Speaker Jack Wiring Question - 4 ,8, & 16 Ohm secondaries

[Wittgenstein]

I am in the process of re-doing my first build in order to fix a few minor issues, remove hum, and add 2 more output jacks to the rear of my chassis. I have the Triode 5E3 kit, but I opted for the larger UL output transformer due to its 4,8, & 16 ohm taps. I know that I do not need the Ultra Linear taps for this build, but I am wondering the best way to wire up all three taps (4,8 & 16 Ohm), since this will be a head.

The chassis had 2 holes for 8 ohm and external speaker, but I punched 2 more (total of 4 holes for jacks on back). I was thinking I could just use the 8 ohm and external as normal, and wire an extra jack for 16 ohm, and the forth jack for 4 ohm. Is there a better way to do this, and why?

Most importantly with me being a noob still, could someone be kind enough to draw up or point me to a wiring diagram of what this would look like.

I have read about using switching jacks (switchcraft 13A) to allow for more options, but I'm not sure this is even necessary. I know that I am building it into a head unit, so being able to play out of many different cabs is preferential.

[Alex R]

You can have a different jack for each output, or a selector switch and one jack. The Marshall method was a switch leading to parallel jacks, which is very flexible and allows the use of two cabs.

[Wittgenstein]

Right... I am leaning towards not having a selecter switch as I do not think I will be playing out of mutiple cabs at the same time too often. I think for keeping it easy, I would just rather have each jack be its own ohms with the exception of the exernal speaker wired to the main 8 ohm out.

BUT.... what would that look like? It would help me greatly to see a picture of this done. I am very much a visual learner.


Edit: I have included the layout for my build below to assist. I plan on using un-insulated jacks that ground to chassis, and therefore I am not bothering to run ground wires for these sections. I grounded the filter caps to their own lug, as well as the CT and earth ground to their respective lugs. I included the 2 extra speaker jacks in this layout, but I am not sure if the wiring is correct.

[Alex R]

Ground all the sleeve connectors together, with the ground wire of the secondaries. Then wire each tap to the relevant tip connector.

[Wittgenstein]

Ground all the sleeve connectors together, with the ground wire of the secondaries. Then wire each tap to the relevant tip connector.

Like so?

[Wittgenstein]

Or like this rather?

[Bruce / Mission Amps]

You can't use three lug grounded switching jacks with an OT using the different secondaries.
Regular non-switching jacks or not grounding the center switch lug is the way to do it.
Each "mono" jack gets a colored wire, 4, 8 or 16 ohms, and only jack one needs the "OT grounding wire", connected to a lug which is chassis grounded.

[Wittgenstein]

You can't use three lug grounded switching jacks with an OT using the different secondaries.
Regular non-switching jacks or not grounding the center switch lug is the way to do it.
Each "mono" jack gets a colored wire, 4, 8 or 16 ohms, and only jack one needs the "OT grounding wire", connected to a lug which is chassis grounded.

So it would look like this? Does it matter if the jacks are shorting vs non-shorting? Would it be better to use mono jacks like in the second attachment?

[Bruce / Mission Amps]

Either is OK.
Although the std mono-non shunting jack is the easiest way to do this, .... it doesn't really matter if you use the switching jack as long as you do not solder a grounded wire to the middle lug, (the switch bar). Even with it closed, it won't short out to ground with no ground applied.
Some times I'll run into a repair where the tech didn't realize how those work and they will have bent the switch bar away from the tip bar... all they needed to do was unsolder the grounded jumper wire.

[Wittgenstein]

Either is OK.
Although the std mono-non shunting jack is the easiest way to do this, .... it doesn't really matter if you use the switching jack as long as you do not solder a grounded wire to the middle lug, (the switch bar). Even with it closed, it won't short out to ground with no ground applied.
Some times I'll run into a repair where the tech didn't realize how those work and they will have bent the switch bar away from the tip bar... all they needed to do was unsolder the grounded jumper wire.

Sweet, I really appreciate the advise. I just finished soldering up all the tubes and power section last nite, and all I have left is the pots and jacks. I will be sure to post pics when it is finished. It is 10 times cleaner and more organized then my first go at it.

