Guitar How-To: The Mesa Boogie Mark IIA/IIB Ultimate Master Volume Pedal Trick

The Mark IIA and IIB series of Mesa Boogie amps contain a strange but fortuitous function, available only on these early Mark amps, since the IIC killed it off when they implemented a very nice effects loop.

I believe the IIB had a tube buffered effects loop as well, but the IIA had none. But what both of these amps did have was a junction jack. It let you take the signal out, right after the pre-amp and right before the power amp. On my Mark IIA, it’s the jack circled right here:

This preamped signal contains everything the Mesa has to offer short of the power section. That’s right, even the Master Volumes for the Clean and Lead gain stages, the boost, the treble on, you name it, it’s before it. What do you do with this preamped signal? Plug it into a volume pedal. Then out of the volume pedal, you plug back into the amp over here:

This way, you have one last volume control before the power section sends your signal to the speaker. In other words, you have the ultimate Master Control, the master of all other master controls. In this way, you can dial in both channels’ volumes and gains, their master controls, and you’ll still have one more volume control after that to tailor to taste. Makes for some super cool volume swells too, done after the preamp instead of having to be before the amp, and thus you can even swell your overdrive and distortion signals without losing any gain. COOL. Here’s an example of my amp using this trick for both channels (technically they aren’t “channels” but heck, i set them up to be Clean and Dirty so I call them my channels).


18 thoughts on “Guitar How-To: The Mesa Boogie Mark IIA/IIB Ultimate Master Volume Pedal Trick

  1. Great tip! Just bought a mk. II and this sounds very useful. Dó I need to take the amp out of the cabinet to insert the junction jack?
    Regards Christian

    1. No need to remove the chassis, the junction jack is on the bottom of the chassis, access is through the cab, same as if you were changing a tube.

      1. OK, thanks. Now I’m looking for a volume pedal to try this. Any thoughts on choice of volume pedal. I guess the signal input is no longer an instrument signal so what to buy: High or low impedance?

      2. I used a high impedance active Goodrich volume pedal. No reason to think a low impedance pedal wouldn’t work though, for this type of usage.

  2. unbelievably valuable tip! i’m not ashamed to admit I’ve been playing a boogie markiia for 30 years and always wished i could have a master volume on a pedal! i didn’t know i already had it!!!!! i will definitely try this right now and play this way from now on if it works – fingers are crossed!

  3. man it worked! i can’t believe it! perfeeeect! when i gig with this amp i’ll use it this way from now on! i’ve always had the problem that my mark ii needs to be turned up very loud to sound good, but this solution solves that problem! how can i repay you? bless you! ha that’s over the top, but that’s ok – that’s how happy i am about this! by the way i also learned something shocking. for many years i walked around saying my amp was a mark iib. then ten years ago i sent the amp to mesa boogie for repair and someone at mesa boogie wrote mark iia in black marker on the chasis. so i thought oops, i’ve heard the mark iib is best but i guess i have a mark iia. but today i saw that there’s a metal plate inside the cabinet saying it’s a mark iib! and i believe it is a mark iib because today i also learned that i have to use a different plug from the one indicated in the photo above (of a mark iia) as a send, in the photo above you use the jack circled in red, but on my amp, that plug is an eq footswitch, on my amp i had to plug into the 1/4″ jack a few inches below the circled jack in the first photo above. i hope that’s not confusing:) rock on!

  4. Hi, thanks for the inspiring tip. I’ve Got a ’79 Mark ii – looks like new in white tolex. Read your input (great pics!), got a Volume pedal (Ernie Ball) and some cables. The effect is not so good. The Volume sewell is only limited. I can’t turn the Volume off and the dynamics are very limited: only a small increase in Volume when engaging the pedal. Aldi the MV 1 seems to be disabled when plugging it in. Any idea about what’s happening?

  5. I almost got it. I have a Mark IIa I bought in 1979, and NEVER KNEW about this.

    So….I take the under chassis plug that was circled in the pic, send it into my volume pedal, then out into that pre-amp in jack on the back.

    Is anything plugged into the front? Or have I missed the point altogether?

  6. Thanx, Jahnli. NOW I see. That’s how all the effects and guitar get modified in the pre amp by the volume pedal. Super.

    Since you’re so helpful, would you know the settings on a Mark IIa where I could get a near Marshall burn? One of the folks I play with does a lot of Thin Lizzy and Kiss. I love my Boogie sound, but would love to approximate the Marshall as close as I can. I’ve tried and
    I can get a burny overdrive, but it’s not the same. Thanx for any info. If it can’t be done, oh well.

    Currently, with my SG and Boogie, I use 6 on channel drive, a hair of Master drive, I have my lead drive pulled out on about 4, the master at 3 and the EQ at bottom bottom mid high high to get rid of some of the Mesa “honk” from the 15″ Altec.

    1. I treat this beast like a twin reverb with a 15″. More of a platform for pedals than generating its own OD if you want a non-Mesa signature sound. It actually serves that role great, a big clean with plenty of overhead for any type of pedal you want.

      But sometimes you want that Mesa honk so you crank that amp OD and tame the loudness with that volume pedal trick. Or the pedal for overdrive needs to be tamed- volume pedal trick again.

  7. Hi, I’ve got a 1980 Mark II (with reverb and ventilator, without EQ). It is not labeled “A” but I believe the “B” version is later. So I beleive it’s a “A” version. I’ve found the original Manual on the web (PDF). This connection is explained.
    It is written that this connection is an effect loop to insert delay, chorus or other FX. As I don’t speak english (I’m french), could you confirm my understanding ?

    Here you can download my manual, the connection explaination is on page 2 : II_Manual.pdf

    Thanks to everyone for answer / confirmation.

  8. It works! I have to put the vol pedal away, since it’s so sensitive going from pretty loud to stadium volume very easy. So I Can get the sound I want but difficult to adjust volume on the fly. It’s a Mk IIa and a Ernie Ball pedal. Any advise for further improvements?

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