9V tube screamer 50V caps

[jeff]

 I'm building a tube screamer and it sounds pretty good. On the schematic it lists a 10uF/50V tant cap but I can only find a 10uF/16V cap. Seeing that it runs off a 9V battery I can't see how I'd ever exceed 9.xV. Is that rating different because it's AC rather than for DC and a 50V is needed? Is 16V enough of a margin or do you need a 50V part? Right now I'm using a 10uF/50v electrolytic but I hear the tants sound better.

 This leads me to another question. Being a person not smart enough to leave well enough alone I was wondering if you could run a stock tube screamer off two 9Vs instead of one. All the caps/parts seem to be rated high enough(not sure about the transistors, op amps or switching). I'm thinking about getting three 9V clips and wiring then red to black, red to black, red to black to get two 9V in series. Would there be any benifit/harm to doing this? Anyone ever try it?

 Thanks
  Jeff

[six_eight]

16v is fine.  The bit about tantalums sounding betting is hype.  There's only 2 tants in the TS circuit and they both just bleed signal to ground.  If they were in the signal path there might be some truth to it, but they're not.  We all know how it can eat at you to not have the "correct" parts in your build, so if you can find them, use them, but don't worry about it sounding any better.

Yes, you can run the circuit at 18v or 27v, but you will of course need to make sure your caps are all rated accordingly.  The 4558 (and most other op amps) can handle up to 48v.  You'd think that increasing the headroom of a distortion device would be counter-intuitive, but it actually does sound quite nice.  It increases output dB so it works better as a boost, and it makes the distortion more glassy and less fuzzy.  You can run the circuit up to 48v without damaging anything.  I've personally never tried it above 18v so I don't know if it sounds good at 27v or more.  Also, as I said, you won't damage anything, but it may stop producing sound at voltages higher than 18v because it's already configured to produce more gain than the chip was intended.

[jeff]

OK, Thanks.
Would upping the voltage call for and changing of values?

You'd think that increasing the headroom of a distortion device would be counter-intuitive

  I wasn't really thinking of headroom, I was looking at it more from the angle that if you could increase the size of the signal the diodes are clipping than the diodes would actually clip more of the signal. You know, if the diodes clip at 1V and upping the voltage doubles your signal to be clipped, than you're clipping even more of the original signal(at least that's what I was thinking). Will upping voltage actually give more gain? or just increase headroom?

There's only 2 tants in the TS circuit and they both just bleed signal to ground. If they were in the signal path there might be some truth to it, but they're not.

 I never really understood that, though I've heard it alot. What makes a cap better or worse, I imagine, is how it passes the signal. So why would grounding the signal through a poorer quality cap have no effect? Know what I mean? If a cap has flaws passing the signal sounds you wanna hear wouldn't it have those same flaws removing the part of the signal you don't wanna hear?

 For example: If cap A is worse than cap B in the signal path because it doesn't pass the highest of the highs and sounds dark, then when using it to ground to roll off highs, wouldn't also have trouble passing the highest of the highs that you're tring to get rid of and also sound worse too(piercing)?

I did use the electorlytics and they do sound good so I may or may not change them. Although I'll probally wind up building another pedal and just A/B them. I agree that's it's probally hype. What's "better" anyway? They may sound different but I bet neither sounds bad.

Thanks for the help
 Jeff

[six_eight]

No, you would not need to change any values. 

So you want more distortion?  There are mods for that.  Increasing voltage increases headroom and gain, but in this case, it's gain that translates to more dB's, not more saturation.

I don't know the answer to your question about caps.  I understand where the hype about replacing electrolytics in the signal path with film caps came from, but I'm not sure why people make a big deal about the tants in the tubescreamer.  Probably because of all the boutique clones and the fact that tantalum is semi-obsolete and costs a little more.  Builders have to brag about something to make it seem like their clone has some sort of mystical mojo.  But that's just my opinion.