interested in having more than 4 or 6 phase shift stages, the 12-stage mode has notches way up there, as expected.  If you have bandwidth up there, you'll hear it.  If not, then you won't.

[DougH]

It's the "double secret probation" mode. Shhh.... Don't tell anyone... 

I love those Boss mini-rack units. Back in the early 80's I wanted to get the chorus/delay model they had. I thought they were so cool.

Sorry I couldn't be help with your question. But congratulations on a fine purchase!

[Mark Hammer]

Thanks.  It goes nicely with the ROD-10 that I also picked up last year.  Paid $50@.  I think the series is under-rated, most likely because they aren't rack (two fit side-by-side in a 19" rack space) and they aren't pedalboard.  The entire series is remotely footswitchable, though.  One of the other neat features, too, is that they are already set up for power daisy-chaining.  Each unit has two parallel barrel jacks in the back so that you can plug the wallwart into one and run cables to the rest.  Neat idea, in every sense of the word "neat".  Pity that the plastic chassis-mount barrel jacks that so many here use are so damn big and costly, or else I think power daisy-chaning would be more common than it currently is.

[Rodgre]

I have the RPH-10 and the RBF-10 and I try not to talk too much about them because I think they're total sleepers.

The modulation bus (LFO) patchpoint can give you some really mind-blowing tricks. If you bus two units (like I have with the Flanger and Phaser) together, you can get pseudo-random modulation effects. Set one slow and the other one faster and blend both depth controls until you get something cool.

I've also used the C/V out of my Korg Mono/Poly while running an arpeggiated sequence to control the modulation. You don't want to know how cool that was.

The manual says that the settings are I=6 stage, II=10 stage and III=12 stage.

Roger

[Mark Hammer]

I have the RPH-10 and the RBF-10 and I try not to talk too much about them because I think they're total sleepers.

Agreed!

The manual says that the settings are I=6 stage, II=10 stage and III=12 stage.

Maybe so, but there is more going on in Mode II than just adding a few more stages.  I get the sense that a different control current is being fed to the one IR3109 than is fed to the other, and the schematic seems to suggest that.  There is an extra "burble-iness" to Mode II that sort of sounds like the two major sections reach the peak of their sweep at different points/times.  At first I thought they were being counterswept or something.  Interestingly, I made myself an 8-stage Ross/Ropez, and in the 8-stage setting I get a similar phenomenon.  In the Ross case, I think it is a sort of "stagger" resulting from component tolerances between the two boards (main and 4-stage daughterboard) or something rather than anything else deliberate about an 8-stage design.  In the case of the RPH-10, I think it IS deliberate, since the two IR3109s are fed by different source points, one of them with a trimpot-adjusted offset.

Having perhaps more phasers than I ought to, I was fooling around with two cascaded phasers the other night.  I found that if you set the first one in line for a nice long and wide sweep, with not too much resonance, and set the second one for fast and moderate sweep with more resonance, the first one tends to "reposition" the second one in a way that has a bit of periodicity to it, but also has some S&H flavour as well.  Nice.

[Mark Hammer]

Given the patch/insertion point on the rear panel, I whipped up a little daughter board last night with an envelope follower (simple half-wave rectifier) and installed it in the RPH-10.  The input to the envelope follower comes off the existing input buffer of the unit, and the envelope output simply goes to the point on the circuit where it would normally anticipate an external control voltage.  I figured all I would need to include is a sensitivity control, and a toggle for connecting/disconnecting it.  The nice thing about the RPH-10 is that it has a manual offset control and a modulation-invert switch, so you don't really need anything more than what I added.  The on-board controls let you tune it and get upwards/downwards.  Neat!  

I probably need to up the maximum gain of the envelope follower a bit (it maxes out at 105x, and could probably benefit if bumped up to 150x or so), and found I'd like a slightly faster decay, but other than that it sounds great.  Not quite an auto-wah, and not quite a phaser.  One of the cool things is that you can combine the LFO and envelope.  So, say you have the thing set for a slow sweep with moderate width and a low starting point in the sweep.  As it approaches the top, you can "push" the sweep a little higher via the envelope if you want.  Actually, I think Frank Zappa used to do just that with his old Wasatch Flanger.

