Mark VII Channel volume differences

[mace]

Well, I bit the bullet and picked up a Mark VII yesterday! After it a quick play through a couple things of note, which seem way different than other Marks I’ve used (use):

1) the PRESENCE knob does way more than on the V90 etc. It brings in mids and drive as well as the upper frequencies. It almost seems like a treble knob with the amount of drive and actual volume it adds when turned up.

2) the volume level between channel 1 and the others is crazy different. When cloning BOLD and CRUNCH on channels 1 and 2 (all settings equal) CH1 volume on 9 o’clock is as loud as CH2 at about 2 o’clock. This is at all power settings.

While the tones are wonderful across the board, I’m wondering what is going on with CH1 being so dang loud. Is this normal?? Also, is it normal that the PRESENCE knob changes drive and volume??

Anyway, more comparisons later.

 

[Revelation]

I am getting mine next week; for what its worth, the manual provides excellent recommendations on using the tone knobs and EQ sliders on different settings. I printed out that section of the manual, and highlighted in yellow the recommendations. The only question I have for you is, are the wattage settings for each channel the same? I did not notice such a huge difference when I tried it out at the store.

 

[bandit2013]

I had to see for myself. You are correct, set up CH1 and CH2 the same. I was hearing a volume difference between CH1 and CH2 both set to fat. Made sure the GEQ was not turning on. The volume difference was not that dramatic though. Just a bit louder in sound but not like what you are hearing. Then I realized the reverb setting was much higher dialed in for CH1 than what I had on CH2. Dialed in the same amount of reverb for both channels no difference in volume when changing channels. Turned off the reverb and the volume was the same. Switched over to the crunch on both channels not touching anything else and did not have a volume difference as you described. If there was any difference at all it would be based on the tolerance of the pots.

If you have a dramatic difference between CH1 and CH2 with the exact same settings. (reverb, GEQ, etc) I would send customer service an email describing what you have. That is not the way it should be. Either there is a solder joint issue, or the wrong pot was installed. I assume this is with the same gain settings? The amp will be loud at 9am volume setting. Matters not what mode you are running on any of the channels. Mark IIB will be much louder due to change in low end response. But the volume differences between CH1 and CH2 should not be that dramatic. Having 9am on CH1 and pushing to 2pm on CH2, yeah something is off. When cloning the two channels, the only thing that gets switched out are the controls. There should not be a dramatic volume difference between the two channels if everything is set the same (at least mine is that way).

Are you using the footswitch? if so, make sure the channel selector is set to CH2. I was getting some weird things happening when I had the switch on CH3 when using the footswitch. Thought it was a glitch or something like that. Wound up with what sounded like a confused amp and self-oscillating preamp tube microphonic feedback issue.

Where did you buy it from? You may be able to make an exchange for another one. Let the distributor deal with the amp issue.

As far as the presence is concerned, yes, that will influence the tone across the spectrum. It is a negative feedback circuit derived from the output that feeds in the phase inverter. It will alter the characteristics as described. The JP2C does this too. It is a very useful tone shaping control. The more presence you dial in, the reduction in negative feedback so more preamp characteristics will be heard as there is less output signal returned to the phase inverter used to cut back on tone. I will have to mess with that on mine to see how it alters the character. That I have not explored to any extent. The Mark VII is different than the Mark V90. The negative feedback circuit on that amp is not as responsive until you move to the extreme mode on CH3 (reconnects the presence to feedback circuit to the 4 ohm tap and adds in a capacitor to reduce the signal level).

 

[Revelation]

I had to see for myself. You are correct, set up CH1 and CH2 the same. I was hearing a volume difference between CH1 and CH2 both set to fat. Made sure the GEQ was not turning on. The volume difference was not that dramatic though. Just a bit louder in sound but not like what you are hearing. Then I realized the reverb setting was much higher dialed in for CH1 than what I had on CH2. Dialed in the same amount of reverb for both channels no difference in volume when changing channels. Turned off the reverb and the volume was the same. Switched over to the crunch on both channels not touching anything else and did not have a volume difference as you described. If there was any difference at all it would be based on the tolerance of the pots.

This is very helpful information regarding the reverb settings for future owners of this wonderful amp.

 

[bandit2013]

There is so much to learn with this new amp. Clean and fat we are all familiar with. I never really considered the clean mode much, that was until I was doing a comparison of the VII to the Badlander. Push the gain up on the clean mode and it rips. Fat mode does not seem to have that character to it, more suited for cleaner sounds. Clean, crunch and VII are the three basic modes in the Badlander, just different on delivery and overall tone. EL34 vs 6L6 thing probably. Not the same preamp either but the character is there in the Mark VII. Easy to get a good match by reduction in midrange but more so with the GEQ than the parametric. Tone stack on Crunch and VII modes is post gain BTW. I got confirmation from Mesa on that specific question.

