Mesa EQ vs. Mark IV on board EQ

[themetallikid]

I recently fell into a tone I really like with the Mark IV, and was using the separate 5 band Mesa EQ block, before I realized it was included in the Amp block as well. 

 

Is there any difference between them other than the separate EQ block has a level parameter?  I like the eq curve I have, however I also boost the level by 2-2.5db to compensate for the cuts....but I can't do that in the amp version.

[codamedia]

Although very similar... I suspect there will be some difference... mostly due to placement. 

 

On a real Boogie, the EQ lands between the preamp and power amp... I'm sure the amp model is similar to this. When you use it individually, the closest you can get it by placing it between the amp and the speaker... only if you use a separate speaker block. Still not the same. Also... on a real Boogie there is no level adjustment... you had to compensate the lower volume by turning up the master. This "may" have an effect on how things sound, but I suspect only slightly. 

 

If it were me... I would use the amp model complete with it's EQ, and turn the amp volume up a little to compensate for the volume drop. For no other reason than that's how the real Boogies operated :)

[themetallikid]

That makes total sense, THank you for that!

[amsdenj]

The reason for this difference is that if the EQ is between the preamp and power amp, then it's shaping the tone out of the preamp, and into the power amp. If the power amp is not clipping, this won't make much difference. But if it is, and there's sag and bias changes, then what hits the power amp can have a lot of impact on how it distorts. That can be good or bad. The real Boogie put the EQ between the preamp and power amp because that was really the only practical choice. But with Helix, you can put the same EQ block before and/or after the amp for more tone shaping options. 

 

As a general rule, cutting bass and boosting treble before distortion and doing the opposite after distortion stages helps reduce low-end mud and high end ice pick, while providing a nice clean tone when backing off the guitar volume. With Helix, we have the flexibility to try these things that would have been difficult in the hardware domain. Of course EQ after the amp was common in studio and live sound situations, just not with the guitar amp itself as a backline.