My Mark IV issue

Hi everyone,

So a while back I managed to score a new mark IV from a store here in Sweden. I didn't have a cab at that time so it wasn't until this weekend when I could get a recto 2x12 to go with it that I could try and see what was in store for me.

Well, something seems to be amiss because the sound is terrible. I started on channel 1 which sounded very flat, went over to channel 2 and it just sound thin and buzzy. Channel 3 I have heard so much about and it's flat out bad. It sounded more or less the same as channel 2 and there is no sustain at all. Almost gorilla-like in quality and there's no saturation of the gain regardless of what settings I use.

I know that this is a tweakers amp but I've tried approximately 30 different settings, making sure many of them were very different from each other to try out all possibilites and while the tone changed (more bassy to less bassy etc etc etc) the basic characteristics of the sound remains the same. There's simply a lack of decent tone.

As for volume I tried it with the output and bedroom level (1-1.5) and all the way up to 3 and it just got louder, not better or even changing.

What could this be? Because of a bad travel schedule for me it's back at the store (but it's still mine for the moment). I assume the store will check out what's wrong with it but if anyone has any opinions on this I'd love to hear them

have you tried replacing the tubes?

Have you downloaded the manual from Mesa's website (it's free) and tried the sample settings there-in?

MrMarkIII said:

Have you downloaded the manual from Mesa's website (it's free) and tried the sample settings there-in?

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Yep, I tried all the listed settings there.

Sounds like tubes
Do you know what year that head is from?
What tubes are in the power section? Mesa or someone else?

Even though the tone is not there, do you hear any popping or hisses sometimes?

If you start pushing the volume does it start getting a bit flabby sounding? (especially with the clean channel) If it does.

Can you get a hold of or do you have a friend that you can borrow either 2 EL34's or 2 6L6's from?
If you can put them in the outer socket's of the Mark IV and run the amp in Class-A, If you hear a night and day difference (and it sounds better) just retube the whole amp, preamp and power amp section.

Note:
If you manage to borrow a pair of power tubes from someone and they are not Mesa tubes or a different brand not from a Mesa amp just to be safe for the experiment just run the 6L6's in tweed mode, if someone has EL34's full power should not be a problem.

Have you tried the 'instant gratification' settings shown in the manual? If they sound like crap, there must be something wrong with it.

sounds very tubish, indeed.

same happened to me. can't remember how I fixed it, though..

Every time you buy a used amp from someone you should always take it to a tech to get new tubes placed in, biased, cleaned, etc etc.

I mean you spend a good what? 1G+ on the thing and can't spend about 50 bucks more getting it serviced????

This sounds like the tubes are bad.

Elixir said:

Every time you buy a used amp from someone you should always take it to a tech to get new tubes placed in, biased, cleaned, etc etc.

I mean you spend a good what? 1G+ on the thing and can't spend about 50 bucks more getting it serviced????

This sounds like the tubes are bad.

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The amp isn't used though, this was a new amp that they never managed to sell I suppose. But the store is working with me and we'll hopefully sort it out. Thanks for all the help guys

ask them for new tubes. It could have been sitting in the store and played a lot. If they don't give you new tubes, try changing the preamp tubes, I had a dead sounding mesa and swapped out my preamp tubes and the amp came to life and got a lot louder too. I had no idea untill I changed the preamp tubes, that there was anything wrong. Is your MKIV loud as hell? it should be, and if not, there's a good chance it's the tubes.