PSA: those with MPC One's considering an external battery

This ol' thread is still high in Google, so let my bring in some new options, escpecially for european users:

I tried two power bank with AC outlet, 220v here. Both of them showed 18,96 volts when measuring with a multimeter at power outlet of MPC one's charger. (Which also showed 18,96 volts, when connected to wall plug).

1) The one from Polaroid (also available with other brandings, I think) is the best option so far, although not perfect: https://www.polaroidenergystorage.com/en/polaroid-ps100

Pro:

- Solid and safe AC outlet, especially for German users e.g. with Schuko plug (the outlet mus cover the whole big plug)
- Affordable - 100 Euro is fair for around 20.000 mAh/80 Watts
- Rechargable via standard USB Input (2,4A) - e.g. in the car
- 30 Watts PD USB output.
- Authentic specifications (300 chargin cycles), less "China random brand appeal" *

Pro/Con:
- Recharging takes 8 hours. But should be more gentle for the integrated battery cells.

Con:

- Fan is very loud, not temperatur sensitive...
(Possible solution for me: I will use the MPC one only with headphones, mostly with noise canceling ones.

- - - - - - - - - - - - - - -


2) RAVPower 27.000mAh 100 Watt (80 in doubt)
Seems to be available only on amazon

Pro:

- Silent fan, temperatur actived (starts after a few minutes of AC mode with the MPC one)
- lean format, not as bulky as Polaroid
- manufacturers respond on amazon

Pro/Con:

- Charges in about 3 hours. But maybe more stress for the battery cells.

Con:

- Only rechargable with the included special charger - a real downside when you are on the road with lots of USB chargers but no wall plug in sight.
- Power socket not completely secure with" Schuko" plug, but takes them
- more "China random brand appeal" *, but packaging and documentation are above the average.

I sent the RAVPower back, and kept the Polaroid, but both are cool, at the end.

Maybe this helped somebody, cheers!

* not meant as disrespect to chinese people, culture or trustful businesses - and no bashing (we all buy chinese products). Only relating to some branding and reselling business culture.

oh, sorry for all the typos and, since editing is not possible: both batterys delivered around 4 hours of power for the mpc one - enough for my playing around outside.

You can Edit your posts. The red button on the Left.(little cogwheel on your post)

The amp rating on any power supply (wall-wart or battery) is a maximum rating. The device attempts to draw what it needs at any given moment (this will rarely be constant) and the power supply will comply up to that maximum (at least). If you go ever, thing can break or shut down.

A 3.42A power supply does not constantly put 3.42 amps into the device. The MPC Live and X come with the same power brick, as far as I know? But the X will use more power with its larger touch screen and all the OLEDs etc. The entire device presents itself as a load (resistance) to the power supply, and the amps required to run it are a function of the input voltage and that resistance, per Ohm's law.

Whether the device will accept a lower/higher voltage depends on its internal circuitry. Even if the device has internal regulation and protection, going over the recommended voltage might lead to extra heat and strain, and going under can be even worse, because you might end up only supplying enough voltage to feed some parts of the device, which can fry out things. It is best to stick to what the manufacturer recommends if you don't have detailed knowledge of everything that's going on on the other side.

I do not have this certain, detailed knowledge and you most likely do not either, so regardless of what's below, know that powering your MPC from less than 19V has the risk of decreasing its lifetime into the milliseconds as has been said.

That being said, here's some midnight speculation: There is a some reason to expect the MPCs other than the Live to work on a lower voltage.

The Radxa SoMs that form the heart of the machines use only 5V input and all the voltages that the main processor and RAM need are generated on board by specialized circuitry[0]. Most of the other boards (audio and control surface) are connected via internal USB connections, i.e., 5V. 2.5" drives run off 5V only as well. That leaves the screen, which I don't know the details of, but screens of the right size and resolution that run directly from USB power are readily available.

So why a 19V power supply if everything would run off a (large) 5V PSU? Well, you need enough watts, and a 19V, 3.42A power supply is a completely standard part (used on many cheap laptops), whereas a 5V PSU of more than 3-4A is considerably more specialized - or at least was, before USB-C power delivery, which hadn't really rolled out when the MPCs were developed. So if any of the models (or other InMusic products that share the MPC's guts) require more than, say, 20W, using a higher voltage and stepping down makes sense, and this will work as well for a 7V input as a 19V input, so long as the power supply (battery) can deliver enough watts (volts times amperes).

Now, remember I said that it might be different for the Live: The battery charging circuitry might need the higher voltage. I don't know the specs of the battery in the Live at all. I don't know why you'd run the Live from an external battery, but I'd be even more careful with that than a One. LiOn battery packs can catch fire if not treated correctly. But it's not inconceivable that the Live needs the 19V and the others just use it because it was simpler that way.