 

[bandit2013]

Missed the last part on the presence affecting the volume. Mine will do that too. Drop in presence all the way and you are basically increasing the negative feedback signal level, this will cut volume down. I tried this with the badlander I have next to it, there is a slight volume change but not much. Not sure if that amp uses a real adjustable negative feed back or is the control just a high pass filter and the negative feedback is fixed. JP2C as I said is similar but not sure if the volume changes like this. Will have to get it set up and hear if it does the same thing.

 

[mace]

Thanks for the replies.

So, unplugged the speaker and ran the XLR CabClone out into the computer to measure the level difference of CRUNCH. IR 1 was used for all channels. The REVERB and LOOP were off. There is about 9 to 12 dB between Ch1 and Ch2 for the same settings. CH3 set to IIc+ is close to Ch2 at same knob settings. The above was true for all power modes.

The volume of Ch2 has to be at just shy of noon to match Ch1.

Channel one volume pot seems to be messed up or something is wired wrong. Big bummer.

So, yeah, unfortunately is messed up with this expensive and awesome sounding amp. I’ll get ahold of the store where I got it.

Edit: here is a photo of settings when volume is matched. I notice now the TREBLE setting is a bit different but that doesn’t explain a 10 dB difference:

 

[bandit2013]

The difference in the tone controls would not cause this.

How loud would you say the loudness of CH1 is relative to another amp you may have? And would you say that CH2 and CH3 are not very loud or rather weak at 9am. Running at 9am would be near a low end of gig level on all three channels. If CH2 and CH3 are at gig level but CH1 is at concert level, that is a problem. If it is the other way around, CH2 and CH3 are somehow stuck at bedroom level but CH1 is where it should be. If the pot was wired backwards, it would get louder with a counter clockwise rotation and quieter with a clockwise rotation. That is a tech call thing for sure.

In case there is a confused midi control units in the footswitch or in the amp, disconnect the footswitch with the power off and try changing the channels with the mini toggle. Not sure that will do much at all.

 

[mace]

Well, I just did a direct comparison (quickly) to the V:90 using crunch with same dial settings (V:90 with LOOP bypass ON, reverb OFF, no EQ). So, only the MASTER's were active for setting channel volume, like the VII. The V:90 was definitely more like the VII volume on Ch2 and Ch3 for a given MASTER level. When going to VII Ch1 the volume really went up. Using an iPhone dB app it was showing about 110-112 dB for the V:90 and VII Ch2. When going to VII Ch1 it spiked to about 120 dB. (Note, the iPhone was pretty close to the speaker, so that's why it was so loud).

So, it seems that Ch1 is the odd-ball channel on this VII.

It was interesting that both Logic X and an actual microphone in the room were showing about a 10 dB increase of Ch1 over the others. So, the measurements seem to be pretty close.

Both footswitch and mini-toggle channel switching for the VII had the same effect, Ch1 was really loud.

Now, when the VII Ch2 and Ch3 are turned up to noon or so they will also get super-crazy loud, so there doesn't seem to be any issues with those MASTER's.

 

[mace]

Missed the last part on the presence affecting the volume. Mine will do that too. Drop in presence all the way and you are basically increasing the negative feedback signal level, this will cut volume down. I tried this with the balander I have next to it, there is a slight volume change but not much. Not sure if that amp uses a real adjustable negative feed back or is the control just a high pass filter and the negative feedback is fixed. JP2C as I said is similar but not sure if the volume changes like this. Will have to get it set up and hear if it does the same thing.

Thanks for that info. Good to know that the PRESENCE is wired different on the VII than on the V:90. The VII PRESENCE seems to have a much larger effect on tone than the V:90. To me, this is a good thing.

 

[mace]

Ends up Sweetwater will swap the VII out and they have a combo in stock for replacement. So, hopefully the second go around will bring more joy!

 

[bandit2013]

I was messing around with the Mark VII after you posted your findings. I did not notice the effect of the presence control originally. That was a good find and yeah, it does alter volume more than one would expect it too. Now I have to see if the JP2C makes as much of a change in volume. I would assume they share some common topography in the preamp design except for the mass amount of relays used to reconnect the lead drive circuitry for the crunch and VII modes. Also one being a Simul-Class and the other is a Class A/B.

Aside from the odd volume jump on CH1, what is your thoughts on CH2 and CH3? From my findings, the IIC+ mode is a complete duplication of the JP2C but to get the JP to that level you need the STR415 power tubes. The alternative would be the STR448 (TAD red base 6L6GC). I did experiment with different Mesa branded 6L6GC tubes in the Mark VII, STR440 and the STR448. The JJ 6L6GC (STR445) tubes just sound great in the Mark VII. Hopefully that will continue to be a resource for Mesa moving forward. They are hard to get as replacement parts though.

 

[mace]

I was messing around with the Mark VII after you posted your findings. I did not notice the effect of the presence control originally. That was a good find and yeah, it does alter volume more than one would expect it too. Now I have to see if the JP2C makes as much of a change in volume. I would assume they share some common topography in the preamp design except for the mass amount of relays used to reconnect the lead drive circuitry for the crunch and VII modes. Also one being a Simul-Class and the other is a Class A/B.

