Volume contols on original MK 1

[boogie-boy]

Hi !
I aquired my second original MK 1 recently, and today I had the time to A/B test them.

On the older one, a 1976, Volume one is totally out of circuit when plugged into input 2. Only volume two and master i active.

On the "new" one, a 1977, both volume 1 and 2 are active, both on input 1 and 2.

Witch one is the usual or "right" one ?

They also react very different. when they are about equal on volume the master volume on the 76 is about 2, while the 77 is about 6. I know two are never like, but i find this difference fairly unusual. On ten they seem the same however, exept the 77 is a bit weaker on input one.

Both amps has pull bright, but My ears can not hear any effect on neither of the amps.

Please describe yours, and help me shine a light on the subject. I have noe other amp availiable to compare with.

Regards !
Stian
Norway

 

[MrMarkIII]

Mesa probably adjusted the taper on the later iterations to dial in slower, and thus be more user-friendly.
The Pull-Bright, I believe, is designed to dial itself out as the volume is increased. At least, that's the way it works on the Mark III.

 

[mark1406]

The volume 1 should not be operating when you are plugged into input 2. This diagram best illustrates this.

Mark 1 reissue preamp circuit

Regards

Mark

 

[bluebug]

On my Mark 1 (03-1978) volume 1 has no effect when connected into input 2. And I have the more drastic master volume curve.

 

[mark1406]

Hi !
I aquired my second original MK 1 recently, and today I had the time to A/B test them.

On the older one, a 1976, Volume one is totally out of circuit when plugged into input 2. Only volume two and master i active.

On the "new" one, a 1977, both volume 1 and 2 are active, both on input 1 and 2.

Witch one is the usual or "right" one ?

They also react very different. when they are about equal on volume the master volume on the 76 is about 2, while the 77 is about 6. I know two are never like, but i find this difference fairly unusual. On ten they seem the same however, exept the 77 is a bit weaker on input one.

Both amps has pull bright, but My ears can not hear any effect on neither of the amps.

Please describe yours, and help me shine a light on the subject. I have noe other amp availiable to compare with.

Regards !
Stian
Norway

The only was volume 1 would effect the amp when plugged into input 2 is if the volume 1 were wired the wrong way around.

Regards

Mark