• TalkBass has been independent since 1998. Add your voice.
    Create a free account to reply to discussions, view embedded media, and browse with fewer display ads.
    Join free Log in
    Want zero display ads or expanded classifieds tools? Compare plans.

Tube guru's ... help me

#22
Norre said:
I'm looking for a smoother, less agressive tone
Click to expand...

I pulled the Mesa relabeled powertubes out of my 400+ and definitely got a smoother and less grainy tone with a new set of JJ's sold by Eurotubes for the 400+. Although I was comparing a very old Mesa set against the brand new JJ's...

I later had an adjustable bias mod preformed on this same amp. It still maxed out around the same 270 watt clean maximum level, but had less crossover distortion and sounded better overall.

Depending on your current powertubes tubes condition, you might have your tech just do the bias mod first and then see if you still need new powertubes or not.
 
#23
skipped ahead, sorry if i'm repeating. mesa's way of not having a bias adjustment and their own tubes is so they more or less force you to use their tubes and buy more of their product. their tubes are usually the cheapest/cheaper ones relabeled. their bias thends to be quite cold, so they last a while.

fitting a bias adjustment pot will mean you can use better and probably cheaper tubes, and adjust the bias to a level that suits you and your sound.

6l6's would be the best bet to go in there. 5881's would be fine as well, but i'd be hesetant to put anything else in there, as el34's 6550's and kt88 all use significantly more heater current, and when you have so many tubes it makes a big difference in current. a blown PT wouldnt be ideal.
 
#24
I would suggest for Power Tubes use =C= (winged C SED) 6L6's and for Preamp Tubes try the JJ ECC83 for extra smoothness and use a JJ ECC82 for that 12AU7 slot.


BTW folks if an Tube Amp is Class AB and has a Bias Pot it is Fixed Bias.

Fixed Bias has nothing to do with having an adjustable Bias Pot or not. A Mesa Booge Bass 400 + Plus is Fixed Bias but just does not have a Pot and has some fixed resistors in place instead.

It is very very very easy for a qualified Tech to set the Bias without a Pot or a Mod. It is just a matter of changing the resitor values to match the "Matched set of Power Tubes.

Cathode Bias is a sort of auto Bias Circuit but I have never seen a Cathode Bias Tube Bass Amp. It lends itself to less Clean Headroom and Punch.

Boogie sells more than just Sovtek Tubes. They pretty much sell all brands, test them, label them and ship them.
 
#25
If he is willing:

Make a bias point for EACH power tube. its more time consuming but very helpful. JJ/Teslavek 6L6's would be a decent bet. And I kinda snikker at Mesa saying the tubes are not stressed. Mesa cooks their tubes. Also the sandblocks should be upgraded to 10watt instead of normal 5 watters.
 
#28
Check the reviews on the Watford Valves website. The tested a number of the tubes mentioned here in a Bass 400+ if I recall correctly. The top tube was the Svetlana Winged-C 6L6.

I can vouch for 'em... I love them in my Boogie Buster.
 
#32
I wouldn't buy mesa tubes, too much money and poor matching, -maybe that's why mesa's blow so many tubes. I'm emailing with an ebay guy who seems to know Mesas, he buys 5881 (Sovteks) in bulk and matches, just like the guys with the fancy labels do. I think I'm going to get a set of 12 for my 400+ from him for about $150. It does also appear the the Eurotubes guy knows Mesas, I'd be comfortable ordering JJs from him. Groove tubes "5"s seem to be right-on too (about 32mA).
I've been messing around with trying to find Mesa tubes that all run at an acceptible idle current, -I've got about 22 low hours Mesa labeled tubes, and they're all over the map, from 20 mA to 45mA, I've got 9 in the range of 28-35 mA right now and that's where I'm stuck. If you buy a well matched set that pull the proper mA, you just plug and play, no bias mods necessary, and with that many tubes you're going to want a decent match, which is a whole lot harder than matching pairs! So, even if you do an adjustable bias mod, you're still going to want some sort of match per bank, -you're not going to want to try to find some happy medium while using a wide range per tube.
It appears to me that it's just the 'necessary evil' of the 400+ that you need to get a set of well matched tubes.
 
#33
Tapp said:
I've never looked at a Mesa 400+ but I can bet that if it's like other Mesa branded fixed-bias tube amps they want you to buy replacement tubes from them. The reason, they do not install a potentiometer to adjust the grid bias voltage. They buy tubes that have certain characteristics that "fit" Mesa amps without adjustment. At one time, certain people (aka Lord Valve/NBS electronics) could sell you "non-mesa" branded tubes with these same characteristics and no bias pot mod was needed. If a bias pot mod has been installed then any matched set could be used if bias is set correctly. "Fixed-bias" is only a term meaning a fixed voltage is injected into the tube's grid to set it's bias. It does not mean that this "fixed-voltage" cannot be adjusted.

Tapp
Click to expand...
...Lord Valve still can...give him a shout, oh, and pass on the 5881s in favor of Shuguang 6L6s...
 
#34
Just for the record, though I've posted this several times, a 5881 is NOT a 6L6GC. It's a ruggedized version of the 6L6GB and as such has less plate/anode dissipation than the newer GC variant. This equates to less output power from the amplifier. These tubes are liked by guitarists as they run out of steam and start to distort at a lower power level. The equivalent is 6L6WGB.

Paul
 
#35
scuz said:
Mesa/Boogie tubes are Sovtek tubes that have been put through the paces at M/B. So the cream of the Sovtek crop get bought and re-branded with the M/B logo. I think you can save yourself a few bucks by just getting Sovtek 5881/6L6 tubes. I'd go with these.
Click to expand...

There is this urban legend/marketing ploy about Mesa Boogie that they buy lots of tubes then test them and only sell the ones they don't reject.
I used to work across the street from Mesa Boogie for about a year. I checked the dumpster behind that place constantly out of hope that I might see some gear that was salvageable.
Only once or twice did I ever see any tubes in there, and they were boxed up and ready to go and looks like they got smashed in the shipping dept.
Boogie imports tubes from China (where they are pre screened with boogie logos) and to a lesser extent Russia. All of the Boogie preamp tubes I have are Chinese for example. Pretty easy to spot with the shiny metal "H" clips on either side of the plate.
So basically what I am saying here is that Boogie Chinese tubes are just as bad (or good) as regular Chinese tubes.
 

Latest posts

Top Bottom
Back