THd Yellow Jackets schematic

[jgriff123]

Hey guys, its been awhile since I've been on here.  Does anyone have a schematic laying around for the thd yellow jackets?  Thanks ahead of time. JG

[jgriff123]

basically what im trying to do is run el84s in a dlitethat I built.  I would like to be able to run either 6l6's or 84's.  I was thinking about putting in a couple 9 pins sockets so I can run eithewr tubes.(not at the same time)  Any suggestions would be great.  JG

[FYL]

The schemo below was posted here a while ago...

[kagliostro]

Give a look here

Kagliostro

[jgriff123]

thanks guys, that is exactly what I needed!  JG

[jgriff123]

one more question.  Why do they use zenor diodes and could you use regular diodes instead?  JG

[FYL]

The Zener string drops B+ to levels compatible with EL84s.

[mesa3077boogie]

Hey guys! First post here nice to meet you all!

I have two questions. #1Can anyone shed some light on the PDF attached above for the el34 to el84 converter? #1A Is the purpose of this to be able to use a physical 4pdt switch to switch between the two in the same amp?

On a related note I am interested in building that switch externally where I would run 2 dummy EL34's to the existing tube sockets. Those would then route to an external box that would feed the switching components and the two separate sets of tubes.

My question is regarding the diagram on the PDF that is connecting to the 4pdt switch. on the second row down, 3rd lug over from the left. #2 Can you confirm that that black line is a ground connection?

[pompeiisneaks]

Hey guys! First post here nice to meet you all!

I have two questions. #1Can anyone shed some light on the PDF attached above for the el34 to el84 converter? #1A Is the purpose of this to be able to use a physical 4pdt switch to switch between the two in the same amp?

On a related note I am interested in building that switch externally where I would run 2 dummy EL34's to the existing tube sockets. Those would then route to an external box that would feed the switching components and the two separate sets of tubes.

My question is regarding the diagram on the PDF that is connecting to the 4pdt switch. on the second row down, 3rd lug over from the left. #2 Can you confirm that that black line is a ground connection?

No the yellow jacket is an adapter that lets you put the yellow jacket into an EL34 socket and has a 9 pin socket on the top that you can put EL84's into the same amp.  I think you could still replicate the idea on a switch but that doesn't actually help that the pinout and pin count is different between the two.  Are you thinking of having dual sockets on the amp and depending on switch position it swaps the output tubes?

~Phil

[mesa3077boogie]

Hello! Yes I realize what the yellow jacket is and that EL84's an  EL34's have two completely different sockets and pinouts.

The first image posted above shows the layout of how you convert the EL34 to an El84 replicating the yellow jacket and I understand that.

The PDF link however shows a completely different set up with a 4pdt switch that is what I'm asking about. If I did what I said by using dummy EL34's to an external box, then yes o would use 2 different sets of sockets on a switch. I am inquiring about that lug on the 4pdt that is Second row down third from the left.

[sluckey]

The PDF link however shows a completely different set up with a 4pdt switch that is what I'm asking about...   ...I am inquiring about that lug on the 4pdt that is Second row down third from the left.

Yes. That is ground.

[pompeiisneaks]

doh, sluckey's got ya, but didn't realize there was the second pdf there.  my apologies :D

~Phil

[mesa3077boogie]

So does this schematic run the el84s in pentode? I think so.. asking because yellow jackets are offered in pentode or triode versions.

FWIW, My parts are almost here. No longer think I want to put the parts on s switch, just probably going to build the converters like a set of yellow jackets.

[mesa3077boogie]

So does this schematic run the el84s in pentode? I think so.. asking because yellow jackets are offered in pentode or triode versions.

FWIW, My parts are almost here. No longer think I want to put the parts on s switch, just probably going to build the converters like a set of yellow jackets.

Bump

[pompeiisneaks]

I don't know for sure, but would assume you'd decide ahead of time which you prefer, the higher output of pentode mode or the reduced output triode mode.  You can do either in your build pretty easily.   You could even add a switch to switch between modes if you did it right :D.  You'd just need to ensure the switch could handle the screen voltage and current. 

