Archive for the ‘Effects’ Category

Update: This is the final version of the DR Booster:

Dr Booster final

The R10 is actually a pot, not a resistor.  With R10 at 10k, the boost is 19.1 dB; At 0 it is 3.5 dB.  The frequency band is 33 Hz – 2.9 kHz, with 330 Hz as the center. (more…)

The McBooster

Posted: June 29, 2016 in DIY, Effects, Ideas To Be Developed

I breadboarded a simple and basic booster which began as a MXR Microamp clone.  I was looking for something to push the amp into a certain sweet spot and the Microamp wasn’t quite right.  I thought it was too farty, frizzy, and prone to clipping for what I wanted.  I changed many of the part values, moved the pot to the feedback loop, and adjusted frequencies a couple of times to have a wide-band-pass filter which increasingly loses treble as the gain is increased.  The gain of the booster is also decreased to 8 (18 dB), versus a gain of 20 (26 dB).  This is to prevent clipping the op amp to an extreme with modern humbuckers.  If a person is using vintage pickups, the values can be changed to get greater gain, but it isn’t really necessary.  I used it with my humbuckers in pseudo-single coil, parallel wiring and it made them pop right out, adding clarity and girth. (more…)

HarmonicI like this boosted filter.  The 400 Hz peak is accompanied by a 3.2 kHz peak of a smaller amplitude.  This accents the 4th Harmonic, which is consonant.   (more…)


Basics of the Signal Path

The input to the Boss GE-7 Graphic EQ has a buffer which is active at all times.  There is a slight emphasis around 2 kHz to help the guitar sound stand out.  Immediately after the buffer is the amplifier for the level control.  It’s a differential type with only one source voltage split with the level’s sliding potentiometer.  This slider will either boost or cut the whole signal when it is moved from the zero line.  From here, the signal is split; one path goes to the EQ section and one part goes to the positive input of another differential amp.  The EQ section feeds the negative input of the differential amp. (more…)

I put together a rudimentary representation of the effect on filter curves when setting a graphic EQ.  It isn’t exact.  Use it to get a general idea for the way a graphic EQ shapes the signal. (more…)

Blank Settings Form For Boss GE-7

Using an equalizer to boost the guitar’s input signal makes a lot of sense.  It provides a clean gain and a lot of headroom.  Aside from boosting the signal, it can, of course, be used to carve out specific frequencies.  Unlike most overdrive pedals, an equalizer has the ability to be very precise with multiple frequency bands and can create special effects.

The downside to this specific pedal is noise.  It uses cheap tantalum capacitors in the signal path.  This creates a hissing sound when the sliders are moved away from the zero mark.  The MXR 10 Band EQ is reputedly better, but I don’t own it and can’t comment about it further. (more…)

Awhile back, I found this page while doing research for building effects pedals or amplifiers.  Jack Orman has some really great information and ideas on his site for many different circuits, modifications, and adaptations.  I’ve found it to be quite inspiring and I encourage anyone who is interested in guitar or effects technology to check out his site. (more…)

While this is written about a 3 Channel Dual Rectifier with an FX loop modification to serial, the basic idea will apply to any amplifier with a serial loop.  As well, the Nova System can be substituted for another device with a speaker simulation.  The speaker sim is in the Utility menu. (more…)

I e-mailed Mesa Engineering awhile back about the loop mod for the 3 Channel DR parallel fx loop to make it serial.  I received the same schematic that I now know everyone else gets.  I can see the appeal for someone who doesn’t want their signal to be “tainted” by a pair of jfets, but they aren’t amplifying, only opening to allow the signal through.  It’s no different than having any other quality part in the path.

More recently, I saw that a company is advertising their bench fee for a different mod and the loop retains some of the functionality afterward.  I thought to myself, what would do that?  One thing that came to mind while off on one tangent is the idea to pinch the dry channel off. Then the light bulb flashed and blew up over the idea I’m writing.  This is not only easier than adding a part or bypassing the jfets, it is entirely reversible.  Here’s how to mod the fx loop and gain a killswitch:



This graph would not be possible without Duncan’s TSC  @