Speaking of contrarians. Mk VII owners; can you try something for me? Power tubes problem?

[JiveTurkey]

In the past I've pull a couple power tubes to get in there.

Now, my JP2C sits with the front panel off.

I assume I can pull the 4 front screws to do that?

 

[Deadpan]

I assume I can pull the 4 front screws to do that?

Yep

 

[TSJMajesty]

Oh, so you "can" get them out, but it's not as easy to see what you're doing when aligning the key of the tubes, putting them back in?

Why not stick your phone in there, and take a pic, so you can see where that tab/key is located, then when you reinstall the tubes, you can hold that key in the right position. Just trying to think of a way you can keep that chassis in there, so you can swap tubes, and fire it up right away to see if it solves the issue.

 

[JiveTurkey]

Yep

Thanks!

Oh, so you "can" get them out, but it's not as easy to see what you're doing when aligning the key of the tubes, putting them back in?

Why not stick your phone in there, and take a pic, so you can see where that tab/key is located, then when you reinstall the tubes, you can hold that key in the right position. Just trying to think of a way you can keep that chassis in there, so you can swap tubes, and fire it up right away to see if it solves the issue.

Got the 2 center tubes out now. We'll see how it goes

 

[TSJMajesty]

Thanks!

Got the 2 center tubes out now. We'll see how it goes

You'll be fine. Something tells me this ain't your first rodeo.

 

[Desertdweller]

Yep. There is no room to safely maneuver.

I haven't checked but you might be able to get to the 12ax7 you need through the front.

 

[JiveTurkey]

Pre amp is quieter on 3, poweramp louder….I’d navigate on the assumption it’s “as designed…and I’ll eat my shoe if there’s some sort of issue causing this.

I think you are 100% on the money. I went through each preamp tube. No matter what; it worked that way.

The only way to test this as an owner would be using the FX send to something else and tap it there. My issues with the stomp volumes on channel 3 appeared at the send out on the Stomp which would be that send tap from the amp itself. It has got be designed this way. If you put something in the loop of the VII and go from that multifx/whatever back to the VII's return; the channel volumes are as they should be. It's only if you tap channel 3 at the amps send that you get that volume discrepancy. What an odd design choice.

 

[James Freeman]

Why pull tubes before understanding how the loop works?
The Master on each channel work as either Send or Return volume controls, they are either before or after the loop.

The JP2C had an official FX Loop revision where they moved only Channel 1 Master after the fx loop.
This could be different on the VII.

You want to check if the Master volumes on each channel are before or after the Loop,
Plug your guitar into the FX Retrun and check if the Master of each channel controls the volume after the loop.
This is suggested in the link below by MESA.
*Start with all master volumes on 0 to not blow anything.

"We moved the location of the Ch1 Master pot, from before the Send to after the Return. This change only affects Ch1, and does not affect the tone at all. The Gain control now becomes the Send level, instead of the Master. Thanks!"

Source

Official loop update info:

https://mesaboogie.zendesk.com/hc/en-us/articles/115003821813-Does-my-JP-2C-have-the-loop-update-

 

[JiveTurkey]

Yeah…seems to me no problem as long as you don’t insert other amplification methods in the loop. Adding a 2nd amp for a stereo setup would come with some complications to tackle.

If there's a complication; I'll certainly find it

 

[PBGas]

Just tried. Ran mine into the H90 and out to the KSRPA50 to cab.
They are pretty close as it not that much change in volume that I could detect. Very slight if anything.

Now as far as changing tubes goes....this is why I bought the rack versions for both amps. 4 screws, slide the chassis out and off you go!

 

[JiveTurkey]

Just tried. Ran mine into the H90 and out to the KSRPA50 to cab.
They are pretty close as it not that much change in volume that I could detect. Very slight if anything.

Now as far as changing tubes goes....this is why I bought the rack versions for both amps. 4 screws, slide the chassis out and off you go!

Thanks for checking! There's a very noticeable dip in mine. I'm not planning on running it in this manner so I'll probably just deal with it as is

 

[Deadpan]

Thanks for checking! There's a very noticeable dip in mine. I'm not planning on running it in this manner so I'll probably just deal with it as is

Message Mesa at least.

 

[JiveTurkey]

Message Mesa at least.

I will next week.

 

[JiveTurkey]

Why pull tubes before understanding how the loop works?
The Master on each channel work as either Send or Return volume controls, they are either before or after the loop.

