Exact effect of Contour control on Exp 5:25?

[sotto]

What is the exact acoustic effect of the "Contour" control on the Express 5:25? The Mesa website suggests it's a 5 band EQ in a single knob, but what specifically is the frequency shaping of the signal that occurs. It's not really clear by listening, and I'd like to know how I'm changing the freq response when I use the control.

Thanks.

 

[jvk]

With the F-series, I worked out the the contour to be of this shape, which is a 4-band solid-state inductor EQ, Mesa stylee:

Not sure if the Express has the same shape. You'd have to get me a close-up shot of the circuit board.

 

[Sling Blade]

I read in my 550 manual that the Express is already scooped. It said that most Mesa users set their amps up with a scoop so they set the Express up this way right out of the box. I believe I read that if you roll your contour off (turn it down or to the left) You will get less mid range freq. making your guitar feel like it is easier to play. which is true. And the more you turn it up it adds more mids in return makes it feel like you need to play your guitar harder.

I prefer my contour setting set at about 9 o'clock.

 

[jvk]

The Express is an evolution of the F-series, and it's contour function is basically the same as the F-series, only they've added a knob to control the effectiveness of the EQ, and I'm willing to bet that it's the same basic circuit.

That EQ shape that I've worked out is not a guess-timate or the typical EQ shape, it's derived from looking at the circuit and mathematical equations.

I read in my 550 manual that the Express is already scooped. It said that most Mesa users set their amps up with a scoop so they set the Express up this way right out of the box. I believe I read that if you roll your contour off (turn it down or to the left) You will get less mid range freq. making your guitar feel like it is easier to play. which is true. And the more you turn it up it adds more mids in return makes it feel like you need to play your guitar harder.

You've got it completely wrong.

When you roll the contour off, you get more mids. The higher the contour setting, the more "scooped" the sound becomes, and if it makes your guitar easier to play, it's because it hides the nuances in your playing! (or masks the mistakes / lack of clean technique )

 

[Sling Blade]

The Express is an evolution of the F-series, and it's contour function is basically the same as the F-series, only they've added a knob to control the effectiveness of the EQ, and I'm willing to bet that it's the same basic circuit.

That EQ shape that I've worked out is not a guess-timate or the typical EQ shape, it's derived from looking at the circuit and mathematical equations.

I read in my 550 manual that the Express is already scooped. It said that most Mesa users set their amps up with a scoop so they set the Express up this way right out of the box. I believe I read that if you roll your contour off (turn it down or to the left) You will get less mid range freq. making your guitar feel like it is easier to play. which is true. And the more you turn it up it adds more mids in return makes it feel like you need to play your guitar harder.

You've got it completely wrong.

When you roll the contour off, you get more mids. The higher the contour setting, the more "scooped" the sound becomes, and if it makes your guitar easier to play, it's because it hides the nuances in your playing! (or masks the mistakes / lack of clean technique )

Mask the mistakes/lack of clean technique!!! I better go turn mine all the way up then!

 

[sotto]

Thanks for the feedback. I, too, tend to run both contour controls at 9 o'clock-ish, but I don't tend to run either master volume up nearly as high as the examples in the 5:25 user manual. It's just not necessary for my purposes, and I get less hiss on the clean channel.

My impression also is that running the contour up seems to enhance some frequency bands. I don't notice a mid-range enhancement so much, though.

 

[jvk]

To put it more clearly, more contour means less mids and more highs and lows. The highs and lows are more dominant than lack of mids.

 

[sotto]

John T. at Mesa Hollywood got back to me about my question:

"Its basically a graphic eq type of circuit which is between the preamp and
power amp .As you increase
contour control the low and high freq increase
John T. Mesa Hollywood"