USB 9V Batteries

ADawg

Recently I've been playing with only 1 pedal (an SD-1) and I've been powering it via battery instead having another wire snaking around. Sadly, I can be a forgetful sod and I sometimes leave the cable plugged in after finishing up. After accidently draining another battery this week I thought why not try some rechargeable batteries instead? I found some on amazon with integrated usb ports, which I thought seemed convenient. But, looking at the reviews some people have mentioned that the batteries' output isnt actually 9V. I used a multimeter to check and have read 8V. I've given one a try in the pedal and it seems to work fine.

My question is; is there a downside to powering a pedal below 9V? Will I break anything?

Danny1969

A typical drive pedal bias's it's opamp at half the supply so if you give it 8V it will be at 4V and can swing down to 0 or up to 8V  ... your just run out of headroom quicker as it has 0.5V of headroom less each way

Other pedals with more sophisticated I.C's might not start or function properly but most will  ... generally you won't damage anything going under voltage unlike going higher would 

ICBM

No downside as long as you don't hear a problem. It will reduce the headroom as Danny said, and might change the tone slightly. And the LED will be a bit dimmer...

ADawg

Good to know nothing will fry! I was just playing around with it now, if there is a difference in tone I can't hear it.

So, I'm still a beginner when it comes to the electronics side of things. I've seen some videos on amp headroom - if I'm understanding correctly, less headroom would mean that an amp would distort easier at lower volumes. Is this the same principle for drive pedals? I'm pretty much just using the SD-1 as a boost with the level usually set between midway or max. Since I'm not actually using any drive, would the lessened headroom have no real effect?

Danny1969

You run out of headroom when there's not enough voltage on the rails to preserve the input voltage wave form.  Imagine you play an A note of 440Hz and it has an RMS voltage of 1V coming out of your guitar. This is an AC waveform, swinging from 0 to +1V to 0 to -1V etc 440 times a second. Now imagine you are going into a pedal which has a voltage gain of X 4.5 ... so will amplify the voltage from the guitar by a factor of 4.5. One  volt going in is going to be amplified up to +4.5V -  0 - 4.5V 440 times a second. A  common pedal runs from 9V and allows that voltage swing by biasing it's self halfway at 4.5V  .... so has enough volts on it's rail to preserve the waveform but so you can see running the pedal from 8V would mean it's run out of headroom. It can't swing 4.5V either side of 0V because it's biased at +4V so can swing up 4 volts and down 4 volts .. meaning the half volt would be clipped leading to distortion. That's the same deal on the input of an amp or any audio coupled stage 

PetGerbil

I thought to myself a while back,"They should make a USB 9v rechargeable battery,why don't they do that ?" And then I thought to myself"hmmm,maybe they don't do it because there would be an increased chance of shorting the terminals and maybe exploding, what with the terminals being so close together..." 
But it turns out they do make them, and I'm still unsure whether they would explode. Would they explode if shorted?

Revolting1

18650 lithium cells, 2 in series would be the easiest setup - 7.4 to 8.4 volts approx

 They are available in protected form, that is a must in case of a short .

 You should still case them in a fireproof box.

 Do not use  fully charged unprotected 18650's , they are very explode'dy if shorted.

                                                                   

 Fairly combustable if charged in the wrong manner too.

    Specialist 18650 chargers must be used for safety.

      

  Don't use very cheap chargers or you'll come home to a real fire.

                                                                                                    

Great batteries if used properly.

ICBM

ADawg said:

I'm pretty much just using the SD-1 as a boost with the level usually set between midway or max. Since I'm not actually using any drive, would the lessened headroom have no real effect?

That’s actually the way you will hear any difference - the lower headroom will affect the maximum output level, not the headroom in the overdrive stage which is limited by the clipping diodes to a much lower fixed voltage which is a characteristic of them.

Even at that, the difference between 9V and 8V is only about 0.5dB, so you’re unlikely to hear much difference.

ADawg

Ok I understand now. Thanks @Danny1969 and @ICBM. I might just give them a try for a bit and see if it affects my playing noticably.

@PetGerbil I checked the manual for the ones I bought. There is indeed a risk of explosion when shorted...

andy_k

I saw a review on youtube by a guy called bigclive.com, of a green 9v, that he tested and got 9v from. 
They are available on e-bay, but quite scarce in uk I think, slightly more expensive at about £10 each, but I bought a few to use as supplies for pedals with no battery. They seem good quality, and it shouldn't take long for them to pay for themselves.
I found some small arduino boxes, which have switches, but found that they are reverse polarity for most pedals.I had to swap the wires round, but with a bit of velcro on the back they are quite a neat solution for a board that has no power supply.
Just have to remember to disconnect them, if I leave the pedals plugged in.

clarkefan

Danny1969 said: You run out of headroom when there's not enough voltage on the rails to preserve the input voltage wave form.  Imagine you play an A note of 440Hz and it has an RMS voltage of 1V coming out of your guitar. This is an AC waveform, swinging from 0 to +1V to 0 to -1V etc 440 times a second. Now imagine you are going into a pedal which has a voltage gain of X 4.5 ... so will amplify the voltage from the guitar by a factor of 4.5. One  volt going in is going to be amplified up to +4.5V -  0 - 4.5V 440 times a second. A  common pedal runs from 9V and allows that voltage swing by biasing it's self halfway at 4.5V  .... so has enough volts on it's rail to preserve the waveform but so you can see running the pedal from 8V would mean it's run out of headroom. It can't swing 4.5V either side of 0V because it's biased at +4V so can swing up 4 volts and down 4 volts .. meaning the half volt would be clipped leading to distortion. That's the same deal on the input of an amp or any audio coupled stage 
@Danny1969 can I ask, what happens when the battery goes the other way?

I bought a pack of cheap batteries recently and a couple of them measured 10.5v-ish.  

I'm trying to "force" the phase effect in a Phase 90 to be more pronounced (it just disappears with gain) so I used the higher voltage ones.  

Now I'm thinking your description means I might have given the circuit too much voltage, is it possible to damage an old school analog circuit with 10% extra voltage?

ICBM

clarkefan said:

I'm trying to "force" the phase effect in a Phase 90 to be more pronounced (it just disappears with gain) so I used the higher voltage ones.

This won't work at all because it's a completely different problem.

I assume you're running the phaser before the distortion...

jpfamps

clarkefan said:

Danny1969 said:

You run out of headroom when there's not enough voltage on the rails to preserve the input voltage wave form.  Imagine you play an A note of 440Hz and it has an RMS voltage of 1V coming out of your guitar. This is an AC waveform, swinging from 0 to +1V to 0 to -1V etc 440 times a second. Now imagine you are going into a pedal which has a voltage gain of X 4.5 ... so will amplify the voltage from the guitar by a factor of 4.5. One  volt going in is going to be amplified up to +4.5V -  0 - 4.5V 440 times a second. A  common pedal runs from 9V and allows that voltage swing by biasing it's self halfway at 4.5V  .... so has enough volts on it's rail to preserve the waveform but so you can see running the pedal from 8V would mean it's run out of headroom. It can't swing 4.5V either side of 0V because it's biased at +4V so can swing up 4 volts and down 4 volts .. meaning the half volt would be clipped leading to distortion. That's the same deal on the input of an amp or any audio coupled stage 

@Danny1969 can I ask, what happens when the battery goes the other way?

I bought a pack of cheap batteries recently and a couple of them measured 10.5v-ish.  

I'm trying to "force" the phase effect in a Phase 90 to be more pronounced (it just disappears with gain) so I used the higher voltage ones.  

Now I'm thinking your description means I might have given the circuit too much voltage, is it possible to damage an old school analog circuit with 10% extra voltage?

There is a supply voltage effect on the Phase 90 which will also depend on which version you have.

To work optimally the JFETs in the Phase 90 need to have the correct bias voltage applied to them.

This is done with a trimmer inside the pedal and is set at the factory.

There are two ways this voltage is derived in the Phase 90.

One version of the Phase 90 derives the "raw" bias supply with a zener diode, which means that the bias is the same as long as the input voltage is above the zener voltage, so the JFETs will be biased correctly.

The other version the voltage is derived via a voltage divider, so the bias voltage will vary with the input voltage and if it strays too far from the input voltage the bias was set for you will lose the phasing effect.

From memory the original Phase 90s and the "posh" reissue have the voltage divider and all other versions have the zener circuit.

clarkefan

ICBM said:

clarkefan said:

I'm trying to "force" the phase effect in a Phase 90 to be more pronounced (it just disappears with gain) so I used the higher voltage ones.

