I've not covered many Vox sounding pedals on the blog so I thought I'd stick one up - the HipKitty Oxblood Distortion. It's supposed to be able to turn your huge full stack into a little boxy Vox AC15! Right-o..
Here's the description from the HipKitty website;
"The Oxblood Distortion was designed to emulate the tone and response of an old Vox AC15 with added gain at the input stage. Unlike other Vox-like pedals which emulate the tone and response of the Vox AC30, only the Oxblood Distortion emulates a boosted AC15.
Unique to the Oxblood Distortion is it's ability to make a "large" amp sound "small" and in hyper-drive with the tone of the AC15.
Also unique to the Oxblood Distortion is it's controlled output. While other distortion pedals use greater than unity gain at output to alter the user's amplifier input stages, the Oxblood Distortion does not. This keeps the true tone and response of the effect intact throughout the initial preamp stage of the amplifier in use."
And a demo video of the Oxblood Distortion in action;
It is quite an interesting tone - very boxy, it really does seem to make an amp sound smaller! Here's the schematic, it's yet another one of WhiteKeyHole's;
So, it's not a complex circuit - broken down it's a buffered silicon fuzz face with a treble cut control. The first transistor stage is a simple emitter follower, the second and third transistor stages make up the fuzz face with the treble cut control tacked on the end - that's it! The 10k trim pot is used to bias the fuzz face correctly, you can use it to dial in the sort of overdrive you're looking for - anything from around 4v to 7v on the collector of Q3 sounds decent. So why does it make the amp sound small? It's due to those small coupling capacitors - they cut the bass content down and really accentuate the middle and treble frequencies this gives that "boxy" tone.
So if you want to build one up here's a vero layout for you;
Finally here's the freestompboxes.org forum topic for reference; http://freestompboxes.org/viewtopic.php?f=7&t=4270