(Scientific?) Test of Battery Type and Voltage in a Fuzz Face

[afrogoose]

Hi Everyone,

I re-ran my experiment testing different battery types and battery voltages in a Fuzz Face.  Thanks to induction, psychedelicfish and gus for some valuable suggestions on how to make the experiment better.  If anyone is curious to hear what effect a battery has on a FF, you can check them out and decide if/how significant it is.  Also, for fun, I also ran the same test on a Tube Screamer.

Let me know what you think?  Did I miss something or describe the circuits incorrectly?

http://www.andrewmartinmusic.net/the-lab/blog/a-battery-of-tests-part-i-fuzz-face

http://www.andrewmartinmusic.net/the-lab/blog/a-battery-of-tests-part-ii-tubescreamer

Thanks!
A

[Seljer]

You could also measure the internal resistance of the batteries used in the tests. You hook up a know load resistor, say a 100ohms or so, and then again measure the voltage on the output. Because you know the value of the load resistor you can calculate the current, then from the drop in the voltage you can calculate the internal resistance

Rin = (Vopen - Vloaded)/(Vloaded/Rload)

Might be interesting do an AB test of the battery compared to a regulated power supply and the same resistance installed inbetween.

[psychedelicfish]

Interesting...
There's certainly an audible difference when the pickup sim is used, but now I can't hear quite so much difference between the batteries and the PP2.

As Simon says, it would be interesting to measure the internal resistances of each battery, before discharging and after. Also, I note you discharged the fresh batteries down until they measured 9V, and I'm assuming you did this with the batteries unloaded. What you'll find is that with a fresh battery it will measure 10V or so, but as soon as you plug it in to anything that pulls a reasonable current it will drop down closer to 9V. It would be good to know what each battery measures when plugged in to the fuzz face.

If you were to use a signal generator to apply an audio signal of a constant voltage (from a signal generator, perhaps something like this) you'd find the voltage from the battery will drop a bit, so it would be interesting to see how much each battery charged and discharged would sag with 200mV or so signal into the fuzz face. More sag=more compressed sound.

[Mark Hammer]

It is the dynamic sag that produces the type of compression people value.

[kingswayguitar]

deja vu mon ami. didn't we just have this debate? but i used the headphones this time and still can't consistently see a difference ('cept for some choked out tones with the dead batteries, and the control). man my ears are bad.

but maybe that's why i love fuzz.

great playing by the way

[afrogoose]

Thanks for the compliment kingswayguitar! 

Mark, can you elaborate a little bit about "dynamic sag?"  I'm not quite sure what that means.

I'm worried that maybe my method for draining batteries isn't directly comparable to what happens when a battery drains slowly over time due to normal usage.  My method was this: I measured the battery with the DMM, then I would discharge it with something metal (screwdriver, stack of quarters, etc...)  Then I would measure again with the DMM.  The voltage at this point has dropped below where I want it to be, but it slowly rebounds back up.  I would keep measuring until it was in the range I wanted it to be, and then I would throw it in the effect, and record the clip.  Then, I would immediately pull the battery out and measure it one final time.  That final measurement was the one that I was using.

I'm wondering if the fact that the voltage was slowly moving means that I'm not measuring it correctly?  Or maybe that has an effect on the fuzz, one that's different than if the battery was just "resting" at a voltage?  I'm also wondering if I need to go lower than 6v to really achieve the dead battery fuzz tone?

FWIW, psychedelicfish, this was also my method for new batteries too.  One of the batteries measured around 9v right out of the box, but the other two had to be discharged a bit to get there.  The Pedal Power 2 only goes up to about 9.08v, so I had to use that as a ceiling.   

[Mark Hammer]

"Dynamic sag" refers to the current delivery capability in response to big transients (and I don't mean 300lb hobos  ).  As carbon-zinc batteries start to age, not only does the internal resistance change, and the max voltage decline, but they acquire this trait of being able to provide brief spurts of current, followed by much less - like someone who can sprint like a gazelle for 10 yards, then runs out of breath and stamina and is hunched over with their hands on their knees, wheezing and saying "Just a sec, hold up guys."  It is not exactly like, but is somewhat analogous to, the gain-reduction and recovery that happens with compressors.

