AC/DC Tones and A Vintage-Like Clean

These settings are for an approach to getting some vintage tones from a Mesa Boogie Dual Rectifier.  The Clean uses the ideas I’ve been developing about a higher gain setting against a lower Volume setting.  It also has less Bass dialed in.  This made the moderate use of Mid and Treble possible to control sizzle and distortion.  The Presence is just an extra treble control, because Channel 1 has no negative feedback in the power amp.  This setting is very full through the mids and has enough bass and treble to sound good, without either dominating.

The Dirty setting is copping a nice late-70s AC/DC tone.  It sounded really good for many Classic Rock tunes that aren’t fuzzed up.  Raw has a lot of top and bottom rolled off.  It only needs a little nudge to move into Plexi territory, though it could take some more Mid if a person wished to do so.  The Solo is engaged and dialed-in just enough to change the top frequency response.  

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Mesa Rectifier Design Concepts: Introduction, Input Stage, and Clean Channel

1. Input Stage
2. Stage 2: Go With The Flow
3. Stage 3: Clean It Up
4. Skip The Nerd Talk: Putting It All Together

Introduction

I’ve been thinking a lot of about modifications recently and I’ve been going over the schematic for the 3 Channel Dual Rectifier on a regular basis for quite awhile.  I was recently thinking back to when I was starting out and how it was difficult to understand why or what a part of the amp was doing.  I don’t consider myself an expert.  I was taught solid state theories in school and had to buy books and read websites regarding tubes and how they apply to guitar amps.  I wished there was more information about the design concepts.  So, I thought I’d break down the preamp for the Dual Rectifier into the stage circuits and just talk about the general, overall concept of what each does on its own and together with its neighbors.  This might help the users with tones and circuit designers and hobbyists with ideas and insight.

The FMV Tone Stack and Dual Rectifier

(11/15/15: Edited information about the Presence and Treble)

Modern, high gain, guitar amplifiers generate much larger signals than vintage amps, hence high gain (high increase).  Compared to a vintage amp, modern amps can produce much more distortion and saturation.  In addition, the low frequency content of a Recto is fairly great.  Stages 1, 2, and 4 of the dirty channels are shunting the lows at about 88 Hz, -3 dB.  While the amp voicing is another topic, it’s important to have an idea of what is coming into the tone stack if you wish to shape it.  Since I own a Dual Rectifier, I’m using it as the example, but these concepts and this tone stack are applicable to many amplifiers.  I’m focusing on the Vintage mode of the Orange Channel.

Our topics for this discussion are: target frequencies, response of individual controls, the interaction of the controls, and dialing in useful tones more easily.  Some of the information is simplified for clarity.

Mesa Dual Rectifier 3 Channel: Jimmy Page

 

Jimmy Page-inspired settings.

 

(Updated 12/26/15: Second example added)

These are settings I use for classic rock.  The Presence and Treble should complement the other by having one to the lower setting if one is higher.

1990s Tones

The Clean is about what I use normally with the tube rectifier and sounds good with the other settings.  The Soundgarden setting in Channel 2 is based on Fell On Black Days (turn your guitar volume down) and Let Me Drown.  It’s more of a setting for Cornell, since he did the rhythm on his songs and Outshined sounds pretty good on it, too.  Channel 3 sounds pretty close to Tool’s Stinkfist, H, 46+2, and Third Eye.  All the channels compliment each other pretty well and would work as a basis for finding a personal tone.

Let me know what you think of this.

The Vox Tone Stack (Modified)

 

This graph would not be possible without Duncan’s TSC  @ http://www.duncanamps.com/tsc/