Studio 22 EQ problem

[maftheonly]

I have a Studio 22 (not the Plus model, no graphic EQ) that seems to work fine except the Middle knob behaves strangely. On the clean channel, it seems to function fine, I turn it down and the tone sounds scooped. On the Lead channel, it only makes the tone slightly louder & more blaring if I turn it up, there's no mid scooping if I turn it down. Just constant roaring mids. If I turn the Treble & Bass down below 3, the Middle knob just behaves like a 2nd Gain control: it sounds loud & upfront on 10 but distant & muted on 0. Is this just a quirk of the model? I opened up the amp & cleaned out the pot and it stopped crackling when I turn the knob, but it still acts odd on the Lead channel.

 

[IronSean]

I'm copying a reply I made on this thread: http://www.grailtone.com/forum/viewtopic.php?f=33&t=74079

The Lead channels on the Mark series amps are not like other High Gain amps.

Most High Gain amps are laid out "Marshall style", with a bunch of gain and drive stages with some internal shaping to get the distortion tone, then an EQ section after the drive to do shaping of the final result. Most High Gain amps have their BMT (Bass Mid Treble) controls here.

However, Mesa's Mark series started life as modded Fenders, and thus use more of a "Fender style" topology, where your input goes straight to an EQ (BMT) then gain and drive.

This means the BMT controls are the first thing your signal sees inside the amp, and it's shaping work happens before the gain and distortion, leading it to do less overall shaping and instead just affect the character of the overdrive by modifying what's hitting it to actually overdrive. You can simulate this on other amps by putting an EQ pedal in front of it, or even changing pickups, etc.

This is why Mesa became such fans of the 5-band Graphic EQ: That GEQ acts at the place where most other high gain amps do their tone shaping with BMT controls, giving you back the sculpting ability lost by keeping the BMT so early in the circuit.

This is also why they're so flexible, because on most amps the BMT and other early signal shaping are all locked at whatever the designer chose, and you only get to shape the final result, but on the Mark series you get to tune in the input signal and the output signal.

But it also means the BMT on their own don't seem as effective, instead offering Bass - tightness, fullness, flub, Middle: kind of texture/fullness/stiffness, Treble - Gain and bite.

The Owners manual actually goes through a lot of this in detail, including the recommendation to keep the Bass low as the Gain increases, because the bass knob is still a fender style one that is very powerful for clean signals but quickly gets out of hand under gain.

TL;DR: The BMT controls are before the gain, so they shape the signal being overdriven, and therefore adjust the character of the sound more than the overall shape and EQ itself.

So basically, it's working as expected, and the manual would probably explain that too (available online). This is why the GEQ was created in the first place. You might try an MXR 10-band in the loop to see what you're missing.

 

[maftheonly]

The manual explained really only that the Treble is the most powerful of the controls and if set higher than about 6, the Bass & Mid knobs would sound like they had almost no effect.
Anyway, I'm relieved to hear my amp isn't broken!
I've hooked a Danelectro Fish & Chips in the FX loop and despite it being probably the crappiest sounding EQ out there, I can sculpt the sound like I hoped. Does an onboard Mesa EQ sound better in these amps than just any EQ in the FX loop?

I'm copying a reply I made on this thread: http://www.grailtone.com/forum/viewtopic.php?f=33&t=74079

The Lead channels on the Mark series amps are not like other High Gain amps.

Most High Gain amps are laid out "Marshall style", with a bunch of gain and drive stages with some internal shaping to get the distortion tone, then an EQ section after the drive to do shaping of the final result. Most High Gain amps have their BMT (Bass Mid Treble) controls here.

However, Mesa's Mark series started life as modded Fenders, and thus use more of a "Fender style" topology, where your input goes straight to an EQ (BMT) then gain and drive.

This means the BMT controls are the first thing your signal sees inside the amp, and it's shaping work happens before the gain and distortion, leading it to do less overall shaping and instead just affect the character of the overdrive by modifying what's hitting it to actually overdrive. You can simulate this on other amps by putting an EQ pedal in front of it, or even changing pickups, etc.

This is why Mesa became such fans of the 5-band Graphic EQ: That GEQ acts at the place where most other high gain amps do their tone shaping with BMT controls, giving you back the sculpting ability lost by keeping the BMT so early in the circuit.

This is also why they're so flexible, because on most amps the BMT and other early signal shaping are all locked at whatever the designer chose, and you only get to shape the final result, but on the Mark series you get to tune in the input signal and the output signal.

But it also means the BMT on their own don't seem as effective, instead offering Bass - tightness, fullness, flub, Middle: kind of texture/fullness/stiffness, Treble - Gain and bite.

The Owners manual actually goes through a lot of this in detail, including the recommendation to keep the Bass low as the Gain increases, because the bass knob is still a fender style one that is very powerful for clean signals but quickly gets out of hand under gain.

TL;DR: The BMT controls are before the gain, so they shape the signal being overdriven, and therefore adjust the character of the sound more than the overall shape and EQ itself.

So basically, it's working as expected, and the manual would probably explain that too (available online). This is why the GEQ was created in the first place. You might try an MXR 10-band in the loop to see what you're missing.

 

[IronSean]

The onboard is quite good, and will be tuned to create some of the typical mesa mark tones, but any good EQ should do a good job as well. The EQ and Effects loop happen at a similar stage in the amp so will produce similar results. With something like an Empress ParaEQ or an MXR 10-band you'll have even more control than the typical 5-band, and plenty of artists in the studio used both at once.

(Those classic Metallica tones on Puppets and Justice are combinations of the 5 band GEQ and external Parametric EQs, for instance.)

When I had my rocket 44 112 combo I just kept an MXR 10 band in the back of the amp for the same purpose.

 

[maftheonly]

Cool, that's what I was hoping: the onboard Mesa EQ & FX loop outboard EQ's being patched through in basically the same spot. Was gonna sell my Studio .22, now I'm keeping it for life.