Aside from the odd volume jump on CH1, what is your thoughts on CH2 and CH3? From my findings, the IIC+ mode is a complete duplication of the JP2C but to get the JP to that level you need the STR415 power tubes. The alternative would be the STR448 (TAD red base 6L6GC). I did experiment with different Mesa branded 6L6GC tubes in the Mark VII, STR440 and the STR448. The JJ 6L6GC (STR445) tubes just sound great in the Mark VII. Hopefully that will continue to be a resource for Mesa moving forward. They are hard to get as replacement parts though.

After a week or two I'll post some thoughts on the amp and modes. First impressions were great on the general tones of channels 2 and 3. I like to let things soak in a bit first before commenting.

 

[cgscotto]

You could also have a failing preamp tube. I had V1 go microphonic in the first week I owned the amp. Specifically, V3B and V4A are limited to channels 2 and 3. I am sure if you call Boogie, that will be the first thing they tell you to check. Could be a power tube as well, but all channels would be affected if that was the case. I would also say that something might be partially grounding a pot, but again that would not, I hope, affect both channels 2 and 3. Call Boogie and let us know what they say.

As far as the controls go, they remind me most of my MKIII. The controls on my MKV felt like they painted the tone in big broad strokes meaning you would really have to really change the knob position a lot to hear significant change. The controls on the MKVII make drastic changes with small incremental changes to the controls. I actually had to dial back my MKV settings on the VII. I like them better this way. I feel like I have more tonal variations in each mode and channel.

Another thing that was surprising to me was that I could dial in a nice clean sound on channel 1 (fat mode) and simply flip the mode switch to crunch for a great crunch sound. This reminded me of the MKIII again in trying to balance the controls so you could get good sounds in each of its three channels. It was always a compromise. It actually works really well on the VII, at least from fat clean to crunch. Flipping the switch sounded and felt just like turning on a drive pedal.

I found I can do the same thing or something similar in the VII mode on channel 2. Once I get the sound I like, I can get a great heavy rhythm sound with EQ on, and a great lead sound with EQ off without adjusting any of the controls.

 

[bandit2013]

I hope the next one is more rewarding. Good to hear you have some resolve on this issue.

I usually just jump in and end up with a blog. I will not hold back on issues I find either. At least the glitch issue was resolved as it was related to a micro-phonic tube. Took a while to get some preamp tubes in but those fixed the problem. Now the Mark VII sound even better than it did. That for sure is not the issue you have with yours. Even with a micro-phonic preamp tube, I did not discover the volume upset between channels except when using the Mark IIB mode if you do not make adjustments for that particular mode vs leaving what you dialed for the IIC or IV modes.

 

[bandit2013]

V3B is used on CH1 and CH2 in the crunch mode. The tube task chart is not straightforward. I made an attempt to simplify the array of triodes based on the information. I did email Mesa to get confirmation if the tone stack is pre-gain or post-gain in crunch or VII modes. Turns out they said it was like the Mark V90 CH2 as the tone stack is post-gain.

CH1 does not make use of V4A. I did not map out the clean or fat as that is like the top row without V3V or V4A in the circuit. I was more interested in the non-clean modes. I could update the graphic and include the Clean and FAT modes.

Not sure if this helps anyone. I found it useful. Much easier to follow than the excel matrix I created based on the tube task chart as it was written. It is a bit more comprehensive than just the Mark VII as I included the V90 and V35 in the matrix. Was curious how they managed to get the modes in the Mark VII with only 5 tubes vs 6 or 7 like the previous models.

 

[bandit2013]

Just being helpful, or at least trying to be helpful.
You can correct me if I am wrong on this. The tube task chart in the manual was not easy to follow and I make mistakes.

 

[mace]

Now that a replacement is secured I was going to reach out to Mesa and get their thoughts.

But, the issue cannot be a pre-amp tube or any tube. Ch1 and Ch2 FAT and CRUNCH are identically wired. The fact that when Ch1 and Ch2 MASTERs are set the same and Ch1 blows my head off qand Ch2 is at a comfortable volume means something is wrong with the MASTER on Ch1.

 

[bandit2013]

That sounds like the pot has a bad ground connection. Instead of providing a variable voltage divider you are getting an adjustable grid stopper.

From my experimentation, the volume controls follow the FX loop similar to what the MV90 has with its global output control. I found the JP2C and Badlander are designed this way as well.

I tried to slave out to another amp to determine if the GEQ was before or after the FX loop. It is after the loop and so is the channel volume. I got a full tilt effect salving into an amp that has no final volume so it was really loud.

 

[Revelation]

I received my Mark VII today and the volumes on each channel are pretty much the same. So hopefully your new amp won't have the problem.

Background: I went to the Guitar Center today and purchased a new one out of a box Before I left the store, I tested each channel, and their modes. I also looked for any damage to the unit in transit. I was surprised how much stuff they put in the back of the amp including the wheels, manual, foot switch and its long cable.