A modulation pedal to rule them all

[Mark Hammer]

EHX just released this monster.  And you thought the Super Pulsar was something?  Lots of great ideas in there.

[Danich_ivanov]

They are on the roll lately. I've been working on some modulation stuff myself for sometime. And i considered making a single thing instead, but it seems that i can get more out of each separate unit, and price won't be as touchy. But awesome non the less.

[ElectricDruid]

For me, the key feature of this pedal is that the LFOs are all synced to the musical tempo. You can set one LFO to play at quarter notes, while another sweep operates across a whole bar, for example.

If it wasn't for that, you could easily do something similar with three or four pedals in a row. But *with* that feature, it's a different story - you'd have to somehow have pedals that could sync together and you'd have to be able to set the frequency of each at multiples of the sync frequency. That's possible, but puts you firmly in digital LFO territory. Easier to have it all integrated in one box.

Another nice touch is that they've not been fussy about *how* you get the tempo. You can tap it, you can use a MIDI Clock, or you can feed in analog pulses from an old drum machine or analog sequencer. That's pretty versatile.

Otherwise it's really just a digital multiFX in a pedal housing. We've seen a few of those. It's hard not to like something with that many coloured lights though!

They'll sell plenty though, I reckon, and we'll see them being used with synths a lot. It's *almost* not aimed at guitarists. One for the Korg Volca crowd, in my view.

[deadastronaut]

needs more leds...

[Mark Hammer]

For me, the key feature of this pedal is that the LFOs are all synced to the musical tempo. You can set one LFO to play at quarter notes, while another sweep operates across a whole bar, for example.

If it wasn't for that, you could easily do something similar with three or four pedals in a row. But *with* that feature, it's a different story - you'd have to somehow have pedals that could sync together and you'd have to be able to set the frequency of each at multiples of the sync frequency. That's possible, but puts you firmly in digital LFO territory. Easier to have it all integrated in one box.

Remember the Anderton/PAiA "Master Synchronizer" project that appeared in Contemporary Keyboard magazine?  It allowed you to divide down a master clock.  Coupled with a way of turning pulses into other waveforms, that could approximate the same thing.  https://www.paia.com/talk/download/file.php?id=213&sid=cfe4369f08f664ad565028f538937049

[Ben N]

You could do this with multiple modulation pedals that take MIDI clock input. But why would you? On another note, can a Strymon Mobius not do these tricks?

[Mark Hammer]

Perhaps, but only one effect at a time, as I understand it.

[ElectricDruid]

You could do this with multiple modulation pedals that take MIDI clock input. But why would you? On another note, can a Strymon Mobius not do these tricks?

Yeah, course you could. I could build three or four pedals using my TAPLFO and sync them together and I'd get the same thing. They've just (a) done it already, and (b) made it simple. That's a pretty big gain.

There's nothing fundamentally new here, it's just neatly done and simple to use. But that's exactly why the Minimoog was a success forty years ago and why they're *still* making them again now!

[anotherjim]

It does look impressive.
A question I'd ask, if you power off and on, does it come back how you left it? This is a major killer for me with a lot of digital gear. I don't care if you can save it as a preset, it should remember its last state.

[ElectricDruid]

I agree, but that's actually pretty fiddly to do, Jim. It's not impossible, but it's a bit of a pain.

One way is the following:
Have a resistor+LED or other diode across the power supply for the pedal. From the junction of the LED/resistor, feed that voltage to an ADC input on the processor.
The voltage across the diode will remain the same even if the power supply varies a bit. This is also true when the power supply voltage starts to drop when power is turned off. Now, if the processor's ADC reference voltage is also that same power supply voltage, when the power supply drops, the ADC reading from the diode actually goes *up*! This is because the steady voltage across the diode is now a larger fraction of the falling reference voltage. When the processor detects this, it knows the power is going down and it has as many milliseconds as it takes for the supply to die entirely to save the current state into non-volatile memory (a bit of EEPROM on the uP chip usually).
Like this, it's possible to make a digital pedal that remembers the state it was last in even if you pull the plug out.

I've done it as a demo with a couple of buttons that toggle the state of a couple of LEDs, but I've never used it for anything serious. Perhaps I should.

[PRR]

With modern Flash-ROM (non-volatile RAM), state-saving should be trivial. Every time the user changes a setting, write a copy to Flash. If the brain wakes-up blank, get values from Flash.

[anotherjim]

It bothers me that so many MCU's have a brownout detector on chip, but it's looking at the power supply on the chip. If the 5v or 3.3v supply is dropping out, it probably is already too late to do much about it. I think it has to be looking at the immediate power supply input before the regulators. That voltage starts dropping before the regulated.
But, yeh, as Paul mentioned, keep the state in non-volatile memory and load it at power up instead of a preset. Use BOD to prevent any new changes that might be corrupted when the supply voltage starts dropping.

[Rob Strand]

It bothers me that so many MCU's have a brownout detector on chip, but it's looking at the power supply on the chip. If the 5v or 3.3v supply is dropping out, it probably is already too late to do much about it. I think it has to be looking at the immediate power supply input before the regulators. That voltage starts dropping before the regulated.

Indeed!   Like if your battery is going flat the transition from trip to actually failing to work could be some time.  However if someone rips the power out you really need to have some big caps to hold the power up.  Many systems don't!

[ElectricDruid]

With modern Flash-ROM (non-volatile RAM), state-saving should be trivial. Every time the user changes a setting, write a copy to Flash. If the brain wakes-up blank, get values from Flash.

The only potential snag here is Flash ROM's write endurance, which is often as low as 10,000 writes. If someone is a bit of a knob twiddler, you're going to burn through that pretty fast.

I suppose you have to do something clever like only update the state when the knob stops moving, rather than every time there's a new value (which would cause 100+ writes as you move the knob from min to max).

[EBK]

You only really need to read the EEPROM's stored state at power up and flash the final state at power down (I'm assuming a controlled power down, not a power failure, although you could certainly design for that if you wanted to).  Everything in between can use volatile memory.