Tube boost + overdrive running off a 9 volt battery

[frequencycentral]

Hi again,

Sorry I have taken so long to respond about my Valvecaster.

I took some voltages, ans was wondering if anyone could compare theirs to mine? To me it just sounds really poorly biased. I also found out my 9V 500 mA power supply actually runs around 12.6 Volts when not plugged into the jack on my Valvecaster, it is an EH power supply. when the jack and take a reading across the positive terminal and ground I get a reading of 11.05 Volts, but I have gotten readings as low as 10.9V. Here are my voltages:

Pin 1: 7.63V
Pin 2: 0.00V
Pin 3: 0.72V
Pin 4: 0.00V
Pin 5: 10.99V
Pin 6: 4.46V 
Pin 7: 0.37V
Pin 8: 0.00V
Pin 9: 5.52V

A lot of these voltages seem to fluctuate slightly while taking them. I don't know if that will help diagnose the problem. I'll try to get a picture up later perhaps, but I don't know how helpful that will be, right now my project sort of looks like an octopus.

Nick

Pin 1: 3.02v
Pin 2: -0.518v
Pin 3: 0.00v
Pin 4: 0.00v
Pin 5: 11.97v
Pin 6: 8.21v
Pin 7: -1.285v
Pin 8: 0.00v
Pin 9: 5.91v

DC power in is reading 11.99v.

Gain at maximum.

Edit: My gain pot is 100K not 50K.

[sengo]

Pin 1: 3.02v
Pin 2: -0.518v
Pin 3: 0.00v
Pin 4: 0.00v
Pin 5: 11.97v
Pin 6: 8.21v
Pin 7: -1.285v
Pin 8: 0.00v
Pin 9: 5.91v

DC power in is reading 11.99v.

Gain at maximum.

Edit: My gain pot is 100K not 50K.

Thank you very much Rick, I really appreciate it! It looks like I may have messed up the resistors going to pins 1 and six, seen as my voltages are nearly opposite yours. I've checked them numerous times, but I've made mistakes like that before...

Thanks again,

Nick

[Renegadrian]

Else you could try the vero version if that helps...It's more than verified 

[Jimmy-H]

I also tried some tubes labelled 5963 - they work.
but as you can read they're part of the same family.

http://www.nj7p.org/Tube4.php?tube=5963

I just tried this Tube in my Pepper Shredder.
There's not much difference in sound compared to the 12U7 tubes I used.
The tube was a 5963 made by Beckman.
I never heard of this label.
But probably it's a relabeled GE tube (according to google....).
And one good thing about this Tube, is the price.
I payed 4 Euro for one tube, that's  cheap (in Holland).

The only difference between a 5963 and a 12AU7 is the maximum plate voltage.
250 V for 5963 And 330 V for a 12AU7.
But eeh... we are running from 12 volts here! 

So Adriano it's good that you mentioned this Tube.

And I didn't kissed the Tube ..........Yet

[frequencycentral]

And I didn't kissed the Tube ..........Yet

Maybe 5963 tubes are better kissers than 12au7's?

[Jimmy-H]

Maybe 5963 tubes are better kissers than 12au7's?

Let's see      ..........Yeah definitely!!!!


   

[Darkness, Darkness]

Hi everybody,

Has anyone tried some 6112 tubes ? I can't get any sound of it  Maybe the 6112 does not work at all with low voltage ? After all tubes are designed for high voltage... 

- I've build a Voltage regulator for the heater -> OK :  6,3v, the tube lights up

- At begining I was trying to replace the JFET in the first stage of a working distorsion breadboard project just to test, and as is what not working I build on another breadborad the first stage of the valvecaster without more success I must say. Only difference : I run it at 24V (so I replaced the 220K  by a 1M pot to be able to set the bias...)

I've check, double check, and check again pins layout but it is good. (Even tried to invert anod/cathod just to be sure...) I don't get any sound and when trying to bias the tube at half supply voltage, there is almost no drop voltage on the bias pot (24-> 22V with a 1Meg pot set at full), meaning there is almost no current flow through the tube I would say 

What's you opinion ? Should I forget using these tubes ?

