Valve tolerances.

[Wayno]

Funny how a certain setting can make or break a tone for an individual. Never know how specific an opinion could be until i got the boogie 8)

Did you try any EL34's? If so what you reckon?

 

[SamuelJ86]

EL34s will run beyond max dissipation in full power - they should be used in Variac mode only.

Really? Doesn't mention that in the manual? only says to make sure the bias switch matches the tubes in use?

It could be clearer and more definitive, but it is indeed in the manual, recommended on page 43 to use Variac when using EL34's. Thanks!

This information is news to me too. I've read the manual many times and I've never read anything close to that. So I had to go to page 43 and investigate:

NOTE: Using the AC POWER switch set to VARIAC POWER will reduce the strain on EL34 tubes (and 6L6 as well). If you prefer the sound of this setting, you will reduce the likelihood of tube problems and greatly extend their toneful life, as they are basically coasting.

This is what I assume Authorized Boogie is talking about. But this does not say to use el34s in variac mode, it doesn't even recommend it. By Authorized Boogies logic, you should run 6l6s in variac too, because they're mentioned here with el34s.

I've never had a problem running my el34s in full power. And the manual does not, in any way, say that I shouldn't run them in full power.

 

[Wayno]

It could be clearer and more definitive, but it is indeed in the manual, recommended on page 43 to use Variac when using EL34's. Thanks![/quote]
This information is news to me too. I've read the manual many times and I've never read anything close to that. So I had to go to page 43 and investigate:

NOTE: Using the AC POWER switch set to VARIAC POWER will reduce the strain on EL34 tubes (and 6L6 as well). If you prefer the sound of this setting, you will reduce the likelihood of tube problems and greatly extend their toneful life, as they are basically coasting.

This is what I assume Authorized Boogie is talking about. But this does not say to use el34s in variac mode, it doesn't even recommend it. By Authorized Boogies logic, you should run 6l6s in variac too, because they're mentioned here with el34s.

I've never had a problem running my el34s in full power. And the manual does not, in any way, say that I shouldn't run them in full power.[/quote]


Thats how i'd always read it and interpreted it too.

As Authorised Boogie said it's not particularly clear in the manual and it should be re-written really to remove any confusion as the general feeling i'm getting from some of the posts in this thread indicate that EL34's run very hot in the Mark V and it should always be run in Variac mode to protect against damage. Glad i found that out before i ran into problems as i would think repairs to the Mark V can run very expensive!

 

[JOEY B.]

Scroll down this page until use see the pictures of the Bias-Rite meter. The readings were done in Full Power mode. I can see why MESA would suggest Variac mode for EL-34 power tubes, based on the 53mA reading of the inner sockets.

http://forum.grailtone.com/viewtopic.php?f=33&t=38013&start=30

 

[Wayno]

Scroll down this page until use see the pictures of the Bias-Rite meter. The readings were done in Full Power mode. I can see why MESA would suggest Variac mode for EL-34 power tubes, based on the 53mA reading of the inner sockets.

http://forum.grailtone.com/viewtopic.php?f=33&t=38013&start=30

That was an interesting thread, just read through it and there's a lot of information there.

Really starting to think that the manual could do with e re-write though as it looks like, so far as my limited knowledge and understanding can deduce, that EL34's really need to be run in Variac mode as Full Power seems to be far to hot to be considered safe for the amp. Also, the fact that it doesn't seem to be common knowledge should be addressed really, especially if it prevents a lot of Mark V's running El34's from going into meltdown.

 

[Nicklotsaguitars]

Joey any idea what your plate voltages are?
Taking a reading of say 53ma with no plate voltage is only answering half the problem. 53ma at 470v for instance would be fine for class A. Biassed at 100%. So as long as the plate voltage is near 470v, I don't see a problem with that. The outer sockets at 43ma @470v comes in at 80% which is a shade warm. Nothing unusable though.

Be interesting to know as reference. I'll be measuring mine tomorrow.
I also use a 4 socket bias meter, not Weber.

 

[Nicklotsaguitars]

Sorry, just saw your plate reading of 450v, which makes things better still. The class A/B sockets are a shade over 75%

 

[JOEY B.]

Sorry, just saw your plate reading of 450v, which makes things better still. The class A/B sockets are a shade over 75%

The inner sockets are not reallly Class A untill you go to 10 watt mode. Here is a great page to calculate tube bias.


http://www.tedweber.com/bias-calc

 

[SamuelJ86]

Thanks for linking that thread Joey. Very interesting. You got me wondering now. I've always been on the fence about mixing el34s and 6l6s. I know the manual says no but I saw that you were doing it back at the time of that thread. So I was wondering, did you ever have any problems, of any kind, from mixing the different tube types? I might experiment with mixing if I know someone else never had any problems. And that thread was years ago so if anything was going to go wrong it would have by now. Thanks.

 

[JOEY B.]

Thanks for linking that thread Joey. Very interesting. You got me wondering now. I've always been on the fence about mixing el34s and 6l6s. I know the manual says no but I saw that you were doing it back at the time of that thread. So I was wondering, did you ever have any problems, of any kind, from mixing the different tube types? I might experiment with mixing if I know someone else never had any problems. And that thread was years ago so if anything was going to go wrong it would have by now. Thanks.

The amp was not played with the "grey" color code STR 450's. When I saw those inner socket numbers, I shut it down. I believe that the Groove Tubes were used for a while, they were on the ragged edge of safety. Ultimately he (lesterpaul) went back to 6L6's for the better clean sounds. No problems with the amp, though.

