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Mesa 400 vs. 400+

T

traynorbassmate

Jun 17, 2009
108
1
#1
Hi everyone.

I know there a bunch of threads going on regarding this head-to-head match up...er...no pun intended...but I guess I have some specific questions regarding a post I read once but can no longer find. Sorry for beating a dead horse...

I once read something about these types of amps having a higher-than-average plate voltage on the output tubes as well as having a fixed bias (non adjustable) and that some tubes handle this application better than others...yet I can't find that particular post.

First, I take it that 6550 and 6L6 are fully interchangeable, yet I have my doubts. The 400 schematic says to use one or the other.

The point of the 'post' i'm in search of mentions something along the lines of "X tube can handle the higher plate voltage much better than Y tube can, hence X will have a prolonged tube life" etc etc. I generally understand the concept that military grade tubes are a number one choice (svetlana's or GE/Philips Jan). But does the high plate voltage tolerance between tube number also come into play?

Then there is the tonal difference between tubes. I'm a Leslie sucker so i'm biased and would, off the top of my head, go for the 6550's (also beceause the svt uses them). The online consensus seems to be that people like the tonal qualities of the 400 over the 400+. Does tube choice alter the overall sound characteristics by a significant amount that the average person can distinguish between?

Also, i would love to hear some input regarding the post title in general.

Much appreciated,
Cheers!
 
#2
6550s handle more power than 6l6s, IIRC. Like double almost. Not sure how that works in the 400 though - might not have enough voltage to push the 6550s hard enough, I dunno.

Adding an adjustable bias is not prohibitively expensive (100-200 bucks depending on how extensive you get it).

I don't know what the tonal propaganda is like but I loved my 400+'s sound - great, light for a tube head, sounded amazing. The only thing I hated was the number of tubes. 12 power tubes is just a giant pain in the ass.
 
#3
I never played a 400 but I love my 400+.

Everyone told me that 12 power tubes would be a pain in the ass, but guess what. After three years of heavy abuse and touring all over europe, last week one of the tubes stopped glowing.

One tube in three years isn't that bad for me.it still works and sounds great, there is just a loss in volume. I'll go to the shop tomorrow to buy a new pair, replace the bad one and have one spare. So i don't mind the fixed bias.

We played squats in Poland and Check Rep. where the electricity came from generators, the amp stayed in the van over night in Sweden at sick temperatures, it's built like a tank reliable as hell.

The only problem with the mesa is that bass players from bands we're playing with suddenly have problems with their amps and want to borrow the mesa ;)
 
#4
I use a 400 with KT-88's in it (6550's basically).

The main thing I like about it is that it's a little more old school and rare (1200 made I believe) than the 400+, so thus a little cooler to me. I'd probably be just as happy tone wise with either one, I bet JJ's in the power section of a 400+ would be great.
 
#7
chaosMK said:
I use a 400 with KT-88's in it (6550's basically).

The main thing I like about it is that it's a little more old school and rare (1200 made I believe) than the 400+, so thus a little cooler to me. I'd probably be just as happy tone wise with either one, I bet JJ's in the power section of a 400+ would be great.
Click to expand...

thats what i have--- JJ's in my 400+, along with USA preamp tubes, including the (in)famous 12AU7 PBG dealy. eurotubes specs sets for the 400+ in a
in a hotter grade to get that cold factory bias up a little
Click to expand...
while my amp would run on the "mesa" sovtek tubes that were installed when i got it, the screen resistors had to be replaced before it would run the JJ's. it is very big sounding, and (so says my tech) gets near 300 watts at clipping on the 8 ohm tap. between mesa and the 'net, ive seen specs from 200 watts to 400+ (:bassist:!).
 
#8
Here's some input in general. I can't comment on anything technical. Here's a pic of my credentials.

[Invalid or Expired Link Removed]

In my experience/in my opinion, based on the amps I owned, YMMV:

400 with 6550s sounded so close to the 400+ that playing with a band the difference would not be noticed. The 400+ was perhaps a tiny bit "fuller" sounding. I did not notice a volume difference, but I didn't try for max volume out of either one. Both were easily very loud.

400 with 6L6s had the familiar Mesa tube tone at lower volumes, noticeably less full sounding the 400+ but still likely the difference wouldn't be noticed with a band. Broke up pretty quickly as the volume was turned up. The distortion was beautiful. In contrast, when I've forced my 400+ to distort (something it generally doesn't do) it sounded unpleasantly buzzy.

I performed the tube swaps in the 400 without a bias mod. My 400+ did not have the preamp tube swap. I've played through my (now former) 400+ in the years since I've sold it, and as the tubes have worn out it breaks up easier and seems to have less volume than when I owned it. Then again, I did sell it with a mishmash of functional tubes assembled from my junk tube collection in the first place.

Regarding tube brands in the 400+; contrary to the accepted truth, I found the ultra super matched optimum miracle JJ set from Eurotubes to sound thinner and less "warm" than Sovteks. I like the JJ6L6 for guitar, but the 400+ actually sounded better with its assorted bunch of used Chinese and Russian tubes that I sold it with. The JJs work nice in the D180 since it sometimes gets called upon for guitar use.

FWIW, I sold the 400+ first, then the 400. As long I can still play and have a roof over my head I will not sell the D180.
 
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#9
chaosMK said:
I bet JJ's in the power section of a 400+ would be great.
Click to expand...

