Pedalboard Power and the Mod Duo

They answer that in the piece of text that I had quoted above. (copied below for clarities’ sake)

I interpret their piece of text as if the distribution of current draw between outputs does not matter, as long as the total current draw does not exceed the maximum current draw of all the outputs combined.

I do agree that this is not something that can be considered as a conclusion, and definitely not something that should be assumed without contacting Truetone first.

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Word of caution…

Make sure you are not using the power supply beyond what it’s labeled for. It can be dangerous and if it does catch fire and burn down your house, you may not have any ability to collect any compensation from the manufacturer or insurance because you were using the power supply in the manner it was not designed for.

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Ah I see! Their “you can connect a 300mA pedal to a 200mA output, without causing any problems” statement had got stuck in my brain so I was thinking they were saying that 300mA was the limit for that output, but now I realise that was just a somewhat arbitrary example. So if the Duo only requires around 12W, i.e. 1000mA, that leaves 900mA, which explains why it could also power @Treelemon’s POG2 at 180mA plus the Shure wireless at 250mA. And in fact this would still leave 470mA to play with, which could potentially cover 2 or even 3 more pedals.

This got me curious about the current draw of my MOD footswitch extender and Softstep 2, so I got out my USB analyser, and found:

  • The SoftStep 2 seems to draw between 100mA and 140mA.
  • The footswitch extender seems to draw less than what is required to register above 0 on my USB analyser. It just says 0.00A, so presumably it’s less than 10mA?!

Having said that, normally I would power my footswitch extender via the control chain, so I don’t know if the draw would be different vs. when powered over USB.

Anyway, this suggests that in theory the CS6 could power my Duo (1000mA) plus my Nano POG (25mA) plus Headway EDB-2 preamp (200mA worst case) plus SoftStep 2 (140mA worst case), and still have around 535mA of headroom. That sounds pretty promising!

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Wise advice, thanks!

Although one would hope that the CS6 had built-in protection against this situation.

By the way, I found this video by Truetone’s owner which re-affirms the statement on their website that the maximum limit for current draw is based on the total the power supply can handle across all devices, and that the limits per output socket are only there to satisfy certification requirements.

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I feel more secure after watching that video. I’m going to try my setup this weekend at a rehearsal and then at a show this weekend. I’ll let you know how well it goes.:+1:

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Ok, so I chatted (via email) with Truetone about how I’m using my 1Spot Pro CS6 to power a pedal with mA requirement of around 1000 mA. They confidently said that as long as the total mA usage from the 1Spot Pro CS6 was under 1600 mA it should work just fine!

I then noticed they make a mA Meter.
http://truetone.com/ma-meter/

This has the purpose of being able to see how much mA is actually being drawn by a pedal. So…I got one today and used it to see how many mA my MOD Duo was actually drawing from 1Spot Pro CS6.

Most of the time it was drawing 470-500 mA, and when I got CPU usage to the 80-90% range, the MOD would draw around 500-520 mA.

I’m now much less worried about the 1Spot Pro CS6 ruining my MOD, but only time will tell!

(Also of note, the first test during band practice last night worked just fine. :+1:)

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very interesting information, @Treelemon… thanks for the details!

Experiment 2 went just fine. Live show went just fine without any pedal glitches.
So, now I’m pretty comfy powering my Mod with the 1Spot Pro.

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Thanks @Treelemon this is super helpful!

The official answer is still the same. The MOD Duo requires a 12V @ 2A power supply. If you are using the Duo without any extra accessories either USB or Control Chain, it’s safe to use a 12V @ 1A power supply. Indeed the real consumption is around 500mA but you definitely shouldn’t use a power supply with such a tight specification. There are good reasons to have some free room in the specification. First, the coreboard manufacturer states that the coreboard current might reach 1A. Second, the power consumption might get bigger in the future according to the “enabled features”. Let’s say, for instance, we decided to use the GPU to process some audio data, that would require a few hundreds of extra milliamperes. Third, if the CPU of your Duo is upgraded, the power consumption will increase.

It always worth to remember the MOD Duo has an embedded computer inside and it’s not like the normal stompboxes. And as the fan of your laptop might tell you, the power consumption oscillates according to the triggered events.