As near as I can tell, it is a phenomenon that occurs with carbon-zinc, but not alkaline types, because the carbon-zinc units have six stacked "slugs" with a big contact surface between them, that permit larger current delivery...assuming the electrons are available.  Alkalines, when taken apart, look like 6 sub-AAA units spot welded together.  A better connection between cells, but smaller contact surface area.  Clearly the chemistry is a HUGE factor, but I suspect the qualitatively different contact surfaces play a role too.

[duck_arse]

shorting the batteries to lower the terminal voltage will cause lots of heat internally. this is probably not much good for the battery. a better method might be to use them as something like the power for a constant current source. you could then set the discharge rate easily. you could maybe even use some rechargables as your load ......

[Electric Warrior]

I've looked up the Sunbeam packaging and it says "Super Heavy Duty", which usually means it's a zinc chloride type, an improved version of the carbon zinc battery.

You sure haven't captured much of a difference between battery types in your clips, but sometimes recordings can make things appear to sound more similar than they do in real life. Can you hear any differences in front of your amp?

Personally I like zinc chloride batteries for the high voltage (10V+) they deliver when new..

[afrogoose]

Hmm that is interesting. I didn't realize that the Sunbeam wasn't a carbon zinc.  I feel more than a little bit embarrassed by that mistake!  I might have to track down a true carbon zinc battery to see if it responds differently vs zinc chloride and alkaline....

Does anyone know where I can source known carbon zinc batteries?

Truthfully, I spent a while micing up the amp and trying to get the most balanced recording I could.  If there was some nuance that was only audible in the room and not in an the recording, than it would have to be so slight that I would never know if it was real or something I was imagining. 

[Electric Warrior]

I guess they will sound very similar. At least they work in the same way. http://en.wikipedia.org/wiki/Zinc_chloride_battery#The_zinc_chloride_cell

edit:
And they're still considered as being carbon zinc types.  

I did some more research and it appears the general purpose/heavy duty gradings can apply to both, regular carbon zinc and zinc chloride batteries. Confusing.  

Zinc chlorides seem to have a lower internal resistance. Maybe you should add confirmed zinc chloride and carbon zinc batteries to your test. Golden Power makes both. The "Super Heavy Duty" labled ones are zinc chlorides, all others are carbon zinc according to their catalogue.

[afrogoose]

Thanks Electric Warrior.  I guess I'll have to go on the hunt for some carbon zinc batteries! 

[Mark Hammer]

Does anyone know where I can source known carbon zinc batteries?

The red Eveready Classic.

[Electric Warrior]

Right on! The datasheet lists the chemical system as zinc-manganese dioxide. Exactly what you're looking for.
http://www.eveready.com/batteries/Pages/super-heavy-duty.aspx

[Mark Hammer]

Eric Johnson-approved.

[Electric Warrior]

I thought Johnson preferred Duracell? 

[Jaicen_solo]

A few months ago, Guitarist magazine ran a blind test of a handful of amps, from mid price combo's to high end boutique. The results were interesting.
The amps were played blindfold, and all the testers listened to each other play. Those litening found it hard to discern a difference between the high end and the bog standard stuff, however the guy actually playing in each test was able to 'feel' a difference, and was much better able to tell that the amp was a higher end model, even though nobody was able to see or hear the amp before hand.

This is all a roundabout way of saying that sometimes, it's the way the amp/pedal/guitar feels and responds to your playing that's important, and that's something that a bunch of recordings can't capture.

[Mark Hammer]

"Intention" - which the player has, but blind listeners probably don't - has two aspects.  One is certainly to provide a point of reference/comparison, as you describe, such that the player can determine how things sound compared to how you expected them to sound.  But another is that expectations have a way of being confirmed and perverting perception by that means.  Six of one, half-dozen of the other.

[Quackzed]

This is all a roundabout way of saying that sometimes, it's the way the amp/pedal/guitar feels and responds to your playing that's important, and that's something that a bunch of recordings can't capture.

This is soo true, in my opinion. theres more to it than a recording can show you. the immediacy and responsiveness of an amp that you feel  may or may not be noticeable on a recording. like latency, 30ms of latency and 2 recordings may be exactly the same to a listener, but to the player that kind of lag is really disorienting and kills the fingers/speakers connection,not to mention many other things that you hear less than you feel.

[Jaicen_solo]

That's pretty much what I was alluding to.

I feel it's a similar situation to modelling, in that it sounds right, but doesn't 'feel' right.