Powering 9v effects at 12v

[screamingdaisy]

Hi.

Just wondering if this is safe?

I was having trouble with lack of headroom on my Small Clone, and bumped it's power supply upto 12v.  It seems to have cleared up the problem.

I'm also wondering if what this'll do to other effects?

Is it generally safe on anolog stuff?  I'm assuming it's a no-go on digital?

Cheers.

[Hal]

it should be ok.  Things you have to watch out for are blowing LEDs and capacitors, and few ICs.  Also, you might mess up the bias on transistors.  However, most of these problems should not be relavent.  Caps are usually rated at a _minimum_ of around 15v.  Most are 25 - 50 or more.   and most LEDs are not using hte minimum value resister.  Most op-amps can run up to 18-24 v (?) I think.  

If you didn't blow it already, odds are you won't.  

i don't think the higher voltage would make any tonal differance in digital effects, so this should be irrelavent.  But yes, they are ususally more sensative.

[niftydog]

it totally depends on which pedal you're plugging in.  Some will be fine, other more sophisticated effects might shut down (over voltage protect) or worse, kick the bucket!  (although, that's unlikely)

Other thing to be wary of;  an unregulated 9V supply might put out as much as12-13V at low current.  An unregulated 12V supply might put out as much as 16V or even higher at low current.  When you're getting close to doubling the expected voltage, you're running the risk of blowing something.

Older pedals are usually a safe bet.  My old analogue boss delay NEEDS 12V to work properly, same with my boss phase shifter.

[Duff]

Hi, I have a question since english is not my first language, what do you mean with headroom? what pedals can have or not have this quality?, by the way, how do I put an image in a post?

Rock´n roll!

[niftydog]

Headroom refers to the circuits ability to produce the output voltage you require, without being pushed to it's limits.

Say you have a requirement to produce a 1V signal.  Your circuit is capable of producing 2V, then you have a lot of headroom - the circuit is doing the job easily, without stress or overloading.

If your circuits maximum output is 1.2V, then you have less headroom and the circuit is operating near it's maximum capability.  Less headroom, more likely hood of overloading.

To post an image, you first need to put it on the net somewhere.  If you have a webspace, post it there and put the URL inbetween the "Img" tags.  (see button above)

also, see this sites FAQ!

[screamingdaisy]

Thanks.

I just went and tested the supply.

It seems it's putting out 13.5v on the 9v setting and 18v on the 12v setting.

I guess it's a good thing that Small Clone can take 18v :wink:.

Do these voltages drop under normal use (ie. when there's an actual load vice just having a multi-meter on them)?


EDIT: HA, one of my 9v supplys is kicking out 17.2v :shock:.

[niftydog]

yes, the voltage will drop, but not much when connected to a light load!

If your supply is rated at 9V 2A, that means it delivers 2A max, before the voltage drops below 9V.  So running a little pedal, drawing maybe 40mA, it ain't gonna drop much at all!

But, if it's only rated for 100mA, and you're drawing half that, then it's gonna be closer to the rated voltage.

[Mark Hammer]

It is impôrtant to distinguihs between an easily available supply voltage and a *necessary* one.  Nine volts is a standard package which designers work around.  A higher supply voltage would either mean more batteries or a requirement to use an external supply.  If you want a pedal to sound the same with a wallwart as it does with a battery, then you design around a 9v supply.

As was pointed out, many of the components in pedals are tolerant of higher supply/working voltages, some only slightly higher, and some much higher.  Most op-amps used in pedals are very comfortable with 18v supply voltages or more, but many pedals also use CMOS chips which will be damaged if you use more than 15v.  Many pedals use capacitors rate for 16v or more, but higher voltage ratings usually require a bigger package and higher cost so cap ratings are one way companies shave a few pennies off the production price.  The general rule of thumb is to use caps rated at twice the supply voltage or close to it.  With a 9v supply, a 16v rating is fine.  With a 12v supply is it risky, but still more or less okay.

More important is whether the circuit is designed to perform a certain way with a given supply voltage.  In the case of fuzzes, sometimes they are.  This is also true of some chorusses, phasers, and flangers.  What links these devices is often bias voltages, which would need to be reset with another supply voltage.

In some cases, however, a higher supply voltage can noticeably improve performance.  I have an older Boss BF-1 flanger that sound okay with 9v but much better with 12v.

[Mark Hammer]

It is impôrtant to distinguihs between an easily available supply voltage and a *necessary* one.  Nine volts is a standard package which designers work around.  A higher supply voltage would either mean more batteries or a requirement to use an external supply.  If you want a pedal to sound the same with a wallwart as it does with a battery, then you design around a 9v supply.

As was pointed out, many of the components in pedals are tolerant of higher supply/working voltages, some only slightly higher, and some much higher.  Most op-amps used in pedals are very comfortable with 18v supply voltages or more, but many pedals also use CMOS chips which will be damaged if you use more than 15v.  Many pedals use capacitors rate for 16v or more, but higher voltage ratings usually require a bigger package and higher cost so cap ratings are one way companies shave a few pennies off the production price.  The general rule of thumb is to use caps rated at twice the supply voltage or close to it.  With a 9v supply, a 16v rating is fine.  With a 12v supply is it risky, but still more or less okay.

More important is whether the circuit is designed to perform a certain way with a given supply voltage.  In the case of fuzzes, sometimes they are.  This is also true of some chorusses, phasers, and flangers.  What links these devices is often bias voltages, which would need to be reset with another supply voltage.

In some cases, however, a higher supply voltage can noticeably improve performance.  I have an older Boss BF-1 flanger that sound okay with 9v but much better with 12v.

[puretube]

watch out: some B*SS pedals got 10V el.-caps in`em!!!

[Mark Hammer]

Correct me if I'm wrong, but the 10v rating is only problematic if the cap is intended to manage the power supply or some other voltage in a manner that might stress it.  In many instances in Boss pedals, a 10v rating is actually an overrated component, although obviously you have to know a bit about the circuit and what sorts of voltagesmight be in effect in different parts.

For example, a cap that is intended to smooth out the Vref of 1/2 the supply voltage (4.5v) could easily be rated at 10v and do fine with a 9v or even 12v supply.  Similarly, an electrolytic cap in the signal path is generally not anticipating anything more than a couple of volts hitting it., so 10v ratings are fine.  If the pedal uses one of the MN32xx series BBDs, it is probably powered by +5v (in comparison to the op-amps which get the full 9v treatment), which means that it can tolerate some lower-rated caps in some places.

My ppoint is not that you should throw caution to the wind, but that not ALL caps have to be "uprated" and replaced when switching to a higher supply voltage.  Ton's advice is useful and correct, though: WATCH OUT!

[SuperGeo]

yesterday i was trying to use an 12V power supply in my homebuilt mxrdist+...

it just didn't work, i measured 12V in the board so i think it's alimented but the sound didn't came =/

do you know why is this happening? it was supposed to work right?[/b]