STM800 (BoobTube Twin)

[redbean]

Fantastic!!

I'd like to build something like that, and I have some old 12AT7s I'd like to use.

[dbharris]

more fenderish...dumble ODS based perhaps?

that would be way cool!

[juansolo]

Well I'll put everyone out of their misery. He's going to have a go at stomp boxing this:



Gonna leave out the eq... Saying that, we've got a couple of 5 band sliders kicking about from an old hi-fi that might work... Probably going a little far for a stomp mind you!

[alanp]

How much does the starved plate design affect the tone, and does it affect the operating lifetime of the valve?

(Does the word 'tube' make anyone else think of bicycle and car inner tubes in the tyres?

[juansolo]

Definitely effects it as it lowers headroom. Tonally though, plugged into my clean 6v6 amps return (just using the power stage and by-passing the pre), it makes it sound very Marshall. It's actually how it works best. If I didn't already use the loop for some other things, it'd become a permanent fixture there as it's got a handy loop bypass switch on the back. Maybe it's time to make a loop switcher box... *rubs chin*

We're at 60v on the plates vs around 300v in an amp. Heaters are running at the correct voltage so it's tough to say what valve life will be. In theory it should be longer. Who knows though.

The toob thing comes from our friends across the pond calling them vacuum tubes rather than thermionic valves (which sounds far sexier).

[Vallhagen]

This one is absolutely wonderful.

Very inspiring to enter a forum and see things like this!

Cheers!

[juansolo]

I take it back about it being better as a pre than a stomp... We found a mistake that we'd made with the power section meaning voltages were seriously down. Fixed it today and bloody hell it's impressive. I mean, without the grunt it was good, now it's properly ticking along with the power it should be, it's awesome. Very happy bunny.

[CarpathiART]

This is something else man.. great build!

[bigmufffuzzwizz]

So badass! You guys have done so much work on this project its incredible. One day I'd like to build one for myself. 

[karter2000]

I'd love to give this one a try, but I'm confused on how to wire the heaters.  Are both tubes still run at 6v?

[juansolo]

Yep, the heaters for both tubes run at 6v. Run the +6v feed from your regulator to pin 9 and run pins 4&5 to ground on each tube.

[wasteofspace]

I take it back about it being better as a pre than a stomp... We found a mistake that we'd made with the power section meaning voltages were seriously down. Fixed it today and bloody hell it's impressive. I mean, without the grunt it was good, now it's properly ticking along with the power it should be, it's awesome. Very happy bunny.

What a great effort!

Did fixing this error change the schematic in any way?

[juansolo]

Nah, it was me trying to tap into the charge pump halfway through using the newer one that doesn't like that at all. Schematic is all as was and I changed the power veros to cover my mistake

[dmac]

I know this one was put to bed long ago, but if I wanted to slip a brightness switch into this, where would be a good place to put it? (I'll muck around with values)

[juansolo]

In the amp the presence control in the power section deals with it. We added the two 10ks and 2n2s at the end to tame it a little in ours so you might want to mess with those.