Secrets of the Mesa Bass 400 Revealed

[chaosMK]

The Bass 400 (non-plus) has to be my favorite amp of all time. I love how you can put some KT-88's in it. I own my second one right now (foolishly sold my first, which was pristine).

There are a bunch of stories about the history of this unit... D180, 6550's, etc. Most are probably true.

I noticed this on an old pic of my first one (Serial 363):


D-180!

Current Bass 400 (Serial 718, Feb '88):


B 400-A

They are probably pretty much the same circuit, but it intrigued me. I didn't realize my original was such a low number. It was loaded with 6L6's, so if they ever made them with 6550's it must have been just the first few.

Anyone have anything interesting about this particular head? Supposedly only 1200 or so were made, but I have no idea where that comes from.

[Caca de Kick]

Right, the graphic EQ board is the same for the D180 and 400.

My mainstay Bass 400 is serial # 55x. Can't remember the last digit right now, but it is also dated 1988, but I wanna say it was spring 88.

I had a spare 400 that was an earlier 87 build date, but I can't even remember what serial range it was. But it had the early details like; the eq board, and chrome 1/4" jacks, and had a non-textured flat-satin finish instead of the textured low gloss-satin that my '88 has.

[chicago_mike]

They started out with 6550's. Then moved to 6l6's. The pinout is the same but the current draw is way different.

[LiquidMidnight]

Is there any coding to Mesa's serial numbers that will reveal the date they were made?

[Caca de Kick]

You have to remove the bottom lid (careful! don't touch any caps while plugged in, or in recent use!), and if it still has the factory caps then it will have the build date written on it.

[chaosMK]

My older one had a much smoother finish. This one has more of a textured powder coat. I thought that the previous owner just tried to spraypaint it or something.