[Wittgenstein]

One more queston... Since I am not grounding the input jacks, would I still need the jumper wire from the ground lug to the shorting lug, like they are in the top two input channels. Or would I omit these as well and only have the blue and yellow wires hooked up to the tip? I would like it short out to ground when no insturment cable is in, so that way no sound is heard.

[Wittgenstein]

Could my input jack wiring scheme be causing my hum? So I attached the outputs jacks, input jacks, and pots last night using the attached schematic. When I fired it up it was fine, until I throw the standby. Then I hear lots of hum, worse than before even, and my hand being near the chassis changed the frequency / tone of the hum. My question is still, are the input jacks wired properly? They are shorting jacks with the sleeve only connected on the bottom two jacks. Would I need to run a little jumper from the ground to the shunt on the top 2 inputs as well (see attachment in post #11)? I'm have not had time yet to go through everything and make sure it is working properly, but I will post more info tonight. If I do not receive an answer by then I might try a few things to pinpoint the issue, like removing the AX7 & AY7 tubes to see if the hum persists, and maybe removing the input jacks from the chassis to break the ground. I was hoping to not have to measure the pin voltages on my tubes until the amp was in working order, but I will see.


Looking at Triodes site, the jacks they provided have to be switchcraft 12A for inputs and main 8ohm out, with the rest being switchcraft 11 Mono Non-Shorting Jacks.

[Wittgenstein]

Bump.... I will be home from work in a few hours, and I will upload photos of what I've done then. After some more reading and thinking about the way shorting jacks work, I think I will try making up some alligator clips to connect the ground lug to the shunt on the top 2 jacks (see attachment). As I said before I am using un-insulated jacks and therefore did not run any ground wires, but the way I have it wired now would lead me to believe that there are always 2 open inputs grounding out to my chassis. I am really hoping that this is the root of my problems.


Update: There is no hum present whatsoever when i removed the 12ay7 tube, which narrows it down a bit. I next tried using alligator clips like I mentioned and the hum was far less but still defiantly there. I did notice that the antenna affect that I mentioned with my hand near the chassis did not occur and that if I moved the alligator clip wires it would change the tone. This has to be a step in the right direction, and I'm thinking if I just solder some short 1 inch coated wires in instead of long crappy wires on the alligator clips, it might help a bit.

[Bruce / Mission Amps]

The shorting bar must be connected to the grounded lug, on the top two jacks in order for them to work correctly... you picture with the green jumpers is right.
Most builders just use the extra lead length of the 1M resistor to jumper those two lugs together.

One or two of the shorting bars on the jacks might not be actually touching with no 1/4" plug inserted.
Ground the grids of the 12AY7, lugs 2 and 7 , to see if the noise goes away.
It will never be dead quiet with the switching jacks working correctly but it should be 99% unobtrusive.

[Wittgenstein]

I did exactly that soldering the lead of the 1M resistor through all 3 lugs on the top 2 shorting jacks. When I fired my amp back it sounded worse then before with parasitic oscilaton happening depending upon the levels of the volume and tone. It almost sounded better when all pots were turned to 7 as opposed to off. Then I turned everything off to flip the amp upside down to peer down inside while runing, and when I fired it back up there it would no longer produce sound from a guitar. It is as if it is not sending signal out to the the output jack. I do not want to harm the transformers by running it too long. I guess I will start with just the rectifier in and take heater pin measurements and go from there by adding the 6v6's to measure the B+ and so on.

I did notice however that when I first fired it up with the input jacks properly wired, that whenever I touched the chassis anywhere with my hand, it would change the sound of make a popping noise, which leads me to belive there is a bad grounding issue. I forgot to take some pics yesterday, but I will be sure to tonight, and hopefully the pin voltages to aid in troubleshooting. I can't wait for the day when I can plug my tele into this amp and have it work with no hum... sigh.

I have a 5f1 champ clone that I built from scratch (including making punching a stainless steel chassis, turret board, and currently working on the cab) that is ready to go, just needs to be soldered up, but I want to figure out this 5E3 before I jump into another project.