New ... I have no idea what ... day

[Frank]

This is what happens when I'm sat round bored and I find a spare unloved valve lying round in the spares box. It's a 12 Volt powered ECC82 preamp with gain, tone and master volume. Doesn't get really distorted at all but it sounds lovely as a bass preamp. And it hums a bit but don't we all.

[Toe-Knee]

I love it.

Did you just mash stuff together and have a happy accident? Or did you plan ahead?

[Frank]

I started out planning to make the Valvecaster box but I took one look at the schematic and decided I hated it. So this is pretty standard stuff, two identical gain stages with a gain knob inbetween and a master vol and tone at the end. I may even try to squeeze a voltage regulator in there too. Or I might give it to my brother, it's his birthday on saturday. That's less effort, I'll do that.

[Toe-Knee]

I started out planning to make the Valvecaster box but I took one look at the schematic and decided I hated it. So this is pretty standard stuff, two identical gain stages with a gain knob inbetween and a master vol and tone at the end. I may even try to squeeze a voltage regulator in there too. Or I might give it to my brother, it's his birthday on saturday. That's less effort, I'll do that.

:D See if you can stop it humming first!

[Frank]

Yeah, I'll bung a big cap across the "high" tension :) Although the hum's not too bad and he's not a really serious muso, he probably won't even notice it.

Incidentally, it's fun to build low-voltage tube stuff, especially when your realise you can mess around with the plate circuit while it's powered up! Plus the caps are ridiculously cheap and the power supply is ready-made as long as you have a spare wall wart PSU from some discarded bit of electronic gear.

[juansolo]

I started out planning to make the Valvecaster box but I took one look at the schematic and decided I hated it. So this is pretty standard stuff, two identical gain stages with a gain knob inbetween and a master vol and tone at the end. I may even try to squeeze a voltage regulator in there too. Or I might give it to my brother, it's his birthday on saturday. That's less effort, I'll do that.

Something like this then (valve is a 12AU7A for this one):



That runs from a 9v PSU with some charge pumpery.

As does this:


...and this:



I like messing with tube effects

http://juansolo.demon.co.uk/stompage/toob.html

[Frank]

It's pretty similar to the "Boob tube" then but without the charge pump, may try that next time I get bored. Plus I added grid stoppers. It did a fair job of picking up radio coverage of a football match without them.

[Frank]

Just looking at the twin version, isn't that just a Marshall preamp running on low voltage?

[juansolo]

Just looking at the twin version, isn't that just a Marshall preamp running on low voltage?

It is indeed ;)

[juansolo]

It's pretty similar to the "Boob tube" then but without the charge pump, may try that next time I get bored. Plus I added grid stoppers. It did a fair job of picking up radio coverage of a football match without them.

We found ours didn't need it and adding it pulled too much out of the signal. Baby and Twin has them though.

[Frank]

Big fat capacitor across the power and we're good to go. That was a cheap but somewhat time-consuming birthday present. Probably buy him socks next year.