As far as mixing goes, the 6L6 bias point is so far off from what the EL-34 tube needs, I wouldn't even bother with it. Funny how opinions change with time. :lol:

Even the "red" color coded MESA tubes will be too hot for the inner sockets in Full Power mode.

Unless you have a bias meter, stick with MESA tubes, and Variac mode with EL-34's, just to be safe. There is nothing like seeing smoke roll out of your favorite Boogie, and I know from experience. :roll:

 

[Nicklotsaguitars]

Finally did it, lobbed the EL34's out of my JMP2203 in the MKV.
Variac, 42ma inner 28-30ma outer.
Full power 52ma inner 38ma outer
So yeah in full power 70% of max on the outside. 95% of max on the inside.

 

[Nicklotsaguitars]

So the Variac setting biases 45% and 63% (roughly) of max power. I thought Class A was meant to be biassed at 95-100% of max. Which is what the full power mode gave me on the centre valves and 70% of max on the outer valves. Which is traditionally where class AB settings bias to.

Is this some new practice of amp makers, to bias amps cold, or advise that they're run cold? The past couple of Marshalls I've bought were both biassed cold. A 2203KK with KT88's at around 30% and a JVM at 40%.

 

[Wayno]

What do you think to the tones your getting with the EL34's??

Isn't the Mark V fixed bias actually a bit hotter than usual for Mesa? Or this that just in a particular circumstance, i.e. with 6L6's???

 

[Nicklotsaguitars]

Wayno, I have so much going on with the amp that I love and so much that I'm not too keen on. It's hard to give a definite answer on my preference yet. I really need to either dial or mod that funny emptiness in the bass end out. I'm sure it's the speaker/cab combination on the combo, mostly.

What I did find was tamer, more appealing high end. Slightly less, more punchy bass end. And a very nuanced middle. I didn't spend much time with them in. A couple of minutes.
I think I'll be going on to them.

 

[SamuelJ86]

It's a pleasant change when you throw el34s in. I thought there's not much to not like about them. Channel 2 gets a lot better. You notice the lack of bass on the clean channel, maybe some roundness or warmth too, but it's not bad. Tweed is awsome. Channel 3, not a huge difference. A little more gain and a darker maybe warmer sound. And I notice that lower midrange crunch that is the el34. The first time I swapped I had to scratch my head. They're pleasant, like I said, but I couldn't really say they're better. It's another great option to have I thought. Then I put the 6l6s back in and the amp sounded massive. More highs, more lows, more bite, just a bigger, more alive sound. It's strange. When I throw the el34s in its a nice subtle change. But when the 6l6s go back in I think wow, it's a huge change. If I had to pick, it'd be 6l6s. But it's great to have the ability to so easily swap them.

 

[Nicklotsaguitars]

See Samuel, it's the lows and highs I have a problem with on this amp. The high end is too ice pick. The lows, too boomy with little support. Were I comparing it to the traditional EL34 amps that I'm used to playing.
Not that it's all the way a bad thing. The entire reason I bought a Mesa was to be able to get away from that sound. I picked the MarkV because I thought, If I'm paying £2500 for an amp, I want it to do lots of things.
I'm struggling to dial those things out, without darkening the amp too much. I found the same on my 2203KK when using KT88's. 900's when using 5881's. I think it's something inherent to kinkless tetrode valves that I don't like.

That said, I'm used to standing in front of a 100watt half-stack. And speaker config is playing a huge part in my malaise. I'm spending this week with that combo and a 4x12 to see where I get.

 

[Wayno]

Wayno, I have so much going on with the amp that I love and so much that I'm not too keen on. It's hard to give a definite answer on my preference yet. I really need to either dial or mod that funny emptiness in the bass end out. I'm sure it's the speaker/cab combination on the combo, mostly.

What I did find was tamer, more appealing high end. Slightly less, more punchy bass end. And a very nuanced middle. I didn't spend much time with them in. A couple of minutes.
I think I'll be going on to them.

I'd be willing to bet that the open back nature of the combo is main problem here. I find the same thing with my combo, at low bedroom volumes it sounds great on everything, but as i get into full band levels the combo on it's own just doesn't have the guts it seems to really cut it in the low end. Don't get me wrong, the bass is there but sounds uncontrolled and pisses my bass player off as it washes out his sound. With the vert 2 x 12 however, i get nice thick low end, at much lower bass settings on the amp and it feels much more under control and doesn't compete with the bass guitar too much so he's happy too. I usually just use the 2 x 12 but ever with the combo speaker on as well the 2 x 12 adds the low end so no need to crank the low end on the amp therefore no boomyness from the combo, just a bit of added bite ( usually only use this on out door gigs ).

 

[Nicklotsaguitars]

I think you may be right mate.
A friend has had my 2x12 for a couple of years. But I plan on going into my 4x12 this week. I've only tried it fleetingly and noticed a more controlled low end.
Apparently Zilla will make a headshell for around the £200 mark. I may be calling them soon.

 

[OryCheyne]

Have had recently added a 212 to my setup and I am really happy with the sounds across the board. Still struggling a little with Ch2, which requires me to dial back volume when using single coils, but overall sounds better through a box. I am interested in early comments in this thread re EL34s and will explore that option.
Commenting on turning the combo into a head. I have found the V sits well on top of a wide cab. I swapped 2 16ohm mc90's into the box, and run the three, combo and cab, out of the 4ohm jacks. The bottom of the cab is ported and produces great bass.
Probably not an option if you have limited space while transporting, but if you can do it I recommend it.

 

[Nicklotsaguitars]

Cabs are really not something I'm in need of. 1960A with V30's. 1936 with 1972 greybacks and a 1960a with 1980 G12-65's.