Tube boost + overdrive running off a 9 volt battery

[psychedelicfish]

to gather the voltages i referenced above I put the positive tip of the muiltimeter to the respective pin and negative to ground

So no, the voltages you measured were not negative relative to ground. Just a tip: a dash next to a number makes it look like that number is supposed to be negative.

[Jdansti]

 

Ok, here are the voltages:

P1 5.2
P2 7.23
P3 7.23
P5  9.04
P6 0.63
P7 0.60

[edited: removed dashes and added leading zeros -jdansti]

fwiw, I tried running it at 12 V using my bbe supercharger and it still didn't work... such a simple circuit - such an epic fail - not a great into to tube circuitry here i'm afraid

Probably a solder bridge, bad joint, or miswiring. It happens on the simplest of builds.

Does anyone know if the voltages above look correct for a 9V supply? 

[psychedelicfish]

Does anyone know if the voltages above look correct for a 9V supply? 

Heck no. Pin 1 should be higher in voltage than pin 2 and 3. Pin 2 should be at 0V, pin 3 should be slightly higher than ground, no more than 1V. Pin 6 should be way higher than it is, pin 7 might be alright.

Are you sure you've got the pins wired right? With the gap facing you and the valve upside down, pin one is on the left hand side of the gap and the pins are numbered clockwise from there. Are your valves getting warm?

Also, just a note, the valve caster will work better on 12V, the filaments are designed for 12V and the characteristics of the valve will change dramatically with the filament voltage.

[bufferz]

Thanks for your responses.

I did double check the wiring and the valve is getting warm (if i turn the lights off i can see the glow)

for some reason i have signal at pins 2 and 3 but the signal never goes to pin 1, that's where it stops.

i did try 12v as well.

[bufferz]

got it resolved, was a bad solder joint on socket.  Thanks your patience and advice

[psychedelicfish]

Glad you got it working, 90% of the time it's something like that  .

[Fatknuckle]

Man, it took me longer to read this whole thread than it did to build one of these Valvecasters, off the original Bevis layout. I am wondering if it is safe to run it on a regulated 18V laptop supply I have, or safer to regulate a line off to 12V?  Really sounds nice on 9V.  Such great work I have seen here! Can't post a pic yet from this computer, but I will soon.

[Jdansti]

You want to keep the heaters at 12V in series (or 6V parallel). The rest of the circuit can be 18V.

[psychedelicfish]

To get 12V across the heaters, put them in series with a 33 ohm, 1W resistor.

[toplak666]

Hey guys. I need some help... Wasn't the idea behind the valvemaster gain pot wiring to eliminate scratching sounds when turning? Somehow my circuit sounds more scratchy than with the original circuit... Any ideas why? Pots are not ALPHA but they are pretty high quality.
Also, I have two more problems with this circuit. (triple valvemaster by the way) First tube on it's own sounds nice but there is a high pitched hissing sound to be heard that I cant seem to figure out where it's coming from. First + second stage sound fine. All stages together sound farty however... Sounds nice when the input signal is high like when you've just strummed a chord, but when the signal gets weaker, like when a note starts dying out, then the sound gets farty...
Changed the cathode capacitors from 10uF to .1uF. Plate resistors for the first stage are 47k, second and third stage have 150k. (all plate resistor are socketed so I can easily swap them if needed) Pedal is powered by an extremely well regulated 24V 1.4A toroid. Regulated 12.6V for heaters and regulated 20V for everything else. Pin voltages check out as far as I can tell...

Any help would be grately appreciated!

Happy tubing

[peterg]

toplak666 - can you post the schematic you're working from?

[toplak666]

Basically this:



But without the tone circuit and not at 9V but 20V. I use relays and 3PDTs for switching between stages. The switching circuit is huge but it's mostly bussing.

[toplak666]

So I fixed the tube 1 problem. Turns out the plate resistors I selected were too high... I'll experiment with different values in the future but for now I'll keep them at 47k. Tube 3 is still an issue though. The sound is fine with a high input signal but when the signal starts to decay the sound gets farty and quite quickly after that dies out.
Any ideas?

[tranceracer]

Is your input and output jack negative connection grounded?  I had similar problem and noticed only the positive (tip) was connected to the ckt.

[toplak666]

Checked. Both are indeed grounded. Dont have a housing yet though... Hopefully I'll have it by the end of next week.

[mobeol]

Hi, I'm a noob in this forum, I was wondering if this can be build using 6922/6dj8 since i had a couple, perhaps with different value of resistors and/or capacitor but keep the 9v power supply? 

[psychedelicfish]

Try it with stock values (except for the valve) and if it sounds bad, post a description (or even better, a recording) of how it sounds. We should be able to make some suggestions from there.

[toplak666]

I'll have it done by the end of the day!

[hopkinWFG]

To all valvecaster builders.. was wondering if you guys ever run the tube at high plate voltage ie 350VDC?

[vigilante397]

To all valvecaster builders.. was wondering if you guys ever run the tube at high plate voltage ie 350VDC?

I've never tried it, as the 12AU7 doesn't require that much voltage to "sound like a tube." If you were going to try it with a 12AX7 then you would need at least 300V across the plates to make it sound like a 12AX7, which would also give you more gain. This can be a desirable thing depending on the sound you're going for.

I've built the original Valve Caster and the Twincaster, which are both great at what they do, but I'm also working on  this pedal that uses around 300V on a pair of 12AX7s and has a lot more gain than the Valve Caster series.

http://www.diystompboxes.com/smfforum/index.php?topic=93936.0

Check it out