The other neat thing is that the sheet metal internal shell/chassis that Boss used seems to have been stamped/punched as a universal shell for the entire Rxx-10 series, so while the legended plastic face may only show holes for however many controls are on the final product, the internal metal shell has holes punched for several additional pots (including tab punchouts for those little tabs on pot faces intended to secure its position as you tighten the nut) as well as numerous toggles.  So, I simply installed two holes in the plastic face to accommodate an added toggle and knob for a pot.  I have some small yellow rub-on lettering that is about the same size/font as what's already on there, so when I finish up, it should look nice, and behave nice. 

Once done, I'll put some picks-n-clips up.  In the meantime, I'm happy.

[Mark Hammer]

Well, the family camera is currently nonfunctional until the batteries are charged so I can't post a pic, but I posted a crude soundclip of what the envelope control sounds like.  Here is the link:  http://hammer.ampage.org/files/RPH-10_with_env.wma

The soundfile strings a few different settings end to end.  It uses two different modes in the RPH-10 with upward and downward sweep, and ends with an LFO/envelope blend that gets you a nice semi-periodic sweep.  The soundfile was done: guitar - RPH-10 - Roland UA-30 - Audacity - Audiograbber conversion.

[Cliff Schecht]

Well, the family camera is currently nonfunctional until the batteries are charged so I can't post a pic, but I posted a crude soundclip of what the envelope control sounds like.  Here is the link:  http://hammer.ampage.org/files/RPH-10_with_env.wma

The soundfile strings a few different settings end to end.  It uses two different modes in the RPH-10 with upward and downward sweep, and ends with an LFO/envelope blend that gets you a nice semi-periodic sweep.  The soundfile was done: guitar - RPH-10 - Roland UA-30 - Audacity - Audiograbber conversion.

That's quite impressive! Very open and airy sounding, like a phaser should be. Can I take a peep at that schematic?

[Mark Hammer]

For somebody even remotely affiliated with PAiA....ANYTHING!

If you go to http://hammer.ampage.org  you'll see a little writeup and links to the schematic for the PH-2 and the RPH-10 so you can compare.

[hangnef]

Long short and serious raise the dead post

Any info on this mod?  Just got one of these and would like to implement it.  I have done mods on most of the other boss units, and this one sounds pretty cool.

Most of the links are dead (and dead on archive.org too)

[Mark Hammer]

Sadly, I didn't archive any of that.  They warn you that "the internet is forever" but apparently not, unless you know where to look.

In any event, since I'd rather not have to disassemble my RPH-10 (it is a real bear of a job to do), I will guesstimate what I did, based on the brief write-up on the old AMPAGE site.

"With that option available, I went ahead and added an envelope follower to provide envelope control of phasing. It was a simple half-wave rectifier, based on the venerable Doctor Q, providing a gain of around 168 at max gain. I used a 10uf cap to smooth the envelope in parallel with a 47k resistor to keep the decay time modest. The resulting envelope voltage is fed through a 10k resistor to the junction of R82 and R58 in the RPH-10."

I am assuming that I tapped the input signal at the source of Q1, where R3 and C2 meet, and put a 1uf cap between that point and the input lug of the sensitivity control.  The stock Dr. Q follower provides a maximum gain of 46x.  Just how I ended up with a gain of 168x, I have no idea, but I gather it would involve increasing the feedback resistor in the op-amp from 2M2 to something higher, and reducing the 47k input resistor.  I likely used a 741 op-amp, and a 1N914 for the diode, but if you use a Schottky of some kind (BAT46, 1N5817, etc.), you keep more of the envelope voltage so you don't need as much gain.  A 4M7 feedback resistor and 47K input, with a Schottky instead of 1N914 ought to be AOK.  Note that the 2nd diode after the cap to ground is omitted, and the envelope fed directly through a 10K resistor to the bus, at the junction of R82 and R58.

As with many envelope-control scenarios, time-constants provide the "feel", and the described 10uf and 47k got me something I liked.  No reason why a person couldn't opt for a longer decay time with a resistor value >47k.

Does that answer your query?