Tube boost + overdrive running off a 9 volt battery

[esdiezy28]

R2 and R3 (220k and 100k, right?) set the gain of the stage. Decreasing the values will lower your overall gain, increasing them will increase gain. As for the full 9V on the plates, there should be a drop from the resistor. My first gain stage plate usually in the 6-8V range (I run mine at 12V instead of 9V personally.) Hope that helps 

[backinnam]

Thanks Tony! So in order to increase headroom I'd probably need a higher plate voltage than grid voltage?

[iccaros]

Hellou,
Anyone have a schematic, if i want to use 6n2p tubes?

6n2p have the same rating as 12ax7 but 6volts only on the heater, 9v would quickly kill the heaters, you would need to lower the voltage for pins 4 and 5, leave them connected as you see but to 6.3 volts if possible. also 12ax7's are not known to do well in this low voltage design, so their use may very. I have a metric but ton of them, and when I build amps I put a switch in v2 where this tube loves to be, as it seams to handle saturation better IMO.  In this design, I still go back to the 12au7 and at7..

[johnravacio]

This have been a long thread so I haven't read it all. From earlier posts, valvecaster doesn't work well with 12ax7. Does that mean it won't really work at all if I place a 12ax7 on it?

Also, I've looked at the Persuader schematic and looks like it worked well with 12ax7. The only difference I spotted is how we supply voltages on PIN 1 and 6. The pin 4 and 5 is I think similar if not the same as the Valvecaster.

http://www.modkitsdiy.com/sites/default/files/product_files/the_persuader_schematic.pdf

Any ideas how I could make 12ax7 work on this circuit? perhaps put a 9v+ supply on Pin 9? not sure really.

Thanks!

[iccaros]

a 12ax7 works, most people do not like the sound, not much boost at 9 volts.  do not put 9volts on pin 9. Its the mid point of a 12v heater CKT. With the 9v valvecaster we are running the heaters at a  lower voltage, meaning we do not get full emissions from the cathode.  the 12ax7, because of trasconduction and plate characteristics, only puts out 3ma at its best, which makes the voltage swing over the plate resister less (voltage == current X resistance) , than say a 12AU7 allowing 7ma to flow.

so to wrap up, you can try a 12ax7, and you may like it, but others have not.  you can try 12v, I find it works better, or do what some of us have an put 12 on heater and use a voltage multiplier to get 70 or 100v on the plates. in any case this is not a distortion pedal but a booster, so the high gain of the 12ax7 will not get you there. At 100v, well now we have a whole different story and design.

Try the standard and then look up valvemaster I think its starting on page 131 or the thread, I have a simple voltage booster at 60v on one, sounds nice..

[johnravacio]

a 12ax7 works, most people do not like the sound, not much boost at 9 volts.  do not put 9volts on pin 9. Its the mid point of a 12v heater CKT. With the 9v valvecaster we are running the heaters at a  lower voltage, meaning we do not get full emissions from the cathode.  the 12ax7, because of trasconduction and plate characteristics, only puts out 3ma at its best, which makes the voltage swing over the plate resister less (voltage == current X resistance) , than say a 12AU7 allowing 7ma to flow.

so to wrap up, you can try a 12ax7, and you may like it, but others have not.  you can try 12v, I find it works better, or do what some of us have an put 12 on heater and use a voltage multiplier to get 70 or 100v on the plates. in any case this is not a distortion pedal but a booster, so the high gain of the 12ax7 will not get you there. At 100v, well now we have a whole different story and design.

Try the standard and then look up valvemaster I think its starting on page 131 or the thread, I have a simple voltage booster at 60v on one, sounds nice..

Thanks a lot for the very helpful information iccaros.

Re: Do not put 9v on pin 9.
Ok noted.

Alright since most have find it better on a 12v, I'll start with that. As you've suggested I'll read through page 131 however, I don't have much confidence dealing with high voltages yet. Is 60v enough to kill me if I accidentally touch these things? If yes, i think i'll better pass

[Renegadrian]

60v will make you burn in flames in 10 seconds, and your ashes will be your only legacy...

jokes apart, the persuader is just another story...playing with pure tube schematics is more difficult than just push a tube with a (mosfet in the persuader case) booster...yes you can do it, but then you got an hybrid circuit and the tube gets less involved in the outcoming tone, so less mandatory (at least in my eyes)
just look at the schematic, no cathode resistors or capacitors...I guess the tube used that way gives very little to the overall performance...but it's just my guess, driven by a dislike of hybrid circuits.

basically you have a super hard on to boost the tube - you still can try it with the original valvecaster schem or the valvemaster. I wrote several times that I find the valvecaster to be a little on the bass side, so while I descourage the use of an LPB before it (being too dark to my ears), a different kind of booster would be a good push - I personally tried the tilman and got nice results, guess the sho is even better as it has a good "presence".

[psychedelicfish]

When I tried it with a 12ax7 at 24V, it sounded pretty good to me... I'm currently working on a low voltage clean all tube boost with a 12AT7 at 24V. It's sounding pretty good ATM, but it still needs a bit of tweaking to get it perfect. I'll probably post a schematic and samples soon.

[johnravacio]

60v will make you burn in flames in 10 seconds, and your ashes will be your only legacy...

jokes apart, the persuader is just another story...playing with pure tube schematics is more difficult than just push a tube with a (mosfet in the persuader case) booster...yes you can do it, but then you got an hybrid circuit and the tube gets less involved in the outcoming tone, so less mandatory (at least in my eyes)
just look at the schematic, no cathode resistors or capacitors...I guess the tube used that way gives very little to the overall performance...but it's just my guess, driven by a dislike of hybrid circuits.

basically you have a super hard on to boost the tube - you still can try it with the original valvecaster schem or the valvemaster. I wrote several times that I find the valvecaster to be a little on the bass side, so while I descourage the use of an LPB before it (being too dark to my ears), a different kind of booster would be a good push - I personally tried the tilman and got nice results, guess the sho is even better as it has a good "presence".

