Tube boost + overdrive running off a 9 volt battery

[Barrington]

I just tried building pedal using this layout http://s47.photobucket.com/albums/f191/krinor/?action=view&current=Valvecasternylayoutmkabler.jpg

Im having trouble, its not working so I got my multimeter out and noticed that everything after the footswitch has a negative voltage, for example pin 5 on the valve socket has a heater voltage of -5v.  What is the problem? Is something wired back to front?

[Renegadrian]

Hello and welcome!
Krinor layout shows that pin 5 is connected to 12V and pin 4 is ground, so 0V.
check the power supply and its wiring!!!

[Freekmagnet]

Hi Fellows,

I've decided to start up a parts list for my first Valvecaster. I've tried my best to skim through this insanely large thread for some of this info, but I realized it might be easier to just ask.

I want to build a no-tone Valvecaster for bass guitar. I'm not looking for a ton of gain, and I'm not looking to color the tone too much. I just want a little wooliness to move a little more air through my solid state rig.

My question is, where should I start with voicing it for bass? I'm assuming I should socket the input and output caps and try experimenting with .1uf cap up front and then go from there.

Any other suggestions?

Thanks!

[Renegadrian]

I used mine with bass, it's stock and I like the sound it gives out, more "air" but stays quite neutral.
You can find some layouts and parts lists in my gallery.

[sundgist]

So, this weekend I summoned up the courage to start reading through this thread from start to finish. Thanks to everyone who has contributed to this great little project.
Below are my results. Not yet boxed as I'm too busy playing.






Trimmers are used for the plate resitors and everything else is socketed to play around with different values.
Valve is 12at7, running on 21v. Tried with 12ax7, some good sounds in there but found 12at7 more usable.
I've used 100k for the Gain pot for a good helping of dirt.
R1 = 470k
R2 = trimmer at 100k 'ish
R3 = trimmer at 100k 'ish
R4 = 220k
C1 = 33nF
C2 = 22nF
C3 = 1uF

Here is the perf layout I made (my first) to enable the valve to sit within the enclosure but viewable through a cutout between the knobs. Could be better laid out but was changed a few times during building.



and a vero layout for the 12.6v Heater regulator.



Added orange led eye candy, not shown on layout.

Sound goes from clean boost (which can be driven harder with a clean booster or tube screamer type thing) through to Overdrive (which when driven harder gives a nice fuzzy compression).
I've been using this with a very ordinary clean solid state amp and it makes it sound quite impressive. I'm quite enjoying myself with this.

[pleiades]

It appears that I am late to the party.

I've worked with a lot of solid state electronics before, but have yet to do anything with tubes.  I've decided to dive in head first, reading as much as possible, and I think I'm ready to start my first build.  I've worked up a simple design: three cascading valvecasters with separate gain controls, master volume, and a plate voltage variable from 9-12V (using an adjustable voltage regulator) and a fixed heater voltage of 12V.  I plan to power it with an 18V 1A dunlop wart.

Schematic:


Thoughts?  Right now I'm on a (very lengthy) TAD away from my usual tools, but I should be able to scrounge up a cheap soldering iron to fabricate an enclosure-less circuit. 

[kylegood]

hey everyone,
i'm new around these parts, i have built a number of amps from scratch, i have never built a pedal though. i'm also quite terrible at reading schematics..... and wiring switches is the worst.
i have seen all the layouts for this pedal using a 3pdt switch for the led and bypass, but has anyone acheived this with a dpdt? and is there a layout for this aroud here? the reason i ask is that i have all the parts around here to build a few of these pedals to muck around with, but i only have dpdt switches left over from some other projects and dont want to go out and buy more stuff if i dont need to.

layout anyone?

thanks in advance.

[Renegadrian]

i have seen all the layouts for this pedal using a 3pdt switch for the led and bypass, but has anyone acheived this with a dpdt? and is there a layout for this aroud here? the reason i ask is that i have all the parts around here to build a few of these pedals to muck around with, but i only have dpdt switches left over from some other projects and dont want to go out and buy more stuff if i dont need to.

layout anyone?

thanks in advance.

Hi there and welcome aboard!
Actually, the use of 3pdt or dpdt is common to all pedals, I use dpdt in valvies but in all the other pedal as well, it's not something related to a specific circuit but a common way to wire things up (so the method I use is applied to all pedals).
A lot of layouts are available, just go the the gallery and search for them, or other sites like geofex...

[kylegood]

alright im back for some help now.....
i have built the pedal, its running sort of.... i have checked and double check and rewired.... and built a whole new pedal from new parts twice with the same result..
i have a lot of hum... and muddy muddy bass. i gan here the tube faintly through the bass and hum... but its just bass..
does anyone have any suggestions?? do the back of the pots need to be grounded??? i'm spent hours de bugging.... with no luck... the bypass and led and everything for that matter are functioning properly... but i just cant figure it out.

i used krinors layout as posted at the top of this page.

so my only two thoughts are the 1uf caps polarity is incorrect, or the back of the pots need to be grounded. or both

anyone have any suggestions?
thanks in advance.

[Renegadrian]

So you have the 3 knobs version?! Guess you should check the tone pot wiring then.

