Simul-Class or no??

[nebula328]

This may be a dumb question, but I had my Mark III Red Stripe recapped and new tubes a couple of years ago by a very respectable amp service company in Nashville. I asked, at the time, if I could do EL34s in the outer sockets because I have a Simul-Class/Class-A switch on the back of the amp. I was told that I needed to run all 6L6s. I know these guys personally and their resume is flawless, so I'm just curious if they didn't know this amp and were just playing it safe.

So, I have a bad power tube and I need to replace the outer pair. I have the Simul-Class/Class-A switch on the back, so does that mean that I can try the EL34s?? Sorry to ask such a stupid question, but I have been told "no" in the past and I'm not looking to do any damage to 'test the theory'.

 

[megavoice]

Hi,

this is NOT !!! a stupid question as there had been appeared misunderstandings in the past because of a stupid and wrong modified posting of the original "Owner's Manual" of the Mark III in the net.

I recently had a correspondence with Tien Lawrence from MESA about using EL34 or 6L6 in the outer sockets in a simul class amp and he told me: "...that also recently their President made a stantment about this issue and he confirmed there can be put BOTH types in the outer sockets CARELESSLY and this for 100%."

But on the other side some months ago a guy posted here that Mike B. told him that 6L6 would rather wear down there.

I've a redstripe since 1987 and I'm using exclusively EL34 in the outer sockets. In the first years from time to time I had some problems (glowing red, very loud banging), but through the years it seemed that there had been a tube improvement and in the last years there appeared only the common problems like humming when getting old.
I'm using exclusively MESA-tubes.

I've now a second redstripe for a few months with 6L6 in the outer sockets and also is working with no problems.
Just the sound is different.
But this difference does not only derive from different tubes. It appears that both amps are slightly different.
Tien also confirmed that there had been changings from one amp to the other through the years at every time. So my opinion is that concerning the sound of every amp you can forget the stripe/dot history.

Enjoy your amp !!!

 

[screamingdaisy]

I ran EL34s in the outside sockets of my Mark III/Red Stripe.

From what I understand Mesa started to caution against doing it back in the day because EL34 production quality had gone down and they were concerned that people would experience poor tube life... but that was probably 20 years ago.

 

[MrMarkIII]

The original Mark III manual contained no such recommendation against EL-34s.
The following is from the revised mid-1990s Mark III manual:
(Remember, this is NO LONGER true)

"NOTE: In the past, MESA/Boogie advertised the "interchangeable power tubes" feature of the Mark III Simul-Class. We told players
that they could use either EL-34's or 6L6's in the outer (Class A) power sockets. However, in recent years we've observed a much
greater reliability factor with the use of EL-34's in these outer sockets, with much fewer incidents of tube failure. Therefore, today we
strongly recommend using EL-34's in the outer sockets and 6L6's in the inner sockets of your Simul-Class Boogie."

Mesa warned against using 6L6s in the outer sockets, NOT the EL-34s.

This was in the mid-1990s when the quality of 6L6s was questionable.

It must be added that tube quality control issues were not Mesas, but the tube manufacturers.
Mesa does not make tubes, they never have.

 

[Neptical]

Go el34, it's the best of both worlds!

 

[Whoopysnorp]

If the switch on the back says Simul-Class/Class A, then you can definitely run EL34s in the outer sockets. I'd agree that it's the way to go with a Mark III.

 

[megavoice]

Mr.MarkIII,

I'd advise MESA to publish EVERY modifications of owner's manuals and everything else one their own homepage (Excuse me please, when I didn't note at that time when they did) otherwise we should all take a look at Tien Lawrece' conclusive and wise words: "...you should not notify any nonsense that had been published in the net."
Ohterwise sometimes, I think, we have to shake dice to get an answer to our issues or have to go to Rome to the pope to ask for help.

 

[RectoStudioGuy]

Go el34, it's the best of both worlds!

Indeed!!!