Thanks

[aab0mb]

Hi everybody,

Has anyone tried some 6112 tubes ? I can't get any sound of it  Maybe the 6112 does not work at all with low voltage ? After all tubes are designed for high voltage... 

- I've build a Voltage regulator for the heater -> OK :  6,3v, the tube lights up

- At begining I was trying to replace the JFET in the first stage of a working distorsion breadboard project just to test, and as is what not working I build on another breadborad the first stage of the valvecaster without more success I must say. Only difference : I run it at 24V (so I replaced the 220K  by a 1M pot to be able to set the bias...)

I've check, double check, and check again pins layout but it is good. (Even tried to invert anod/cathod just to be sure...) I don't get any sound and when trying to bias the tube at half supply voltage, there is almost no drop voltage on the bias pot (24-> 22V with a 1Meg pot set at full), meaning there is almost no current flow through the tube I would say 

What's you opinion ? Should I forget using these tubes ?

Thanks

Maybe try a different tube.  I just built this little circuit and had a similar problem of no/low output w/ a 12at7.  I popped in a standard 12ax7 and it fired right up.  Not the best sound ever w/ a 12ax7 but at least it works.  If you can try different tubes first.  They all sound different.  Also, what kind of wallwart adapter are you using?  My OneSpot adapter works great but the other unregulated 9v and 12v that i had either didn't work or sounded like it was broken.  Good power supply is a MUST for this circuit IMHO.  Good luck w/ your project.

Aaron

[Darkness, Darkness]

Maybe try a different tube.  I just built this little circuit and had a similar problem of no/low output w/ a 12at7.  I popped in a standard 12ax7 and it fired right up.  Not the best sound ever w/ a 12ax7 but at least it works.  If you can try different tubes first.  They all sound different.  Also, what kind of wallwart adapter are you using?  My OneSpot adapter works great but the other unregulated 9v and 12v that i had either didn't work or sounded like it was broken.  Good power supply is a MUST for this circuit IMHO.  Good luck w/ your project.

Aaron

Thanks Aaron, I will try the spare tubes on tomorrow and a 12AX7 to check the circuit if it does not work better.

Concerning the power supply, I use a power supply for electronic labs (?? not sure how to say it in english ?? ? sorry  )  It allows to get up to 30V/3A. I set it on 24V and the current limitation status is OK. I've also checked voltage of heater and circuit when everything is powered up and it was OK

let's try this on tomorrow so... 

Fab

[Jimmy-H]

Hi everybody,

Has anyone tried some 6112 tubes ? I can't get any sound of it  Maybe the 6112 does not work at all with low voltage ? After all tubes are designed for high voltage... 

- I've build a Voltage regulator for the heater -> OK :  6,3v, the tube lights up

- At beginning I was trying to replace the JFET in the first stage of a working distorsion breadboard project just to test, and as is what not working I build on another breadboard the first stage of the valvecaster without more success I must say. Only difference : I run it at 24V (so I replaced the 220K  by a 1M pot to be able to set the bias...)

I've check, double check, and check again pins layout but it is good. (Even tried to invert anode/cathod just to be sure...) I don't get any sound and when trying to bias the tube at half supply voltage, there is almost no drop voltage on the bias pot (24-> 22V with a 1Meg pot set at full), meaning there is almost no current flow through the tube I would say 

What's you opinion ? Should I forget using these tubes ?

Thanks

Hi Darkness,

On page three there was this reply from Jered:

Dano, I forgot to add, I tried 6112 and 6021 tubes and the sounded horrible. That's all.
  Jered

So there most be comming some sound out of your tube, even when it sounds like sh*T !!!
I think with 24 volts this tube will sound great.
There has to be something wrong with your build.
Keep in mind that jered only used 9 volts!

I hope that you will find what is wrong! 

