5E3 Build Ground Hum (Probably Loop) Issues

[Kitarist]

So i just built another 5E3 build and this time i have Ground hum issues.

I'm using Ceriatone Style Grounding. http://ceriatone.com/images/layoutPic/fenderLayout/5E3Ceriatone.jpg

Also when i put guitar into the input jack the ground hum amplifies.

Anyone got a clue what it could be? I tried moving cables around etc...

I'll post some pics when i can :D

[Willabe]

Did you use plastic Marshall type jacks for the input's on metal frame Switchcraft type input jacks? If you used plastic type input jacks, you might need to also move the 'Y' ground lug to just below the input jacks......

but Try this;

[jerrydyer]

i just built two of those. they are very particular about grounds. follow it to a t and maybe even move the Y ground to over by the input jack. that one 16 uf cap next to the others cant be grounded with them...... just like said above.    lol

[pompeiisneaks]

One one (of my two!) builds in general I found that if you accidentally have any of the coax shielding touching the input at the tube side it adds a ton of noise when the jack is plugged in.  That's at least one thing to double check.

~Phil

[p2pAmps]

How about some detailed gut shots of your build so we can look closely at what you have...

~m

[Leevi]

Also when i put guitar into the input jack the ground hum amplifies.

Do you hear any hum when the guitar is not plugged and the volume is opened?


/Leevi

[Kitarist]

Long time no reply was really busy with other things and just decided to let this project rest for a while.

Because i wa suspecting the plastic jacks i went and got the "original" jacks that were used in those kind of amps.

Well the hum is always present now whetever the guitar is plugged in or not and also increases with volume.

Here are some pics:

http://imgur.com/a/orc0W

[sluckey]

Can't really see the input jacks wiring good enough to say if they are wired properly.

Refer to the attached pic. Use a couple gator clip leads to connect the two "red circled" turrets to chassis. If the hum goes away then the input jacks are not wired properly.

[jojokeo]

Regardless of what you find it's always advisable (and easy) to elevate your heaters in a cathode bias amp as shown to minimize heater hum.

[Kitarist]

I did forgot to say that the amp does behave properly when i plug the guitar but hum is always present and increases if i also increase volume. But yes i'll check the inputs again even tho i checked them 3 times already.

I can try to make more pictures tomorrow :P

Thanks for everyone for taking their time i really appreciate it!!! :)

[ats]

I just finished up my first build (5e3) so im a novice but looking at the photos you linked to it seems the backs of your pots are not grounded. Not sure if its  necessary  but  i bent the ground lug down and soldered it to the pots body and connected them all with the yellow green wire to the same ground as the input jacks.  no hum at all.

[Kitarist]

I tried all the options you guys provided and problem still persists.

Here is an album with more detailed pictures:

http://imgur.com/a/yOiby

Thanks :)

[sluckey]

My suggestion was not meant as a solution but just a 'divide and conquer' test to eliminate the input jack wiring as a possible cause. Did you actually try it?

[jojokeo]

I tried all the options you guys provided and problem still persists.

The one photo I was trying to see and you didn't capture it - plus it's too hard to follow with using the same green w/yellow stipe all over. Check your heater wiring polarity to see if you have both power tubes' heater wires ran to the same pins? Meaning the same wire is attached to bot pin #2's and the other to both pin #7s?
 
Despite what others will chime in on this - I have experienced this on 5E3 builds before. In fact I got a steal on buying one off of eBay years ago w/ GT tubes and everything for $100 bucks because the guy didn't know what he was doing. A quick heater wire fix and that was that. Perfect.

[Kitarist]

Rewired the heaters, redid and rechecked the polarity the problem still persists...

Problem is like in this video:

! No longer available

But its even louder and more sensitive and it leaks a bit already even on standby.

I'll buy another set of output tubes and a rectifier tube to see if the tubes are the prob but i doubt it.

[HotBluePlates]

Rewired the heaters, redid and rechecked the polarity the problem still persists...

Problem is like in this video ...

