Analysis of Tone: MarkIV Full Throttle

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mrd

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Hey guys... I've been seeing a lot of threads lately regarding the MKIV and its tone. Some love it, some are having trouble with it. Today I had the idea of doing a few simple "tone tests" with the MKIV to see how different settings can produce different sounds. Maybe it will help illuminate to some people how this amp works, if not, it's just kind of cool anyway. And what better way to test settings than to run the channel and output volumes at maximum? I can't really think of one.

First, some preliminary words about my setup. My MKIV power tubes are new (2 weeks old), stock Mesa 6L6s, and the preamp tubes are Groove Tubes ECC83/7025s all around. For the test I was running full power on the front, class A and triode on the back. Like I said, channel and master output were both set to 10, and all the tests were done on the Lead channel with some mild EQ.

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Somewhat of an unconventional EQ I guess, considering I play mainly metal. When you crank the amp up this loud, the cab lends its own bass voicing so running the conventional V-shape is hugely overkill. Even running no EQ at all has way, way too much bass, so I kill it down a few notches, and then just leave the high-end as-is. Speaking of cab, for the test I'm using a Soldano 2x12 cab with two Eminence Legends 75watt speakers in it. I miked it up with an Apex460 tube condenser mic that has a low-gain ECC81 12AX7 in it. It's about 16-18" in front of the speaker, slightly offset from the centre. From there, I run it through another tube-preamp with the gain set to 0 (playing this loud requires no extra help from this pre-amp, I just run it through for the extra voice from that tube). From there, it's on to my Mackie board, through the soundcard and into Goldwave, which is what I always use for any recording that only requires one track.

Oh yeah... the guitar. I'm playing an ESP LTD KH-602 with EMG-81s (yea yea, Boogies + EMGs = lame. Want to lend me $2500 for a PRS? Didn't think so). Planet waves cables all around... plugged straight in.. blah blah blah. I think I've covered everything, let's get to the fucking test.

Since I play metal, this test is based mainly around gain, drive and treble settings. I usually leave my mid and bass knobs in the same spot no matter what. Mids I set to 6-7, bass is off. For the test, the first thing I did was see how the gain and drive knobs interact with each other, both pushed and pulled. From there I did a quick test of how the treble knob affects tone. I played the same boring random riff for every test so each setting had a level playing field. I didn't do any lead playing; the file is already almost 12 minutes long as is plus I don't think my neighbours appreciate hearing the same **** over and over again at obscene volumes during dinner hour. Tomorrow I might do another run through and fiddle with some new settings and do some lead playing to see how the settings affect that. At the end of the file is a little snippet of one of my songs.

Here's the file: http://members.shaw.ca/mrduplicity/tone_test.mp3 - 21.3 mb Sorry about the size, I encoded it at 256kbps to try and preserve as much sound info as I could.

First five-set of riffs is with gain pulled, drive pushed. Drive stays at 4.5 for all 5 snippets, gain goes progressively lower like so: 8, 6, 5, 4, 3.

Next five-set of riffs is again with gain pulled and drive pushed, but this time the drive stays put at a higher setting; drive stays at 8 pushed, gain goes up progressively like so: 3, 4, 5, 6, 8.

Next four-set of riffs is with gain pushed, drive pulled. Gain stays at 8 pushed, drive goes progressively higher like so: 4, 5, 6, 8

Next five-set of riffs is with gain and drive BOTH pushed. Gain stays at 8 pushed, drive goes progressively lower like so: 8, 6, 5, 4, 3.

Next six-set of riffs is again with both gain and drive pushed. Drive stays at 3 pushed, gain goes progressively higher like so: 3, 4, 5, 6, 7 8.

I didn't do any set with gain and drive both pulled, partially because I forgot and partially because when you play that loud, pulling them both and going beyond 6 or so on the knobs just turns your tone into mushy crap. If anyone wants, let me know and tomorrow I can do a set of it.

The next five-set of riffs is a treble knob test. I left gain at 8 pulled, drive at 4.5 pushed, mids at 7, bass off. Treble goes progressively higher like so: 0, 2, 4, 6, 8.

After that, I left the treble where it was then played a snippet of one of my songs for kicks.

Also, just a note, the only post-processing I did is this: normalize to 0db, peak-limiter compression to give it a mild haircut at -3dB, then another normalize to 0dB.

Hope you guys enjoy it. Got any questions, just ask.

EDIT: Forgot to write, the presence was set to 0 pushed for the entire time. I tried a bunch of different settings and stuck my head down by the cab and this setting had the most gnarly, throaty growl of all of them, so I stuck with it.
 
A bit too fizzy for me. How 'bout some lead playing.

~trem
 
Awesome effort, man. I hope you'll start a trend here - this is a great way to objectively study an amp.

I can't imagine how loud this must have been. With lead gain at 8, drive at 4-5, channel volume at 2, and output at 3.5 (full power, simulclass, pentode), I'm louder than the drummer by a noticeable amount. I think my head would explode if everything was dimed.

One thing I find interesting is that compared to your recent R2 sample, there doesn't seem to be as much swirl with the lead channel here. When I play at performance volumes (as above), I get lots of swirl on the lead channel. I think it might have to do with the fact that the signal out of the final gain stage of the preamp (i.e. the dimed channel master) may be much larger than the power amp circuitry and power tubes were designed for. It may be interesting to repeat a small piece of this experiment with the channel master much lower (maybe around 2-3) and see how it affects the tone.

Anyway, thanks for the demo. I hope others on the board will be inspired to do something similar with the other Mesa amps too. If I didn't live in an apartment, I'd record something similar on the mkiv revA, which would be an interesting comparison.
 
I think the mic position had a lot to do with the sound this time around. That R2 clip from before was about 1" from the speaker, this time it was more than a foot, plus the polar pattern was set slightly different so the room-mix may have been higher. Listening back to the clip now, I'm not too impressed by it. Of course it always sounds better in the room. Maybe tomorrow I'll spend more time with the mic position.

It wasn't actually that loud. If you run it on class A and triode it's not too loud. I was wearing earplugs and it was fine. I was even sitting right in front of the cab and listening to how the sound changed when I fiddled with presence and stuff to see where I should set that. The real volume boost is when you go from class A to simul-class or from triode to pentode. Simul, Pentode and Full Power is absolutely painful and deafening once you start getting up there. Starts getting to the level where even non-palm muted chugs (stuff like feedback or just single note lead stuff) will rattled your guts.

As for channel volume... I prefer to set it all the way up for stuff like this. I don't think the power amp "expects" a certain level of signal or anything. Diming the controls just lets all the tubes open up and fly at full capacity which is how they are designed to run. Obviously they burn out way quicker that way, but that's fine to me. Part and partial to owning a tube amp.

One thing I noticed today when I was playing very loudly is that once you reach the clip point of the power tubes, turning up output doesn't make anything louder, it just makes it sound more gnarly. If the channel volume is dimed, the output puts out its max volume around 4 or 5, anything past that is just insane creamy tube saturation. Same thing if you dime the output and start boosting the channel, after you reach about halfway, the volume stops going up and it just gets gnarlier. The extra headroom comes in when you switch to simul-class or pentode or whatever. I would never even dare to dime this amp on full wattage settings and be in the same room. My cab would probably fucking explode.

Anyway I'm going to bed, I'll do some more tomorrow and post it up here.
 
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