~Phil

[mesa3077boogie]

I don't know for sure, but would assume you'd decide ahead of time which you prefer, the higher output of pentode mode or the reduced output triode mode.  You can do either in your build pretty easily.   You could even add a switch to switch between modes if you did it right :D.  You'd just need to ensure the switch could handle the screen voltage and current. 

~Phil

Hey Phil thanks for the reply! I will probably stick with pentode. Thanks to the forum I installed a pentode triode switch on the amp itself. I assume it will still function with the YJ tube converters.

I got started on this and wow it's all pretty crammed in there! A lot of components for a small area. So far I have all the components soldered into the EL34 base.

Is it safe to hot glue or epoxy the legs or parts of the components onto the bases for stability?

Not sure how hot these bad boys are gonna get but it would be nice to stabilize this somehow.

[pompeiisneaks]

I don't know for sure, but would assume you'd decide ahead of time which you prefer, the higher output of pentode mode or the reduced output triode mode.  You can do either in your build pretty easily.   You could even add a switch to switch between modes if you did it right :D.  You'd just need to ensure the switch could handle the screen voltage and current. 

~Phil

Hey Phil thanks for the reply! I will probably stick with pentode. Thanks to the forum I installed a pentode triode switch on the amp itself. I assume it will still function with the YJ tube converters.

I got started on this and wow it's all pretty crammed in there! A lot of components for a small area. So far I have all the components soldered into the EL34 base.

Is it safe to hot glue or epoxy the legs or parts of the components onto the bases for stability?

Not sure how hot these bad boys are gonna get but it would be nice to stabilize this somehow.

Hot glue doesn't work super well in hot environments, it tends to get soft again.  Non acid curing silicone is often the best for this.  I like GE Silicone II to keep components from moving too much.

~Phil

[mesa3077boogie]

Do you have any product examples of something I can get locally? I am seeing some caulk cannisters that are non acid curing silicone. Will anything with that description work?

[Willabe]

Do you have any product examples of something I can get locally?

I like GE Silicone II to keep components from moving too much.

[mesa3077boogie]

Awesome thank you. I am concerned about the heat and whether or not the glue will hold up in this circuit. The only thing I could find about a temperature was the data sheet for the GE II having a flash point is 200 degrees f. I had to Google flash point. I am not sure this circuit gets 200 degrees or if the flash point should even be considered.?

[sluckey]

If all the components fit inside the tube base just pour it full of epoxy.

[pompeiisneaks]

Awesome thank you. I am concerned about the heat and whether or not the glue will hold up in this circuit. The only thing I could find about a temperature was the data sheet for the GE II having a flash point is 200 degrees f. I had to Google flash point. I am not sure this circuit gets 200 degrees or if the flash point should even be considered.?

Silicone can handle a TON of heat.  if it was on the glass of a tube it might get 200, but I'd bet that 200 is C not F, also most of the data I can find on GE II is 400F for the max temp range. 

~Phil

[mesa3077boogie]

 I completed the project and I am very pleased with the sound! surprised nothing went wrong lol.

I just need to seal these bad boys up with some epoxy or GE II so they won’t break when I change back to EL34’s. Will the GE II dry stiff?  I really need to make sure that the top and bottom bases don’t move independently of each other..

Anyways,
The EL84s have so much more touch sensitivity it’s wonderful! they are brighter and a bit more thin in comparison but they sound great! So many harmonics and overtones. I don’t think it’s the tubes themselves that are more thin, I think it’s the way the amp was designed. It was obviously designed for EL34s.  But man I miss EL84’s!

Thank forum!

[sluckey]

The GE silicone II will have a soft rubbery feel when cured. Take your DIY yellow jacket to Lowe's and see if you can find some pvc pipe or other plastic tubing that can house the components between the sockets. Look for a snug fit on the octal base. Then fill the entire assembly with epoxy.

[mesa3077boogie]

 So interestingly enough a prescription pill bottle fit perfectly around the EL34 base that I am using! I drilled out the top Of the bottle to fit the EL 84 housing. cutting the bottle straight across was rather difficult so I had to grind it down smooth being the perfectionist that I am. I grinded it down a little bit too far tight after it was relatively close to being perfect. Crap. oh well looks like I will be going to the hardware store and looking for a cylinder shaped tube that is a little bit more simple to cut like PVC.