This won't work at all because it's a completely different problem.

I assume you're running the phaser before the distortion...

Oh and the rest

Right now I'm running it on its own into the amp, with everything else (flanger, delay, reverb, tuner!) in the fx loop, trying to keep everything else out of the way.  Amp does the drive, no drive pedals.  To be fair this approach has helped.  But it's not VH1...

Seems that, no matter what amp, or phase 90 variant I use (been many of both) the effect gets smothered and eradicated by gain.

ICBM

clarkefan said:

Seems that, no matter what amp, or phase 90 variant I use (been many of both) the effect gets smothered and eradicated by gain.

That's an inherent characteristic of putting modulation effects before distortion, whether from a pedal or an amp.

That's one of the reasons why effects loops were invented, although of course the sound of the same effects *after* the distortion is quite different.

clarkefan

ICBM said:

clarkefan said:

Seems that, no matter what amp, or phase 90 variant I use (been many of both) the effect gets smothered and eradicated by gain.

That's an inherent characteristic of putting modulation effects before distortion, whether from a pedal or an amp.

That's one of the reasons why effects loops were invented, although of course the sound of the same effects *after* the distortion is quite different.

Yes, the sound difference is not subtle

Seems like sometimes people eg EVH can use the effect, with a driven sound, with a presence in the sound that I've personally never been able to. Maybe it's a (mahoosive) volume thing.  Frustrating. 

ICBM

clarkefan said:

Seems like sometimes people eg EVH can use the effect, with a driven sound, with a presence in the sound that I've personally never been able to. Maybe it's a (mahoosive) volume thing.  Frustrating.

Massive volume and less gain than you think.

The more distortion, the more it mushes together the differences in the input signal and obliterates effects, especially those which mix dry and wet signals - eg phaser, flanger, chorus. You still hear tremolo and vibrato fairly clearly because the whole sound is modulated.

clarkefan

ICBM said:

clarkefan said:

Seems like sometimes people eg EVH can use the effect, with a driven sound, with a presence in the sound that I've personally never been able to. Maybe it's a (mahoosive) volume thing.  Frustrating.

Massive volume and less gain than you think.

The more distortion, the more it mushes together the differences in the input signal and obliterates effects, especially those which mix dry and wet signals - eg phaser, flanger, chorus. You still hear tremolo and vibrato fairly clearly because the whole sound is modulated.

Thanks for the advice ICBM.  Yeah keeping the gain down seems to help. Just need to compensate with a boatload of volume and I'm sorted haha

andy_k

Just got this thing running,  


It is basically, 2 x 9v daisy chains running off 2 of the batteries I mentioned above.
They are branded 'Znter' and are advertised as being able to output an actual 9v, with 600mAh. 
I bought a couple, and they seem like good quality, charge from a standard 5v USB lead.
I also bought a couple of an other brand, 'Smartools' which are 9v, 650mAh, although it does say they put out less than 9v.
It looked a bit messy with 5 of them velcroed around the board, so I thought I would experiment with a couple of 3 way daisy chains, I only had 5 of the batteries anyway, and the Tommy is the only one that actually takes a battery, so this way looks a lot neater. It is something to just pick up and play with, and I am just seeing how long it lives for.
It is a Klon (Klone) into a Guvnor (clone) into a Timmy (Tommy clone) into a Magneto dual drive ( tubescreamer-Rat combo) into a Triangle fuzz (clone) into a Ghost echo (clone), and the only one that is on all the time is the Ghost, so it is just plenty of gain options really.
When I am not using it, it is just a case of disconnecting the 2 daisy chains and it hangs on a cupboard door by the handle at the top.
Came out well in the end.
The batteries are about a tenner each, and state 1200 charge cycles, so should probably outlive me. 

mart

ICBM said:

clarkefan said:

Seems like sometimes people eg EVH can use the effect, with a driven sound, with a presence in the sound that I've personally never been able to. Maybe it's a (mahoosive) volume thing.  Frustrating.

Massive volume and less gain than you think.

The more distortion, the more it mushes together the differences in the input signal and obliterates effects, especially those which mix dry and wet signals - eg phaser, flanger, chorus. You still hear tremolo and vibrato fairly clearly because the whole sound is modulated.

Could you get there by putting lots of drive before the phaser and just some after? I'm thinking you could achieve the same overall level of drive, while not crushing the phase effect so much.