Tube boost + overdrive running off a 9 volt battery

[firethorn]

Measure from the pin to ground right? Sorry.. Relatively new to this but getting the hang of it.

Pin 1 to ground is 9.2V
Pin 5 to ground is 9.2V
Pin 6 to ground is 4.8V

The rest are at 0V? Supposed to measure from Vref to these pins?

[frequencycentral]

Measure from the pin to ground right? Sorry.. Relatively new to this but getting the hang of it.

Pin 1 to ground is 9.2V
Pin 5 to ground is 9.2V
Pin 6 to ground is 4.8V

The rest are at 0V? Supposed to measure from Vref to these pins?

It would be nice to see voltages at all 9 pins. Here's mine, running at 12 volts, with the gain control set to maximum:

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

As you are running at 9 volts, all your voltages will be 25% less than mine. Your voltage at pin 1 is much too high, it should be 25% of the power supply voltage, so you do have a problem around that pin, perhaps the resistor value is wrong or you have a short? Also, what power supply are you using? Is it filtered/regulated? What voltage does it supply? What is its ma capability? The arrows on an electrolytic cap point to it's negative side.

[Big Dan]

Here is a question for you folks. Will a 5964 tube work in this apllication? I know it is a 7 pin and I would have to change the pinouts, but would it work? I only ask becasue I have a few of them and I may try building it with it instead.

http://tdsl.duncanamps.com/show.php?des=5964

Dan

[frequencycentral]

Here is a question for you folks. Will a 5964 tube work in this apllication? I know it is a 7 pin and I would have to change the pinouts, but would it work? I only ask becasue I have a few of them and I may try building it with it instead.

http://tdsl.duncanamps.com/show.php?des=5964

Dan

With that particular tube both the cathodes are connected, so you would have to tie pin 7 to ground, ditch the Valvecaster gain control and instead have an interstage gain control in place of the second stage grid resistor.

Also bear in mind that the heater is 6.3v / 450ma, so you will need to drop voltage for the heater with resistor ( 13 ohm / 3 watt @ 12 volts, or 6 ohm / 2 watt @ 9 volts should do the trick) or voltage regulator (7806 or LM317)

http://frank.pocnet.net/sheets/127/5/5964.pdf

[Big Dan]

Wow, thanks for the informative reply. I guess I will stick with a 12AU7 for my first go around. Maybe after that I'll try something different.

Dan

[firethorn]

Measure from the pin to ground right? Sorry.. Relatively new to this but getting the hang of it.

Pin 1 to ground is 9.2V
Pin 5 to ground is 9.2V
Pin 6 to ground is 4.8V

The rest are at 0V? Supposed to measure from Vref to these pins?

It would be nice to see voltages at all 9 pins. Here's mine, running at 12 volts, with the gain control set to maximum:

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

As you are running at 9 volts, all your voltages will be 25% less than mine. Your voltage at pin 1 is much too high, it should be 25% of the power supply voltage, so you do have a problem around that pin, perhaps the resistor value is wrong or you have a short? Also, what power supply are you using? Is it filtered/regulated? What voltage does it supply? What is its ma capability? The arrows on an electrolytic cap point to it's negative side.

Actually I meant the rest are at 0V. The resistors are correct. Probably a short.. Weird though.

Am using a 1spot think it's v2. Puts out "9V". ~9.2-9.4 when measured without load. It's regulated and can put out 1.5A. SMPS but very well filtered.

With this information in hand(esp the sample values) I can now try to troubleshoot it myself. Will post back once I get something.

Thank you very much for your reply. Most people don't realise that even the simplest things can spark off a chain reaction for someone else in the direction of self discovery. =D. Again, thanks. =)

[firethorn]

Retested the resistors and noticed that R2 was coming up at 0R. Switched it out and it worked. Weird though that when I measured it before, it read correct. Not the "I could've sworn it was correct" situation, but the "I know what I saw" kind. Very odd.

Pedal is lovely. Can't seem to tell much difference when using a 12ax7 or the 12ay7 though. Will have to try it out on a bigger amp probably.

Thanks so much for the help frequency central. I've fixed my pedal and I've learnt about a half a dozen new things.

