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Mesa D180/400 Tube Question

#42
Yeah... I checked out the manual. Pretty vague about the tone controls.

I also did not see anything about a switch thats located on top of the rear panel. There is ground lift switch & fan switch on the right side, but another switch is on the left. Not labeled ...hmmmm :hmm:
 
#43
joetiii said:
Yeah... I checked out the manual. Pretty vague about the tone controls.

I also did not see anything about a switch thats located on top of the rear panel. There is ground lift switch & fan switch on the right side, but another switch is on the left. Not labeled ...hmmmm :hmm:
Click to expand...

I believe the one on the left is a ground switch for the balanced line out...that's what it is on a 400+ for sure...
 
#47
My preamp tubes are named on the chassis with a label. Looking from the rear, from left to right, there are two 12AX7's then an AT7 and the last on the right is an AX7.

I believe the AT7 is a phase inverter but I am probably way off on that.
 
#49
So last night I tested out the slave out on my Boogie 180.

I put the 1/4" in to the aux in my Eden combo. When I fired up both amps, and turned up the slave output, the eden speaker cones stated to move in and out to create what I call a low rumble. I never played any notes... just powered it up. Is this a grounding issue? I don't think so because when I turn the Master control down off of 10, the cones stopped moving.

Afterward, I noticed the same type of speaker cone movement attched to the regular output going to my other speaker. I switched over the ground lift and it went away.

Why would running the master a full cause this situation?

hmmmm :help:
 
#50
Spoke with George from Mesa Boogie today. He cleared things up for me on the D180 preamp configuration. Apparently there are three versions... one had 2 12AX7's in the preamp, a 12AT7 phase inverter and one more 12AX7 in the final master stage. A second version had one 12AX7, 2 x 12AT7's and a final 12AX7. The last version had 4 12AX7's. The amps were only labeled if/when they had different tube sockets.
 
#51
I just learned that you should not run the slave out without having a 8 or 4 ohm cab hooked up to the std 1/4 output. Something about impedance mismatching.

My question asks whether this applies to the XLR ouput as well. Can I run the XLR w/o a speaker being driven by the amp?:confused:
 
#52
This is an excerpt from an old Mesa brochure. The interesting thing is that within the Japanese (my apologies if it's something else) text you can see "STR-6550" and "M-180" appearing interestingly close to each other in the text bit near the D-180 pics.

Is there someone who could translate this and/or take a peek at the English version of this brochure? It would probably answer the question as to whether 6550s could be used as a direct replacement in the D-180/M-180.

Why do I care? An M-180 is on it's way to my place... :D
 
#53
It seems that the linked pic has disappeared. Anyhoo, here are the links to the brochure I was referring to. The D-180/M-180/M-190 stuff is on page 4.

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#54
joetiii said:
I just learned that you should not run the slave out without having a 8 or 4 ohm cab hooked up to the std 1/4 output. Something about impedance mismatching.

My question asks whether this applies to the XLR ouput as well. Can I run the XLR w/o a speaker being driven by the amp?:confused:
Click to expand...
Do NOT run the amp without a speaker load, no matter what you have connected to the line out.

As an aside, you may like running the amp with an additional lower gain pre-tube in it. I used to run mine (i've since sold it) with a 12AT-7 in the 2nd position, which is the front end of the bass channel. The volume doesn't creep up so quickly, and it's easier to dial in. You don't have to try and inch the volume 2 knob between 2 1/2 and 3 to hit the level you need. With a 12AT-7 in there, the sweet spot moves more towards the middle of the volume pot sweep and the sound get more balanced.

These are great amps. I only sold mine because I stopped playing bass (for a while). Now that i'm back in the game again, I wish I still had it.

-Nick
 
#55
I've been contemplating rolling a few other tubes in my D180. I have a set of amperex 12ax7 bugle boys on the way and I'm dieing to hear how they sound against a pair of triple mica JAN 5751's.The 5751's run about 60% of the gain compared to 12AX7's and they're a bit cleaner sounding and definitely alot more quiet. When I rolled a 5751 into my Eden head, it was definitely not as warm sounding as the Mesa 12ax7. Though that was just one tube in the preamp feeding a SS power section. We'll hear what they sound like.:bassist:
 
#56
Resurrecting an ancient thread. A Boogie tech told me 6550s would work in my 180 without modifications, so I tried it. For about 30 seconds. 3 of them started glowing much brighter than the other 3 very quickly. I never even tried it out with a bass, just shut it down immediately. Tubes and amp are both still working fine, but I'll stick with 6L6s. After experimenting with various 6L6 and preamp tubes, I ended up using JJ power tubes and a selection of vintage US preamp tubes. I don't like the JJs for bass, but I've set the 180 up as a guitar amp so I picked the tubes that sounded best with guitar.

I have a deposit on a 400, and my bro still owns my old 400+, so provided the 400 passes its health exam I will soon be able to compare all 3 Boogie rackmount tube heads.
 

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