Jack Orman Rat Ebook

Browse the free pedal building info in the Projects section, the Lab Notebook, the Guitar FX blog or many of the links in the left column. Enjoy!

PC Boards are available for purchase for many of my projects, including the AMZ Mosfet Booster, Mini-Booster, SOS overdrive, dpdt relay switch, power supply pcb and more!

Latest posts from the AMZ blog page:

Okay, maybe 'good' is subjective, but they are FREE! I have updated the band names page. Check it out!AMZ Free Band Names Pag ..<more> This is an early mini-booster pedal that I found in storage yesterday when looking through some boxes of pedals.By early, I me ..<more> One of these things is not like the other..But they are both dual op amps. The one on the left is an integrated circuit, while t ..<more> If you are interested in how much noise is contributed by a resistor in your circuit, then try out the new thermal noise calculator i ..<more> If you are a pedal builder that likes to experiment with different op amps in your Rat pedal, then you should try the NJMOP07D chip th ..<more> Blind testing a 1 db difference in volume: https://www.audiocheck.net/blindtests_level.php?lvl=1 I was surprised that when I repeate ..<more> This is the basic schematic of a PNP germanium fuzz face. Some players find that the output volume is too low, but there is a si ..<more> Just got a new package from OSHpark with some prototype pc boards. Besides the Squeezer compressor, there is a new op amp fuzz and ..<more>

Some of the projects that can be made with the AMZ pc boards:

• Jfet mu-follower boost
• Mosfet booster pedal
• Guitar Direct Box
• Dual Output Booster
• Boost and Buffer
• Dual Buffer
• Re-amplifying Interface
• Silicon Transistor Booster
• AMZ Muffer
• AMZ Muffmaster
• A Dirty Boost
• AC128 Germanium Transistor Booster
• PNP Rangemaster-type Treble Booster
• Germanium Transistor Buffer
• Jfet Transistor Booster
• Jfet Transistor Buffer/Line Driver
• Mosfet Transistor Booster (not the AMZ Mosfet Booster)
• Mosfet Buffer
• Power Supply Filter
• 9v-to-18v charge pump
• True Bypass Relay System

GERMANIUM TRANSISTORS: I have plenty of the 2N1309 and 2N404 germanium transistors, fully tested and guaranteed. They work great in fuzz or booster circuits. Order a pair before they are gone.

Quick Links to AMZ Content
• Technology of the Mini-Booster
• The Case Against True Bypass?
• Is it Legal to Clone?
• How to wire a DPDT Switch
• Fretboard Care
• My Homebuilt AX84 Amp
• Free Soundcard Oscilloscopes!
• How to Solder
• Dr. Quack, Mosfet Boost, Mini-Booster and more!
• Capacitor FAQ
• Info About Copyrights
• AMZ Sitemap

Family (Feat. Kyo 2014 flacco.

Update - Read about the history of the AMZ Mini-Booster circuit, its origins, and pre-Internet status.

NEW ARTICLES!Bypassing the BMP tone control is a new article in the Lab Notebook section of the site. The Double Tone Control, Tone Clippers and the basics of Pedal Impedance are also recent additions.

The Mosfet Booster, Mini-Booster, Overdrive Pro, Shaka 5 and other complete, ready-to-build guitar effects are located on the AMZ Projects page. Top quality and Excellent sound is Guaranteed. Build one today!

Is it Okay to Clone? Get the info about circuit cloning and copycat pedals!

The Q&D Compressor articles are still available here but the SSM2166 chips are sold out.

The previous AMZ home page is still available as it contained a few links not on this revised version.

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I bought a ProCo Rat and after some testing I decided that I did not like it too well because it had a harsh edge that did not go well with my playing style. It was either sell the box or modify it to produce a better sound and after some deliberation I had formulated a plan. The idea that I finally settled upon was to revise the circuit to make it conform to my Fat Gnat design as near as possible. The original Fat Gnat circuit was published in RECORDING magazine in the October 2000 issue and is available on the AMZ CD-ROM.

Since there are numerous basic similarities between the two circuits I was able to incorporate most of the elements of the Fat Gnat into the modified ProCo box. Listed below is a summary of the changes that were made to the circuit.

1. Input impedance was lowered.. yes, lowered. This reduces noise and helps smooth out the sound. It also changes the low frequency rolloff to make string noises less apparent but still allows the full guitar range to come through.
2. A socket was installed so the IC can be easily switched.
3. The op-amp was changed to a high speed, ultra-low noise chip (NE5534AP). This chip also has the advantage of being able to better drive capacitive loads such as the tone control of the Rat. You could alternately use an LM741, which is a single opamp similar to the sections of the 4558, to see if that provides a better tone, but it does not have the drive of the 5534. A TL071, TL081 or similar opamps can also be tried for slightly different sounds.
4. The gain setting R-C combination was changed to the Fat Gnat values. This re-defines the treble boost of the gain stage and while similar to that of the original, it provides a little smoother response.
5. Bias filtering was increased 10x for less hum and noise.
6. Minimum gain was increased - now the sound does not completely disappear at minimum Distortion settings.
7. The tone filter was altered to the Fat Gnat design values. This reduces the top end response - but still it covers the full range of hearing. This reduces noise and allows for some additional tonal characteristics on the bass end of the spectrum.
8. An ultra-brite blue LED was installed to replace the stock red one. I may have to cut the current to the LED because it is nearly blinding with the stock Rat current-limiting resistor!
9. A germanium diode was added to the clipping section to sweeten the sound and introduce asymmetrical clipping for more even-order harmonics. Typically, even-order harmonics are thought to be be more tube-like in character and also more pleasing to the ear.

Furthermore, when the 'Distortion' knob is set to its minimum, the Rat now acts as a clean boost! - It's no longer a one-trick-pony. At moderate gain it has a lot of the sound of a Tube Screamer without the mid-range hump (i.e. flat mids). It has slightly more maximum gain than before but with all of the harshness removed.

The modifed Rat can now do clean boost, blues drive and full tilt boogie! What a change in sound these mods have made.. it sounds like a totally different effect!

BTW, do not be tempted to run the original Rat at voltages higher than the stock 9v. The power supply filter cap is only rated for 16v and higher values could damage the unit.

NOTE: I am modifying the Muff-Rat eBook to include a schematic that shows all of these changes in detail so that you can make your own Fat Rat.

Update Aug 2017: My Kindle ebook with new information on the Rat and the mods is now available from Amazon: