Thoughts about using yellow jacket el84's in a mark III

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jakedawgwhite88
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Thoughts about using yellow jacket el84's in a mark III

Post by jakedawgwhite88 » Wed Nov 10, 2010 12:38 pm

Hi guys I'm new here and had a couple of questions regarding my first mesa boogie purchase. First off I purchased a mesa mark 3 blue stripe and I absolutely love it. Unfortunately it came with relatively cruddy tubes. This is not a problem really but I know newer tubes will warm up the sound. The real question is when I retube I know its a simuclass amp meaning I can use el34's on the outside (which mesa recommends via manual) but has anyone ever heard of using el84 yellow jackets in the outer sockets. I really like the vox chime and warmth , more so than the el34 marshally bite. Has this ever been done?? What might be some pros and cons of trying this???

Thanks

94Tremoverb
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Re: Thoughts about using yellow jacket el84's in a mark III

Post by 94Tremoverb » Thu Nov 11, 2010 12:59 pm

Not sure. You should probably email THD and ask them - the outer sockets in a Simul-Class are a bit different from most amps because they are wired for Triode operation. I don't *think* that should matter, but it may be worth checking. In every other way, they're the same as any other regular fixed-bias (note: they are *not* cathode-biased, even though they're called Class A, which they aren't either!) tube position. But, Yellowjackets won't make your amp sound like a Vox... I had a pair in my DC-5 for a bit and all it did was sound like a DC-2.

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by kdorsey » Sat Nov 20, 2010 9:29 am

Boogie amps are already some of the most versatile and flexible models ever made, by virtue of Simul-Class. Their intended tube use and options are clearly publicized because they've already done the research and regression testing to back it up. The results are predictable and reliable. Anything beyond that is outside the intended performance envelope and the liability falls on the user. If you know exactly what you're doing, feel free to experiment...and there are tons of posts around here on just about every mod known to Boogie. Add to that the fact that EL84s have a completely different operational requirement (plate voltage max of less than half of an EL34, for starters) and, I believe, that the EL84 has a completely different base diameter and pin count. Don't hold me to that! (I don't have any smaller amps using the EL84).

With the MkIII, adding EL34s to the power stage actually adds warmth, compared to the 6L6. It's a very nice combo. Been using it for 20+ years.

If you're looking for Vox tone, the MkIII is probably the wrong place to start.
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Re: Thoughts about using yellow jacket el84's in a mark III

Post by MrMarkIII » Sun Nov 21, 2010 12:22 am

Read this:
http://www.thdelectronics.com/pdf/yj.pdf
Since the Yellow Jackets convert the sockets to Class A, it's unclear what would happen if you install them in a Mark III's outer sockets, as they are already Class A.
But they should work in the inner sockets. Bear in mind Yellow Jackets reduce the output power of those sockets by at more half. So even in Simul-Class, you're getting 40-45 watts total (15 watts from the outer Class A sockets, maybe 30 from the Yellow Jackets).
It'd be simpler to get a Tech 21 Liverpool pedal. they sound great and have a variety of Vox AC-30 flavors. :D

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by 94Tremoverb » Sun Nov 21, 2010 5:47 am

kdorsey wrote:Add to that the fact that EL84s have a completely different operational requirement (plate voltage max of less than half of an EL34, for starters) and, I believe, that the EL84 has a completely different base diameter and pin count.
Yellowjackets take care of both of those things, and the very different biasing requirement. They are a plug/socket converter that also contains other components to drop the plate voltage and bias the tube independently of the amp.
If you're looking for Vox tone, the MkIII is probably the wrong place to start.
I totally agree. Yellowjackets do not make any amp sound like a Vox, no matter that the tubes they run are EL84s. They make it sound like the same amp with much less headroom and a slightly different character. I had some that I used in my DC-5, and they made it sound almost exactly like a DC-2, not at all like an AC15 (which I also had at the same time, so it was an easy comparison).
MrMarkIII wrote:Since the Yellow Jackets convert the sockets to Class A, it's unclear what would happen if you install them in a Mark III's outer sockets, as they are already Class A.
Neither of these is true, regardless of what either company says in their marketing. The Simul-Class outer sockets run in fixed-bias, triode Class AB. The Yellowjackets run in cathode-biased pentode Class AB. You can prove both these things quite easily with a scope or by checking the current draw at various operating levels. There is so much BS about "Class A" in guitar amps that the easiest and almost always accurate way of putting it is that every time you see an amp described as Class A, they're lying. (Kind of like politicians and speaking... :))

Putting the Yellowjackets in the outer sockets *should* work, and it will result in running in cathode-biased triode mode, but I'm not 100% certain how the Yellowjackets are wired internally so it may be wise to check with THD first. It probably still won't give Class A operation though.
But they should work in the inner sockets. Bear in mind Yellow Jackets reduce the output power of those sockets by at more half. So even in Simul-Class, you're getting 40-45 watts total (15 watts from the outer Class A sockets, maybe 30 from the Yellow Jackets).
You get about 18W from a pair of Yellowjackets in a standard 470V 2-6L6 amp, so I would expect the same from the inner sockets.

