Wall wart

Hi everybody

Is there a recommended wallwart to be used with the shruthi-1?

thanks for the info

From the manual…

“1: 2.1mm DC power jack. The Shruthi-1 can be powered with a 7.5V-12V unregulated supply, or with a 9V battery adapter. Make sure that the connector has a center pin (or tip) positive / outer collar (or sleeve) negative pin polarity. Most universal power supplies allows the polarity to be selected — the polarity being often represented by a diagram like this: – (o , or by the indication tip:. The power supply has a reverse polarity protection and can handle voltages up to 15V. Note that VCF/VCA boards distributed by third parties might not follow these specifications and have different power supply requirements.”

The Shruthi doesn’t generally draw much current, so most 9v DC ones will work.

…although a 9-volt model rated at around 300mA is more likely to output 9 volts when loaded by the Shruthi-1, and therefore the Shruthi-1 will run cooler than with a higher rated PSU (500mA, 750mA etc.)


Linear regulators output any excess voltage as heat, so you want to try to minimise that. The closer to 7v the better. Typically the regulators want about 2v above their stated output voltage to work.

@6581punk: I perfectly agree in theory (as I demonstrated in the tests I posted in this thread, when I found the ‘perfect’ output voltage for my 750mA PSU was the setting marked 4.5 volts)

However, in practice I think it’s clearer to recommend a PSU marked 9 volts @300mA :wink:


Many of them are marked with theoretical maximums, determined by looking at datasheets rather than by real world testing. So it’s often better to have a little more current than you need.

@the_fourth_wall: Shruthi-1 user Titus Raindrops recommended this Godlyke Powerall with the red adapter cables (to convert its -ve tip to +ve tip). It’s overkill, but will power up to four Shruthi-1 perfectly if you feel like taking over the world.

Personally I use a variable one similar to this, since it’s only £4 from Amazon :wink:

You just need to set it to its lowest setting with the tip set to positive, plug it into your Shruti-1, and then monitor its output voltage at that wire link Olivier mentions in the filter board build instructions. Click the voltage output switch on the PSU until your Shruthi-1 measures around 7 volts at the wire link and you’re sorted :slight_smile:


Lloytron, the hallmark of quality :slight_smile:

I’ve got a few of these:

They show you the internals and everything, which means they’re either trying hard to convince you they are good or they are good and they’re showing off. I’m not sure which :slight_smile:

They DO look good, and from what I can see from the circuitry inside, the output voltage is regulated as well - this could be the best recommendation yet!

(apart from making the Shruthi-1 run hotter than a 7 V version ;-))


It’s true, I like Godlyke Poweralls. They work great for every 9V application and provide enough hooks and adapters to power your entire neighborhood. They’re designed for guitar pedalboards where you are powering lots of 9V pedals at the same time. So it provides enough current for plenty of boxes and comes with a bunch of adapters to fit different kinds of jacks and different jack polarities. They even include a 9V battery adapter. Good stuff.

There’s no problem supplying regulated into a device with a regulator? you’re just wasting a little electricity I guess?

Most wall warts are switch mode regulated now which is more efficient but can produce more noise in the audio. I imagine the regulators and caps on the filter board will take care of this?

A linear regulated wall wart will be big and heavy. Switch mode are small and have no weight to them.

I haven’t noticed any noise from the Poweralls, with any of the devices I have used with them…

nope no problem with regulated input, as long as the voltage is high enough