Tube boost + overdrive running off a 9 volt battery

[VintageVenzi]

Hi,

Welcome to the forum!

I would like to point out that cross posting / duplicating posting is frowned upon here. Also when you start a new thread please use a descriptive subject title. "Newbie needs help!" is not appropriate.

I hope you enjoy our community. Good luck.

Andrew

Thank you and sorry about the cross posting won't happen again I promise

Thanks man! yep I'm a bass player and I did use the Valvy on bass with good results...it boosts in a good way, without being "too much" - that in the stock version, but with no tone control.

Well that sounds good for me but do you mean with "boost" also overdrive and do you mean with stock version this http://www.beavisaudio.com/projects/ValveCaster/MatsuminValveCaster.gif ?
P.S. Where should be the footswitch in the plan?

[nbabmf]

I built a stock Valvecaster per the Beavis schematic.  I can see how it would sound great for bass but had too much low end for guitar... it made even my Tele sound muddy even with the tone knob dimed!  I brought down the input cap to .018uF and that helped some.  I then knocked down the coupling cap to .018uF, but I couldn't tell much difference... I think my ears were tired by that point. 

I have a little extra wiggle room in the enclosure... what's the difference between the Valvecaster and the ValveMASTER?

[Jdansti]

>P.S. Where should be the footswitch in the plan?

Most effects schematics don't show the bypass switch and LED indicator. Here's how you do it:
http://www.generalguitargadgets.com/diagrams/switch_lo_3pdt_ig_dcjack.gif?phpMyAdmin=78482479fd7e7fc3768044a841b3e85a

[Squirrels]

New member, just finished my first Valvecaster and love it... except for the noise. I picked up a 7812 regulator today by mistake, I needed a 7809 since I'm running 9 volts. Can I still use the 7812 or do I need a 7809?

[Jdansti]

New member, just finished my first Valvecaster and love it... except for the noise. I picked up a 7812 regulator today by mistake, I needed a 7809 since I'm running 9 volts. Can I still use the 7812 or do I need a 7809?

I run mine on 12V with no problem, but make sure the heaters are connected in series (12V across pins 4 and 5 and no connection to pin 9).

[Mustachio]

The voltage regulator you have, the 7812 needs a minimum of 14 volts I believe. check the data sheets. Your gonna want 12 volts for the heaters and the rest can run higher. So I suggest keeping the 7812 for the heaters and get yourself a power supply that can put out more then 12volts. I think the 7812 max is around 30 volts and min 14volts.

[Jdansti]

The voltage regulator you have, the 7812 needs a minimum of 14 volts I believe. check the data sheets. Your gonna want 12 volts for the heaters and the rest can run higher. So I suggest keeping the 7812 for the heaters and get yourself a power supply that can put out more then 12volts. I think the 7812 max is around 30 volts and min 14volts.

Good point. I should have mentioned that I'm using a 24VAC wall wart. I rectify to DC and regulate in my Valvecaster enclosure.

[Squirrels]

I'm really new to electronics so I'm unsure what that all means right now. I guess I'll get a 7809 tomorrow in the meantime. I've still got quite a bit to learn... and only a 9V power supply. Thanks.

[Mustachio]

a 7809 needs a minimum of 11 or 12 volts so if you only have a 9 volt power supply its still not gonna work.

Don't forget to look at the output of the wall warts amps or miliamps ma. 12ax7 and the others that are alike pull about 300ma or so. I think the 12Bh7 pulls a lil more amps. If your walwart cant supply enough amps or its just on the edge you may get some hum/noise from it as well.

Your really better off picking up a 12 or 18 v 1amp wall wart from ebay for 10 bucks or less. If you get a 12v adapter then dont use a regulator because you need at least 12 on the heaters. If your using 14v or more then use the 7812. You really dont need a 7809.

I believe if you feed the heaters only 9v it will possibly not sound good and shorten the life of the tubes. I know this is a big thread but all the answers are in it. You might want to check out the voltage multipliers for the plates since stock this is starved plate.

[Jdansti]

I'm really new to electronics so I'm unsure what that all means right now. I guess I'll get a 7809 tomorrow in the meantime. I've still got quite a bit to learn... and only a 9V power supply. Thanks.

One thing you should know about using 78xx regulators is that the input voltage (Vi) has to be at least 1.5V greater than the output voltage (Vo).  If you only have a 9V supply and you try to use a 7809, you'll be disappointed.  Ain't gonna work.

Before you spend money on certain parts, you need to refer to data sheets to understand  what the requirements are for the thing to operate properly.  You don't have to look up every 1/4 watt resistor, but semiconductors such as transistors, and integrated circuits are more complex.  If you don't understand the data sheet or if you have a question that's not covered on the data sheet, then the forum is here to help you.

Here's the data sheet for the LM7812 (and other 78xx regulators): http://www.fairchildsemi.com/ds/LM/LM7805.pdf



The 7812 data sheet says that a Vi of 14V-27V and a current draw between 5 mA and 1A will yield a Vo of 11.4V to 12.6V, with the typical being 12V.

I'm sure we can help you find an option that will work-hopefully low cost (for example, if you could get a used laptop PS at a thrift store that puts out around 18V and 2-4A, it wouldn't cost much to get you to 12VDC).  There's a lot of great help here on the forum, and we all want to see you succeed! 

