Emulating Marshall Tones With A Dual Rectifier

Posted: July 8, 2015 in Ideas To Be Developed, Mesa Boogie Dual Rectifier, Tube Amps
Tags: , , , , , , , , , , , ,

Before we begin, I’d like to note that Dual Rectifiers produce much more low boost in their preamp and the use of 6L6 will also produce a much more “round” bottom.  Beyond the bass boosting, there is not a massive difference in pre-EQ, preamp frequencies from a Marshall.

Another consideration is that frequencies below 70 Hz will make speakers rumble and fart.  Frequencies over 6 kHz become attenuated by the speakers.  Frequencies close to 2 kHz are part of the Rectifier presence circuit, which is not represented by this calculator.  Because the Rectifier has SO much low end, judicious use of the bass control is recommended for anything other than Modern Channel 3 (Solo) or Channel 4 (Roadster/Road King).

Some users may find it difficult to dial in their sound when switching over from a Marshall or an amp that follows the basic Marshall design or may want to get somewhere closer to a Marshall for any reason.  Here are some examples of settings by matching the EQ according to it’s approximate equal shape, or a shape that will get a person to similar sound.  I’m using Duncan’s Tone Stack Calculator to do this.  For all comparisons, the Marshall tone stack is: Bass-5, Mid-6, Treble-7.  This may not be a setting a person might be using, but using the calculator will enable one to experiment with settings they like to get “in the ballpark” with the Dual Rectifier.  Just remember: these are simulations are kind of a rough guide; in the end, your ears are the most important tool.


Marsh Vs VintageExample 1 represents a straight across duplication of the shape without considering the actual frequencies being shaped.  The EQ settings shown are for Vintage on Channel 2 (or Channel 3 of a Roadster).  This will definitely be a clear, punchy sound.  I would wager that it will possess more bass than the Marshall, but would be balanced pretty well for a Recto.

Marsh Vs Vintage2

For example 2, I decreased the bass and mids to compensate for the frequency differences.  The treble was also slightly increased to bring the upper mids back into the right shape.  The Presence control can attenuate the treble above 1.6 kHz to keep it bright, but remove brittle sounds.

Marsh Vs Vint Vs Mod

Example 3 compares Ex. 1 against Modern Channel 3 (4 for Roadster).  This mode has no negative feedback to the phase inverter.  This equates to a more open treble and presence.

The mids are reduced quite a bit to have a similar curve.  One may wish to play with the bass on the amp a little and go easy on the presence.  Where the lines diverge in the presence frequencies is not a concern.  That area will be cut by conservative presence settings and by the speaker’s frequency roll-off.

I hope this is helpful and I wish everyone the best of luck on their tone search.


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s