I bought my 400+ with JJ 6L6's, and it is sweeeeeet ('course, I have no clue what the stock tubes sounded like lol). I've still got the stock 12AX7's in it...guess who ever had it before me didn't see the need to change those out. As for sound, it doesn't really break up to much if I keep the pre down (I do use channel 2 though). It just gets some nice grit to the sound (master at around 4/4.5). I also use the GE.

Fealach, is your D-180 missing two EQ knobs/buttons?
 
#11
Holy Sh!t! That is an amazing picture.

I guess I'm kinda sold on the 400 since its cheaper to re-tube and i'd rather use the 6550's (not to mention all the other band's who will magically forget their bass amps at home and need to borrow...).

I'd like a bass amp to have the potential to break up, but if it can crank out a smooth tone that would be great too. I've played the 400+ live (stock 6l6's) and it was great. Problem is it was a rental (it is currently sitting on hold with a refundable deposit, its the LAST one in stock in the Long & McQuade computer system, Canada wide! Only problem is...$1800 CDN before tax...$2040 after!). Anyone here in Canada want this amp? its gonna be released back onto the floor and they'll ship to any other store if you want itttt.

So the D-180 is the grandfather, eh? What changed internally throughout the years between this and the 400 and the +? (aside from the output section). What tubes is the D-180 supposed to run on?

I take it that the differences between the amps (400/+) are negligible with a full band behind you. How is the power section of 6 tubes able to compete with that of 12?
 
#12
I had:
D180
400 loaded with 6L6
400 loaded with KT88's (this is the one I still have)
400+

During this whole time I've always hung onto my 'main' 400 with KT88's because, while I like the D180 and 400+, I just ultimately like the tone of the 400 most.
I never found the need to do the bias mod, and I'll switch between 6L6 or KT88 tube depending on what I want to get with the amp (more grit or more fat). You can touch the tubes after a while of playing and notice that the 6L6 run hotter, and the KT88 don't get as hot.

The D180 runs on 6L6's.

Yeah, I get SVT fridge owners all the time on the same bill wanting to use my rig when they hear it.
 
#13
On the other hand, just sold my 400+ with JJs and 12AU7 and bought an SVT-VR. The 400+ served me well and never missed a beat after an initial problem. Do I miss it? Not the tone, the SVT is more my style and has heaps more clean headroom and is easier to dial in. But I sure as hell miss the sense of invulnerability that 400+ had, it took a real hammering over the years and just kept asking for more. Guess I won't get that same feeling of confidence from the SVT until I've hammered it for a year or more with no problems. Kinda wish I could have afforded to have kept it, but the wallet was empty and the guys in my band feel the SVT sits under the mix more which suits us as a three piece. No doubt I will pick up another one day.
 
#15
chaosMK said:
Nice credentials! Why won't you sell the D180?
Click to expand...

Because it's awesome. It gets very close to the tone of 400+ and 400, has a great overdrive, and makes a deadly guitar amp. I love the basic tone characteristics these amps all share, but the D180 does that and more. Some people prefer one of the others, but the D180's the one for me.

I've seen Mesa literature from the D180's production years that show it with 6550s. It may be possible, I've thought about calling Mesa and having my tech see what he thinks, but I'd imagine the change would result in more headroom like it did with the 400, and that's not what I want from this amp.
 
#17
traynorbassmate said:
So the D-180 is the grandfather, eh? What changed internally throughout the years between this and the 400 and the +? (aside from the output section). What tubes is the D-180 supposed to run on?

I take it that the differences between the amps (400/+) are negligible with a full band behind you. How is the power section of 6 tubes able to compete with that of 12?
Click to expand...

The preamp section of the 400 and + are the same. The 400+ has 2,4,and 8 Ohm outputs where most 400s and all D180s have 4 and 8. Someone here (I think Caca de Kick?) was told by Mesa the 400 could be run at 2 Ohms safely and has done so with no problems despite the printed ratings on the output jacks.

I don't have a copy of the literature, but I recall seeing old Mesa brochures online (I think an Ebay auction) that showed the D180 with 6550s, but that's all the information I have on it and wouldn't want to just try it out without more than that.

The D180 has a unique input arrangement where input 1 runs through input 2. Plugging into 1 yields more gain than plugging into 2, so 1 is recommended for guitars and 2 for basses. The 2 channel volumes interact when using input 1. The Master volume works differently than any other amp I've seen; think of 10 as "normal" for bass, gives the cleanest sound. Turning it down increases distortion as well as volume. It does take some time to get used to what looks like a very simple control layout but is actually complex and subtle. With the 400 and +, both inputs may be used simultaneously, but this is not possible with the D180.
 
#19
Hi again. thanks for all the input.
I bought the 400! (currently running mesa 6550's)

can't wait to get my hands on it, i'm pretty pumped. My current cabs are a Ampeg classic 115 and 210 (I believe 8ohms a piece). This means I plug each 8 ohm cabinet into the two 4ohm outputs, correct? (I always thought mesa amps were a bit vague in their output markings)

I plan on keeping this amp running on 6550's. How do I know if/when the bias mod should be added?
 
#20
traynorbassmate said:
Hi again. thanks for all the input.
I bought the 400! (currently running mesa 6550's)
(snip)
I plan on keeping this amp running on 6550's. How do I know if/when the bias mod should be added?
Click to expand...

Have the bias adjust mod done as soon as you want to or at the least when you REALLY need to retube. Adding the bias adjustment can extend the life and tone from your existing good output tubes.
 

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