RC-50 - The New Adventures of the RC-50 and Beat-Synced Delay

Started by Threeleggedyoyo, January 13, 2013, 01:38:59 AM

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Threeleggedyoyo

Some of you are familiar with my struggles to get beat-synced MIDI delay to work with the RC-50.

Long and the short of it is that slight warbles in the 50's clock will disrupt delay pedals as they try to recalculate previous echoes. This is not an issue with any other type of effect, since they don't work retroactively.

Up until recently I could not pinpoint what caused these glitches. Sometimes they'd happen a lot, and sometimes only rarely or not at all. Then I stumbled on something.

Some of the BPM settings (all are between 40 and 250) are producing glitches and others are not. I am using a GT-6, but the behavior was similar with an Adrenalinn III. Watching the BPM readout on the GT-6 shows that sometimes the beat wobbles between a couple numbers, and sometimes not. This wobbling is NOT evident on the RC-50's readout, but it seems fairly clear it's an issue with the 50 since it has happened to me across multiple MIDI-synced delay units now.

Anyway what's really interesting is that its consistent. On some BPM settings it happens constantly, on some it happens only once in a while, and on some it never happens. For example, 156 is terrible. But 157 is glitch-free.

What I want to know is: is there come kind of pattern? Here is my audit. It is not complete, and it does not account for severity (only for "glitches" and "doesn't." Some that glitch only do so a little, and some are almost constant.

The effect is relatively linear. There are no glitches from 40 up until about 140. From there some numbers have glitches until about 180, after which almost every setting glitches.

157
153
151
165
166
168
119
129
128
127
194
126
88
89
90
91
92
40
14
150
145
138
136

BAD NUMBERS:

156
192
155
171
173
174
161
191
193
196
167
169
146
141
250
239
182
183
184
185
186
187
188
189
173
174
175
178

I'd like to be able to detect some kind of pattern so that I can predict which numbers will be "Good" or "Bad" without having to memorize them all. However, they don't seem to follow any discernible pattern. I'm hoping someone here who is good at teh maths can help me detect such a pattern.

The only pattern I can really see is that there don't seem to be any "Bad" numbers until you get up to the 140's or so, and that the higher you go, the more "Bad" numbers there seem to be, but not with any certain frequency. But even that I'm not sure of without going through every single one.

Note that the 300 had similar issues with external beat-synced delay when I tested it. Of course, it has an onboard delay module which seems to negate the problem.

Syph

Very interesting dude...

My first thought would be what other midi information is the rc50 putting out?

If it is sending some crazy sysex msgs and/or CC msgs etc it could me causing problems with the midi bandwidth, which (at higher tempos) would then delay the midi clock pulses, hence your slight bpm variations. Also, remember that since midi is hexadecimal based, glitchy bpm that may seem random in decimal may visually leap out in hex....

I haven't had any issues syncing my rc300 with either the A3 I tested or my GT100, and i can think of 3 possible reasons. First, i may have lucked out. Unlikley.  Second, I didn't test the A3 extensivley, and the GT100 may have been "fixed" in regards to the delay bug. Third, considering I never really play faster than 110 bpm on the looper it may be as I stated above, that I am playing slow enough that the midi has enough time/bandwidth can function accurately enough.

One potential work around could be to half any tempos that would start straying into glitch territory, program your drums accordingly. Not ideal admittedly, but it would keep you in the clear bpm range.

I am off to bed now, so my apologies if either my ramblings are stating the obvious or my fanciful delusions are getting the better of me. Some point on the morrow I'll try doing some meth.... I MEAN MATH!!! (Panics and runs away)

*while I can see how the rc300 delay can be viewed as a work around in this context, I hate having my delay ALWAYS at the end of my chain (it just sounds sooooo good to have delay running into a dirty amp!) so I don't think that is a valid fix.... At least for my high and mighty delay complex...


Threeleggedyoyo

I'd be interested in hearing if you get the glitch at faster tempos with your GT-100. When I field tested the 300 along with the A3 I was getting the same glitches.

Threeleggedyoyo

Discovered today that unlike I previously thought, the RC-300 does not have this issue with the GT6... exactly.

Seems like it only glitches if the tempo is not a whole number (156.5, etc).

The RC-50 settings I was using before WERE whole numbers, though.

So that pretty much confirms my original suspicions... something about the 50 is not exactly the numbers it says it is. Not a problem in most cases but an issue with stuff like this.

With the 300, this only becomes an issue when you tap tempo. It's too bad there isn't a setting to tell the tap tempo only to work on whole numbers.

BUT it's nice that the 300 has now solved my delay problems twice over... with both an onboard delay function and the ability to get along with the GT6. Had I known this I might have kept the Adrenalinn III... actually, no. That thing was haunted.

FreeTime

Sounds like there's some superheterodyning going on. The BPM calculation vs the RC50s clock. Maybe its integer based vs real number, giving you a remainder that would make the output fluctuate, sum of the difference sort of thing, sort of like a ring modulator.

Threeleggedyoyo

Quote from: FreeTime on February 18, 2013, 02:02:57 AM
Sounds like there's some superheterodyning going on. The BPM calculation vs the RC50s clock. Maybe its integer based vs real number, giving you a remainder that would make the output fluctuate, sum of the difference sort of thing, sort of like a ring modulator.

I don't totally get that, but yeah, sounds about what I thought in the first place... the RC-50's idea of a unit is not exactly the same as the GT-6's.

Glad it's working with the 300, though... between this and the onboard effects, it's solved my problem twice over. :)