18V vs 9V: What are the differences?

[Tag Intel]

Does anyone know what benefits you gain on a (dirt) pedal running on 18V instead of 9V, assuming the pedal can take either?

[Scruffie]

Some people think the higher voltage gives more head room and depending on circuit it can, it can also effect how they sound as the circuit is less starved, it'd be different for each pedal and may work on some effects or have no effect on another.

[Jack Deville]

I'll second Scruffie's notion.
Circuit design is paramount. Some circuits can maintain similar characteristics when supplied with different voltages, some circuits will be completely neutered/augmented, and some circuits just don't care due to regulation or intentional design practices.
Sadly, there isn't a blanket rule save detailed analysis.

[Jero]

I wouldn't go to 18v without checking the circuit over a bit, 12v maybe...but yea, it's like Pete and Jack said.

[Tag Intel]

Thank you guys. The 9V/18V pedals I have are the Dirty Little Secret and SFT, and Blackout's MANTRA. I suppose Kyle can answer the MANTRA one. I should post that there.

Does the extra voltage lower the noise floor? That's kind of a general question. I would also think that the output can get a little hotter with the VOL knob.

But I do prefer a more "compressed" sound from my dirt pedals, but that may be because I am only playing at "apartment" levels and can't really push the amp section into sagging (not the preamp, that's easy), on a Mesa LSS at 5W or a Carr Rambler at 14W.

I suppose the extra headroom before "real, circuit" distortion is a plus for the pedals above. But I don't worry about overloading the pedal as I normally go straight in to a dirt box with non-active pickups. Never had an issue that way. In the end, the question is why bother with 18V at all?

[Jack Deville]

Thank you guys. The 9V/18V pedals I have are the Dirty Little Secret and SFT, and Blackout's MANTRA. I suppose Kyle can answer the MANTRA one. I should post that there.

Does the extra voltage lower the noise floor? That's kind of a general question. I would also think that the output can get a little hotter with the VOL knob.

But I do prefer a more "compressed" sound from my dirt pedals, but that may be because I am only playing at "apartment" levels and can't really push the amp section into sagging (not the preamp, that's easy), on a Mesa LSS at 5W or a Carr Rambler at 14W.

I suppose the extra headroom before "real, circuit" distortion is a plus for the pedals above. But I don't worry about overloading the pedal as I normally go straight in to a dirt box with non-active pickups. Never had an issue that way. In the end, the question is why bother with 18V at all?

IIRC, the Dirty Little Secret can run happily at 18VDC. Shoot erksin an email if you are concerned. They're on top of their game and usually respond quickly.

On noise: noise is kinda...hmm... designed into the circuit. Just as changing supply voltage does not necessarily guarantee changing gain/response or otherwise, changing voltage doesn't guarantee changing the noise floor.

So, why 18V? Good question. Again, its really dependent on design and design practices. Most opamps found in guitar effects are designed to run at +15VDC/-15VDC. 9VDC can be compromising the ICs capabilities, but often times 9VDC is what we are working with. Many of the transistors (BJT, MOSFET and FET) can handle 30VDC - 60VDC across their controlled terminals so we're not really approaching what the maximum rated values are with 9VDC.
Here is where design comes into play. If the circuit in question is specifically designed to produce distortion (the enemy in many other electronic pursuits) and the available supply voltage is part of the limiting characteristics of the circuit, then increasing the available voltage *may* make it more difficult for the circuit to achieve distortion. Now consider a circuit designed for un-distorted amplification. If the primary limit to the circuit's capabilities is supply voltage, then it follows that increasing available voltage *could* increase the available amplification!

I think it is good to re-iterate that design practices heavily affect these changes. If varying supply voltage is neglected during the design of the circuit, unexpected behavior (for better or worse) may result from a change in supply voltage.

As always, YMMV.

[McSpunckle]

More voltage allows the transistors in a circuit to amplify further without clipping. This doesn't apply to diode circuits.

I know you already got good answers, but I wanna answer anyways just to feel useful.

In some circuits, higher voltage will result in less compression/clipping-- it's great for cleanly boosting your signal, but, honestly, 9V is plenty for damn near anything... except maybe super loud clean boosts.

[Tag Intel]

If the circuit in question is specifically designed to produce distortion (the enemy in many other electronic pursuits) and the available supply voltage is part of the limiting characteristics of the circuit, then increasing the available voltage *may* make it more difficult for the circuit to achieve distortion.

Jack, you answered my kind of unstated question. This is what I have been hearing in the pedals. Not only do you have more headroom in some designs, but with some designs you have to feed it a hotter signal to get the same amount of dirtyness. So it is 9V for me. Perhaps that will change when I can turn it up loud enough to hit the amp section as it should be hit.

See? This is why I post here. Great answers, great posters! Thanks! Love you guys. Oh, and fuzz, too!

[smallsnd/bigsnd]

Thank you guys. The 9V/18V pedals I have are the Dirty Little Secret and SFT, and Blackout's MANTRA. I suppose Kyle can answer the MANTRA one. I should post that there.

Does the extra voltage lower the noise floor? That's kind of a general question. I would also think that the output can get a little hotter with the VOL knob.

But I do prefer a more "compressed" sound from my dirt pedals, but that may be because I am only playing at "apartment" levels and can't really push the amp section into sagging (not the preamp, that's easy), on a Mesa LSS at 5W or a Carr Rambler at 14W.

I suppose the extra headroom before "real, circuit" distortion is a plus for the pedals above. But I don't worry about overloading the pedal as I normally go straight in to a dirt box with non-active pickups. Never had an issue that way. In the end, the question is why bother with 18V at all?

IIRC, the Dirty Little Secret can run happily at 18VDC. Shoot erksin an email if you are concerned. They're on top of their game and usually respond quickly.

On noise: noise is kinda...hmm... designed into the circuit. Just as changing supply voltage does not necessarily guarantee changing gain/response or otherwise, changing voltage doesn't guarantee changing the noise floor.

So, why 18V? Good question. Again, its really dependent on design and design practices. Most opamps found in guitar effects are designed to run at +15VDC/-15VDC. 9VDC can be compromising the ICs capabilities, but often times 9VDC is what we are working with. Many of the transistors (BJT, MOSFET and FET) can handle 30VDC - 60VDC across their controlled terminals so we're not really approaching what the maximum rated values are with 9VDC.
Here is where design comes into play. If the circuit in question is specifically designed to produce distortion (the enemy in many other electronic pursuits) and the available supply voltage is part of the limiting characteristics of the circuit, then increasing the available voltage *may* make it more difficult for the circuit to achieve distortion. Now consider a circuit designed for un-distorted amplification. If the primary limit to the circuit's capabilities is supply voltage, then it follows that increasing available voltage *could* increase the available amplification!

I think it is good to re-iterate that design practices heavily affect these changes. If varying supply voltage is neglected during the design of the circuit, unexpected behavior (for better or worse) may result from a change in supply voltage.

As always, YMMV.

remember too, that while the transistors/opamps may take a higher voltage without damage, the caps in the circuit may not be rated high enough. i personally try to buy 35v electrolytics just in case people try higher voltage supplies, but there are certainly plenty of 16v caps that might get fried with an 18v supply... best idea is to always ask the builder/company before trying a weird supply.