Mark V: Mark IV mode squealing, need help

[Mark III Madness]

I've got it all working great now! Just replaced preamp tube V3. It was very microphonic. That's what worked for me! Now this Mark V rules!!!! The Mark IV setting on Channel 3 is ultra rowdy!

So, my conclusion is... now that I've got fully functioning preamp tubes, this Mark V sounds incredible! Yay!!!! :lol:

 

[jressell]

I replaced all of the preamp tubes and still had the squeal... did replacing them really remove it for you?

 

[Mark III Madness]

For sure. Just replacing V3 got me there. Now I've a fully functioning Mark V. Sorry the same didn't work for you. :?

 

[jressell]

I replaced V3 and V4 together and removed some of the squealing.... I wonder if I have a full set of bad preamp tubes.

 

[gplex]

I replaced V3 and V4 together and removed some of the squealing.... I wonder if I have a full set of bad preamp tubes.

Does it only squeal when the bright switch is on mark IV mode? I can use more gain when in normal. When I click on bright it starts to squeal. If I lower the gain to 2:00 and it goes away. I think it's just how it is. I have been using MKIV in normal with the gain at 3:00. No squeal's at all.

 

[Scrapinger]

I had a lot of issues with squeeling in the Mark IV lead channel with most of my guitars. I bought a new Gibson Explorer and I can generally crank it up now and not get it. Also, I have to take the lead channel out of mid-gain, pull bright in. With those modifications done I can get by with my other guitars too.

 

[scott from _actual time_]

how are your pickups? any chance they could be microphonic?

i get squealing in the Mk IV mode (Bright switch on and gain pretty high) when using any pickups that are even slightly microphonic. even if they work fine with other amps and Mk V modes, they squeal uncontrollably on Mk IV mode. but with all my pickups that are solidly non-microphonic, i have no squealing at all.

eventually i will repot those couple pickups in fresh wax to fix them.

 

[Scrapinger]

My axes that squeel are def of the unwaxed type. I have a 81 les Paul Heritage with the original patent applied for pickups. My other is a 81 Ibanez Artist 335 copy that has the same situation. They have great classic tone, but they can't handle high gain.

As an aside here....I had a lot of squeeling and hum in my Mark IV head in R2 and Lead until I got rid of Boogie 12ax7's and replaced them with Tung Sols.

 

[Mark Fore]

Does anyone truly believe playing with those original settings (gain 3 o'clock, volume 3 o'clock) would NOT warrant excessive squealing? You can waste your money on swapping out tubes, but man... if you can get those settings not to squeal, let us know what you did to fix it.

 

[4406cuda]

Turn the channel master volume down and the squealing goes away!

 

[Mark III Madness]

From my own experience of having the trouble of having a microphonic tube (V3 in my case) and the replacing it, I'd say it was worth the trouble. Even though I could have avoided the squealing by keeping the channel’s master volume down, IMHO, the channel truly starts to sound best when the master is turned up to around the “noon” area. So, I think a master volume setting of nine o’clock is a safe way to operate, but twelve is where I think the wicked tone starts to kick in!

 

[Scrapinger]

Amen brother. I agree. Some Boogie techs have told be over an issue regarding my R1 being much much louder and brighter than my R2 to turn my R1 gain down, but if I do so, I loose the tone I am looking for. As we all know it's all about the tone...why else would we own Boogies? They ain't cheap. :lol:

 

[4406cuda]

I run my channel Master in the Mark IV mode around noon with no squealing. It starts to squeal if I go above one o'clock, especially if you have the bright switch turned on.