Building Valve Pedals
BoobTubes - How we did them

BoobTube

This is essentially a Valvecaster that has a proper gain control between stages instead of messing with the bias, and it runs on a lot more voltage. With some cap changes it is brighter and tighter in comparison. It's more of a smooth treble boost. Putting it on the front of my 5w single channel amp gets me AC/DC sort of tones.

By far the easiest way to build this effect is to get a Valvetizer kit from TH Custom. Which is a modded Boobtube. Otherwise, if you want to do it the full DIY way, the first thing you'll need is power.

Below is a layout that covers all your power needs for running this and the Baby Boobtube. You put 9v in and you get out a regulated 6.2v (or there abouts) and a charge pumped 60v. The high current heaters run from the 6v feed and the high voltage plates run on the 60v feed.

Make sure your caps are rated for more than 60v. Also it's also very tight so the parts will need to be very small.

Then it's simply a case of building the following. It's entirely possible to do this point to point. How you build the effect will determine how noisy it is. I'd advise connecting as much as possible to the back of the valve socket itself. The more wires in this, the noisier it gets.

Where it says 40v, it's your plate feed (we used a different supply originally). The tube we favour for this is the RCA 12AU7A cleartop. It just has the best balance of tone and current draw we've tried (and we've tried a lot!).

Baby BoobTube

This is another, more simple valve OD, with a very different flavour to the BoobTube. It's a pentode rather than a triode for a start, so just a single stage and it's based on the first section of a Vox AC30 amp. It's a much thicker, full range boost in comparison to the BoobTube. Power once again comes from the same Renegadrian Voltage Multiplier layout.

The above schematic is specifically for the 6BR7 valve, which is a anti-microphonic EF86. The pin-outs are different so don't put an EF86 in there, it needs to specifically be a 6BR7.

Again the same principles apply when it comes to keeping the noise down, keep the components as close to the socket as possible. If you're feeling particularly adventurous, you can actually get them all on there and they'll fit through the hole in the enclosure:

Though it's not really necessary to go that far ;)

BoobTube Twin V2

A lot of people ask me about building this one as their first valve effect. My response usually is don't. The reason being that it's stepping into valve pedals at the deep end. Someone also mentioned that it was incredibly loud. Yup, it will be, you're essentially strapping another three stages on the front of your pre-amp (the Baby and the BoobTube are one and two stages respectively).

With that out of the way, the V2 version of the Twin is a beast and in my opinion, one of the best sounding of the lot. It is, more or less, a JCM800 pre-amp. Though it has a few tone tweaks here and there to compensate for the lack of presence control, which is located in the power amp section normally.

Now this is where I have to cover my arse. You're playing with proper voltages with this one. If you're not confident DON'T build this. The power supply is another fettled Renegradrian layout. Again to give all the power you need and to use a bigger inductor.

Don't go over 190V as it becomes a little unstable, and bear in mind that the two 47uF filter caps that follow it will need to be able to handle the voltage.

Pay particular attention to the yellow link under the board. I did it like this just to keep it as small as possible. Put that in first and continuity check it all before carrying on. You will need two heatsinks for this supply also.

The parts are non-negotiable on this PSU. It'll not work if you sub in a different diode for the UF4004 for example. Stick to it, it's tried and tested.

A note on heat. The Fet will get warm (around 85F) and the regulator will get properly hot (130F). Both need heatsinks on them. The reg you could bolt to the case, the Fet you must not as it's live.

At this point you should know what you're doing. This one works really well built on tagboard. Valves want to be 12AX7. Enjoy!

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Big Baby

The Big Baby is a progression of the BabyBoobTube. Given the amount of poke the BBT had, but the lack of control, we've added a gain control on the front and a Baxandall tone stack on the back. There is a hifi style input buffer utilising one half of the triode, the other is a second buffer between the pentode and the tonestack. This is much more of a pure valve OD than the BoobTubeTwin which is more of an amp-sim when used as an effects pedal.

Powered again by the 555SMPSv2, this isn't for the beginner.

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