 

[nebula328]

I got the EL34s today and they sound AMAZING!!! My only regret is that I didn't do it sooner!! Thanks for soothing my nerves before the install!!

 

[Restless Rocks]

Just some freindly advise; be sure you put your EL34's in the OUTER sockets only. I just finished an extensive repair on a MkIV where the owner mistakenly thought he could use EL34 in all sockets. That is a big no-no!!!. This caused arching and burning of the circuit board and even the tracks from the bias supply (on the underside of the board) were burned off. The carbonizing of the area of the board around the grid reisistors and the PI coupling caps/plate resistors was so bad I had to reconstruct off the main board. Be sure to use Mesa spec tubes or Mesa tubes in those outer sockets.

 

[megavoice]

Great advice !!!!

I'm wondering so much these dangers are not spoken about in the manual and there's no warning. There's only one sentence that says we should not put them in the inner ones.

Great Thanks !!!!

 

[paaes335]

I own a MKII simulclass head built in 83. It came with 4 6L6's and the early MarkIIB literature I have when the simulclass feature was introduced mentions nothing about using el34's in the outer sockets.
All of the ad photos from early 80's showing simulclass switch on MKIIB's have 4 6L6's running in them.
I had a blue stripe MKIII with the el34/6L6 mix and it was great sounding amp.

Anyone know if you can put el34's in a MKIIB outer sockets?

 

[Heritage Softail]

Are el34L tubes equal to El34?

 

[screamingdaisy]

Are el34L tubes equal to El34?

Kind of. I don't know all the details of exactly what they are, but JJ E34Ls have more bottom end than your typical EL34. They're popular in Rectos with dudes who want more mids without giving up as much bottom end. I found them particularly useful when I was using an Orange 4x12 but I switched back to 6L6s once I acquired another Recto cab.

 

[Mister Joshua]

Are el34L tubes equal to El34?

Depends on what you mean by "equal." From a physical stand point yes. The same pins do the same jobs on both and they operate to roughly the same electrical tolerances. So they are perfectly interchangeable. As far as sound goes not really but kinda. The L is put on by JJ. As far as i know they are the only ones who use the L. They supposedly have more headroom than the regular EL34s and as pointed out already a bit more bass. Matter of preference.

Peace,
Joshua

 

[kdorsey]

AFAIK Simul-Class allows EL34s in the outside sockets on regardless of amp model. I've been using EL34s in my green stripe for decades flawlessly. The class A sound alone is worth it. 8)

 

[PENNYbLACK]

I have many mesa amps. Mainly because I am trying to get the awesome tone that I get from my MkIII blue, LH. It is not apparently a SimulClass, yet the original owner has always had EL34s in the outer slots. The amp was order for him by his tech and always serviced by him as well. It is my impression that he special ordered a 100 watt simulclass, which I know (from reading everywhere) does not exist.
I only mention this because of what I read here. This amp has been running mixed tubes since 1986. I stopped using the amp (after a year or so), because I love it and do not want to blow it in this configuration. The amp performs without flaw as is.
I was actually here searching for info related to my newest rig; MkIVB, but had to tell this story since I am at a loss here. I have not yet removed the chassis for inspection and markings. If there is an interest I will do so and post pics. Perhaps someone can advise as to what I should pic.

Side note: When my fifty/fifty arrived form GC it had all EL34s and as I understand it there is no issue with this config. except tonal sacrifice. They gave me new set of 6L6s.

This MkIII has the most amazing sound with or with out pedals and rack effects.

 

[Paul Johnson]

Spoke with Mike B. on March 6, 2017.

He said I could use 6L6's in the outer sockets of my 1988 Blue Stripe Simul-Class.

BUT...use matching Mesa Tubes in Yellow or Red.

Cheers,Paul

 

[gts]

Bring out your dead! :roll:

 

[SamuelJ86]

Bring out your dead! :roll:

I'm laughing out loud, again! :lol:
Paul must have a different understanding of the concept of time than the rest of us.
What will he dig up next?! :lol: