would you modify a Mark IIa?

[breogan]

Hi!

If you've seen my previous posts you'll know that I have a 79' Mark IIa (60W, graph eq, no reverb). I only have the chassis but a cabinet with a EV 12L is on the way (don't know the year of the cabinet) After going through the circuit the only mod that has been done is to remove the fetron. This means replacing two non-tone involved components.

This amp makes a quite loud "pop" when switching and the efects loop is not much useful. Modifying the swithching method and the loop would make this amp much more usable in live situations, and take full potential of its two channels. And this mods doesn't affect amp's tone at all. But,

Do thing is reasonable to modify it? This amp is a landmark in tube amps (first switchable channels amp) and very few were made (about 1500) but doesn't seems to get much appreciation in the used market. So this mods aren't going to make the price drop, it looks like even may raise it a bit. I don't know...

What would you do? Mod it for better or just leave it the way it is.

 

[Betos]

Hi,

Not sure what you mean about the effects loop not being usable (because I don't use effects). I have heard that on the MK-IIa if you run a volume pedal into the return it acts as a gain level. That could be an interesting feature, and you might lose it with the mod.


As far as the 'popping sound' mod - if it doesn't affect tone, and you're having it done by Mesa, it shouldn't be an issue. As you've correctly stated, these amps aren't really burning up the vintage market (like they should be).

Betos

 

[breogan]

I decided not to do any modification yet. I am finishing to adapt the cab I've bought and, after that, I am going to play a bit with it to get a general feel of what this amp is capable to do. Then I'll reconsider any modification.

The switching noise is quite annoying so I guess I'll mod it anyway. This involves to sold a small cap in a non signal-related area of the circuit and is completely reversible. So I guess I am not ruining anything.

 

[carlosasi]

You need to make the amp usable for your tastes, so if it is reversible no harm. You obviously know what you're doing. I'm not affected by the pop, you just have to time it right. I love the Mark IIA obviously not the stallion in the line but a unique voice that has a great clean channel and a classic rock lead channel. I've been using my Mark IIA for cleans and with an AYB switcher simultaneously using my Mark III lead channel blended. What a wall of sound.

 

[breogan]

You need to make the amp usable for your tastes, so if it is reversible no harm. You obviously know what you're doing. I'm not affected by the pop, you just have to time it right. I love the Mark IIA obviously not the stallion in the line but a unique voice that has a great clean channel and a classic rock lead channel. I've been using my Mark IIA for cleans and with an AYB switcher simultaneously using my Mark III lead channel blended. What a wall of sound.

Yeah! I love the rock tone of the Mark IIa. And the Graph Eq does really make a difference! Few days back some me and other guitarists met to jam and try different amps and gear. We plugged the Mark IIa to a 4x12 with V30. That moved some air!!

The gain isn't over the top (not Metallica tone here), but is just perfect for hard rock. For some Metal styles that may not be enough, but you can certainly play Metal on this amp. I all depends on your speakers and the Graph setting. Set the gain high, a "V" shape eq or a bass heavy setting and you'll be on the top of the world!

Move the eq to a mid punch eq and you'll get a Marshall tone!

Very nice...