 Or, I will just buy a set of yellow jackets, disassemble them and take out the components and use that case for my project lol !

[sluckey]

Pill bottle is a good idea. Go to your favorite drug store. I bet they will give you a bottle.

[mesa3077boogie]

I found some PVC "enclosures" for the circuitry that ended up fitting perfectly over the components. The EL34 base I am using is basically just the lower part of the base EL34 without the "cup" or "shell".

The makeshift housing I found at the hardware store fits against the El34 base and over the EL84 base. This piece kind of covers everything up. I first put epoxy around the inside of the components so that they would not move around. After that epoxy dried I filled the PVC with epoxy then basically stuck the PVC over the EL84 base and up against the EL34 base. I let it all dry for about 2 days.

Tonight I tested it out and it immediately smells like burning epoxy and burning plastic in my house! 1 el84's plate and grid, well all of it, is completely bright red! It looks unsafe and like it will blow up at any minute so of course I turned at The Amp off.

Running these without the epoxy worked really well. They didn't look as hot or bright and didn't smell. They actually sounded pretty decent today but they physically looked like they were going to explode.

When filling the covers with epoxy I was extremely careful and I am 100% certain that nothing touched each other in order to Ark so I'm not sure what the deal is..

Kind of a bummer to scrap this project as I put a good amount of time into building it so nice and so clean. Eerything up until filling it with epoxy went so well. And now it's scrap waste of time and cash..  Oh well.. Live and learn I guess.

[mesa3077boogie]

http://imgur.com/Qvp7c5d




{EDIT-- changed link to image instead of Imgur page -- PRR}

[mesa3077boogie]

 Hello wondering if anyone knows if the 360 ohm resistor needs to be a 3W? I’m going to build this project again but all I have easy access to right now is 1 Watt.  I can order 3W resistors but I just want to make sure that is needed and not just overkill..

[PRR]

It could be over 1 Watt dissipation. Running resistors AT their rating gives short life, months. Also they are jammed in a small adapter. 3W does not seem like overkill to me.

[mesa3077boogie]

 OK 3 W it is. Just ordered em. I don’t actually think I will enclose my tube converters this time like I did my last set. They just seemed more dangerous being exposed. I supposed since the Amplifier has a rear cover blocking them that it should be OK

[Willabe]

I don’t actually think I will enclose my tube converters this time like I did my last set. They just seemed more dangerous being exposed. I supposed since the Amplifier has a rear cover blocking them that it should be OK

Wrong, very dangerous!  Bad idea!

Full B+ dcv exposed! 

[shooter]

Willabe's correct, for testing, leave it exposed til you're sure you're wired correctly, but after that, cover it, you can get by with a few layers of shrink-tube over a couple wraps of tape, or your glued tubes once everything is working.

[mesa3077boogie]

So I covered (surrounded) the last set with PVC and filled with epoxy. Something burned and the stench was awful so I stopped using the DIY yellow jackets. If I could find an appropriate housing but not need to fill it with anything that would be ideal. Based on a few trips to the hardware store I could not find anything that would fit perfectly and not allow any play Between the top and bottom sockets. That's why is needed the epoxy. If I can't find the right size housing to hold everything in place maybe I can just fill with epoxy around the top and bottom edges so that epoxy is not touching the actual circuit..

Do you have a product name I can search that matches your recommendation? Or do you just mean regular old large diameter black shrink tubing?

[sluckey]

I would just wrap it with electrical tape until I was sure nothing was gonna smoke again.

[mesa3077boogie]

To be clear it was the Epoxy that was smoking. when I ran the yellow jacket uncovered and before filling it with Epixy it ran flawlessly. Are you suggesting something else?

[sluckey]

To be clear it was the Epoxy that was smoking.

Really? Which epoxy did you use? Did you allow ample curing time? Most epoxies are very good insulators. I know JB Weld is. Some well known amp builders have used epoxy to hide their super secret mojo circuits.

Some info on epoxy...

     https://en.m.wikipedia.org/wiki/Epoxy

You can find out about a particular epoxy by visiting the manufacturer's website.