[Squirrels]

So I'd have to use an 18v wall wart to use the 12v regulator? Sounds simple enough. Regarding the heaters, I used the layout from this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=99239.0

It worked well besides the noise and blowing an LED since I didn't use a resistor at first. What would I have to change to run at 12v? Also will a 500k or 1meg gain pot increase the overall drive?  I'm used to having a TS9 in front of my Dark Terror to push my high gain sound a little more, right now the VC doesn't cut it.  With my Strat with a DiMarzio Injector bridge it works fairly well but in my PRS with Dragon II's it doesn't do much... and adds a lot of noise. With lower gain it sounds great.

Thanks for the data sheet for the regulator. I'll read it more tomorrow. After I label it, I'll post a few shots.

One more question, I'm using a "Fender Style" socket with what I'm guessing is another pin in the center. Is that a ground and can it be removed to fit an LED under the tube to light it up?

[Mustachio]

I think in this thread there's info on increasing gain. I don't remember if it was changing a resistor to the plates or if it was just a larger gain pot. If you read this entire thread by the time you get done you will more then likely have a much better grasp on electronics then when you started. This thread is chalked full of goodness.

The center lug in the tube socket Is not grounded. It holds the tube socket together actually, and if you remove it the socket will come apart. If you remove it just be careful, if it separates you can get it back together with the pins correct and put a lil super glue in maybe. I used large shrink wrap on a tube socket once held it together well. Also try a 3mm led they fit much better in the hole might get away with not removing the metal plug or tabbed insert.

3mm orange high bright looks nice

[Jdansti]

>So I'd have to use an 18v wall wart to use the 12v regulator? Sounds simple enough. Regarding the heaters, I used the layout from this thread:

http://www.diystompboxes.com/smfforum/index.php?topic=99239.0

You need something between 14 and 30ish V.  I just mentioned 18V because that's about what many laptop supplies put out (a quick check of a website selling these listed models between 12VDC and 19.5VDC).

Regarding heater voltage, if you look at pins 4 and 5 on the schematic you referenced, you'll notice that 4 is connected to ground, pin 5 is connected to the + side of the power jack, and pin 9 is not connected, so that means that voltage will flow through both heaters in series.  Good for a 12V supply.

Here's a more detailed view of a 12AU7 tube.



If you follow the lead from pin 4, you'll see it goes through the left heater at the bottom, then past a center tap lead connected to pin 9, then through a second heater, then to pin 5.

Each of the two heaters has a max voltage rating of 6V.  So if your heater supply is 6V, you could put +6V on pin 4 , +6V on pin 5, and connect pin 9 to ground.  

But if you heater power is 12V, you could put +12V on pin 4 and connect pin 5 to ground and vice versa. Since the two heaters share 12V, the voltage drop across each is 6V.   Make sense?

Regarding VC gain, it's not a high gain circuit, so you're only going to get so much distortion from it. You have a few options. One is to cheat and use simple diode clipping on the output. Hardcore toobies would not do this, but if you like the sound, go for it.  Here's a great write up on the subject with some example circuits: http://www.muzique.com/lab/sat.htm

If you want to stay all toob, check out the dual caster: http://www.diystompboxes.com/smfforum/index.php?topic=89561.0. There's also a Triplecaster somewhere on the forum.

A third option is to try a different tube such as the 12AT7. There is some anecdotal opinion that the 12AT7 has higher gain. The 12AX7 does have higher gain, but most people don't like the sound.

Edit: Removed my nonsensical comment about heater current.  

[Ark Angel HFB]

I could be wrong... but regarding the above post... I'm pretty sure that the heaters take 300ma at 6+ and only 150ma at 12+.

I could be wrong but go read back through the first few pages of the thread and I think that is gone over...

[Jdansti]

I could be wrong... but regarding the above post... I'm pretty sure that the heaters take 300ma at 6+ and only 150ma at 12+.

I could be wrong but go read back through the first few pages of the thread and I think that is gone over...

Thank you!!!  That's what happens when I rely on my memory and don't use Ohm's law or look at the data sheet!

I'll correct my earlier post.

[Squirrels]

That makes sense. I just need to learn to do it. I'll be ordering new tubes for my amp soon (hopefully) so I'll try out to 12AT7 and 12AX7 in the VC. I'm using an orange 3mm as the indicator light so I'll try to pop that under the socket and add a 5mm as the indicator. The 3mm is too small anyway. A bigger one would look better.

[Squirrels]

Will the way I have it wired now handle 12v? I have an 18v wall wart from a Dust Buster I can use until I have a chance to get a dedicated one for my VC. I have to double check it'll fit first. I figure I can put the regulator and cap in and try it out for awhile.

[Ark Angel HFB]

it should be fine... but thing to consider...

Make sure the power pin is tip negative and sleeve positive...

Also the heaters will like 12v not 18v... so you could test it but I don't think it be good for teh tube to keep it that way for very long...

I'd go with an http://www.taydaelectronics.com/ic-integrated-circuits/voltage-regulators/l7912cv-lm7912-l7912-7912-voltage-regulator-ic-12v-1-5a.html for the + that is going to the heaters and the rest is up to you dude... ^_^.

This was the first circuit I ever built... and it is very VERY forgiving... mess with everything it is a lot of fun to try stuff... I suggest keeping a record of things you try out.

[Squirrels]

I have a 7812 and cap I'm going to put in tonight to try with the 18v wall wart. I'm also looking to add a bright switch.  I think that would definitely help with a humbucker.

[Jdansti]

I'd go with an http://www.taydaelectronics.com/ic-integrated-circuits/voltage-regulators/l7912cv-lm7912-l7912-7912-voltage-regulator-ic-12v-1-5a.html for the + that is going to the heaters and the rest is up to you dude... ^_^.

7912 or 7812?