18VDC supply for the Tube Screamer?

[Mark Abbott]

I was wondering if there is much if any benefit from running the TS on 18VDC instead of 9VDC?

I have a Screamtendo 64 board to build into a pedal, Any comments or criticisms about RG Keen's board?

Aside from the internal switches of course.

Yours Sincerely

Mark Abbott

[Ben N]

Can't speak directly to the TS, but I tried it with my Barber Direct Drive, which is kind of similar to a TS in gain structure and eq (I use it more or less interchangeably with an SD-1), and which Barber advertises can handle 18v. I found there to be very little difference, and nothing I would consider enough of a benefit, to justify the extra wall-wart. I think that is because headroom is dictated here by the design (clippers), rather than the power supply rails. Similarly, a rail-to-rail type of opamp would be wasted here.

If you happen to have an 18v supply (which, for testing purposes, can be nothing fancier than a couple of battery snaps in series) then there is really nothing to building up your board with 25v-rated caps so that either way, you are good to go. Assuming, that is, that you are using the usual suspects (4558, 4559, 5532, TL0x2, etc.) as your IC. If you are using something less ordinary in this application, be sure to check the data sheet for its power supply limits. So, as with all things, the best thing is to try it.

[Mark Abbott]

Dear Ben

Thanks for the reply. I suspected the difference is subtle at best. I will try two batteries and see how it goes. I do want a significant improvement for the extra battery. After all it is an extra item that can cause failure.

Yours Sincerely

Mark Abbott

[BAARON]

Ben is right.  The signal swing in a standard tube screamer never comes close to the voltage rails with a 9v power supply, so any difference with an 18v supply will be extremely subtle.

[cpm]

i think the difference in sound is more significant when the diodes (or, leds, transistors, whatever) have a higher forward voltage threshold.
I mean, with Vf 3v and up, those 18v make possible getting higher gain without going into a too big feedback ratio, then producing more distortion from the clippers.

[petemoore]

  Yes, as long as everything is cool that is, I haven't personally checked the voltage ratings on each component to determine that 18v supply is safe, sure it's been done and I haven't read about the damage so...check that the components can handle the applied voltage.
  Other than that what is it going to do to a diode-feedback amplifier-clipper ?
  Allow the opamp to run clean, though I'm not sure theres noticable dirt at 9V supply.