Thanks Adrian for the suggestions. With the parts I bought today, I'm going into the SHO+Valvecaster.

When I tried it with a 12ax7 at 24V, it sounded pretty good to me... I'm currently working on a low voltage clean all tube boost with a 12AT7 at 24V. It's sounding pretty good ATM, but it still needs a bit of tweaking to get it perfect. I'll probably post a schematic and samples soon.

Thanks, I'll look forward to your schematics soon.For now I'll just go with the SHO+Valvecaster built.

[zaubertuba]

OK I've read at least through 100 mind-numbing pages of this thread and everything's starting to blur together, so forgive me if I'm reposting old questions here... 

Has anyone tried putting a TS-808 (or clone) in front of it to get more distortion?  Do you guys recommend running this linear or in parallel blended with a clean signal?  Anyone running this in a HiFi amp/cab setup or direct?

Here is the schematic for my latest dual 12AU7 circuit. It is currently still on the bread board and I think it sounds great. It is designed to run on 9 volts. It goes from clean boost all the way up to "brown" type gain. It cleans up nice with the guitar volume as well.

Sorry to dredge up an old post but has anyone else tried this variant?  I'm currently proto-boarding it...looks a bit more refined from my limited first glance at it.

[Renegadrian]

mmm I guess that could be done, altough I find it too much...but yeah guess what you would find if you open a tube driver or a tonebone...yeah a 4558 pushing the tube!!!

[Henry89789]

Hello folks:

I was last on this thread about a year ago all enthused about progressing to the next stage of pedal building with a tube overdrive pedal .... I bought all the stuff, I breadboarded one (and it worked!), but then after reading many pages of this thread I realized that there was still a lot of uncertainty about which circuit is the best.  So I put it aside for awhile. 9 volt?  12 volt? 12AX7?  12AU7? Well, I am back and I was hoping that there is a concensus now on which is the best way to go  and that you all can direct me to the schematic for the consensus tube overdrive. Thanks.   

[iccaros]

@Henry

Sorry to say there will never be a consensus , this is music and everyone has a different want and need.  since you have a bread board, try the different ways, play with it, if you like it that is the best one, if not.. try the next.

Tubes at low voltage are fun as they are hard to kill unlike a transistor. AS LONG as you do not screw up the heaters.. that is..

But if you hook up a tube backwards at 12 or 24 volts.. no harm no foul..

[toplak666]

Have to agree with iccaros on the consensus and experimenting part. However if you don't know where to start and are looking for versatile sound I'd suggest a 12AX7 double valvecaster with the valvemaster circuit. You'd need 12V for the heaters and at least 18V for everything else... I found that 12AX7s are more or less useless with anything less than 12V, however with 18V or more they sound great. With this design you'd be able to get some nice crunchy crunch from the first stage and (at least from my experience) HEAVENLY drive with the second stage kicked in.
Anywho, those are my two cents... Hope it helps.

[Henry89789]

Toplak666:

Thanks. Perhaps "consensus" was the wrong word to use, but your response is exactly the type of suggestion I was looking for. It sounds good too. I am going to look for the schematic. 

[valve999]

I wanted to thank everyone on this forum - I've built my first stompbox (a valvemaster housed in an old, non-working, wah enclosure). I think it sounds great on single coils and humbucker, giving my low budget but reasonable set-up (solid bodied Pacifica and H&K Blue 60r) a bit of valvey goodness! A bit farty on high gain - what could I try to improve this? Different valve or change some R and C values?

[iccaros]

change your coupling cap, use  smaller number, if your using .1 use a .01 or .022 ect.. you will roll off some more bass.

[jmwreck]

Hi, this thread is very informative, I have learned a lot about power supply and tubes in particular. One thing that concerned me is the power to be used on the circuit. I have read that the heater must be 12 volts to pin 5 and Ground to 4 or vice versa for the tube to be optimized and can lived long. I have understood that the circuit itself can have a different voltage, it can be from 9v-whatever is the maximum. I have a charge pump (for some of my pedals) right now based on madbeans layout with two outputs, 15v and 18v. I wanted to use the 18v to supply this pedal, but it won't be ideal for the heater, therefore, I need to give 12v to it.

1. How can I integrate A 12V regulator (and other components) inside the circuit and connect it to the heater while its Vin comes from the 18v supply of the entire circuit?
2. What are the necessary components to be placed aside from a 7812 regulator?

The main PS I'm using is a 1-spot. I have build my layout based on the Dual Caster:



-----





If you find errors on my layout, please let me know.
It is a stock Dual Caster based on THIS

[iccaros]

use a 5 volt regulator and shunt it to give 6.3 (2 diodes on ground should do it, but what ever diode you use look up the voltage drop, you want about 1.3 volts total) and use the alternative wiring, pin 4 and 5 tied together with + 6 volts and pin 9 ground. you will need a heat sink and notice the tab on the LM7805 is positive so you will need a mica separator.  two tubes will pull 600ma for heaters in 6.3 volt mode..

[jmwreck]

use a 5 volt regulator and shunt it to give 6.3 (2 diodes on ground should do it, but what ever diode you use look up the voltage drop, you want about 1.3 volts total) and use the alternative wiring, pin 4 and 5 tied together with + 6 volts and pin 9 ground. you will need a heat sink and notice the tab on the LM7805 is positive so you will need a mica separator.  two tubes will pull 600ma for heaters in 6.3 volt mode..

is there any other way than this and what is the difference if I'm going to use the 12v regulator instead of the 5v? thanks