Mesa Boogie Mark IV - Revision A vs Revision B

Here is a (as close as you can get it) direct comparison between
the Mark IV rev A & rev B lead channel (pull fat is ON for leads).
Signal chain for both amps ;
Guitar - ESP LTD F50 (Seymour Duncan JB) & Sterling JP60 (stock) for leads
Elixir nanoweb 10 - 46 on both guitars tuned to Eb standard.
TC Electronic Wiretap Riff Recorder (for the reamped track)
TS9 clone
Mark IV's
Tubetown ToneHound reactive load
Audient ID44 (insert)
Amplitube Cab section (2x12 recto honrizontal)

Settings on both amp :
Lead gain 8 (pulled for leads)
Treble 8
Bass 1
Mid 2
Lead drive 7 (pulled)
Volume 4
Master 2
Presence 1.5 (pulled)
Simulclass/Triode/Harmonics

Riffs from Dream Theater.

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Cheers !

[cunjoz]

Thank you for that wealth of Dream Theater riffs (I see you're a man of culture as well) and for this awesome comparison.
As I've grown to prefer tones that aren't that scooped because they sound bit fuller to me (wall of sound and stuff), I prefer rev A in this video

[washingtonirving]

The B is far brighter. Looking at the schematics I see three spots that might be responsible for this; on the 2nd lead stage the B has a larger lead bright cap and is missing a cap between the voltage rail and the plate, then in the phase inverter it has a smaller cap between the differential signal paths. Aside from this and the inevitable pot taper differences, some (don't know how many but mine did) B's have a 200k lead treble pot (not a 250k that measured low) which thins out the midrange a bit. Supposedly also they are running a much higher plate voltage on all of the preamp tubes in the lead mode than the A but I don't really know if this, or yet another difference which is the lead stages being split between two tubes, makes a difference as far as brightness goes. Nice comparison.

[jameslane]

Nice comparison man I love these amps. My buddy has a Mark iv revision b he's selling me in a couple weeks. I can't wait. I'm on the lookout for a Mark 3 black strip also.

[forevermore]

Very interesting. The B sounds a little more scooped and compressed. I liked the Rev A better.

[snk]

After a while I just stopped listening for the differences and got lost in the awesome playing, both tones are great though

[crankyourampupalltheway]

A is better I think. How did you set your ts9 clone? Gain 0, Level max? Is it generally useful for tight rhythm to use ts9 for Mark series amps? What do you think? Your clip sounds amazing!

[kmanick]

I have owned both over the years and found "A" to be a bit warmer sounding, but the R2 channel on "B" was much more usable.

[giorgosk]

A is a bit more raw than b i think which is warmer and less chunky-best for leads and A for riffs

[rockitmanvideos]

really good comparison! I have a rev B. To me, REV A is a little more open sounding in the treble zone, REV B is slightly more compressed sounding overall. I think I will keep an eye out for a possible REV A addition to my collection....

[stevestevens]

Is song on 2:06 an original? If not, tell me the name please.

[thrasher]

Rev B for me, sounds more full and modern. Although A sounded better through my phone before I got some good headphones ha

[Tiger.]

What a coincidence, I was just opening up YouTube to search for this exact comparison and this was #1 on my recommended videos list! Very helpful and well done. The Rev A is more in line with what I would prefer. The new Mark VII release reignited my interest in trying out a Mark again. Only used the model of the IV in the Axe Fx, which got me by for ~5 years, then owned a IIC+ for a bit before going all in on a few Wizard amps, but now I'm thinking of trading out one of my Wizards for a Mark. Let me me know if your ever interested in considering in trading the Rev A for a Wizard MTL 100w el34.

[juliochingaling]

Great video. I may be the only one to notice, but the Rev B is the black covered, the B has the 2 rockers by the master vol. Vocing and EQ. I had both, still have the B, 1996.

[Turboy]

Tone is so subjective, two people might describe the difference in two ways that are mutually exclusive.

I hear very little difference between the two, but I hear the B as pushing the lower midrange a bit more. I'd really like to see high resolution frequency response plots of both amps with the EQs turned off and all controls at 5.

[micropaint.limited]

Great comparison! How did you capture the sound? Did you simply use a Shure SM57 microphone and a Mesa cabinet, or something else?

[mikerichardson]

I noticed that the A has the EQ on but the B does not. That will make a HUGE difference for the comparison between the two amps.

[jakeb]

both sound great. sound wise i think i lean more tword the B. what are your thoughts ? i would think the A, having an older transformer, may actual be better in the room and playing.

[nunoharris]

Hi.. whats the year of your amp ? Thanks

[UncleYoshi]

The Rev A sounds a tad nicer, especially the lead tone, very nice milky liquidity sound. What's the major differences b.w a Rev A and Rev B?

[puppet-m]

looks like you have the A&B mixed up on video? My revA looks more like your B and all the RevB iv seen have that light switch over top of each other?