Note that this is all just (somewhat informed) speculation. If you power your devices with off-brand power supplies at your own risk. Just because it works for five minutes doesn't mean it'll work for ten. YMMV. Etc.

[0] See the last pages of the schematic: https://dl.radxa.com/rock2/docs/hw/radx ... 140927.pdf

40Beatz wrote:You can Edit your posts. The red button on the Left.(little cogwheel on your post)

Thank you! But I only can report my own post Maybe a restriction for new users or so... [edit]Okay, another typo and I found out, I can edit this. Logical conclusion: first post had moderator approval so this may be the limit in the cog button then... Sorry and thanks [/edit]

Whoa....I think You're right Bruh! My Edit feature is gone as well.....My Bad

Edit....lol

It may be a Time Feature. Because i can edit posts right away but not my old posts

It doesn’t matter if you your power supply outputs more amps as device will only take what it needs but no less otherwise it will starve and that’s not good at all! Now Voltages are different then Current! More volts then device is rated at usually in most cases ends up with blowing it up or at least power board( depends on design as there might be fuses on board too but different kind of fuses then your usual ones from uk power plugs) on the other hand if this device is rated at 19v I’m really surprised it does even power up! So I’m getting mpc one in next week or two and I’m going to meter out that power supply as most arm devices I have seen works at 5v so only thing I can see would be that screen but we have 5v screes too so maybe Akai did that on purpose to keep people away from buying cheap battery since that will cannibalise mpc live market. Hmm interesting, I would love to meter out that portable battery too if mpc one power supply does output 19v.
If anybody have mpc one and multimeter, please can you measure it’s output and share it with us here?

Amperage doesn't matter unless its under the units draw, volts does. No matter what amperage a power supply is rated at, the unit connected to it only pulls the amps it needs. This is why you get 2A power supplies with pedal chains that can run a zillion 9V Boss pedals that only pull like 10mA each.

Now mismatch your volts and you're asking for trouble. Go under and you'll **** the circuit up by not giving it the juice it needs to run properly, go over and you just blew something up.


EDIT: Yeah what that guy above me said hours before me. Thats what I get for replying before going to page 2 hah.

Cray23 wrote:I would love to meter out that portable battery too if mpc one power supply does output 19v.
If anybody have mpc one and multimeter, please can you measure it’s output and share it with us here?

I have the Live 2 (the One, Live/Live 2. and X all use the same power supply wall wart):

Cray23 wrote:most arm devices I have seen works at 5v

There's far more than just a single ARM processor going on in the MPC One/Live/X. Suggesting they baked-in a high energy requirement for them just to avoid cannibalizing the Live market doesn't seem logical, as if they truly only needed 5 volts to work, they could have made the Live a lot smaller and lighter with a smaller battery, or kept the same size and offered far more usage time when running on the battery.

The processor board doesn't even use the 5V, it just uses it to generate the 1V or whatever for the core and 3.3V for the i/o. True 5V electronics have been rare for a good while, it's just used for power distribution because it's easy to get a good 3.3V supply out of a 5V supply that might be +/- a few percent.

There's nothing weird about having a 19V PSU and battery to power a system that regulates that down (in a few stages) to the very low voltages used by modern fast electronics. Computers do that. The battery size is determined by the Watt-hours needed, that's volts times amps. A 12V battery pack of 10,000 mAh would be the same size as a 6V pack of 20,000 mAh.

As I wrote in my long post above, the only thing that's really likely to actually use anything above 3.3V or 5V inside the Live is the battery charging circuit.

rvense wrote:The processor board doesn't even use the 5V, it just uses it to generate the 1V or whatever for the core and 3.3V for the i/o. True 5V electronics have been rare for a good while, it's just used for power distribution because it's easy to get a good 3.3V supply out of a 5V supply that might be +/- a few percent.

There's nothing weird about having a 19V PSU and battery to power a system that regulates that down (in a few stages) to the very low voltages used by modern fast electronics. Computers do that. The battery size is determined by the Watt-hours needed, that's volts times amps. A 12V battery pack of 10,000 mAh would be the same size as a 6V pack of 20,000 mAh.

As I wrote in my long post above, the only thing that's really likely to actually use anything above 3.3V or 5V inside the Live is the battery charging circuit.

Are you suggesting the current MPC line only really needs more than 5v to... charge the battery? Totally confused...

Yeah, I think so.

Modern digital electronics that actually does stuff don't use anything like 19V - most of it is 3.3V, but the faster it goes, the lower voltage it's likely to be. Modern desktops CPUs use 1V signals internally or less. They might use a lot of amps, but at a low voltage.

