Tube boost + overdrive running off a 9 volt battery

[tuckster]

Hi,
during the last few days I built the standard valvecaster without any mods. The sound is (some others had this problem too) very low in volume. Gain and volume to max is a bit quiter than the bypass sound.
The parts are soldered to the tube socket. and there is no part connected with a wrong pin, everything is soldered the right way (I checked it again and again...).
Here are my pin voltages (I run this box with 9V):
1: 8,60
2: 0
3: 0
4: 0
5: 8,92
6: 8,72
7: -0,11
8: 0
9: 4,44

I tried to lower the voltage on pin1 like rick recommended on page 55 but I can't get lower than ~7V on pin 1 with a 1M pot instead of 220k (R2). The same problem with R3.

[zambo]

what layout did you use? pin 9 is usualy disconected. usualy heaters are wired w/ 9 volts to pin 5 and pin 4 grounded.

[zambo]

here is a sound clip as requested by some members. camera mic is not the best but you get an idea of what it sounds like. This is one of my first ones. http://www.youtube.com/watch?v=Lzucs8PRVgA

[Renegadrian]

what layout did you use? pin 9 is usualy disconected. usualy heaters are wired w/ 9 volts to pin 5 and pin 4 grounded.

pin 9 is not used, but is connected internally, so you will find half the voltage just because you give voltage to 4 and 5.

[tjp78704]

The 12AU7 heater filaments use 6.3v - 12v. See the specs, http://www.audiomatica.com/tubes/12au7.htm

Each filament is intended to run on 6.3v. The 12AU7 is a dual-triode, so it has 2 filaments (one for each half). So if you are running them in series (only pins 4 and 5) you supply 12-12.6v. You can also run them in parallel, 6.3v to pins 4 and 5 and wire up pin 9 as a common ground.

Basically, either way you do it you should ideally read something close to 6.3v from pins 4 to 9 and from pins 5 to 9. Although other voltages will definitely work, I've heard you can really reduce the life of a tube by going too much over (or under) the specified voltage.

Tim

If you have anything on the brteadboard, you could also try a buffer!!
If your Amp does not fit the impeadance requirements of the valvecaster, that may be a good reason for your volume loss! You can stop it with the buffer.

Your mods give even more gain and should make the thing louder. So dont worry about that. The mods are good, I tried similar things. Thats for sure not the reason - but the impeadance might be...

EDIT: And you should also try 12 V - better 30 or 40! It makes a NICE difference - and gets louder
Do you have active or passive pickups?

[tuckster]

I relsoldered the whole components including the pots and so on and I still got the same values on the pins. Maybe i should solder the resistors, caps etc. on a perfboard but I don't think it will help a lot.

Zambo: I used the pcbless layout drawn by dano from page one.

Is it possible that I killed the tube? Because I resoldered a cap with the tube inside the socket before I tested it the first time.

Edit: i forgot tho say that I'm using a ECC82 that's the european version of the 12au7 --> same specs.

[Anon]

I wired a 6 pos. rotary switch with different caps across the gain pot to get different tones. It sounds great but I was getting loud pops when I turned the switch. I wired 5.1M resistors across the switch to get rid of the pops similar to this pic

The pops are totally gone but now the Valvecaster is noisy. the noise wasn't there before I added the resistors. Is there a way to get rid of the noise? maybe a different way to wire the resistors to get rid of the pops?

[DavenPaget]

Resistors make alot of noise .

[Govmnt_Lacky]

Resistors make alot of noise .

Actually, I believe he chose to use resistors here in order to prevent switch "popping" when selecting between cap settings while the unit is ON.

[DavenPaget]

Popping ?  If there are popping noises , it's got to be arcing elsewhere .

[anchovie]

Resistors make alot of noise .

Actually, I believe he chose to use resistors here in order to prevent switch "popping" when selecting between cap settings while the unit is ON.

Solution: Remove the 5M1 resistors and don't change the switch position when the pedal is on. It's unlikely that there will ever be a need to crouch down and alter the setting while in the middle of a riff!

