Mark IVa versus Mark IVb?

[giantstepjoe]

Can anyone tell me the exact differences between a Mark IVa and a Mark IVb? I am aware the controls are updated somewhat on revision b but I'm more interested in the sonic differences. Were there changes made to circuit for revision b? I only ask because I just got my hands on a Mark IVb combo and have a/b'd it against my bosses' Mark IVa combo with the exact same settings and to my ears mine sounds alot better than his. They both have the same evm12l speaker. His combo is hardwood walnut with a wicker grille and running 4 6l6s and mine is stock in black tolex running a pair of 6l6s and a pair of el-34s. So is it just the difference in tubes?; or is the different cabinet wood the cause; or did revision b just improve the sound of the Mark IV drastically?

 

[zodiac272]

tubes will make a difference, i think especially if one has EL-34's. The hardwood may resonate a bit different
if you could, wait a minute for the tubes to cool and swap the power tubes. also, maybe try using the same cab when a/b... can the cable reach the other taps if the combos are back to back or stacked on top of each other?

scott

 

[giantstepjoe]

Thanks for the advice. Could there really be that much difference between two different evm-12ls? I'll give it a try if you think so. I'll also try the them with the same tubes.

 

[zodiac272]

i was thinking the hardwood may sound different than the tolex cab... but maybe not that different. Preamp tubes will make a big difference too. If there is a way to use the same set of those, that would help level the field

scott

 

[mxr2000]

Voicing of the amp on IVa is Vintage closer to the IIC+ and the IVb voicing is more modern "petruci style" plus you will find stereo option and eq out to use with Mesa Simul Satellite head.

 

[mule#1]

Voicing of the amp on IVa is Vintage closer to the IIC+ and the IVb voicing is more modern "petruci style" plus you will find stereo option and eq out to use with Mesa Simul Satellite head.

I have had both and would agree with the comments on the A. The B is more compressed and a little darker or more modern sounding. I have owned both and there is not enough difference to say one is better than the other as you can certainly make the B version sound about as bright as the A. However the A will not get as compressed as the B.

The tubes should be the same to AB them as your EL34's will make even more compression (tighter sounding) than his. And I'm pretty sure since it is voiced differently the same settings would not sound as good. IMHO I think the B version has to have the mids a lot higher than the A.

Check out this post by Shep from the board! http://forum.grailtone.com/viewtopic.php?f=27&t=5987

Good Luck!

 

[dodger916]

I doubt the type of combo cab (hardwood vs tolex) will make a significant difference. You could always get (or make) two female-to-male speaker extension cords and run the speakers from the other amps.

I agree with Rob (mule#1) above, and would add that the B is considered to be smoother and the A voiced more aggressive.

 

[mule#1]

I doubt the type of combo cab (hardwood vs tolex) will make a significant difference. You could always get (or make) two female-to-male speaker extension cords and run the speakers from the other amps.

I agree with Rob (mule#1) above, and would add that the B is considered to be smoother and the A voiced more aggressive.

+1 on all counts Frank!

 

[giantstepjoe]

Thanks to everyone for their input. I haven't had a chance to do another a/b test yet. I'm going to try all 6l6s in mine the next time I do so both amps are at least running the same tube configuration. I must admit I think el-34s will be staying in the outer sockets of mine semi permanently. I'm loving the way the amp sounds and I prefer the sound of R2 on mine to my boss'. I finally looked behind the power tubes to see what kind of preamp tubes are in it and was surprised to see all JJs. I've read alot of mixed reviews of JJ tubes. I've used their 6l6s and 12ax7s once before in another amp and never had issue. I know that their 12ax7 is popular in v2 for some preamp cocktails but have read on several occasions that it's a harsh tube for v1. Is this the general consensus? Right now the amp sounds great to me but if I could swap out a couple preamp tubes and it will make it sound better I'm going to. I'm interested in finding out Mark IV owners opinions on this.

 

[mxr2000]

Voicing of the amp on IVa is Vintage closer to the IIC+ and the IVb voicing is more modern "petruci style" plus you will find stereo option and eq out to use with Mesa Simul Satellite head.

I have had both and would agree with the comments on the A. The B is more compressed and a little darker or more modern sounding. I have owned both and there is not enough difference to say one is better than the other as you can certainly make the B version sound about as bright as the A. However the A will not get as compressed as the B.

The tubes should be the same to AB them as your EL34's will make even more compression (tighter sounding) than his. And I'm pretty sure since it is voiced differently the same settings would not sound as good. IMHO I think the B version has to have the mids a lot higher than the A.

Check out this post by Shep from the board! http://forum.grailtone.com/viewtopic.php?f=27&t=5987

Good Luck!

You know the mark V is more modern sounding and thats why there should be an Modern/Vintage voicing switch this and an stereo Option along with eq remote switch for a satellite to use it on stereo..

 

[mule#1]

Thanks to everyone for their input. I haven't had a chance to do another a/b test yet. I'm going to try all 6l6s in mine the next time I do so both amps are at least running the same tube configuration. I must admit I think el-34s will be staying in the outer sockets of mine semi permanently. I'm loving the way the amp sounds and I prefer the sound of R2 on mine to my boss'. I finally looked behind the power tubes to see what kind of preamp tubes are in it and was surprised to see all JJs. I've read alot of mixed reviews of JJ tubes. I've used their 6l6s and 12ax7s once before in another amp and never had issue. I know that their 12ax7 is popular in v2 for some preamp cocktails but have read on several occasions that it's a harsh tube for v1. Is this the general consensus? Right now the amp sounds great to me but if I could swap out a couple preamp tubes and it will make it sound better I'm going to. I'm interested in finding out Mark IV owners opinions on this.

Rhythm 2 was greatly improved on on the B version and is probably the biggest difference. As far as the JJ's I think they are harsh but many like them. As far as the EL 34's I say if you like them use them! The cleans will suffer but tone is subjective to each of our ears. I can say that all tubes sound different and you can try a lot until you find what you really like. Same goes for the pre-amp tubes. Move them around until you find the combo that works for you.

 

[giantstepjoe]

Thanks to everyone for their input. I haven't had a chance to do another a/b test yet. I'm going to try all 6l6s in mine the next time I do so both amps are at least running the same tube configuration. I must admit I think el-34s will be staying in the outer sockets of mine semi permanently. I'm loving the way the amp sounds and I prefer the sound of R2 on mine to my boss'. I finally looked behind the power tubes to see what kind of preamp tubes are in it and was surprised to see all JJs. I've read alot of mixed reviews of JJ tubes. I've used their 6l6s and 12ax7s once before in another amp and never had issue. I know that their 12ax7 is popular in v2 for some preamp cocktails but have read on several occasions that it's a harsh tube for v1. Is this the general consensus? Right now the amp sounds great to me but if I could swap out a couple preamp tubes and it will make it sound better I'm going to. I'm interested in finding out Mark IV owners opinions on this.

Rhythm 2 was greatly improved on on the B version and is probably the biggest difference. As far as the JJ's I think they are harsh but many like them. As far as the EL 34's I say if you like them use them! The cleans will suffer but tone is subjective to each of our ears. I can say that all tubes sound different and you can try a lot until you find what you really like. Same goes for the pre-amp tubes. Move them around until you find the combo that works for you.

At the very least I'm going to try a tung-sol reissue in V1.

 

[mule#1]

Let us know how that works!