People often prefer Tube Screamers because they do just that: tighten up your tone.

As for the "Tone" control, it's really more of a high-mid/low-treble boost; like the bass, high treble is also de-emphasized.

I think I prefer the TS-9 model in the DigiTech RP series over the Screamer model in the HD series.  The higher-end DigiTechs also have a "modded" version of the TS-9 that doesn't cut the lows.

Ax3M4n wrote:

 

Thanks for response.  I'll give it a try again with the "50% = zero EQ effect".

50% for the bass and treble controls only = zero added EQ effect to the original TS808 being modeled.  This is a far cry from saying the Screamer will have no EQ effect overall.

I play an open chord and let it ring while switching the Screamer On and Off listening to the change - what I want to hear is added grit - without added EQ...  hope that makes sense.

...then the Screamer is probably not the model you want to use.  In addition to adding overdrive, Tube Screamers color your tone; there are no two ways about it.  If The Edge is using a Tube Screamer, then it is adding color to his tone.

If you want to go for a flatter response, I suggest you increase the bass above 50% and adjust the treble and tone against one another until the tone sounds most even thoughout the treble region.  After doing this you may find that the treble will also be above 50%.  As I said earlier, the tone control boosts the upper-mids/lower-highs, but not the upper-highs.