First some technical background: A (step-down) power regulator is a device that takes in a high voltage and outputs a lower one. But the high voltage doesn't need to be exact, it just needs to be a little higher than the desired output. So if you need a 3.3V, you can put in, say, 4.5V or 12V or maybe even 19V (depending on the regulator, probably not everything likes going so far above), and you'll get a nice flat 3.3V out. But the watts (which is amps * volts) that you can draw from the regulator is the same on either side - so if you connect the 19V/3.42A supply on one side of a 3.3V regulator, you'll be able to draw up to maybe 18A of 3.3V on the other side. (Well, it's the same minus some less in the converter itself, but good modern ones are quite efficient.) Simpler ones (linear regulators) that were very common previously are much less efficient and turn the excess voltage (difference between input and output) into heat, so with older equipment using a much higher voltage than you need becomes a thermal problem.

The reason you use higher voltages for power distribution is, as far as I understand it, that voltage drops when it runs through a wire or trace on a circuit board. So say you have a bunch of chips on several boards that need 3.3V. If you just generate 3.3V in one place, the last chip in the far corner might not get 3.3V, it might see 2.9V, and it might not like that. But if you run a 5V across the wire or as a big fat power distribution trace, maybe it drops to 4.5V, but a regulator can still generate a pristine 3.3V supply from that. On desktop PCs most of the power is actually delivered to motherboard as 12V and then regulated down to the small voltages needed in many different places by the various subsystems. This approach also means they're isolated from each other, a chip can send noise back into its power line which can disturb other chips that are connected it, but not through a regulator.

So what do we know about the Live?

The CPU board (SoM) takes in a 5V supply and regulates it down itself, there's a specific chip that takes 5V in and brings the different power supplies that the CPU needs online in the right order when it boots up. The CPU (and maybe RAM) also need both a 3.3V line and a 1.5V and maybe even one that's lower. The schematics for the SoM are available, linked in my previous long post.

2.5" drives only expect a 5V power supply.

The audio board and interface are connected via USB (not actual USB connectors, but four wires like what are in USB cables, like you have internal USB headers on PC motherboards that you can connect to a front panel), so these subsystems also run off 5V (though they only use it to create lower voltages locally.)

The screen *might* need a higher voltage, I don't remember how its power is connected. Maybe I'll take the back off my Live tonight and look/measure. But I have a display of roughly the same size as the one in the Live which runs off 5V... Actually now that I type it out, it's possible that the larger display in the MPC X could require a larger voltage for its backlight. But in the Live it might not.

That leaves the battery. Batteries are charged by putting a (slightly) higher voltage into them that what they currently have, more or less. I don't know anything about how the battery pack in the Live is configured. It might have a high voltage or a low one. I don't know much about batteries, there might be some physical reason why it's easier to store some number of amp-hours at 19V rather than twice the amp-hours at 9.5V, or whatever. This could be the reason for the 19V power brick, but it could also be that the 19V cheap laptop standard was just the cheapest 60W power supply that Akai could find, so they picked that even though nothing needs the high voltage.

Um, actually, I need to modify that "Yeah, I think so": Not 5V, but maybe it does not need much more. The mainboard takes 19V in, and that gets turned into one or more 5V lines, so you need enough to feed those 5V regulators. And of course you need enough watts to drive everything. But I'm not surprised if people are successfully running their MPC One off, say, a powerbank with a 6V output or whatever it was, since it that'd be enough to generate 5V off, and a battery pack is able to deliver quite a lot of amps at once. And the main unknown for me in the LIve is the battery. If there's a charging circuit (and the battery itself) that's expecting to be fed 19V and you give it 6, that might **** something up.

You should have detailed knowledge of the circuit before plugging in a power supply that's not to the manufacturer's specification.

And especially with lithium batteries you want to be careful, since their possible ways of failing include catching on fire in a way that triggers a chemical reaction which releases oxygene to sustain the burning, which means you need a special kind of fire extinguisher to put it out. Don't play with lithium batteries unless you know what you're doing.

rvense wrote:You should have detailed knowledge of the circuit before plugging in a power supply that's not to the manufacturer's specification.

And especially with lithium batteries you want to be careful, since their possible ways of failing include catching on fire in a way that triggers a chemical reaction which releases oxygene to sustain the burning, which means you need a special kind of fire extinguisher to put it out. Don't play with lithium batteries unless you know what you're doing.

^^ This is the crux of the issue, and the reason why I wholeheartedly feel users just throwing various battery bricks at it without supplying the same voltage as the stock brick does is not a wise move.

Thanks for your comments above!