[Darkness, Darkness]

Hi Darkness,

On page three there was this reply from Jered:

Dano, I forgot to add, I tried 6112 and 6021 tubes and the sounded horrible. That's all.
  Jered

So there most be comming some sound out of your tube, even when it sounds like sh*T !!!
I think with 24 volts this tube will sound great.
There has to be something wrong with your build.
Keep in mind that jered only used 9 volts!

I hope that you will find what is wrong! 

Hi Jimmy-H

I was thinking also that with 24 V it should be better...

I tried this morning another 6112 tube without more success. Haven't tried yet some 6021... But I tried a 12AX7 as suggested by Aaron and it works ! So my breadboard project is right  With half a 12AX7  I managed to make a booster that sounds great !!! Funny as I was thinking it would sound crap if it would sounds.... So I am playing around with a 12AX7 (JJ Electronics). Even funnier....I wasn't using this tube a lot because I thought it was not very good sounding in my Emery Sound amp  I will try other 12AX7 just to check....  Maybe I will continue my project with 12AX7 ?

I'll keep you posted of my results 

Thanks !

[Renegadrian]

Sure do, any entry is welcome!!! 

[Renegadrian]

I added a new VERO version for the double valvy - it should work - Please check it out!!!
In the LAYOUT GALLERY search for TWINCASTER.

PS actually it's 2 layout, with and without the R1 at the beginning at the second stage. Someone said it's better to add that res...

[Darkness, Darkness]

Hi everybody,

Today, I've played with 12AX7...well more in a plexi preamp way than the valvecaster   but I am quite happy with the results   even if it remains lots of tweaking and tests to try ! Once I've got something well advanced i'll create a thread to share with you without hijacking this thread   And i will for sure have some question for you  

Anyway just to say it also works great with some 12AX7 tubes : OK for a JJ/Tesla, OK for and EH but it does not work good with a Tung Sol (Breadboard powered at 24V)

This thread is just a killing idea !!!!! Thanks dano12  

To be continuated  

[snap]

from Bugera, the guru of tone:
scroll down to 12ax7Q valves!

[Renegadrian]

...Once I've got something well advanced i'll create a thread to share with you without hijacking this thread  And i will for sure have some question for you   

Well, I believe our admin should change the title of this topic, I think nobody in this forum runs valves from a battery!!! 
So it has turned into what we'd call "LOW VOLTAGE TUBE CIRCUITS".
Said that, your creations are more than welocmed in this very topic!!!

HINT, HINT: please, change that topic title!!! 

[aka_basse]

Allright, decided to biuld this thing, (valvecaster) but since this thread is 30 pages long Im going to need some clarifications. (I did however read through it)

1. is there a good schematic for this thing including switches and whatnot? It seems to me that everyone is building different versions - im confused.
2. Is 12 V the power you want?
3. I was thinking of adding a switch for tube heating so that it can be kicked in without any delays - necessary?

It would be great if someone could explain and summarize this whole monsterthread a bit. (A huge FAQ for this project would be great for noobs like me)

[Jimmy-H]

Allright, decided to build this thing, (valvecaster) but since this thread is 30 pages long I'm going to need some clarifications. (I did however read through it)

1. is there a good schematic for this thing including switches and whatnot? It seems to me that everyone is building different versions - I'm confused.
2. Is 12 V the power you want?
3. I was thinking of adding a switch for tube heating so that it can be kicked in without any delays - necessary?

It would be great if someone could explain and summarize this whole monsterthread a bit. (A huge FAQ for this project would be great for noobs like me)

Hi AKA_BASSE

1. Just build the original one on page 1.
   You can tweak it from there if you want.
    For instance if it's to bassy, make C1 smaller (20nF or 10nF).
    You can also make the tone control switchable. (switch between C4 and the connection of C3-VR3).
    If you like it without the tone control, You can leave it out.
2.Yep!
3.No, you don't need that.
  when you power it up, the tube get it's power also.
  the circuit always get it's current.
  the only thing that gets bypassed is the signal.(this is with every stompbox)

I hope that this is helpfull!! 

Success with your build and keep us posted!