Cheers,
firethorn.

[frequencycentral]

Retested the resistors and noticed that R2 was coming up at 0R. Switched it out and it worked. Weird though that when I measured it before, it read correct. Not the "I could've sworn it was correct" situation, but the "I know what I saw" kind. Very odd.

Pedal is lovely. Can't seem to tell much difference when using a 12ax7 or the 12ay7 though. Will have to try it out on a bigger amp probably.

Thanks so much for the help frequency central. I've fixed my pedal and I've learnt about a half a dozen new things.

Cheers,
firethorn.

No problemo! Glad you got it debugged and working, and glad to have been some help. I found this awesome forum via this particluar thread less than a year ago, I have learned so much, so it's good to give some back. 

[syndromet]

Man, this thing sounds great! Thanks a lot for such a wonderfull and easy project. Great project for "tube-starters".

[Mtaya]

Hi everybody,

I'm still looking for modifying my Valvecaster & I would have a little technical question about this :

I know that "Heater power Voltage" is around 12V under 150mA but I would like to know how to mesure "plate voltage" ?

Thank's for your help

Taya

[armstrom]

plate voltage is just what it sounds like. If you measure the voltage between the plate of a triode (pin 6 or pin 1 on a 12AU7) to ground, that is your "plate voltage". Now, when most people talk about a particular plate voltage they're really talking about the plate voltage at idle (no signal applied to the input of the circuit). The plate voltage is primarily affected by the power supply voltage, the plate resistor, the cathode resistor and the transconductance curve of the triode. Another interesting voltage to check is the cathode voltage. This dictates the bias point of your tube (assuming you're using a self-biasing scheme).

[Mtaya]

Thanks a lot for your help 

[dcd666]

hey everyone!
i'm a newbie and i'm having trouble with this simple box.
here are voltages:
pin1 - 8.91v
pin2 - 0.40v
pin3 - 0.00v
pin4 - 0.00v
pin5 - 9.12v
pin6 - 9.02v
pin7 - 0.27v
pin8 - 0.00v
pin9 - 4.36v
my wallwart is 9.12v
any ideas?

[frequencycentral]

hey everyone!
i'm a newbie and i'm having trouble with this simple box.
here are voltages:
pin1 - 8.91v
pin2 - 0.40v
pin3 - 0.00v
pin4 - 0.00v
pin5 - 9.12v
pin6 - 9.02v
pin7 - 0.27v
pin8 - 0.00v
pin9 - 4.36v
my wallwart is 9.12v
any ideas?

Here's mine, running at 12 volts, with the gain control set to maximum:

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

As you are running at 9 volts, all your voltages will be 25% less than mine. Your voltage at pin 1 is much too high, it should be 25% of the power supply voltage, so you do have a problem around that pin, perhaps the resistor value is wrong or you have a short? Your pin 6 voltage is also far too high, it should be about 70% of the supply voltage, check the value of the plate resistor at pin 6 and check for shorts.

[dcd666]

i've replaced both resistors: R2 & R3 and it's still the same.
voltages on pin1 and 6 are much too high.
i've followed by this schem:
http://www.aronnelson.com/gallery/main.php?g2_view=core.DownloadItem&g2_itemId=32777&g2_serialNumber=3
any ideas what i'm doing wrong?
i'll try to post some photos later.

edit:
here are photos:

[firethorn]

Have ye triplequad checked that all the resistors are functioning with an ohmeter?

[dcd666]

yep.

[kurtlives]

General Note after playing with a new 12AU7 pre-amp all day on the breadboard....

Increase grid leak resistors from 720K - 1M5 for a brighter clearer sound. Wont be as boomy and dark. Don't go too high, the affect will be minimal and those large value resistors are noisy. I think you can go as high as 22M though, that's if your plate current does not exceed 5mA.

[dcd666]

ok. now it works. it was just a matter of bad wallwart.
but i can't figure out how to put a DPDT with LED into it... (i don't need a true bypass).
can you help with it?
by the way - it's nice a sounding box

[firethorn]

http://www.geofex.com/tektips.htm

Right at the btm, stomp switch wiring