The JP2C had an official FX Loop revision where they moved only Channel 1 Master after the fx loop.
This could be different on the VII.

You want to check if the Master volumes on each channel are before or after the Loop,
Plug your guitar into the FX Retrun and check if the Master of each channel controls the volume after the loop.
This is suggested in the link below by MESA.
*Start with all master volumes on 0 to not blow anything.


Source

Official loop update info:

https://mesaboogie.zendesk.com/hc/en-us/articles/115003821813-Does-my-JP-2C-have-the-loop-update-

This is (as I expected) how it works. Straight in to fx return and channel master is volume control. And doesn't explain why the preamp volumes are so different. Contacting my sales rep tomorrow.

 

[la szum]

Other than times like this; I like the small headshell. I might be able to get the power tubes out as the cage has just enough clearance. I don't trust the ability to dig around on the preamp tubes side though and then get the pins back in correctly with that limited visibility and space to move. Reading the tube layout isn't really any clearer than talking it out here either

Holy 20 pounds of shit in a 10 pound sack!!

 

[MCII KT150]

Holy 20 pounds of s**t in a 10 pound sack!!

Didn't think they could cram much more in after the MKIV.

Don't care for the ribbon cables in the JP2C. But more MFr's seem to be using them.

I'll post gut shots of my MKV, MKVII, MKI, MKIIC+ if I ever get them uploaded.

 

[mbenigni]

This is (as I expected) how it works. Straight in to fx return and channel master is volume control. And doesn't explain why the preamp volumes are so different. Contacting my sales rep tomorrow.

The TA-30 is similarly quirky, in that channel 1 has Master Volume post-FX loop and channel 2 has Master volume pre-FX loop. Meaning, if you're running 4cm on channel 2 and you accidentally pull the Mesa preamp out of the equation, you're (very suddenly) getting the entire power amp blowing your hair back. (In my case, all that's required is for my HX Stomp to run out of battery power. )

If you're dealing with a similar issue, then diming the Master Volumes on the MkVII should (approximately) normalize the preamp outputs across all three channels.

 

[JiveTurkey]

The TA-30 is similarly quirky, in that channel 1 has Master Volume post-FX loop and channel 2 has Master volume pre-FX loop. Meaning, if you're running 4cm on channel 2 and you accidentally pull the Mesa preamp out of the equation, you're (very suddenly) getting the entire power amp blowing your hair back. (In my case, all that's required is for my HX Stomp to run out of battery power. )

If you're dealing with a similar issue, then diming the Master Volumes on the MkVII should (approximately) normalize the preamp outputs across all three channels.

Yeah this relates to the reply I had for Stratzus in one of the other bazillion Boogie threads here about why I am not going 4cm with the FM. The VII (certainly) is toggled/eq'd/loop'd/reverb/mode'd up to the hilt to a point where it's too much for me beyond having a single channel set to face melt through a curated set of speakers with nothing else and no channels getting switched

 

[mbenigni]

Yeah this relates to the reply I had for Stratzus in one of the other bazillion Boogie threads here about why I am not going 4cm with the FM. The VII (certainly) is toggled/eq'd/loop'd/reverb/mode'd up to the hilt to a point where it's too much for me beyond having a single channel set to face melt through a curated set of speakers with nothing else and no channels getting switched

Yeah, I've come to the same conclusion, even with the relatively simple TA-30. Better to just use the Stomp in the TA's FX loop for post effects. I have a great drive pedal (the Black Country Customs TI Boost) up front and I don't really need much else. (Though I am seeking advice about a good, cheap wah pedal in a separate thread...)

If I do ever want the variety of HX preamps in place of the TA preamp, that will be 4cm in channel 1 only. Putting the MV in radically different places on the two channels of a single amp is a bit batshit IMO. I think Mesa did this in order to accommodate the non-MV push switch (subbing a Vox AC Cut control.) Which, by the way, I find equally batshit. If anything it should be pull for non-MV. (Better still, another toggle switch.) As is, it's way too easy to brush up against that switch and knock half your teeth loose.

 

[jellodog]

Didn't think they could cram much more in after the MKIV.

Don't care for the ribbon cables in the JP2C. But more MFr's seem to be using them.

I'll post gut shots of my MKV, MKVII, MKI, MKIIC+ if I ever get them uploaded.

Say what you like about Friedman, but his gut shots look way nicer.


No... WAIT.