What to backup Mark IIB during gig?

[TheHysteria]

Hi guys,

If I were to gig with this, but I don't want to bring an extra amp along (because my other one is 15 watts), would a few power tubes and preamp tubes be good enough?

Say for example, my left 6L6 tube is blown. Can I go to the store and purchase any 6L6 tubes and replace it with the 'left' blown tube? Or is there a specific indicator like a 'right' 6L6 or a 'left' 6L6?

Furthermore, how does the Mesa bias thing work?

Input appreciated.

 

[6L6C]

The bias adjustments for Mesa Boogies are fixed so no adjustment necessary.
If you blow a power amp tube yeah you can put any 6l6 in there but not a great idea it might sound fine and it might sound like garbage.
Power amp tubes are sold in pairs and quads. Power amp tubes are matched so replacing one not a great idea but it will get you through a gig. It has to do with the way they work together, pushing and pulling speaker.
Preamp tubes on the other hand no problem. But I still rather replace tubes in sets if one goes.

 

[twally]

Just have at least two balanced power tubes and a couple of pre amp tubes.

That should do it.

TW

 

[stokes]

"The bias adjustments for Mesa Boogies are fixed so no adjustment necessary."

So long as the tubes are in the right bias range for that amp.Fixed bias means a fixed amount of negative voltage is applied to the grid to control the current draw of the tube,if the tubes arent Mesa's, or tubes graded to fit their scheme they wont necessarilly work right,if the bias of the tubes is too hot you could have problems.

 

[Dutchman]

I've watched my buddies Mark IIB head get knocked of a 4X12 cabinet and bite a wood floor, broke 2 knobs off and still worked and sounded great. They are really rugged. It's not a bad idea to have spare tubes with any tube amp when touring. I've been using the TAD 6l6GC STR in my Mark IIB and they sound great. Perfectly matched from
http://www.thetubestore.com/tad6l6gc.html

I use JAN 7581A's in the studio

 

[TheHysteria]

"The bias adjustments for Mesa Boogies are fixed so no adjustment necessary."

So long as the tubes are in the right bias range for that amp.Fixed bias means a fixed amount of negative voltage is applied to the grid to control the current draw of the tube,if the tubes arent Mesa's, or tubes graded to fit their scheme they wont necessarilly work right,if the bias of the tubes is too hot you could have problems.

Bias range....

How do I know the range for my IIB? Are all Mesa's the same within the range?

BTW, replacing tubes in pairs. So basically, that would mean if one tube is blown and the other is okay, you still want to replace both of them. Isn't that kind of a waste though? What about te other tube that is still working?

 

[stokes]

Although I dont use the Mesa tubes,I believe they are all "safe"-they are graded to have a different breakup quality.Maybe somebody who uses these tubes can give you a more detailed explanation.Tubes should be changed in matched pairs or quads.It is most likely that if one tube goes because of age,and not something wrong in the amp,the other is likely to be not far behind.Mixing a late break up tube with an early break up tube most likely wont sound good,but tone is subjective,so there may be people who like it.But the hotter tube is going to die before the colder one.

 

[Harry the Horder]

so what are the grades for these valves? the way I understood it is that my MK2B is set up for the Yellow grade and that I should not use any others as that is the Bias range for my amp?? How many grades are there??

 

[stokes]