[tuckster]

That damn thing is going to move in a drawer and will never come back on my desk again...
I rebuilt it on vero on renegadrians layout and the voltage values are same as before. I used 1m pots for R2 and R3 but I couldn'tmanage to get lower than 7V on Pin1 and Pin6.
http://www.aronnelson.com/gallery/main.php/v/Renegadrian/Valvecaster+v0_5.jpg.html
Next step: order a new tube....

[merlinb]

That damn thing is going to move in a drawer and will never come back on my desk again...
I rebuilt it on vero on renegadrians layout and the voltage values are same as before. I used 1m pots for R2 and R3 but I couldn'tmanage to get lower than 7V on Pin1 and Pin6.

7V sounds pretty reasonable to me...

[tuckster]

Well I tried to get to the values that Rick postet:

Yup, your pin 1 should be 25% of the power supply voltage - about 2.3v in your case.
Your pin 6 should be 66% of the power supply voltage - about 6 volts in your case.

This seems to be a common debug problem with Valvecasters - the plates being too high.

Those voltage of mine that Adriano posted were taken with the gain set to maximum (ie first stage cathode grounded) by the way.

If you are sure everything is correct (though it can't be if your voltages are off), you could replace the 220K resistor with a 1M pot (use the pot's lugs 1 and 2) and tweak it until you read about 2.3v at pin one. Then measure the resistance between lugs 1 and 2 of the pot. Do the same with the 100K at pin 6, though I think pin 6 will come into line when you sort out pin 1.

This is not possible with my build. I wonder why so many people have correct values and on the other side there are still so many people in this thread with values like mine. And I still talk about 9V not 12V.
I don't get it.

[iccaros]

@tuckster

Not trying to but in, but I just finished mine, and with my 9V wall wart and 9 Volt Batt, I had similar results as you. I now am running a 13.5v with voltage regulator and I get 11.79 and more volume.

Mine had big issues with hum, not matter what I did with power, I broke down and bought a adjustable wall wart from Radio Shack (13.5 and 30V) so I can play with higher voltages.

So I do not think your readings are bad, As a matter of fact one of my EH Tubes sounds awesome at those levels, but my other three, not so much.

I'll check my pin one and see what I get on it.

[tuckster]

Ok now it works. I don't know why... I put in a new Pot for R2 becaus ethe last one was realy burned after all these resoldering adventures.
I still got the same pin values for 9V and it also works for 12V but then I obviously have different values.
I tinkered around with R2 and R3 to get a nice sounding pedal. I'm going to post the pictures in the pitures thread.

[xelalien]

hi guys! DIYstomps newbie here!

just finished building the Valvecaster (pcb-less), used a 12AU7, will take pics tomorrow after putting 'em altogether in the enclosure.

btw guys, try to change C4 to a 22nF one for a more use-able tone control
(dunno if this was already posted before).

anyway, many thanks to the contributors in this thread, and to matsumin himself!

[zambo]

Welcome and congrats on your build! @ Tuckster- Glad it worked!

[Dongle]

Hi guys!
I encountered a new problem: I am running the valvecaster with 30 - 40 V (7660S, PIN 1 connected) and a buffer (OPA2134) at the output.

If I adjust my potentiometer to high gains (low resistance), I get a steady tone. Very annoying. It starts quite abrubtly on a certain gain level.

Any ideas how to get rid of this? Does anyone else have this problem?

[zambo]

if its a high pitched squeal or wistle kind of sound its oscilating. Welcome to tube distortion....check your layout and start replacing input wires and signal wires with sheilded wire. only ground the sheild on one side. usualy the side away from the noise (input side etc.). Thats all I can think of. you could start adding grid stop resistors but those suck the tone i think. a cap to ground from the plate works for the excessive highs. 500 pf caps work well for that but once again you are killing tone. try to solve it with better layout if you can. higher voltage makes higher volume and more gain. This design is really for lower voltage. you start getting all these squeals and stuff as you raise it. Good luck, hope that helps. Greg