Tube boost + overdrive running off a 9 volt battery

[BarnyardBill]

OK, I built the valvecaster today and left out the tone pot.  I used a 12V wall wart for pin 5 and a 30V wall wart for the heaters pin 1 & 6.  Then I connected both of the wall warts ground to the ground on my breadboard.  It was giving me some really strange noises when I had the gain and volume up.  I mean if I turned the knobs on my guitar it making noises like a wave generator or something.  Then, I started smelling something burning and I think I may have blown both my wall warts.  Does that make any sense electronically.  I will have to find another wall wart and try again.  My room really smells like burnt electronics now.  (cough cough)

-Bill

[tipetu]

You used 30V for the heaters?? Since they are connected in series it needs 12,6V. Correct me if I`m wrong

[BarnyardBill]

well, I am not sure.  All I know is that my wall warts do not read on my voltmeter.  I rigged up another one and it is working, but I get some muddy notes and even sounds like some lower octaves are sounding too.  Also, a very loud hum in the frequency of B.  Still working on it .

[kaalaraab]

Does anyone have any ideas about why I am not getting a distorted sound? Do I have the circuit wired wrong?

As I know, generally this project is a booster much more than an overdrive, and overdrive depends on several circumstances. For instance, when I first built mint, I was using an EH 12AT7, it sounded pretty harsh for me, so I changed to EH 12AU7, it was ok, with a light yet warm overdrive. I try a RCA Clear Top, no overdrive, but a really good and warm sound. On the other hand, check the gain pot, it could be not working well.

[BarnyardBill]

kaalaraab,

that is reassuring to hear that you seem to be getting the same results as me.  The only way I get any overdrive/distortion is by changing capacitors and it is not a distortion that I would ever want to use.  Anyway, I just heard some of the samples on youtube and a lot of them had distortion.  I guess they used an amp or pedal for that?  I personally prefer the warm boost and tone enhancement like you described.  I do have a LARGE amount of hum and noise from my wall wart, so I hope to be able to clean that up with one of the rectifier circuits around.  Do you think a rectifier circuit would be better than a 12V regulator? 

Thanks,

Bill 

[kaalaraab]

I guess they used an amp or pedal for that?

I've been trying with boosters and buffers in front of my valvecaster inside the same stompbox. By now, Omega, from runoffgroove.com is which I liked most, in gives a really nice boost That overdrives the valvy creating a warm distortion. I'm using a 3pdt switch to by pass it.

Do you think a rectifier circuit would be better than a 12V regulator? 

I have a very lousy wall wart that throws between 18 and 22 volts. With the regulator suggested by Renegadrian ( http://www.aronnelson.com/gallery/main.php/v/Renegadrian/regulator.gif.html ) I have no hum and any other problem with it.

[PaulBass]

OK, I built the valvecaster today and left out the tone pot.  I used a 12V wall wart for pin 5 and a 30V wall wart for the heaters pin 1 & 6.  Then I connected both of the wall warts ground to the ground on my breadboard.  It was giving me some really strange noises when I had the gain and volume up.  I mean if I turned the knobs on my guitar it making noises like a wave generator or something.  Then, I started smelling something burning and I think I may have blown both my wall warts.  Does that make any sense electronically.  I will have to find another wall wart and try again.  My room really smells like burnt electronics now.  (cough cough)

-Bill

instead of using 2 wallwarts you can use just one with a voltage divider to pin 5. It's pretty easy, it's just 2 resistors. you can use this calculator to get 12 volts from 30V http://www.raltron.com/cust/tools/voltage_divider.asp you connect pin 5 to where the 2 resistors meet. the other side of resistor 1 taps into +30V. the other side of resistor 2 connects to ground.

[zambo]

did you make sure both walwarts are dc, and also that they are tip negative? I ve seen a couple guys i built this pedal for plug in the wrong polarity adaptor and smoke the regulater on the dc jack. It smells.... The tubes usualy lived through it though.

