Channel switching for Mark I...how?

[TPM]

First, I know it's not supposed to be a channel switching amp. That being said, is there a way to hook up some cables to it so I can switch between "channel" 1 and 2? I tried my Boss Line Selector pedal, and for some reason, it did not work (unless I hooked it up wrong). Is this something that can be bought from Boogie? Thanks.

Tom

 

[Dirt123]

Yup. Check it out:

http://mesa.stores.yahoo.net/bfootswitch.html


There's gonna be a huge volume change when you do this, though.

 

[RR]

A/B box where the two outputs goes to each inputs on the Mark I and the other goes to guitar (duh).

As for your other question, a Mark II has little more control on the footswitching capabilities over Mark I since you just have one guitar input, and then a relay footswitch and you have extra control of the volumes between the two channels.

That's why many of us (except Mark IV owners) say the Mark IIC+ is MESA Boogies' "ultimate" Mark Series.

 

[TPM]

A/B box where the two outputs goes to each inputs on the Mark I and the other goes to guitar (duh).

As for your other question, a Mark II has little more control on the footswitching capabilities over Mark I since you just have one guitar input, and then a relay footswitch and you have extra control of the volumes between the two channels.

That's why many of us (except Mark IV owners) say the Mark IIC+ is MESA Boogies' "ultimate" Mark Series.

Hmm...my Boss line selector pedal (which I thought was basically an A/B box) should work shouldn't it? I'll have to try it again...I thought maybe there was something funny about the two inputs in that if both are plugged in, maybe they cancelled eachother out? And yeah, I've been thinking about a Mark II, but I'll see if I can get this work first. Thanks.

 

[RR]

I'm not familiar with Boss Line Selector. Maybe I should check it out Musician's Friend.

The A/B box I'm talking about just has a STDP (or is it DPST?) footswitch and is passive. I'm pretty sure you know what I'm talking about.

Uh, just juggle between the two channel during a gig, aren't you quick enough? Just tell your band to hold extra bar so you could switch to the drive channel

 

[TPM]

I'm not familiar with Boss Line Selector. Maybe I should check it out Musician's Friend.

The A/B box I'm talking about just has a STDP (or is it DPST?) footswitch and is passive. I'm pretty sure you know what I'm talking about.

Uh, just juggle between the two channel during a gig, aren't you quick enough? Just tell your band to hold extra bar so you could switch to the drive channel

HA! Yeah, I'll just scream "SOLO TIME!" and then run quickly over to the amp, pull out the chord to volume 2 (*crackle*), slam it into volume 1 (*crackle*), adjust the master, and then start ripping...shouldn't take me THAT long, sheesh.

Well, as far as the A/B goes, I thought I knew what it was, but when my Boss pedal didn't work, I wasn't sure. Hell, I probably hooked it up wrong. Thanks for tips!

 

[RR]

I used to own a Mitchell Pro-100 EQ/Rev which was a poorman's version of M/B Mark I. => http://forum.grailtone.com/viewtopic.php?t=3827

I used a passive DOD A/B swtich stomp box.

But I'm looking at Today's A/B boxes and they're battery operated to eliminate "pop" noise. Now I'm not sure what's happening in your case.

but my DOD box had this footswitch inside. I'm not sure if they making them anymore 'cause they seemed to be running off batteries.

 

[JOEY B.]

The footswitch has to be wired internally in a specific way. Your garden variety A/B box may not do it. I spoke with MESA about it. The volume drop is HUGE, I would not recommend channel switching this way. On my Mark I an overdrive pedal is used to get the lead sound. You can then switch off the pedal and/or reduce the volume knob on the guitar to clean up your sound. I can't figure out why the Re-issue was not offered with the Graphic EQ and Pull Gain and Pull Bright Knobs. The Gain boost footswitch jack underneath the chassis on my original Mark I gives me four channels with the pedal.

 

[Kinx]

I use mk I RI with both volumes set about 9, and volume drop between two inputs isn't huge in my opinion, I played many gigs with these settings and everything worked fine except that channel 2 isn't very clean anymore, but personally i love this sound.

 

[TPM]

The footswitch has to be wired internally in a specific way. Your garden variety A/B box may not do it. I spoke with MESA about it. The volume drop is HUGE, I would not recommend channel switching this way. On my Mark I an overdrive pedal is used to get the lead sound. You can then switch off the pedal and/or reduce the volume knob on the guitar to clean up your sound. I can't figure out why the Re-issue was not offered with the Graphic EQ and Pull Gain and Pull Bright Knobs. The Gain boost footswitch jack underneath the chassis on my original Mark I gives me four channels with the pedal.

Thanks for the insight...yeah, something tells me there's something else going on with the A/B. I tried it the other night again with my Boss pedal, and for some reason, volume 2 is huge but volume 1 is reall quiet...anyway, I'm going to call Mesa. As far as the graphic EQ and pull knobs, yeah, I keep hearing how great those sound on the MK1, I wish they had put them on as well. I wonder if I could get the amp modded by Mesa to have the gain boost footswitch, that sounds really cool. Does it work for both channels? Probaby only channel 1 I assume. Anyway, thanks again.

Tom

 

[JOEY B.]

The way I understand it , Input 1 feeds through Volume 1 then through Volume 2 and on to the tone circuit. Input 2 only feeds through Volume 2 and this knob only has the pull bright feature before going to the tone circuit. So the footswitch jack for "gain boost" should only affect Input 1. Keep in mind that when the "gain boost" is activated, it bypasses the tone controls (like they're all set on 10). With this activated the only tone shaping that is available is in the EQ.

 

[Sofdiw]

It is really??

 

[RR]

It is really??

Dittto here! :?
The volume controls I understand because that's the preception I got but I did not realize the boost switch bypass the tone controls. Interesting

 

[Dirt123]

If I understand the schematic correctly, the gain switch doesn't completely bypass the tone controls, it shunts around a resistor (I can't remember which one) giving more gain and mids to at one point in the tone stack. The tones controls should still have an effect.

 

[JOEY B.]

You may be correct about the resistor. I was only quoting someone else's post. It may be that the gain is so high (compression), that the tone controls only seem to be much less effective to the ear. The EQ is just as effective with the gain boost on or off. My MARK I has a true effects loop put in by Mike B. during the late 1980's. He said that this mod involves moving the EQ in the circuit so that it is after the FX return in the signal chain . There is also a knob on the rear that reads "POST FX LEVEL". He said that it controls how much of the preamp signal is fed into the power section. This mod can still be done today for around $250 if I remember correctly.

 

[John G]

Hi,
I wonder if you are succesfull at ch switching between the two input jacks how hard it would be to take say the preamp out jack socket point(on the origional MK1) and change it to a stereo one, providing a post pre-amp loop break point. This could be used not only for line level effects but by using a stereo cable(tip-ring-sleeve) you could then run it to the ch switcher box and wire it along with a master vol pot so when the footswitcher switches to the Hi gain input the same f/sw also brings in an additional m/v to control the additional volume. Sounds a bit messy with lots of cables running every where, but it may be a way of controling the volume jump.
Just an idea.
Cheers
John G