Advice On Power Supply For Pedal

Nicenswift

Hi,

My daughter has just bought a Behringer UC200 Ultra Chorus pedal.

The pedal is fine when using a 9v battery but when we try and use a 9V transformer it creates a pulsing hum sound through the amp.

We have tried various 9v transformers with varying amps from 500ma to 1amp but still the same.

We sent a message to Behringer and they said it has to be a 9v 100ma transformer.

Is this correct as I am struggling to find a suitable transformer that is 9V 100ma with the correct end.

Many thanks for your advice.

ecc83

You need a 9 volt DC power supply>https://www.fullcompass.com/common/files/22475-BehringerUltraChorusUC200UserManual.pdf

Check bottom of manual page. Probably easiest and best to get the Behrry one? PSU-SB

Dave.

ICBM

No, that is not correct. What it does need to be is a properly regulated and filtered power supply. Any current capacity above what the pedal actually draws - probably about 25mA or so - is fine if it's properly regulated, the pedal will draw only what it needs.

A Boss PSA230 should work as it's specifically designed for pedals, hence is filtered - I sometimes use one with my Behringer Superfuzz pedals and it's silent. Other cheaper ones may do the same job, but I would make sure it's a proper musical instrument company product and not just something generic from Amazon or wherever.

De_Batz

A transformer will have filtering on to get something like 9V all the time (basically a capacitor between the + and - outs to smooth out the wave). A switch mode power supply (probably what you're trying up to now) may be 9V but have some high frequency stuff that isn't filtered out, especially if it isn't for an audio application.

You can get deep into power supplies, but the bottom line is that if it works it's almost certainly fine... 

Puddlesurfer

The specs show 2.1mm centre negative DC, drawing just 30ma. Any isolated power supply will provide that without a problem. Does the 'pulsing' change when you adjust the pedal's rate setting? If so, the pedal is still passing a signal in bypass mode which indicates a fault/poorly realised circuit design.

ICBM

Puddlesurfer said:

The specs show 2.1mm centre negative DC, drawing just 30ma. Any isolated power supply will provide that without a problem.

Very true, but many are poorly filtered. It was never a problem with the old transformer-based supplies, but it can often be with modern switch-mode ones that aren’t designed specifically for audio applications.

ecc83

ICBM said:

Puddlesurfer said:

The specs show 2.1mm centre negative DC, drawing just 30ma. Any isolated power supply will provide that without a problem.

Very true, but many are poorly filtered. It was never a problem with the old transformer-based supplies, but it can often be with modern switch-mode ones that aren’t designed specifically for audio applications.

Too True! I was given about 8 9V SMPSUs to test (for the then new LT pedals) The range of crap on the DC line was around 30dB! The problem is with the pedals to some extent. The LTs had decent rejection but other makes not so much. That is one reason I say get the Behringer supply. Cannot see it being stupidly expensive?

Dave.

ICBM

ecc83 said:

That is one reason I say get the Behringer supply. Cannot see it being stupidly expensive?

It was, surprisingly - £14.99 according to a Google search. But doesn't seem to be available any more anyway.

The Boss one is even worse, about £25. Likewise 1-Spot and Godlyke Power-All.

The problem is that unless you're willing to just accept paying that much, you have to take pot luck with a cheaper one, and we're back where we started...

ecc83

ICBM said:

ecc83 said:

That is one reason I say get the Behringer supply. Cannot see it being stupidly expensive?

It was, surprisingly - £14.99 according to a Google search. But doesn't seem to be available any more anyway.

The Boss one is even worse, about £25. Likewise 1-Spot and Godlyke Power-All.

The problem is that unless you're willing to just accept paying that much, you have to take pot luck with a cheaper one, and we're back where we started...

Try Blackstar! I am sure the LT supply is available as a spare? The HTs are.

Cheeky perhaps but money is money!

Dave.

ecc83

https://www.amazon.co.uk/BLACKSTAR-EFFECTS-SUPPLY-REPLACEMENT-ADAPTER/dp/B0768JF8H8 ; 'kin ell!

Dave.