Mesa 5Y3 rectifier tube death !!!!

[212Mavguy]

Hi Mick,

Not here to argue with anybody.

Sorry about using the word "Argument." "Viewpoint" is more appropriate and less combative sounding. I don't wish to argue with anyone, either.

Of course Randall Smith put huge amounts of thought into each of his designs. He can not control manufacturing quality of modern tubes, although he can reject those new tubes not falling within tolerances. Tough for him to know ahead of time that some tubes from the current batches are prone to letting go, he is human like the rest of us.

We can agree that we have not seen posts of failure of vintage 5y3 in LSS.

IMHO It's still a better idea to use a vintage 5v4 than vintage 5y3 in LSS due to greater capacities of 5v4, however. The price for vintage 5y3 is prabably not less than vintage 5v4. Modern or vintage 5ar4 would be also a very workable solution, but more expensive. Peace.

 

[stokes]

Yeah,no argument intended here either,just opinions and observations.Like I said earlier,I am not familiar with the LSS,I am basing my thoughts on my experience with tube amps,and I have never before seen a 5Y3 used in a guitar amp over 5watts or so,and for good reason.It seems to me that Mesa has become very "corporate minded" of late,and with their bias scheme they probably turn a nice profit selling tubes to match their amps,so a blown rectifier here and there isnt necessarily a bad thing for them.When you bought your LSS did it have a NOS 5Y3?Probably not.Hey,if the 5Y3 works for you,thats great.But if somebody brought an LSS to me to repair a blown rectifier,I would have to advise them to upgrade to a 5V4,and it wouldnt cost much more than the 5Y3,if at all, and wouldnt hurt the tone,but it will definately outlive any 5Y3,NOS or current production.

 

[Murphy Slaw]

I don't have a dog in this fight.

But if I did................

I would argue! I love to argue! Combat is my middle name.

Murphy "Combat" Slaw!

I kill deer and slice em' into a food supply on a regular basis.

Ahem. Sorry.

I am a big fan of NOS tubes. As a Blue Angel 1;12 combo user, I've considered a LSS for a backup for several months. I gig every weekend and the 1;12 LSS will fit my flight case. But tube failures and headroom issues are making me question the day trip and a meal (you know, nice meal to pay the wife for the road trip to play an amp thing) it will cost me to even go hear one.

Best of luck, but I've never seen a NOS 5AR4 fail.

 

[stokes]

Unfortunately all tubes eventually fail,even a 5AR4,Murph.Age,and more often the abuse we put them thru,will get them,its just part of the price we pay for the tone we need.I'm with you all the way on the NOS,current production cant touch'em.

 

[Mick]

Not really knowing dog doo about the actual workings of the rectifier tube can you guys fill me in on the differences between 5y3's, 5v4's etc. I saw a list of them on somebodys site where they were listed in order of "headroom" with the 5y3 being at the bottom with the least amount of voltage IIRC.

If I use a 5v4 am I stll pushing 5w and 15w in those modes or will it be more like 10w and 20w?


Hey Murph, it's that time of the year here in PA where deer hunting is another religion. Main difference being that deer hunters aren't licensed to run bingo games!

 

[stokes]

While a 5Y3 will usually be described as having less headroom than a 5V4,the difference is almost negligable.No,using a 5V4 wont give you more wattage than the 5Y3,a couple of volts maybe.Without looking at a tube chart,the 5y3 is good for a max of about 125ma of current,while the 5V4 is about 175ma's,dont hold me to those numbers they are an estimate.As you move up to the 5U4 and 5AR4 your max output goes up to about 250ma's.These tubes will also have less voltage drop and will stiffen up your power supply noticeably,resulting in more percieved headroom.

 

[212Mavguy]

Just looked up plate current capacities of our discussed rectifier tubes in Frank's electron tube pages. Stokes had it 100%. 5y3=125ma/plate, 5v4=175ma/plate, 5ar4=250ma/plate... as constant output. There you all go! Peace, and happy deer hunting, Murph!

 

[Murphy Slaw]

So I ask you. Where else can you get this kind of information and a grilled backstrap?

Best of luck.

Murph.

 

[stokes]

MMMM! Grilled backstrap-the only part of a deer the dog will never know.

 

[Mick]

Hey guys, I don't have a whole bunch of NOS tubes, just what's in the amp and a set of spares so I got a question for you NOS vets. Not too long ago I copped a Mazda French military 5Y3 (circa '50's per labeling on the box) that has what I'd call a shiney silver type splotch on the glass probably covers the area of a half dollar but no real defined shape. Is this normal? Also, it's one of those "bubble in the middle" shaped tubes" like something you'd see in an old Frankenstein movie.

 

[212Mavguy]

That's a **** fine and rare 5y3. The shape is typical of the earliest glass tubes. they often have a letter"g" suffix following their type name, like 5y3g, 6l6g, 5v4g, 6f6g, 6v6g, etc. g series tubes are often called coke bottle types due to the bottle shape of the glass envelope. Those early tubes had gorgeous sounds, to my ears the nicest ever for their respective types, but are not very resistant for microphonics, so I would not use my valuable vintage 6f6g, 6v6g, 6l6g power tubes in a combo amp... Don't know about g series rectifier tubes, but I have seen modern mesa/sovtek 5ar4's get pretty sloppy inside after a lot of loud hours of use in combo amps...

