Tube boost + overdrive running off a 9 volt battery

[Renegadrian]

Been there already...I am sure you won't miss it...All my valvies are toneless...
Else you should breadboard a more functional tone control and try it out...but the stock one just sucks!

[frequencycentral]

There's a new dual 12au7 design for bass over at Tube Town: http://www.tube-town.net/diy/lov/lov04-sugar_box.html German language only ATM, but an English version should be out soon. Nice looking PCB.

[Renegadrian]

thx Rick for the suggestion...
Basically it says that it came from some ideas in their forum - that yes it features 2 12AU7 tubes but is rather simple design, and you can have a good bass system coupling it with a chip power amp...and that as other low voltage tube projects, a good power supply is reccomended (they also sell a dedicated power supply)

gotta study this circuit...


As I am writing this, I want to share my experience with my Valvy (my fist one, toneless, 12AU7, with 7812/100µF)
I use it with my bass, so happy with it...but at the end of our weekly reharsal, the last 30 minutes, it becomes dirty and unstable with some hum added...Maybe someone experienced the same problem?!

[frequencycentral]

Tried a different tube? Maybe it needs replacing. Was it new or was it NOS?

[Renegadrian]

It has a EH tube, bought new as I began building it (so 1 and ½ year ago) - I have to try another tube, that one never satisfied me...

[frequencycentral]

Maybe test the voltages too then. And reflow the joints. I bet your soldering has improved in 1 1/2 years!

[Renegadrian]

Yeah I have to give my baby some attentions and care...I'll report if anything goes wrong/strange...

[kurtlives]

Renegadrian how is the regulator heat sunk, if it is at all?

It could be possible it is overheating and failing. Then you would be using some form of "dirty" voltage I would think. That would defiantly cause hum, as we all know very well.

[Renegadrian]

The flat side of the 7812 lays onto the inside of the enclosure, so the enclosure itself should act like an heatsink?!
I was thinking the same, maybe the 7812 works flawlessly until it gets overheated?! I'd have to touch it to feel its temperature...

[kurtlives]

Bolt it to the enclosure.

[silentmike]

Hi, I'm building a valvecaster with a sparkle boost inside it, but I'm having some problems with the switching... (decided to got for something adventurous for my first build!) I've got a 3PDT for the main on/off which I believe is wired in right for true bypass and the rest, and I've got a 4PDT to change between valvy or sparkle boost + valvy. My LEDs light up and the valve gets warm, but I think I was misinformed by my guitarist when he drew me a wiring diagram. Anyone know how to go about doing this? Also, the pedal won't work with my power supply, only batteries. Any ideas there as well?

[Ripthorn]

First, you don't need a 4PDT,  you could do it with a DPDT.  Also, what do you mean by doesn't work with power supply?  Did you wire it for center negative?  Also, if you could post a drawing of the wiring diagram, we would be happy to take a look at it and see what we can find.

Also, what is the rating of your power supply?  If there isn't enough current supplied it won't work.

[silentmike]

Right, sorry I didn't know what you guys needed to have. My guitarist thought I needed the 4PDT switch...   

Here's the diagram I've worked off:



When I say it doesn't work with the power supply it literally does nothing. It'll light up when connected to a battery but as soon as it gets connected to the power supply it doesn't do a thing. The supply is a regulated 9V one with center negative. The socket is wired in right (I've modded my big muff to have one and that works fine with the same supply).

[silentmike]

Right, I think I'm going to blame some of this on my guitarist's unverified vero layout and just build the valvecaster on the back of the socket as I had intended to do anyway! Does anyone know of a vero layout for the sparkle boost or am I asking in the wrong place?

Cheers!
Mike

[Renegadrian]

just a quick search in the gallery and you'll find what you need...

[silentmike]

Aha! Found it! Thank you very much. Now to take it all apart...

[bassmannate]

Ok, I just got an absolutely INSANE idea for a valvy. Please be prompt to shoot me down if this is the dumbest thing you've ever heard of.

What if we were to replace the 1/4" jack out with an XLR and turn it into a phantom powered direct box? it would give us +48v to play with and we wouldn't need a power supply if we were going into a house sound board.

What would be involved in bringing the valvy up to line levels to go direct into a board? Does phantom power provide enough current to power the valvy?

[Ripthorn]

There is no possible way to get enough current out of phantom power if you are trying to run the heaters off of it.  If you were to run just the plates, sure, there's enough juice for it.  I think you would have some issues with impedance matching, plus you wouldn't get the benefit of a balanced signal unless you put in a transformer.  So in short, could do it, not without a separate power supply, but could (means a transformer and some other things).  Worth it?  In my opinion, no.

[bassmannate]

Ok. I figured that phantom power wouldn't supply enough current for the heaters. Just out of curiosity, what is typically the max. current of most phantom power systems?

[Aren]

14mA. Not much