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APEMAN, this is very interesting. Just to make sure are you talking about the ferrite bead which is the first component in the circuit (direct inline from the input jack to pin 2 of the first tube V1A)? I had never paid much attention to that, I assume it is there to attenuate high-frequency electromagnetic interference (EMI). My other brand amps typically use a resistor instead.

I will have to check this out on my 2010 which is plagued with the hi frequency issue as well. Thanks!

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This post is timely. I’m going to have to take my amp to a tech to repair something with the reverb. So I would be very interested having this mod applied also. But, I’m a bit unsure as to what this mod does. You a junpering a faulty part? May I ask why not replace the faulty part with a good one?

I asked Mesa about repairing the reverb and also applying any changes which have been made to the Mark V since 2011 (bought mine new in early 2012). Now, this doesn’t rule out a change since 2010 but this was the statement: “We do not have any updates/mods for the Mark V, so your 2011 unit will be the same as the amps we build today.“

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Well, seems simple enough. And if something changes that is not welcome you could just snip the jumper, right?

Any photos of this this part or the mod you did?

Also, did you do oscilloscope measurements with and without the Fe ring or was it by ear (you mention delays and disharmonic high frequency signals as large as the original signal)?

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APEMAN said:

...It was simply obvious, that the fizzy and annoying top layer in the sound was gone after jumpering it.

Click to expand...

Very intriguing.
Is your amp tamed with the jumper and at7 or ax7? Perhaps both sound good for you now?

I still can’t quite get there with the at7 on my 2012. Mine still needs a little more help.

My amp has not had anything done to it except tube changes. I’m game for this mod. Sounds like the one I’m willing and able to do as my eyes begin to fatigue quickly with this type of stuff.

Really appreciate the info!

I’m going to give this a try with the plan that if it doesn’t help or makes things worse the jumper could be snipped.

Ended up with an unexpected day off. Got the amp out of the box now.

I’m feeling a little claustrophobic in here though. There is a lot. I’m looking at the ferrite bead first in line from input as you suggested. But there’s not a ton of room to work here. I’m not as confident as I was when younger...

As Mace said, is there a photo of the mod you did? A little reassurance would be appreciated.

Thanks!

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Thank you! I’m ok with doing this work... I meant confident in terms of how long I can maintain the focus. My eyes aren’t what they used to be, though I’m comfortable with the precautions needed for the work.

Always good to err on the side of caution- good of you to give the reminder

Thanks again for confirmation, excited to dig back in...

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Same here. I like both, but have landed back with ax7 as well. That’s why I was excited about your post- possibly a solution that I like better...

I''ve stuck with AT7 in V4 for quite a while. But, channels 2 and 3 sometimes just seem to have a bit of a graininess to them. A halo of unpleasantness, like a bad mp3 played in the car stereo with too much treble, but when you turn the treble down the grit is still there. It seems not all the time either, maybe power setting or volume level dependent. Anywho, even after getting the newer 6L6s the inorganic grind was still there sometimes in the Mark V.

I'm really curious what this little "Fe ring" bypass mod does.

It is also interesting to note that the originator of the mighty AT7 mod is back to full AX7's. :shock:

It is really weird how people interact with imprecise things as distorted tones. One day it is the greatest thing ever - amazing, monster, full rich tone - so sweet, best tone ever! then after a while... well, maybe the tone could use a 'little something'. Ever searching for the holy grail. haha

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Could it be that the part you bypassed, might have been faulty when your bought your amp?

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Unfortunately, this is another example completely incorrect information being propagated on the Boogie Board!

The ferrite bead effects frequencies beyond human hearing, and block the introduction of high frequency radio waves. 300k to 5Mhz

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