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Thanks, that’s super helpful! So are there any plans to support a CPU upgrade yet, or is it just an idea at this stage? It would be awesome to be able to do that :slight_smile:

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hey @aspiers… see here:
CPU upgrade?

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GPU ?!?!?

Is there a GPU on the mod ?

There is a built-in GPU in the processor.

Wow ! That is interesting to know !

So I was noodling around tonight with my MOD and found an interesting way to run my the Drop pedal at high fi without having to give up other effects…(maybe everybody else already knows about this?)

I can plug in to input 1 and first effect is a switch that sends the signal either through my standard effect chain (OD, Distortion, Chorus, phaser, EQ, Compressor) that exits at output 1, or it gets sent to a Drop pedal at -12 in high fidelity which then exits output 2. I then have output 2 directly connect back to input 2 and then that runs through the previously noted effects loop and it works just fine!?!?

Is it because once the shifted pitch leaves the MOD then it doesn’t have to be treated like an effect anymore when it comes back in through another input? I am honestly amazed at this, I may be able to rid my pedalboard of my POG2 due to this.

Is there a way to program the MOD “pretend” that the pitch altering pedals aren’t “effects” as soon as the signal leaves those plugins? I know nothing of programming! I’m totally fine with just using the wrap around solution I just figured out, but I’d love to get a free second output back!

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Cool discovery! The Duo signal routing flexibility is a unique and powerful aspect of the device.

I’m not sure I quite follow what you mean here, but here is my understanding of the technical process. The MOD (as a whole) and the individual plugins themselves have no ‘knowledge’ about what state a signal is in. If there is a signal, it will be processed and passed on through each step of the pipeline. In the case, where you have the switch going to your Drop, the overall signal pathway will look like:

* MOD Input 1
* ADC (audio to digital converter)
* Pedalboard input 1
* Drop
* Pedalboard Output 2 
* DAC
* MOD Output 2
* MOD Input 2
* ADC
* Pedalboard input 2
* Effects chain
* Pedalboard output 1
* DAC
* MOD Output 1

In the case where the switch is routing to the Drop, you are doing two passes on the audio signal. This will introduce some additional latency compared to the case where your switch is passing directly to the effects chain. For many users or use cases this is fine, though some performers or listeners might perceive a difference.

Is the reason you don’t route the Drop directly into the effects chain due to CPU? The MOD has a setting for doubling the frame buffer size, meaning you get double the processing time at a cost of double the latency. It might allow you to handle both routes in one pass without having to do the loop around externally.

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Hey unbracketed,

Yes, I’m running the Drop (Hi-Fi) in wrap-around since this oddly works within CPU usage, when running it directly in the effects line draws the full 100 in CPU.

My main question is…why does routing the Drop effect via wrap-around save so much CPU?

Also, I guess I’ll get some latency if I do the wrap-around or doubling the frame latency, but I barely notice it doing the wrap-around. shrug

You haven’t saved any CPU, you are spreading the processing out over more time by doing two passes.

Maybe this will help - imagine instead you have 2 Duos. One is running your effects chain pedalboard. The other is running the Drop. Instead of the plugin switch you have a physical switch that routes between two Duos. Switch out 1 goes to effects Duo. Switch out 2 goes to the Drop Duo. The Drop duo out goes to the effects Duo in 2. This should be an equivalent setup to what you have. When you set the switch to go to the Drop Duo, the amount of CPU consumed will be the sum of the two Duos. It will take twice as long to go through this path, since there is an additional Duo handling data.

Taking this further, imagine you split your effects chain into dedicated Duos per effect (each Duo runs a single effect). Each Duo could be expected to have pretty low CPU use, at a tradeoff of the overhead of converting the signal in each Duo. If you string together several Duos, each one might run efficiently, but each Duo is adding a conversion overhead. There’s nothing free, and there’s no magic here. The good news for you is that for your use, the additional latency of your solution isn’t causing problems (as you report). But the laws of physics and DSP are all still intact :slight_smile:

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I think by not having the dropped signal recombine on the pedalboard the processor can split the signal into 2 paths and spread them into 2 cores more easily. When the signals combine again then suddenly it has to go to the same core for the last few plugins and it might not be able to use multiple cores at all. I’m not sure about how it decides what to do in parallel, but I’m pretty sure a linear graph will always be on a single core.