Amp with equalizer

[HommeMarrBuckley]

I just saw a Fender Showman (Rivera era) and noticed it had an equalizer, similar to the Mesa Mark series. 
Wondering why they're not in many electric amplifiers.
I never played through (utilized) one so have no clue-just was wondering what the other members thought.
Perhaps, if anyone has toyed with them in a circuit and where they would be placed in the signal path.
Fashionably, maybe it's the equivalent of popping your collar, buttoning a top shirt button or wearing a bandana around your knee.
I dunno, just curious.

[P Batty]

What I've experienced is that they are hard to "dial in", they have more versatility but are harder to get that "sweet spot."

[Ed_Chambley]

I like EQ, but on amps I have never seen any benefit.  Where I do like EQ is on my pedal board before modulation effects like delay, chorus, flanger.  Reason is most do not have a volume control and the Boss GE-7 pedal has a buffer as well as a boost.  They are or can be noisy, but it is easy to make them very quiet.  Basically, it is just cheap caps.

I had a Boogie with an EQ and really liked the amp.  It was a Mark 1 and had knob EQ as well as 5 sliders.  It had a switch to use the EQ or bypass it.  Really did not use it much for the EQ for guitar, but it helped with Keyboards keeping the low lows off the 12 inch speaker.

[HotBluePlates]

I just saw a Fender Showman (Rivera era) and noticed it had an equalizer ... Wondering why they're not in many electric amplifiers. ...

In the 80's, my older sister's P.O.S. boom-box had a graphic equalizer, too. It didn't keep that thing from being a P.O.S. 

I think it was a fad at one time. Your amp already has tone controls and/or fixed tone-shaping (unless you're playing a tweed Champ or equivalent). Adding a graphic EQ on top of that is probably redundant. Or easily fouled up by the user. Or both.

There is additional circuitry for (active) multi-band EQ, whether graphic or parametric. A manufacturer might need a lot of incentive to add all the R's, C's, L's and opamp (solid-state or tube) stages to implement a multi-band EQ.

There's a good bit of art to designing a good EQ as well. Audio engineers know there are some EQ's (especially if frequency bands are fixed) which are very intuitive & user-friendly, while others don't seem to work well (or have the center-band frequencies in non-useful places). So picking the frequency center & bandwidth of each of the frequencies on those sliders will either make the EQ destined for greatness, or consigned to failure.

The trend I've seen over the past couple-decades has been a tendency towards "retro, back to basics, simplified, 'no tone-sucking bells & whistles' ", etc. This seems counter to inclusion of a multi-band EQ on top of channel tone controls.

And as Ed points out, a good EQ pedal can go in places amp-EQ can't, while also pairing up with any amp you want...

[alerich]

I gigged with a Mesa Boogie Mark IIC for a few years. I wouldn't own a Mesa Boogie amp without the graphic EQ. I felt it was necessary, not optional. I probably would never own another Boogie period, but if I did it would have to have the EQ.

[hesamadman]

Graphic eQ usually cancels out the tone stack. Not saying it's not a cool option but one or the other. Both is redundant. Mess around with a graphic eq sometime and then adjust the tone stack. Depending on the setting, the tone stack is now useless and does nothing.....

[2deaf]

When you have a preamp with four gain-stages,  it tends to come out rather husky even when a tone stack within those four stages has the bass completely turned down.  This is fine for lead, but too muddy for rhythm in a lot of situations.  A pre tone control and a post tone control is the obvious thing to do and that is exactly what Mesa did with the TMB stack before the overdrive and the equalizer after the overdrive.

A lot of high gain amps have gone to set pre tone settings with a TMB post tone stack (including Mesa).  I'm old school, so I don't much like it.  I was always more prone to putting the treble and mid pre overdrive and the bass post overdrive.  If you want more post overdrive control, put an equalizer in the effects loop.     

[HotBluePlates]

When you have a preamp with four gain-stages,  it tends to come out rather husky even when a tone stack within those four stages has the bass completely turned down.  This is fine for lead, but too muddy for rhythm in a lot of situations.  A pre tone control and a post tone control is the obvious thing to do and that is exactly what Mesa did ...

This is a very good point!

The OP was asking about a graphic equalizer, and I focused on that. But as you're pointing out, it's about having post-tone control, rather than the specific implementation of that tone control.