The silvery splotch is a deposit of material (I think it's barium) on the glass, it started life as a small pellet of material attached to the small wire ring, rectangle, or metal cup directly underneath it. After the tube is assembled, it is vacuumed out and sealed. Then the innards are heated by induction to around 1600 degrees farenheit, that little pellet vaporizes and radiates outward to coat the glass bottle on the inside, provided a large surface area of absorbent material to trap gas molecules emanating from the tube parts during heating up, operation, and cooling down, mostly from the mica spacers. So when you read about a tube being sold on ebay having a round getter, square getter, or cup getter, these structures are simply leftover parts already having completely performed their one time funtions. The real getter is the coating itself on the inside of the glass...and it changes in its look as the tube ages. The appearance of the getter is a clue as to how much the tube has operated, and tube weenies often guage the tube's condition and worth by how that getter looks, not always a good idea. For instance, the 6l6gb series of tubes sold as used often have getters that are nearly gone, and still put out nearly new performance in circuit. I have several of that type and amazingly, they are strong as new and friggin' GORGEOUS sounding. The newer production 6l6gc's don't hold a candle to their forefather's rich sweetness.

 

[Mick]

Many thanks for the detailed info. As you said mine is a 5Y3GB and half the reason I chose it was its shape. Later.

 

[twally]

I just lost my second 5Y3 Mesa tube in about a month. I have only played the amp in the 5 watt mode at bedroom levels. THis last time, the amp made a sound like a shorting guitar cord. Then the amp made an arcing sound, with a slight flash of light, which took out the fuse. I bought a NOS Jan Phillips 5Y3 a couple of weeks ago from Doug's tubes. I slipped that tube in, replaced the fuse and the amp works again. I am now looking into other rectifier tube options.

 

[Mick]

That JAN Phillips will probably last as long as you need it. I ran one for a year and a half without a crackle. The only reason I swapped it out for the Mazda was just to experiment. Also thought it'd be a good idea to keep a spare, plus I can use it if I ever build the amp kit that I've been sitting on for a year.

 

[twally]

I emailed Mesa and Doug's tubes about using a 5V4 Rectifer Tube in place of the 5Y3 tube. Doug siad I needed to check with Mesa, since the 5V4 would output several more volts. Mesa said we can't use anything other than the 5Y3 tube, due to the amp's design.

Mesa is sending me another 5Y3. I may get another NOS 5Y3, just for grins (peace of mind).

TW

 

[twally]

I checked the second blown 5Y3 with an ohm meter and the thing has no shorts. So, I am wondering if I should put the thing back in my amp to make sure it is bad. After recieving the second replacement, I am wondering if the flash and blown fuse were caused by a bad EL-84. I swapped the power tubes around right after the incident, I only use the 5 watt setting, so the (possibly) bad power tube isn't being used right now.

Is this a good idea or should I just trash the suspect 5Y3?

Thanks,

TW

 

[stokes]

I emailed Mesa and Doug's tubes about using a 5V4 Rectifer Tube in place of the 5Y3 tube. Doug siad I needed to check with Mesa, since the 5V4 would output several more volts. Mesa said we can't use anything other than the 5Y3 tube, due to the amp's design.

Mesa is sending me another 5Y3. I may get another NOS 5Y3, just for grins (peace of mind).

TW

"due to the amps design".More likely due to Mesa's warranty policy.Any amp designed for a 5Y3,can safely use a 5V4.

 

[stokes]

I checked the second blown 5Y3 with an ohm meter and the thing has no shorts. So, I am wondering if I should put the thing back in my amp to make sure it is bad. After recieving the second replacement, I am wondering if the flash and blown fuse were caused by a bad EL-84. I swapped the power tubes around right after the incident, I only use the 5 watt setting, so the (possibly) bad power tube isn't being used right now.

Is this a good idea or should I just trash the suspect 5Y3?

Thanks,

TW

Where did you see the flash?In the rectifier or the power tube?Its possible that the 5Y3 doesnt have a "dead short" but when current is flowing there is arcing causing the fuse to blow.If that is the case,the tube will die sooner than later.Of course the power tube scenario you suspect is possible.I wouldnt recomend using a suspect power tube,or rectifier tube.Most likely the fuse will just blow,but if the bad tube takes something else with it,I wouldnt want to be responsible for giving you "bad advice".

 

[twally]

I was facing the front of the amp when I saw the flash, so have no idea which tube caused this.

Thanks for the advice. I think I'll chunk the suspect 5Y3 and not take a chance.

TW

 

[jrkooshman]

hmm,
I just saw this on kcanos. Anyone try? Worth the 30 bucks?

http://www.kcanostubes.com/products/165/NOS-Mazda-5Y3GB-some-labeled-Cifte.htm