Like I said I dont use them,havent even looked at a Mesa tube in over 20 years.Dont know haw many grades they make,or how many different ones will fit your particular amp,if yellow works for you,stick with it,if you feel you need something else,I can only tell you what I do.I use nothing but NOS tubes.To the average player who knows nothing about biasing their power tubes,the Mesa scheme works,no doubt.But to me you just dont get the best tone without fine tuning the bias.I am not saying the average player is wrong using this set-up,if it works for you then that is the way to go.There is just a lot of very good tone to be had if you do a little homework and can adjust your bias.Lets take a set of JJ's for example that are selected to fit this bias range,and I am not saying there is anything wrong with JJ's,this could apply to any tube graded as Mesa does,you pop them in and they just dont do it for you.I see this complaint,time and again right here on this board as well as others.So you put them aside and start trying different tubes till you find the tubes that sound good to you.If you had an adjustable bias pot,those first tubes you tried could be fine tuned to give you what you needed,thereby saving you money and time you spent getting tubes that sound good.All my amps have adjustable bias,even my cathode bias amps,and I have yet to find a power tube that doesnt sound good when biased properly.Even some very old used 5881's that read minimal on my tube tester.The thing about Mesa amps is that the distortion is generated in the preamp and there is very little power tube drive,for the most part.Their bias scheme sets the power section in a very cold,safe range to cleanly reproduce what the preamp gives them,if you bias them a little hotter it brings you to a whole new level.The only time I ever used Mesa tubes in my Boogie was the very first time I retubed it back in the mid 1980's,used what were supposed to be the "proper"range tubes and the amp sounded like a solid state piece of crap.Changed to the adjustable bias pot and the tubes and the amp came back to life.Tube amps are all about tone,and the more you can control certain parameters the easier it is to achieve the tone you want.

 

[TheHysteria]

The thing about Mesa amps is that the distortion is generated in the preamp and there is very little power tube drive,for the most part.

Interesting.

I know I'm getting a bit off topic, but which type of distortion sounds better? Through preamps or power tubes? Or would this be a preference sort of thing?

That said, does that mean Mesa tube amps wear preamps faster than other amps?

I like the distortion from my IIB by the way.

 

[stokes]

It is totally subjective.A Blackface Fender Deluxe pushed hard is a good example of power tubes driven.When you add this to the Mesa pramp drive it can be real sweet or be too over the top too.Its all taste.Mesa's do push the preamp tubes harder than say a Fender,and will shorten the life of the tube somewhat,but I wouldnt be too concerned with it,it aint like they will die in a matter of days.I have an old Ampeg Gemini that still has preamp tubes that are fine,from the early 1970's,I would not expect this life in a Boogie but they should last a couple of years.

 

[Daevid]

Would this be a good idea for my Studio 22+ with it's two EL84 tubes? I have considered getting a bias pot fitted, mainly because of the cost of matched Mesa tubes in the UK

If i had the amp biased a bit hot would that mean that the poweramp would breakup sooner?

 

[stokes]

The main advantage to having an adjustable bias pot is that you are not locked into using Mesa pre-graded tubes.You will still have to used matched sets.Setting the bias to a hotter setting will cause the power tubes to go into saturation sooner.This may or may not be more desireable to you. I find it very good on the clean or rhythm channel.You may have to back off the pre drive on the lead channel. It is totally subjective.

 

[Daevid]

The main advantage to having an adjustable bias pot is that you are not locked into using Mesa pre-graded tubes.You will still have to used matched sets.Setting the bias to a hotter setting will cause the power tubes to go into saturation sooner.This may or may not be more desireable to you. I find it very good on the clean or rhythm channel.You may have to back off the pre drive on the lead channel. It is totally subjective.

Mmm... well i currently use a PodXT for the majority of my sounds (as preamp) atm so too early a breakup might be unwelcome... that said i am considering getting a G-Major later down the line and use the Studio's preamp instead...

 

[Paul Secondino]

The thing about Mesa amps is that the distortion is generated in the preamp and there is very little power tube drive,for the most part.

Interesting.

I know I'm getting a bit off topic, but which type of distortion sounds better? Through preamps or power tubes? Or would this be a preference sort of thing?

That said, does that mean Mesa tube amps wear preamps faster than other amps?

I like the distortion from my IIB by the way.

Any high gain amp will use up the V1 tube quickly if alot of gain is applied all the time.V1 is the first preamp tube in the signal path of your Mesa Mark2. If you have the gain on 10 all the time, you will burn up the tube fairly quickly. But the fact that the preamp section generates alot of gain doesn't mean that your tubes are destined for a short life at all.

 

[stokes]

V1 is not affected by the gain setting of your amp.The gain control comes after V1,in the amp.The only thing that affects V1 is the input signal.If you go straight from guitar to amp then it is the volume control of your guitar,if you use a pedal in front of the amp it is the out put of the pedal that affects the gain of V1.A pedal in the effects loop never touches V1.