Pedalboard Power and the Mod Duo


#21

I ran it with CPU usage in the 80s…I’m truly baffled.


#22

I used to own a Onespot Pro CS12 and use it with my wireless guitar receiver (which drew quite a bit of current too). What you actually ran into was an awesome thing about the Onespot Pro series, I’ll just quote a part of their website (http://truetone.com/cs6/):

"1 SPOT Technology… what does that mean and why should I care? Technically, it’s switching power supply technology, which is very different than what anyone has ever put inside a power brick. Normally, you would find just a big transformer and a handful of small electronic components inside a power brick… old tech that hasn’t changed in decades and has a lot of limitations. We took the same switching power supply technology found in our famous 1 SPOT and scaled it up to make the 1 SPOT Pro models. With much more space to work with, we were able to completely eliminate noise, provide total electrical isolation between outputs, create multiple voltages, and still give you the ability to use it anywhere in the world.

A major benefit of using a switching power supply is that it can handle far more current (power being pulled out of it) than any transformer-based power supply. Although we had to put power rating labels on each output to satisfy certification agencies (yes, we actually certified these, unlike most companies), the outputs can generally handle far more than the label shows. For example, you can connect a 300mA pedal to a 200mA output, without causing any problems. With a transformer-based power supply, you can’t get away with that. The important thing is to not exceed the total of all the labels. With a CS7, the output labels add up to 1900mA total. That means the total current draw of all your pedals should be less than 1900mA. That total current rating is roughly double the current load of the most common power brick, for a lot less money."

TL;DR: because of the architecture of the Onespot, it can actually supply much more than what is said on the labels. If your other pedals draw very little current, you could actually get away with using it with the Duo even in the long run. (Although it is probably not necessarily recommended by Truetone)

//Jesse


#23

Well, holy crap! That explains why it seemingly works! Thanks!


#24

Just so you know, I started out this little experiment because of similar desires. I use my POG2 a lot, and I agree that while I can get the polyphonic octave effect from my MOD (at the high settings), but it just takes too much of the CPU.

I now know that my 1spot pro CS6 is seemingly able to power my MOD (?mA), POG2 (180 mA), and Shure wireless (250 mA) at the same time.

I don’t know if I’d “recommend” anybody else trying this method, but I’ll give it a go (after I figure out how to save all my setups on a USB drive :grin:).


#25

Well, even if an output rated at 200mA is delivering 300mA, that’s still an awful long way from the 2000mA which it is claimed the MOD Duo requires. So a more official answer from the MOD folks on what would make a safe minimum current supply would be pretty helpful in determining whether this configuration with the CS6 can be relied upon.


#26

Yeah, I really hope that future versions of the MOD Duo offer more CPU power. IMHO this is its biggest weakness right now.

Well that’s really awesome :slight_smile: The CS6 does seem like a super-cool brick, but unfortunately the only pair of outputs it has rated higher than 200mA are 9VDC outputs at 500mA, which presumably would not work with the MOD Duo at all. And I don’t want to shell out a lot of money for CS6 without being 100% sure it will work reliably not only with my MOD Duo, but also with the 18VDC 200mA preamp I mentioned above. And there is a similar issue with that - the only 18VDC-capable outputs on the CS6 are only rated at 100mA :thinking:


#27

from above:

need more official than that?


#28

I already referenced that post above, but it still doesn’t explain why a Duo could possibly work on 2.4W (200mA) or even 3.6W (300mA) going on the assumption that the 200mA output on the CS6 can actually drive 300mA loads.

So yes, I’d still love an official answer on why @Treelemon’s Duo is apparently running fine on ~3.6W even when CPU load goes into the 80s.


#29

That is actually because @Treelemon’s Duo is drawing more than 300mA. He is running the Onespot Pro CS6 WAAAAAY out of spec. (which, due to the architecture of the PSU is apparently possible)

The only way to know for sure how much his is drawing is to actually measure the current draw. My guess would be somewhere around 1000mA.

You would have to basically look for an official answer from the folks over at Truetone for a proper explanation of why it is possible.

Hope that answers your questions!

//Jesse


#30

What you say sounds very plausible and I suspect you’re right; however it also sounds quite speculative :slight_smile: If the CS6 is capable of (say) 1000mA from an output rated at 200mA, it begs the question why they rated it so low in the first place. Something in this whole picture really doesn’t add up yet… Yes it would be great if @Treelemon could measure the actual draw, as that would give us hard data which we could then ask Trutone about.


#31

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.


#32

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.


#33

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!


#34

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.


#35

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:


#36

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:)


#37

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


#38

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.


#39

Thanks @Treelemon this is super helpful!


#40

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.