Emma - ReezaFRATzitz

Well, well, well. I just built this thing up. What a suprise - I loved it, which is a suprise seeing as I loath the sound of the "Tube Sound Fuzz" that this circuit seems to have taken it's inspiration from. I really love the Bias control and the tone control is very effective too. It's a much better distortion (In my opinion) than, say, a Rat. Pretty dynamic and cleans up well with the guitar volume pot. A nice find, I've recently started exploring CMOS technology with a view to developing my own distortion! I knew that invertors *could* be used to create a nice distortion as inside those little CMOS invertor blocks there are MOSFETs, and we all know how nice they are :-) Check the CD4069 datasheet here: http://www.datasheetcatalog.org/datasheets/90/206781_DS.pdf

Here's a demo video for the Reezafratzitz;

Anyhow, here is the Marketing blurb from the Emma website:

"Just when you thought you had seen the strangest name for a stompbox, EMMA offers up the Reezafratzitz! Like it's unconventional handle, the RF-1 is a unique type of OD/Distortion unit that stands out in an extremely crowded playing field. The RF-1 offers incredibly rich, full-bodied crunch that is so close to tube-amp overdrive that you''d be hard pressed to choose which was which. The secret to the RF-1's amazing tone lies in it's Bias control. This knob allows the user to morph between Class B and Class A biasing, altering the harmonic structure of the signal and providing a much wider variety of tonal options than your standard distortion. In Class B mode, the RF-1 exhibits a thick, chunky grind similar to a Marshall or Fender amp. Class A mode provides sweet, singing saturation worthy of the finest Vox AC30. Additional controls for Level, Gain, and a Hi Boost/Hi Cut Tone circuit allow the user to fine tune the RF-1 to taste. When you're ready to set trends rather than follow them, the Reezafratzitz will provide the audio inspiration you need to set yourself apart!"

Here is a project put together by thn.technik;

You'll notice this project has a "Bass/mids" mod performed on it, this slight alteration adds a lot of new tones to the pedal and is well worth doing. 

I must say a huge thanks to all those involved - you know who you are! For more info and build reports visit the freestompboxes.org forum.

Landgraff - Dynamic Overdrive

I didn't realise that I hadn't posted this before. Anyhow, the Landgraff Dynamic Overdrive, is, wait for it, a Tubescreamer with a 2 position toggle switch to change the clipping diode type from simple silicon diodes to red LEDs. hmmmmmmm, it's all very familiar...

It's got a great tone;

Check out the schematic below... (See who it's drawn by ;-) ooooooooooohohhhhhhhwwwww) for fun compare the Landgraff Dynamic Overdrive and the Clay Jones Overdrive....

Fred Briggs - Hummingbird Overdrive

I've been working on this pedal for around two months now. From conception to completion it is the longest I've ever spent on a stompbox project. I think it's paid off. Prepare yourself for some "mojo" chatter, here it goes -

The original idea was to create something a little like the BJF Honeybee Overdrive - a slew rate limited overdrive pedal which produces lovely soft overdrive tones (Slew rate is the rate at which a device can react to changes in a signal's amplitude - if you limit the slew rate the audible effect is a softening of the higher frequencies). Unlike the Honeybee though I wanted to keep the highend of my signal intact, unlike the roll off produced when you "dig in" to the Honeybee (created by what I believe is a feedback capacitor from diodes that clip to ground to the - input of an op amp chip, confirmation will be coming VERY shortly :-).

I started out looking at how slew rate limiting was achieved. Mostly it involved the use of an op amp chip such as the LM301 or CA3130 (Keep this chip in your head - I'm sure we'll be seeing more of it in the very near future! ;-) and an external compensation capacitor. I didn't want to use a chip in my design so I decided to go discrete! I started by taking the discrete op amp circuit from the boss blues driver circuit, well know for it's dynamic response to playing styles. This was my starting block. From there I made significant circuit modifications, firstly to induce considerable slewrate limiting and secondly to create a soft, dynamic overdrive that can be stacked very nicely with other gain pedals. After I had my basic sound I then fine tuned each individual section of the build, hand selected parts and tuned values to their optimum tonal values. I settled on a mixture of Metal Film and Carbon Composition resistors with a combination of Paper in Oil, Silver Mica, Metal Film and Tantalum capacitors. 

This rampant, unaffected parts selection ended up with a bill that was not too cheap but definitely worth it; this is, without a doubt, my favorite overdrive pedal. It is as dynamic as the Fulltone OCD while being much softer and playable at higher volumes. The high end is tamed and efficient, it'll still be there even with the gain maxed and volume low and it's always soft and syrupy with a chewy texture that allows notes to melt out from the fretboard. The "Nectar" control I incorporated allows a steady increase in low-end response meaning that you can lower the bass content for bass heavy amps while paying through humbuckers or twin the Hummingbird with brighter, single coil equipped guitars such as the telecaster without any compromise in playability.

I'm so happy with this design that I'm building myself another - the Hummingbird De-Luxe with two extra controls for "Sag" (Which you can see on the gut shot as a small black trim pot) and "Shimmer" (A treble boost/cut control). Check out the shots below!

How did you make that Reverb?

In my previous post HERE I showed how I'd turned a Behringer RM600 Reverb Machine from useless to great. After multiple requests; here is the schematic that I used for my switching and mixing sections:

As you can see I used a Super Hard On for the PreGain circuit and to buffer up the front of my mixer, three other opamp buffers are then used to isolate various parts of the signal chain with the final op amp being used to provide a stable 1/2 V bias point. Series low pass filters on the output of the reverb line help to greatly soften any noise produced by the reverb circuit (Which is running 100% wet). By running the preGain control high and using the two mix controls effectively there is basically no increase in noise while using the circuit at all (A great improvement). I'm very happy using this circuit for other projects as well, I'll be using it on a Behringer EM600 Echo Machine in the future. Have fun using this while rehousing all those bargain pedals into super cool (USEABLE!) effects :-)