[jaki54321]

alright im back for some help now.....
i have built the pedal, its running sort of.... i have checked and double check and rewired.... and built a whole new pedal from new parts twice with the same result..
i have a lot of hum... and muddy muddy bass. i gan here the tube faintly through the bass and hum... but its just bass..
does anyone have any suggestions?? do the back of the pots need to be grounded??? i'm spent hours de bugging.... with no luck... the bypass and led and everything for that matter are functioning properly... but i just cant figure it out.

i used krinors layout as posted at the top of this page.

so my only two thoughts are the 1uf caps polarity is incorrect, or the back of the pots need to be grounded. or both

anyone have any suggestions?
thanks in advance.

I build using that layout too.

Are you running at 9 or 12 volts? Are you using a DC wall jack(wall wart)? If so the hum could be coming from the wall wart being "Unregulated" which means it could be sending in hum from your AC jack. The best thing you can do to kill the hum is to regulate the power. Ill explain here in a sec...

To kill the muddyness i HIGHLY recommend running at 12 volts, it REALLY makes the sound MUCH better, jus 3 more volts makes it ALOT better. And if the sound is too bassy for you, you can change one of the capacitors(C1) to a lower value, maybe .022uF, that will lower the bass to a nice level. If you want, you can increase the gain of the pedal by adding a higher value potentiometer. Change it from B50K to idk, maybe even A1M! 1M audio. That will really up the gain, but it may be too much for your liking, so you can always experiment if u have the money for more pots an stuff. P.S. if ur on a budget do NOT go to radioshack...

As for the hum. You can try this: buy a 7812 Voltage regulator, they are pretty small, an u can get them from radioshack for pretty cheap(but way cheaper online, try Mouser.com), and a 1000uF Capacitor(Electrolytic). I have a diagram from our friend Renegadrian that shows you how to do this, i can post it here for you(With his kind permission of course) and it will show you how to do this. Its pretty simple. Then after you put that in, run the pedal at 18 Volt(if u cant, atleast make it higher then 12 volts.) and play! You will notice a HUGE difference i guarantee it. I just installed my regulator a few days ago an i dont know why i didnt when i first built this pedal xD

If you wana try the regulator, let me know an i will be here to asssit you as best as i can 

[Renegadrian]

This layout is in my gallery, so it's there for everyone to use - no permissions needed.

[jaki54321]

This layout is in my gallery, so it's there for everyone to use - no permissions needed.[/img]

Ya thats it. That should show you how to do it. If u need some help we are here 

[kylegood]

i have got it running. and it sounds amazing.... the 12volts really helped.
question... how terrible would it be to run this on 18 volts?

[frequencycentral]

If you want, you can increase the gain of the pedal by adding a higher value potentiometer. Change it from B50K to idk, maybe even A1M! 1M audio.

That won't increase the gain. Rather it will make for a cleaner boost. 1M is far too high though. 100k would be fine. But neither will increase the gain. Though a cathode bypass cap might.

[kylegood]

the gain it has is great, i'm not worried about that... just for kicks i ran it on 18 volts, and it seemed that it was alot clearer... more defined maybe is the words..... i just want to know if its safe...

[Renegadrian]

Keep in mind that the heaters must always receive 12V. You can go from 12 to 300+ at the plates (pins 1 and 6) but the heaters run always at 12V. Running them at higher voltages will lead to permanent damage of the tube itself.

[jaki54321]

the gain it has is great, i'm not worried about that... just for kicks i ran it on 18 volts, and it seemed that it was alot clearer... more defined maybe is the words..... i just want to know if its safe...

if you have a 7812 volt regulator installed, running at 18 volts will be perfectly safe. If you run at 18 with the 7812 regulator, it will drop the voltage down to 12 volts, which will allow you to run at 18 volts. I personally recommend 18 ONLY if you have that regulator and the capacitor installed. However that 7812 regulator may get pretty hot. I mounted mine on the side of my enclosure which seems to keep it cooler. You can also put a heat sink on it

[jaki54321]

If you want, you can increase the gain of the pedal by adding a higher value potentiometer. Change it from B50K to idk, maybe even A1M! 1M audio.

That won't increase the gain. Rather it will make for a cleaner boost. 1M is far too high though. 100k would be fine. But neither will increase the gain. Though a cathode bypass cap might.

Really? I always heard it will up the gain... hmm... maybe ill give the 100K pot a try. is it worth it?

[frequencycentral]

If you want, you can increase the gain of the pedal by adding a higher value potentiometer. Change it from B50K to idk, maybe even A1M! 1M audio.

That won't increase the gain. Rather it will make for a cleaner boost. 1M is far too high though. 100k would be fine. But neither will increase the gain. Though a cathode bypass cap might.

Really? I always heard it will up the gain... hmm... maybe ill give the 100K pot a try. is it worth it?

http://www.diystompboxes.com/pedals/tubedummy.html

"The cathode resistor along with the Plate resistor control the gain of the tube stage. Typical values are anywhere from 100 ohms to 10K. Smaller values = more gain."

A 100k gain pot will allow for cleaner boost, well worth it.