Posts Tagged ‘Tone’

I don’t have time to type right now, but here are the images from the analysis for a 2 Channel Orange, 3 Channel Vintage on ch 2, and 3 Channel Vintage on ch 3.  The responses of the 2 Channel Orange and 3 Channel Vintage on ch 2 are very close.  Other factors could influence the differences between them.

2ch voicingandpresencevintageorange

2 Ch Orange




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 had just a few thoughts come to mind regarding modifying amps, modifying EQ, or creating your own.

It’s a fact that Mesa Engineering uses two modified forms of the Marshall tone stack for their Dual Rectifier series.  Compared to a classic Marshall tone stack, the Vintage/Raw tone stack moves the center of the “Mid” control down in frequency and has more attenuation.  This carves out some of the meatier part of the guitar frequency to make room for the massive lows and a high-mid emphasis.  The tone stack enabled for Channel 3 Modern has boosted upper-mids, but has a very similar, low-to-low-mid frequency response. (more…)

I ran across this article about Sovteks and how the rating charts for several tube brands compare.  I am needing tube replacements and this seems pretty handy for finding tubes that fall into Mesa’s bias range for their 6L6GC.

I’ve been using Ruby 6L6GCMSTR, which is an excellent tube, and I will likely stick with it, but these others have piqued my interest in differences between the sub-types. (more…)

EQ Schematic

Schematic of tone stacks for Channel 2 and 3.  Note the Presence control circuit and the value differences for its resistors

When Modern Mode is selected on Channel 3 of a Dual Rectifier, an additional capacitor is added to the circuit.  This changes the capacitance value from 500 pf to 680 pf.  By doing this, it moves the frequency from which the treble swings on axis from 1.27 kHz down to 936 Hz.

The effect of this change is twofold: 1) The upper mids receive a greater emphasis in the sound; 2) The overlap of range between the Mid control and the Treble control forces the Mid frequencies to move up in dB, effectively giving a mid-boost throughout the range of the Mid control.  The change also prevents the Mid control from being as scooped at the minimum setting by about a maximum of 2 dB between 600 Hz and 800 Hz.


Here’s an example of the way I’m setting my amp lately.  It utilizes what I’ve learned about the Clean circuit, FX Send, Solo, and other things.   (more…)

I already covered the input stage and clean channel.  I’m not going to repeat the information about the input, except for applications to the dirty tones.

The input stage is followed by a coupling cap and a 2.2 M load resistor in parallel with the voicing circuit and gain pot.  Most amps made prior to the Recto place the grid resistor between the coupling cap and the load.  The load is usually a potentiometer to control gain.  I think Mesa made this change to separate from the load and gain pot, so a 250 k pot value could be used. (more…)

Edit: Since writing this post, I’ve found increasing the Send to be more effective when the bias is colder.  Tubes in the lower range will make the amp run warmer and improves the sound without adjusting the Send.

In the manual, Mesa recommends bypassing the loop to get the best tone for recording or other situations where the fidelity is needed (isn’t that always?).  The loop works by cutting down the signal to send it out (like a volume control) and then re-amplifying it when it comes back in through the Return.  This is great for inserting effects, but people often struggle with the tone, because it’s always going through those amplification stages when engaged.  I found an effective way to get a better sound with the FX loop engaged. (more…)

I found this informative, since most people only talk about the safety portion of this topic.  It’s written to be easy to understand and very straightforward.  Enjoy!

Ohm Cooking 101

Mission Improbable

There are a few reasons I’ve been spending so much time exploring the Dual Rectifier.  Those reasons include: misinformation, biases and myths, and helping others.

The misinformation takes many forms.  Sometimes, it’s just reading about the DR having “active EQ” (false), that it isn’t a “solo” amp (false), or other equally dubious claims about the design that are ridiculous.  Biases and myths also fit in with the misinformation, but are just as much about the insecurities of the users as any misunderstanding of the amplifier.  Claims about early revisions being “superior” or the utility of the 2001 3 Channel version are as ridiculous as the circuit misinformation, because it’s all subjective.  If I was a little more cynical, I’d even think the second hand market is involved in promoting and spreading this kind of bias to increase, and retain the increases on, the obsolete designs.  Seeing as how Mesa designs them, builds them, markets them, receives feedback, and profits most from the sales, if the old amps were superior, they’d swap directly back to it due to customer demands and complaints. (more…)