[BarnyardBill]

I am still getting some really strange sounds from my valve caster.  With the 47nf caps that are suggested, I get a really loud buzzing.  Not a wall wart buzz, but a REALLY loud buzz.  So, i switched to 10nF and then it becomes usable, but I still get some LOUD buzzing when I turn the volume pot on my guitar.  COuld this be caused by loose breadboard parts?  I probably need to invest in those little alligator clips for this type of thing. Anyways, any help in appreciated.

zambo,

yeah I a pretty sure I had them oriented right.  Probably something I plugged in the wrong spot on the breadboard. 

thanks,

bill

[BarnyardBill]

instead of using 2 wallwarts you can use just one with a voltage divider to pin 5. It's pretty easy, it's just 2 resistors. you can use this calculator to get 12 volts from 30V http://www.raltron.com/cust/tools/voltage_divider.asp you connect pin 5 to where the 2 resistors meet. the other side of resistor 1 taps into +30V. the other side of resistor 2 connects to ground.

[/quote]

That's a good idea.  I have a 15V Toshiba wall wart that seems pretty descent and also puts out 3A.  I am gonna try this right now actaully.

[esdiezy28]

are your wall wart's regulated?

[BarnyardBill]

did you make sure both walwarts are dc, and also that they are tip negative? I ve seen a couple guys i built this pedal for plug in the wrong polarity adaptor and smoke the regulater on the dc jack. It smells.... The tubes usualy lived through it though.

Ok, I made the voltage divider and when I connect it to my circuit, the voltage on pin5 drops out?  Do I need to connect pin 4 and/or pin 8 to the voltage divider's ground?  I can't figure it out.


-Bill 

[PaulBass]

did you make sure both walwarts are dc, and also that they are tip negative? I ve seen a couple guys i built this pedal for plug in the wrong polarity adaptor and smoke the regulater on the dc jack. It smells.... The tubes usualy lived through it though.

Ok, I made the voltage divider and when I connect it to my circuit, the voltage on pin5 drops out?  Do I need to connect pin 4 and/or pin 8 to the voltage divider's ground?  I can't figure it out.


-Bill  

pins 4 & 8, the wallwart ground, and the voltage divider ground should all be connected to common ground. when you remove the tube pins 1 & 6 should read near 15V (or wallwart voltage) and pin 5 should be 12V. when you see that, you've got it. to check to see if the tube heater is fried you can check for resistance between pins 4, 5, and 9. If you see a low ohm reading the heater is still good.

[BarnyardBill]

i measured the ohms and got between 6 and 13 Ohms for the reading.  I might just have to order a few voltage regulators and sit tight for a while.  I think I have become obsessed with this.  Maybe I will go back to the fuzz pedal I made and then come back to this.  After all this is only my 2nd project.  Maybe I am expecting too much.  So far so good.  I think I am beginning to understand how the tube works.  Here are my learnings so far: Pin 1 and 6 should read the full voltage.  Pin 4 and 8 should be grounded.  Pin 5 is the heater and should be at 12V(9V) .  So, that leaves Pin 2, Pin 3, and Pin 7.  These pins usually have a reading around ~0.00.  Feel free to explain this relationship of the pins to me.  Is this acting as two triodes?     

[PaulBass]

i measured the ohms and got between 6 and 13 Ohms for the reading.  I might just have to order a few voltage regulators and sit tight for a while.  I think I have become obsessed with this.  Maybe I will go back to the fuzz pedal I made and then come back to this.  After all this is only my 2nd project.  Maybe I am expecting too much.  So far so good.  I think I am beginning to understand how the tube works.  Here are my learnings so far: Pin 1 and 6 should read the full voltage.  Pin 4 and 8 should be grounded.  Pin 5 is the heater and should be at 12V(9V) .  So, that leaves Pin 2, Pin 3, and Pin 7.  These pins usually have a reading around ~0.00.  Feel free to explain this relationship of the pins to me.  Is this acting as two triodes?     

the relationship of the pins is beyond my knowledge. I just make circuits from layouts. I found out when working with tubes I always have several on hand because some might be bad. I've purchased tubes and some of them didn't work, especially the ones off ebay. when 2 or 3 tubes don't work in the circuit it lets you know something in the circuit is not right.

[zambo]

@ Bill. Yes the tube is two triodes. Pin 1 is anode ( plate ) for triode one. Pin 2 is grid ( where the signal comes in. I consider it the input )  Pin 3 is the Cathode ( where all the juice flows to). The gain knob is a variable resistor between the cathode and ground. More resistance equals less juice getting to ground ( roughly ). 4 and 5 are heater. 6 is anode ( plate ) for second triode. 7 is the second grid ( where the signal goes in again ), 8 is the second cathode. Technicly you could put another gain knob here but it would only give you less gain in this instance. Grounded cathode is max gain. Pin 9 is heater ground when you are using 6.3 volt ac heater current. 6.3 ac goes to pins 4 and 5 9 being the grounded pin.
Current flows between anode and cathode. The screen is in between them. The guitar signal is an ac signal. It causes the plate voltage to fluctuate in time with the guitar ac grid signal. As the 9 volt plate voltage fluctuates it creates a bigger ac signal. The decoupling cap  ( the cap from pin 1 ) blocks dc signal but lets the now bigger ac signal through to the next grid where the same thing happens. The next decoupling cap ( off pin 6) keeps the dc from flowing on to the next thing in the chain. The size of the decoupling caps helps shape the amplified signal by limiting how much low end is re amplified. Every stage adds both highs and lows. Multiple stages require attenuation of the lows and highs or you get nasty feed back and oscilation. The input cap stops dc from flowing out the grid to your guitar. If the dc reaches your guitar tyou will have scratchy sounding volume pots. Hope this helps explain how this thing works. I dont know a lot about tubes and stuff but what i do know I learned from the smart guys on here. Good luck, G 

[BarnyardBill]

that helped, thanks a lot for the explanation.  I set up the valve-caster(no tone knob) circuit today and I had one strange thing happening.  The volume and gain knobs didn't work?  I am not sure why this happened.  I double checked my circuit and did't see any errors?  However, I was able to pick up a 7812 today, so that helped with the wall wart. Any ideas about why my pots aren't working?

Bill
 
Edit: never mind, I had some wrong connections.  Now I can try changing the coupling caps to make it sound better.  I guess different humbuckers can require different capacitor sizes?  thanks again.

[PaulBass]

I guess different humbuckers can require different capacitor sizes?  thanks again.

The .01uF input cap is too low for my tastes so I used a .22uF. If you want a fatter tone with more bass you can use a .047 or .1uF at the input. I used a .22uF because I play bass and guitar. since the signal goes through the caps the brand will influence the sound. orange drop caps sound great if you play a lot of rock. I prefer the sound of Mallory 150's and Nichicon polyester films

[BarnyardBill]

I used this layout on mine and I think the volume and gain knob are somehow reversed. It's tough to tell sometimes.  The cap values I like so far is 1pF for C1, 7pF for C2 and 68pF for C3.  This way I eliminate the scratchy static that comes through when I strum.  They are the ceramic caps from an assorted pack at radio shack.  I am assuming that if the numbers aren't 3 digits then they are in pF. Also, my tube is an RCA that is marked for "noise and micro-phonics". I still can't believe the amount of buzz that my wall wart is letting through.  

Do you ever get some really hissing noises when you change to different capacitors?  Sometimes if I have gain and volume all the way up, it makes such a bad hissing noise until I turn it down.  I am tempted to go back and try the tube circuit with only the volume knob.  It seemed to behave better for me.

Bill

[zambo]

i believe on those caps you have to look at the numbers as a code. The code will tell you what size they are. As far as hissing, Mine are pretty quiet. I use a .002 on the coupling caps a lot of times when running multiple valves in series. For a plain valvecaster I run .01 and .0047 for input and coupling caps. I never turn it all the way up as they sound bad to me that way. Volume at 3/4 and gain about the same is my fav. Picofard sized caps i think are to small for any good sound. Bigger caps like stock value sound awesome on single coils. thats my opinion what its worth