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by jakedawgwhite88 » Mon Nov 22, 2010 1:29 am

thanks for all the tips I appreciate it. I'm not looking for a vox sound necessarily but the cleans are just a little to pointed for my tastes and the amp is very powerful I was simply curious if the yellow jacket or any other tube converter using 84's would let me drive the power section a little harder at less volume and take a little focus off the cleans. As far as pedals go I know of a few others as well as vox pedals that might simulate that tone but I really like the looseness of that clean feel with a tube amp with 84's the other guitar player in my band has a dc3 and it has that warm character to it and its all el84's. I was just curious about combining 84 w/6l6 and if anyone had made this venture before. Thanks for the Advise.

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by kdorsey » Mon Nov 22, 2010 9:53 am

Sorry for the quick post. I fell victim to my own haste and ignorance. I had no idea that Yellow Jacket was a separate adapter system. My fault...

Not as if this would have been the first post about cramming a tube with the wrong pin out into a socket supplying twice the necessary voltage. :D

BTW, that is a cool product with an interesting feature. If you decide to do this, let us know how it sounds. Otherwise, to get a more controlled headroom at lower volumes, try flicking the Simul-Class switch... :wink:

Good luck.
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Re: Thoughts about using yellow jacket el84's in a mark III

Post by 212Mavguy » Thu Dec 02, 2010 10:48 pm

If the amp were mine, I'd stick to tubing it in the way it was designed and get a suitable attenuator. I love what having a Weber MASS rated at more than twice my amps' wattages has allowed me to do.
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Re: Thoughts about using yellow jacket el84's in a mark III

Post by jakedawgwhite88 » Mon Dec 06, 2010 11:42 am

kdorsey wrote:Sorry for the quick post. I fell victim to my own haste and ignorance. I had no idea that Yellow Jacket was a separate adapter system. My fault...

Not as if this would have been the first post about cramming a tube with the wrong pin out into a socket supplying twice the necessary voltage. :D

BTW, that is a cool product with an interesting feature. If you decide to do this, let us know how it sounds. Otherwise, to get a more controlled headroom at lower volumes, try flicking the Simul-Class switch... :wink:

Good luck.
I do use the half power switch but 1.5 on the master is still too loud lol the tone of the 84 is what i'm curious about really if the volume bugs me that much i'll get an attenuator.

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by jakedawgwhite88 » Mon Dec 06, 2010 11:45 am

212Mavguy wrote:If the amp were mine, I'd stick to tubing it in the way it was designed and get a suitable attenuator. I love what having a Weber MASS rated at more than twice my amps' wattages has allowed me to do.
What happens when you have one rated for a higher amp do exactly?? I thought that stuff was touchy and needed to be set properly via what manufacturer says. LOL

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by 94Tremoverb » Mon Dec 06, 2010 12:58 pm

Having an attenuator rated for a lot higher than the amp is no problem at all - it's just a maximum, you can use less power and no harm will occur.

Not true the other way round - don't use an attenuator rated for less than the amp or you'll blow the attenuator, most likely followed shortly by the amp...

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Re: Thoughts about using yellow jacket el84's in a mark III

Post by 212Mavguy » Mon Dec 06, 2010 7:07 pm

Exactly! When power is measured in a tube amp, that power measurement is derived at max clean headroom. Cranking the amp up further into the distortion zone causes output wattage to exceed that maximum rating. A convenient in not perfectly accurate factor is 150% of max rating. So if that is the case, a 100 watt tube amp cranked theoretically could produce 150 watts going all out. That exceeds a 100 watt rated attenuator by enough to cause problems. That is why Weber advises their attenuators to be selected with double the amps' wattage as a rule of thumb. A 100 watt rated tube amp needs a 200 watt attenuator with the Weber MASS design.

I have learned that it is best tonally and for amp power section and tube life that you want to turn the amp up just enough to get into the sweet spot, and attenuate as needed for the room or playing situation. Diming the amp and then attenuating for a whisper volume is not the best way to go at all.
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Re: Thoughts about using yellow jacket el84's in a mark III

Post by jerry62 » Sat Mar 24, 2012 9:08 pm

I know this is an old post, but did exactly this a number of years ago (like close to 10 years ago)... put in 2 EL84's with Yellow Jacket converters in the outer sockets... I imagine I got the idea online somewhere. Had a real problem getting properly matched volumes when switching modes. I also had some Svetlana 6L6GC's and 4 EH 12ax7, 1 EH 12AT7.
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Re: Thoughts about using yellow jacket el84's in a mark III

Post by YellowJacket » Wed Mar 28, 2012 8:43 am

Hmm. Get a Mini Recto!

Yellow jackets are weird little things. I have a pair I use (sometime) with my Dual Rectifier. The Preamp gain sounds weird with them. (with the notable exception of the Marshall 1960ax Greenback 100watt 4 x 12) My suggestion is to 'old school' it on the clean channel. Crank the master until the EL-84s start clip and use your volume knob for clean. The power tube crunch sounds awesome and it doesn't need to be so loud as the large bottles.

Not sure how they'd work with a Mark III though...

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