Hum in a new build is build-specific. There is no troubleshooting value in seeing someone else's amp which hums, because while there are a number of things which can cause hum, with a new build it is almost always a builder error (though if you were recycling 50 year old filter caps by using them in your amp, you could have bad parts in a new build).

This is why we need to see a picture of your amp, to see if there are problems obvious to us that weren't obvious to you.

[Kitarist]

I already posted an album of pictures here:

http://imgur.com/a/yOiby

[HotBluePlates]

With the guitar unplugged, clip an alligator jumper lead from the red-circled area of Sluckey's earlier post to chassis. Do that for both of the circles. With no guitar plugged in, do you still have hum?

[Fresh_Start]

I already posted an album of pictures here:

http://imgur.com/a/yOiby

I noticed that you used a Cliff jack for the speaker. Are the ring of the jack and one side of the output transformer grounded somewhere?

Sorry if it's a dumb question - I just can't see it.

Respectfully,
Chip

[jojokeo]

Kitarist - you need to address some wiring issues:

1 - you have the 6V6 heater wires hooked up wrong as I suspected and best I can tell from the photos. Both pin 2's on same wire and both pin 7's should be on same wire (photo 1)
2 - the 2nd input jack's grid wire that you are plugged into is too close to the heater wires at the socket - bend wire away (photo 2)
3 - remove Both Vol preamp grounds from power supply ground lug. Cut one short to attach to each other's ground #3 lugs together, then run single wire to cathode preamp ground on board (photo 3)

[Kitarist]

Thanks for trying to help :)

I did all thes things and the problem was still present.

What i did figure out is that if i unscrew the input jacks from the chasis the hum goes aways as they arent touching the chasis. The hum goes away but another new hum is still present on standby and on amp full on but doesnt go louder if i move the volume i also removed all premp a tubes and output and the second hum was still present so i have no idea what might be causing it or is that "normal" operational hum?


Now question how do i aproach the input jack problem? I actually do i need insulate them right? Thats why cliff jacks are "better" as you dont need to insulate them.

Thanks again.

[Willabe]

Did you ever try changing the grounds like I showed you in reply #1?

This high lighted drawing might be clearer? 

[Kitarist]

Yes i did try but i'll recheck tomorrow. Even tho Hum goes away if jacks are not touching the chasis so i need to isolate them they are causing the loop.

Still not sure why the second "hum" is present its also present if i remove all tubes except rectifier. Not sure whats up with that. Its not loud but its present and doesnt get louder when i turn up the amp.

Also i'll do better heater wiring now to eliminate the hiss when i crank the amp up.

[Willabe]

Even tho Hum goes away if jacks are not touching the chasis so i need to isolate them they are causing the loop.

Yes that tells you you have a loop but you can cut a loop at different points.

You can probably get rid of that loops hum without isolating the jacks.

Still not sure why the second "hum" is present its also present if i remove all tubes except rectifier. Not sure whats up with that. Its not loud but its present and doesnt get louder when i turn up the amp.

Also i'll do better heater wiring now to eliminate the hiss when i crank the amp up.

Fix 1 thing at a time. 

[jojokeo]

I was going to include this with other changes earlier but wanted to wait. The Ceriatone build shows Cliff jacks used but Kit used Switchcraft types. You can use isolating washers available from Doug. What you are learning is that you are mixing chassis ground with circuit ground and creating several ground loops. If you look at the photo attachment, you should cut away the wire that attaches to the input jacks as indicated to remove yet another since the Volume controls and creating signal dividers and should be thought of as "signal ground" but not chassis ground. The improved lead dress in my photos will only help and not hurt. These things should be done no matter if your amp is dead quiet or not if you follow proper building methods. You're learning things like many - the hard (and frustrating) way.
 
Please confirm:
1) Did you change the power tube's heater wiring so that both pin2's go together and both pin 7's?
2) Did you change the location of the heater wiring center tap to go to the cathodes of the power tubes?
3) Where is the ground wire under the board connected that touches the preamp cathode resistor's grounds?