Shielded Cable on 5E3

I'm almost done the build and down to running the shielded cable..i have it soldered on top to the volume, but on the bottom where it goes to V2 pin 2, I notice there is shrink tubing in different photos I've seen , but is the shielding insulated and the live conductor soldered to pin 2 or am I off base entirely??

Thank you..

Yas, the jack has the live wire and the ground shielding wiring...this is cut at the tube end and covered with wrap, leaving just the live to lug 2

So whats the point of having one end grounded only ??

You get a shielded signal without another potential ground loop.

Run shielded if you want but it will make absolutely no difference to noise in a 5E3.

Run shielded if you want but it will make absolutely no difference to noise in a 5E3.

Yep.

Aye. If you follow Leo's layout, shielding doesn't make a lick of difference. It's a beautiful design.

Just wiring the boards in my Deluxe AB763 at this moment (on a coffee break) and pondering the same question! I have used shielded in other higher gain amps but I will run as Leo intended and see how it goes. I have a passive pre/ power loop and I may shield one or both of those, but I suspect that being relatively low gain it aint gonna matter:razz:

thanks guys.. well here's another one for you then.. I ran my twisted heaters wire nice and neat along the chassis and I'm wondering if I should have left the signals up away from them..let me know what you guys think..I also realize I'm missing the 2nd resistor on pt socket.. :lol:

http://i271.photobucket.com/albums/jj134/livtohunt60/12.jpg

http://i271.photobucket.com/albums/jj134/livtohunt60/13.jpg

http://i271.photobucket.com/albums/jj134/livtohunt60/14.jpg

You MUST separate heater from signal wires

how much seperation do they need to maximize hum as it'll depend on bending them up and out of the way or redoing some of them..

how much seperation do they need to maximize hum as it'll depend on bending them up and out of the way or redoing some of them..

I ran my heaters the same way and have a very quiet amp -- no need to do anything special. just keep away as best you can.

Thanks Jcn. so a few of your signal wires were touching the heater wires in a few places and you had no trouble with noise?? I was thinking if I had to move some, I would be able to bend most of them up out of the way, but some I'd have to remove a reposition..

Also, some builds you'll see the positive half of the board they've slid insulation over ever bare wire, ...Is this required.. The thoughts of having all this work into it, and have a noisey amp will be annoying..i'd rather do it properly the first time..

It is best to keep signal wires away from others but another thing to consider is that they pick up less noise if they run 90 degrees from each other.

Thanks Jcn. so a few of your signal wires were touching the heater wires in a few places and you had no trouble with noise?? I was thinking if I had to move some, I would be able to bend most of them up out of the way, but some I'd have to remove a reposition..

Also, some builds you'll see the positive half of the board they've slid insulation over ever bare wire, ...Is this required.. The thoughts of having all this work into it, and have a noisey amp will be annoying..i'd rather do it properly the first time..

like printer2 said -- don't run other wires next to the heater wires. you've put the heater wires in a place where nothing else needs to get very close. keep the signal wires on the other side of the tube sockets and all should be good. of course around the sockets you do the best as you can and cross at 90 degrees when necessary.

it looks like you've only got one red and one yellow wire that should be relocated.

1/2" min. Worst is touching

I removed and repositioned some of the signal leads to get them up and out of the way of the heaters..Regarding the yeller and red, let me know if you think it should be ehh ok yet..on the next unit to do, i'll run the heaters jumpers along the front so everythings in the same area and completely opposite to the signal....live and learn, and so far this is proving to be a great lesson..Look out when it comes time to testing and diagnosing....ohh boy.. :)

http://i271.photobucket.com/albums/jj134/livtohunt60/relocatedsignals1feb112012.jpg

http://i271.photobucket.com/albums/jj134/livtohunt60/relocatedsignalwires3.jpg

http://i271.photobucket.com/albums/jj134/livtohunt60/relocatedsignalwire2.jpg
The black wire hanging over the front right side is the loose shielded wire yet to be soldered

Gibson ran the heater wires like that in their tweed-style chassis'. Running them over the sockets makes sense in a blackface chassis but not in a tweed. Biggest thing I found that reduced hum was to separate the preamp grounds from the power amp grounds.

Biggest thing I found that reduced hum was to separate the preamp grounds from the power amp grounds.

This^^^^^^^^^^

I'm not certain being I'm as green with this stuff as an rookie can be other than that I can solder, strip wires have a love for good tone and music and i'm determined to build a few great sounding amps we'll be prous of and I'm grateful to get your help..so now that i've got that out, regarding the grounding issues, there is a Star grounding point on the right side of the chassis ,which i'm guessing is the pre amp side of things and then another star grounding point to the right side of the power transformer and the last one where the power supply enters the chassis..So ther than attaching the gorund wires to where their indicated to go, I'm not sure what else I should be concerned with.. go easy on greenie here..

Gibson ran the heater wires like that in their tweed-style chassis'. Running them over the sockets makes sense in a blackface chassis but not in a tweed. Biggest thing I found that reduced hum was to separate the preamp grounds from the power amp grounds.

So are you saying TNO that having these wires up over top of the sockets are going to cause noise..

Just wiring the boards in my Deluxe AB763 at this moment (on a coffee break) and pondering the same question! I have used shielded in other higher gain amps but I will run as Leo intended and see how it goes. I have a passive pre/ power loop and I may shield one or both of those, but I suspect that being relatively low gain it aint gonna matter:razz:

Well guess what, I fired it up and after some playing and tweaking, I replaced both channels input to pin 2 and the pre/power in and out with RG174 shielded:razz:

The noise floor is just too high when you have a small chassis (17") two channel amp stuffed full of carbon comps, the shielded takes it right down. I tend to crank things and then take the level down on the guitar. The D*mbeleator is also used as a global master volume too.

Sounds much better but I may still lose a few CCs for some Dale RN65s. Need to balance sterility with old skool hiss:roll::cool::smile:

I have no clue what you just said :)

I have no clue what you just said :)

I think it was Greek :!:

Just reading this. I use to avoid using shilded and thought it was pretty useless but I've learned better. It's good to run sheilded for the input grid to first and second 12ax preamp stages and long grid runs. If you like a quiet running amp use it. Platefire

we ended up replacing the shielded with solid 20awg, and I also had my wires crossed, literally on the volume pot, but we have the proper readings now. we are now on V2 pin 7 which is giving us 20Vdc when it should be 0 and also getting a reading of 56 at pin 8 when it should be 80..credit goes to "Cruisinhome" for helping me along..