GK MB Fusion 800 Issue....A Tube Problem?

[ClassicJazz]

I have has this happen to me twice so far, I would fire it up and there is a loss of power and the bass cuts in and out. But then after 5-10 minutes it is fine with no problems. The first time it happened the amp had not been previously used. The second time, I did a 3 hr gig which it worked fine, then at the second gig (around two hrs between), when I turned it on that issue happened. But as I mentioned, after a couple of songs it worked fine.

Could this be a tube issue? The tubes themselves seem to be seated fine in the sockets.

 

[erigod23]

I have no personal experience, but previous GK issue threads have mentioned emailing their support. Apparently, it is very good.

 

[jlepre]

I don't know alot about this amp, but IIRC the tube is just in the pre-amp section. I wouldn't think that would effect this amp in that way if it was a faulty tube.

 

[RevGroove]

Any update? Having a similar problem with mine, assumed it was the tubes as well...

 

[RevGroove]

I replaced the stock tubes (with GT 12AX7s), still had the same problem intermittently...but killer tone besides that!

Then I took of the top, checked all the Moxley connections...one on the preamp wasn't seated quite right, secured it, problem gone...

 

[kuuuks]

I replaced the stock tubes (with GT 12AX7s), still had the same problem intermittently...but killer tone besides that!

Then I took of the top, checked all the Moxley connections...one on the preamp wasn't seated quite right, secured it, problem gone...

Do you have a link for the particular tubes you bought?

 

[joel406]

Do you have a link for the particular tubes you bought?

Call the number on the GK website.

Talk to Jason. He will email you the link to the tube you need. Their like $10 each.

 

[kuuuks]

Call the number on the GK website.

Talk to Jason. He will email you the link to the tube you need. Their like $10 each.

Thx much

 

[RevGroove]

Do you have a link for the particular tubes you bought?

Here's a link to the Groove Tubes Catalogue and price list (with descriptions): Invalid Link Removed

Model 12AX7C is what I went with this time...your local music store should have them. The stock tubes weren't bad...just different...

 

[Jamo2000]

I replaced the stock tubes (with GT 12AX7s), still had the same problem intermittently...but killer tone besides that!

Then I took of the top, checked all the Moxley connections...one on the preamp wasn't seated quite right, secured it, problem gone...

What is a Moxley connection?

 

[FunkHead]

Moxley connection

??

 

[RevGroove]

What is a Moxley connection?

The connections at the end of the wires:

 

[FunkHead]

The connections at the end of the wires: View attachment 4219265

Aha, You meant Molex.

 

[RevGroove]

Aha, You meant Molex.

D'oh! Thanks!

 

[Jamo2000]

The connections at the end of the wires: View attachment 4219265

Thanks!