Running on 18 volts ??

[HOTTUBES]

What's all involved in getting a basic 9 volt Overdrive TS circuit to run on 18 volts ?




Thanks for any help or tips !

[mth5044]

Besides getting an 18V DC supply, you need to make sure your components are rated for the higher voltage. Resistors are more than likely fine, but you need to check the caps/IC's/transistors.

[HOTTUBES]

What about op amps ??

JRC 4558D , how do they stand up to the 18 volts ?

[GibsonGM]

Yup.   It's a common mod, as long as all your other stuff is rated for more than that.  I'd be most worried that you could have 16V caps in there, so look closely!     

[HOTTUBES]

I should be good then , cause i use alot of electrolytic s than are rated at 50 volts  


These were the components that i was worried about

JRC4558D
2N3904
1N4001
Film caps 1uf , .1 uf , .047 uf , .22 uf  etc etc

[HOTTUBES]

Could i feed my OD board direct from a charge pump output  ??


9 Volt dc > 1044SCPA > dc input on OD board   ...

[J0K3RX]

Could i feed my OD board direct from a charge pump output  ??


9 Volt dc > 1044SCPA > dc input on OD board   ...

yup..

[Mark Hammer]

I wouldn't expect all that much difference in the case of a TS-9/808.  Keep in mind that the headroom advantages to increasing the supply voltage pertain to where it is the supply voltage itself that is constraining the headroom of some gain stage.  So, if you are asking a gain stage to turn a 100mv signal into a +/-5V signal, running off a 9V supply will put an end to that particular goal, and running off 18V will make it a reality.

But in the case of a Tube Screamer, the diodes are in the feedback loop of the op-amp, such that signal amplitude in that stage can never really go above about +/-650mv or so, and ALL clipping will be diode-related, rather than headroom-related, as it is in something like the MXR Distortion+ or the Proco Rat.  Or, said another way, the headroom limitations come from the diodes, not the supply voltage.

If using 18V for a couple of pedals helps to simplify things for you, be my guest.  But if you are doing it for this particular pedal, in hopes of hearing something magical, I wouldn't hold my breath if I were you.

All of that said, I second all of the things to look out for that others have noted.

[garfo]

Just check the opamp datasheet.If it can take 18 vols it's fine.That opamp can take 18 volts.Also, as it has been mentioned before, resistors are usually good for these kind of voltages.Just make sure that all your other components such as caps are rated at least 25 volts, just in case.

[HOTTUBES]

Thanks Guys for all the great info ...

I see alot of Overdrive pedal makers talking about them being able to run on 9 or 18 volts , many players have said that there is a big difference
with them running on the 18 volts etc etc .... so my question now is , what are they doing in the circuit to make better use of the 18 volts
Example Phulltone Fulldrive 2 , its a 9/18 volt OD based around a TS circuit ...

[MrStab]

what are they doing in the circuit to make better use of the 18 volts

imagining or lying.

...or their pedals are quite different from the Tube Screamer. Mark's already summed it up better than i could. there are circumstances in which higher voltages can be beneficial (or at least different), namely circuits where signal preservation is the goal, but it's a fact that's abused and turned into hype. as far as i can tell, anyway. it's something i read a lot on non-DIY guitar forums, where people seem to think you can just plug a higher voltage into anything and it'll magically sound better. ofc, maybe it does... http://en.wikipedia.org/wiki/Placebo.

i guess it's the old "bigger=better" myth (i think i'm average, for the record ).

[Mark Hammer]

Thanks Guys for all the great info ...

I see alot of Overdrive pedal makers talking about them being able to run on 9 or 18 volts , many players have said that there is a big difference
with them running on the 18 volts etc etc .... so my question now is , what are they doing in the circuit to make better use of the 18 volts
Example Phulltone Fulldrive 2 , its a 9/18 volt OD based around a TS circuit ...

It's not ALL hype, but one would be naive to ignore the particular design of a circuit, and treat anything that calls itself an "overdrive" as essentially the same thing.  In some instances, such as all-discrete JFET-based circuits that do not rely on diodes for clipping, varying the supply voltage can result in different qualities of sound.  In others, such as the TS circuit described earlier, other components will govern the performance of the overall circuit more strictly, such that variations in supply voltage will have a very tiny voice in that crowd, by comparison.

Of course, when the objective is to be as clean as possible, raising the supply voltage will go a long way towards maximizing headroom.  For example, take your everyday plain vanilla MXR Microamp, goose the supply voltage with a charge pump or even just double 9v batteries, and it can become a much better mic booster for feeding a mixer or whatever.  If memory serves, the Visual Sound Truetone clean booster, that RG designed, triples the supply voltage for huge headroom.

Supply voltage does have an impact on the performance of tubes, naturally, with some tube-based pre-amp/overdrive makers using what often gets described as "starved plate" (i.e., lower than recommended plate voltage) to yield saggy overdrive.

[mac]

At 18v you'll notice more volume because the pedal has more power.
As Mark noted, if you want a bit more headroom change the clipping diodes for leds.

mac

[induction]

In some instances, such as all-discrete JFET-based circuits that do not rely on diodes for clipping, varying the supply voltage can result in different qualities of sound.

For instance, the Catalinbread Formula #5 benefits greatly from 18V. At minimum on the gain control it's too dirty for me at 9V. But at 18V it gives me the perfect range from clean to dirty as I adjust the volume knob on my guitar.

[Mark Hammer]

Mac,
You are certainly correct that use of LEDs or even a 2+2 set of 1N4148s would undoubtedly raise the volume ceiling, even without a supply-voltage change, but where would the increased power/volume come from, in a stock build?  The stock clipping diodes have a fixed forward voltage, the tone stage has very little gain, and the transistor buffer stages are ostensibly run at unity gain.  If the transistor stages changed their gain via the supply voltage, I could see it, but nothing that would be amenable to supply variation is jumping out at me.  So what am I overlooking? (and I have overlooked MANY things before   )

[mac]

Mark, I took a look at the output transistor, and its emiter voltage would be higher, ie, more power to deliver to whatever follows the TS.
In other words, I thought available electrons not voltage.

mac

[slacker]

That might make a difference if you were connecting it to something with a very low input impedance. I wouldn't think anything you'd normally connect it to would be drawing any significant current though so it wouldn't make any difference.

EDIT: scratch that increasing the supply voltage is only increasing the DC power, not the AC, I think???


At 9 Volts, with a hot enough signal it is technically possible to make the opamps in a TS clip, you're probably talking a lot hotter than a guitar though unless you've got some stupidly loud active jobby.

[HOTTUBES]

So the general consensus is that in a slightly modified TS overdrive circuit , running  at 18 volts will not held a very big difference over its standard 9 volts ?? hmmm Interesting ....

[mth5044]

Ya never know until you try! There are dirt pedals, such as the Fulltone OCD, that do sound different at higher voltage.

[mac]

So the general consensus is that in a slightly modified TS overdrive circuit , running  at 18 volts will not held a very big difference over its standard 9 volts ?? hmmm Huh Interesting ....

I have a Red Fuzz which is a cousin of the TS, and a Dist+. At 18v they have more of everything.
It's not a 100% jump because diodes do limit the voltage, but they are working harder and adding extra harmonics.

mac