SOUND ON SOUND

[Arpangel]

My generic PSU broke yesterday, so I’m running it on batteries, I have an MXR Isobrick that has a free 450 mA outlet, the Zoom is rated at 500 mA, I’m wondering if it’s a concern, using the 450 outlet? From what I’ve read on other guitar forums it’s perfectly OK to run it like this, as the average current draw is a lot lower than the quoted 500 mA.

[The Elf]

I run all my USB-power-able pedals (including MS-70CDR and MS-50G) from a USB power block, similar, but not quite the same, as this:
https://www.amazon.co.uk/Orangeck-Charger-Desktop-Charging-Multi-Port-White/dp/B07T7GLJYJ/ref=sr_1_17?dchild=1&keywords=usb+power+block&qid=1603620279&sr=8-17

It usefully tells you the draw of any attached device. Couple it with a few MyVolts cables and you can power a lot of other external non-USB power devices from it too - makes for a neat system.

[Arpangel]

I run all my USB-power-able pedals (including MS-70CDR and MS-50G) from a USB power block, similar, but not quite the same, as this:
https://www.amazon.co.uk/Orangeck-Charger-Desktop-Charging-Multi-Port-White/dp/B07T7GLJYJ/ref=sr_1_17?dchild=1&keywords=usb+power+block&qid=1603620279&sr=8-17

It usefully tells you the draw of any attached device. Couple it with a few MyVolts cables and you can power a lot of other external non-USB power devices from it too - makes for a neat system.

Thanks Elf, so the USB outputs convert to a standard 9 v lead?
Trouble is, I already have the Isobrick, and I don’t really need that many outputs.

[The Elf]

Thanks Elf, so the USB outputs convert to a standard 9 v lead?

No - the MS pedals will power from a standard USB cable - the same cable you would use to program the MS pedal from Tonelab. Just plug it in and the pedal will power up.

Trouble is, I already have the Isobrick, and I don’t really need that many outputs.

Spare outputs will always come in handy for everything from a looper to a phone. The device I've shown is pretty tiny anyway - devices with fewer outputs are often larger.

Here's one of my MS pedals powered from such a device:

[ManFromGlass]

The photo is confusing me a bit -
Does the Zoom have 2 power inputs? I am seeing what looks like an unused power input on it.
The Orangeck is a brilliant idea if you can go from USB to the right size for a guitar pedal. Which you are suggesting can be done.

[The Elf]

The photo is confusing me a bit -
Does the Zoom have 2 power inputs? I am seeing what looks like an unused power input on it.
The Orangeck is a brilliant idea if you can go from USB to the right size for a guitar pedal. Which you are suggesting can be done.

The Zooms have a mini USB socket, through which you can program it (better than the on-board buttons/dials), and through which it can be powered. So no need for anything other than a normal USB-to-USB mini B (I think!) cable.

But, as I mentioned above, you can *also* get cables from MyVolts that will convert a USB port's power to just about any connection type you need - I have cables that power such as my Roland PK-5 pedals from a USB socket, for instance.

[Arpangel]

The photo is confusing me a bit -
Does the Zoom have 2 power inputs? I am seeing what looks like an unused power input on it.
The Orangeck is a brilliant idea if you can go from USB to the right size for a guitar pedal. Which you are suggesting can be done.

The Zooms have a mini USB socket, through which you can program it (better than the on-board buttons/dials), and through which it can be powered. So no need for anything other than a normal USB-to-USB mini B (I think!) cable.

But, as I mentioned above, you can *also* get cables from MyVolts that will convert a USB port's power to just about any connection type you need - I have cables that power such as my Roland PK-5 pedals from a USB socket, for instance.

Elf, I have a few USB phone type chargers laying around, can they do the same job? I’ve heard that the pedal is noisier with USB rather than the standard 9v supply?

[The Elf]

If the pedal was running on batteries they only provide 3V, so I see no reason why running from USB at 5V should give more noise.

I find all this Volts/amps/Ohms stuff a baffling mystery, so beyond that I can't really help. I can well imagine using USB may cause earth loops for some, but I don't have that problem.

See if your current cables fit. The mini USB B has been superceded by other forms of connector for phones, but lots of gear uses them and these cables are neither rare or expensive.

[Arpangel]

If the pedal was running on batteries they only provide 3V, so I see no reason why running from USB at 5V should give more noise.

I find all this Volts/amps/Ohms stuff a baffling mystery, so beyond that I can't really help. I can well imagine using USB may cause earth loops for some, but I don't have that problem.

See if your current cables fit. The mini USB B has been superceded by other forms of connector for phones, but lots of gear uses them and these cables are neither rare or expensive.

I’ll experiment this morning Elf, could be the solution.
I’ve got that spare 9v 450 mA output on my Isobrick though, if it’ll run on two AAA batteries surely this would be sufficient?

[The Elf]

I’ve got that spare 9v 450 mA output on my Isobrick though, if it’ll run on two AAA batteries surely this would be sufficient?

I would think so, again given the modest battery requirement, but it will need others to offer more credible reassurance!

BTW, it runs on AA batteries, not 'AAA'.

[Arpangel]

I’ve got that spare 9v 450 mA output on my Isobrick though, if it’ll run on two AAA batteries surely this would be sufficient?

I would think so, again given the modest battery requirement, but it will need others to offer more credible reassurance!

BTW, it runs on AA batteries, not 'AAA'.

I know, this current issue, opinions seem very varied.
I only put new batteries in it yesterday, you see, the dementia is definitely kicking in.
I’d like to know the relationship of current draw to voltage, and how dependant they are on each other. The battery option to me, seems like the least favourite option in these circumstances at 3v.

:(

[jjlonbass]

As with many things - it depends.

Traditionally, an effects pedal might use linear regulators to drop the input voltage to that required by the electronics. In this case, the current drawn would be notionally the same regardless of the input voltage, so the device would use more power (Watts = Volts * Amps) at higher input voltages wasting the extra power as heat in the regulator.

Equipment that contains a microprocessor or DSP such as this Zoom will contain one or more switched-mode DC to DC converters as such devices often require power rails such as 3.3V, 1.8V or 1.0V, often all 3. Also, the presence of a switched-mode supply allows the provision of supply rails that e.g. op-amps like to use such as +/- 15V.
Devices like this will use nominally the same input power regardless of the input voltage i.e. the current drawn will reduce with higher input voltages. For example, if the pedal uses 0.5W of power, it will draw roughly 0.167A at 3V, 0.1A at 5V e.g. from a USB supply and 0.056A at 9V.

John

[Hugh Robjohns]

If the pedal was running on batteries they only provide 3V, so I see no reason why running from USB at 5V should give more noise.

It's not the nominal voltage that determines the noise, it's the ripple or noise on top of that nominal voltage you need to worry about! So it comes down to how 'clean' the voltage generation system is.

Batteries are inherently very 'clean' sources of DC voltage.

Ultra-cheap switch-mode power supplies are typically quite 'noisy' sources.

The better the design of the supply, the cleaner it is likely to be.

And of course, the other consideration is the consuming unit's own ability to 'cleanse' the incoming supply.

[The Elf]

There you go - more credible information. :thumbup:

But I certainly hear no additional noise whether on PSU, battery or USB - and USB is more convenient in my circumstances. Make of that what you will.

[Arpangel]

Owing to power arrangements, USB lead lengths etc, I’m going to try the 450 mA outlet on my Isobrick, it’ll either blow up or not.

;)