[frequencycentral]

Allright, decided to biuld this thing, (valvecaster) but since this thread is 30 pages long Im going to need some clarifications. (I did however read through it)

1. is there a good schematic for this thing including switches and whatnot? It seems to me that everyone is building different versions - im confused.
2. Is 12 V the power you want?
3. I was thinking of adding a switch for tube heating so that it can be kicked in without any delays - necessary?

It would be great if someone could explain and summarize this whole monsterthread a bit. (A huge FAQ for this project would be great for noobs like me)

A couple of weeks ago I trawled this thread and pasted various mod ideas into a Word doc, here's what I saved:

"I note that the original schematic and layout specify that the triode at pins 1-3 be used for the voltage gain stage, and 6-8 for the follower.

This isn't usually the best way to do it with a 12A*7.  With battery power or regulated DC going through the heaters, it doesn't matter which triode you use in which position, but if you're using AC or less-than-pristine DC, the triode at pins 6-8 will be quieter, due to the location of the heater pins on the tube.  (You can find mention of this in the data sheets on many 12A*7 series tubes.)



I lower the coupling cap between stages for less bass.



For lowering bass, you could try lowering the value of either the input cap, or the coupling cap between the two tube stages.



I am bypassing the Valvecaster gain pot with a 2.2nf cap. This helps maintain some brightness when the VC gain is turned down. For the input cap on the Valvecaster I am using a combination of caps to give me 2.7nf. This helps tighten up the bottom end.



To tame the gain I would lower R2 and R3. 220k and 100k seem pretty high for a low voltage circuit. Even in a regular high voltage amp the normal value is just 100k. So maybe cut them in half.



if you bring down that 220k to 100k it will def lower the gain a bit.  I built mine with both plate r's at 100k.



A 1M gain pot allows massive, saturated gain. A little mushy in the bass frequencies, but pretty cool. I'm considering putting a "more" switch in, whereby it adds a resistor in series to the regular gain pot.



Adding resistance to the plate resistors(R1 and R2) will increase gain. Adding resisitance to VR1, in series with the gain pot, will decrease gain.



guitarx: replace the 100k resistor with 47k. Replace the 220k resistor with 100k.
Beautiful cleans   

To fellow Valvecaster experimenters -- I've currently got this circuit on a breadboard, switching out everything and I have some items of interest to report, especially for those looking for more gain.

The nicest clean sound I've found so far, is with the following mods:
R2 = 100k
R3 = 47k
C1 = 0.1uf
Remove C4 and VR2



Finally received that 7812 - mounted with the 100uF filter cap on the dc jack - hiss is just a memory... 
put a 100uF cap across the DC jack (positive leg to positive rail, neg. leg to neg. rail), then, instead of connecting the positive rail directly to the circuit, connect it to the regulator's pin1, ground to pin2, and the circuit to pin3. Then screw it on the enclosure. It is a 7812."

I take no credit - its other peoples ideas - I just pulled it together for easy reference.

[Renegadrian]

1. is there a good schematic for this thing including switches and whatnot? It seems to me that everyone is building different versions - im confused.
2. Is 12 V the power you want?
3. I was thinking of adding a switch for tube heating so that it can be kicked in without any delays - necessary?

It would be great if someone could explain and summarize this whole monsterthread a bit. (A huge FAQ for this project would be great for noobs like me)

1. Go to the Layout Gallery and search for VALVECASTER - you'll find my verified vero layouts. Both Tone or Toneless.
Those layouts include jacks, power, switch, so you just cannot fail...
2. Yes
3. no need for that

A FAQ, you say...Well, that could be done...But I just can't figure out what to write about it!!! Maybe we could work at it togheter - you ask, we reply, so we can write down all the Qs' and the As'...
Hope that helps...



PS I'm building my 4th Valvy, a local bass player asked me to build it for him...And the graphics on this one are gonna kick serious a$$!!! I'll post it in some days...



PS Please give a look at my TWINCASTER layouts in the gallery - they should be correct, but hey I need your comments...