First 5e3 build 60 cycle hum Grounding questions

[olgoat]

Just finished my first 5E3 build and it came out pretty well. Sounds good for the most part. I had a couple of issues that I am unclear on and was hoping for some direction and comments.

There is more 60 cycle hum that I would like.  Not sure how quiet these amps are supposed to be.

• ceriatone circuit
• P-TF22772 325-0-325 PT. Does not have a center tap for heaters
• P-TF22913 OT  (12 W 8 ohm)
• P-CF22707 choke 50 ma instead of 5K 1Watt resistor

I tried to follow Doug's grounding scheme. 

• He recommends grounding the preamp and PI caps to the pot ground but in the 5E3 layout these grounds connect to the Screen Grid cap ground which is suppose to go to the PT ground bolt.
• He recommends pot, jack and preamp grounds be combined but do they just rely on firm bolting of pots and jacks to the chassis for ground?

For the heater circuit, I took the PT heater wires right to the pilot light. I wired the 100 ohm resistors from each lug of the pilot light to the pilot light bracket and use the bracket to chassis contact for ground.  (I wired from the pilot to the 1st 6V6 and carried it through to the preamp tubes.  I think I got the phase wired correctly all the way through the tube heaters. )




I have moved the lead dress around leaving the heater wires raised above the sockets and nothing really reduces the hum so far. 

Thanks for you time.

[Willabe]

The blue OT primary lead going to pin 3 on the 1'st 6V6 is supposed to be down on the chassis. From the pic it looks like it's running right by/very close to the B+ of the rectifier tubes pin 8.   _Move it away and down on to the chassis_.

The 2 wires from the power cord going to the on/off switch and fuse should be twisted together _tightly_.

The 6.3v heater wires should be twisted together _tightly_ as should the 2 red high voltage leads (reds look pretty good) and the 2 yellow 5v rectifier heater leads. The 2 green heater wires from the PT to the pilot light look good to me.)

Unless they are twisted together _tightly_ they wont cancel out the noise.

The screen grid wires look a little too long and I can't really tell if the 1 that goes to the 1'st 6V6 is run very close to the 6.3v heater wires.

I don't see any screen grid resistors?

Here's 2 pics of what IMO would be tightly twisted. I'm still learning/working on how to do this, but I don't think these are bad, although I've seen better.

                        
                                   Brad      

[TubeGeek]

• He recommends grounding the preamp and PI caps to the pot ground but in the 5E3 layout these grounds connect to the Screen Grid cap ground which is suppose to go to the PT ground bolt.
• He recommends pot, jack and preamp grounds be combined but do they just rely on firm bolting of pots and jacks to the chassis for ground?

Separate the preamp grounds from the power supply/section grounds.

Move the screen grid filter cap ground off of the preamp buss over to the same ground as the PT centre tap ground.

[TubeGeek]

I can't confirm by looking at your pics but I see a green/yellow ground wire I'm assuming is coming from the ac cord going to a lug on a terminal strip.  The middle lug is the centre tap ground...is the ac cord ground lug connected to the middle terminal lug or chassis ground?

[Willabe]

Did you take the B+ from the rectifer tube from pin 2?

It has to be taken from pin 8.    

That way you can use different rec. tubes, like, 5V4, 5AR4.


                  Brad      

[Willabe]

I can't confirm by looking at your pics but I see a green/yellow ground wire I'm assuming is coming from the ac cord going to a lug on a terminal strip.  The middle lug is the centre tap ground...is the ac cord ground lug connected to the middle terminal lug or chassis ground?

I think your right TG, good eyes!     

[TubeGeek]

Did you take the B+ from the rectifer tube from pin 2?

It has to be taken from pin 8.    


                  Brad      

Yeah, hmmm hard to tell eh!

Good eyes!

[archaos]

Just finished my first 5E3 build and it came out pretty well. Sounds good for the most part.

Congrats !

There is more 60 cycle hum that I would like. Not sure how quiet these amps are supposed to be.

I have to check the pilot light on my 5E3 to be sure it's turned on. 
60 Hz ? Are you sure ?
Doesn't it sound more like stg between a low A# or B on your axe ? If so, you have 120 Hz hum, & stg is certainly wrong with your grounding arrangement.
Actually I fear that you have sveral chassis grounds (when looking at your pics), hence interferences with the currents causing ground loops. For instance, I see that your artificial center tap (2 x 100Rs) is tied to the ground (soldered acually) on the pilot lamp holder, whereas the HT center tap is bolted to the chassis near the PT (BTW, how about the heater -transformer- center tap, is it tied to the chassis as well ?)
You must have a one-and-only connection to be made between the circuit ground and chassis.

[olgoat]

THe Green/yellow power cord wire is connected to the end lug of the terminal strip.  The PT Center tap (red yellow) is connected to the center lug of the same terminal strip.

The brown power cord wire is soldered to one of the black PT 120V leads. The blue power cord wire is going to the fuse.   Wasn't sure how best to connect the power cord wires.

Thanks for taking a close look.

[TubeGeek]

THe Green/yellow power cord wire is connected to the end lug of the terminal strip.  The PT Center tap (red yellow) is connected to the center lug of the same terminal strip.

The brown power cord wire is soldered to one of the black PT 120V leads. The blue power cord wire is going to the fuse.   Wasn't sure how best to connect the power cord wires.

Thanks for taking a close look.

Make sure those two terminal lugs connect to each other.  The green/yellow needs to connect to chassis ground!  The same point as the PT centre tap and all other power section grounds.  

[olgoat]

The ceriatone layout takes the 5V feed from the PT to pins 2 and 8 of the rectifier.  Pin 2 of the rectifier also goes to the standby switch. (my layout looks the same as this except for the PC jacks.


TWC

Did you take the B+ from the rectifer tube from pin 2?

It has to be taken from pin 8.    

That way you can use different rec. tubes, like, 5V4, 5AR4.


                  Brad      

[olgoat]

SHIT!!!   STUPID STUPID STUPID... How did this ever work!!! I forgot to wire all the tabs on the terminal strips connected to the power supply bolt.   Jeeez.   Well that might explain a few things.  Amazing. 

THe Green/yellow power cord wire is connected to the end lug of the terminal strip.  The PT Center tap (red yellow) is connected to the center lug of the same terminal strip.

The brown power cord wire is soldered to one of the black PT 120V leads. The blue power cord wire is going to the fuse.   Wasn't sure how best to connect the power cord wires.

Thanks for taking a close look.

Make sure those two terminal lugs connect to each other.  The green/yellow needs to connect to chassis ground!  The same point as the PT centre tap and all other power section grounds.  

[archaos]

I'd say that Ceriatone grounding scheme is unacceptable !

BTW, the speaker ground ought to be connected to the power amp cathode resistor ground point.

[olgoat]

Doug's grounding recommendations seem to indicate multiple ground points on the chassis.  I would assume that what he refers to as star grounding is a single ground point for all chassis components.  He says star grounding is a no-no so I avoided it. http://www.el34world.com/charts/grounds.htm

Just finished my first 5E3 build and it came out pretty well. Sounds good for the most part.

Congrats !

There is more 60 cycle hum that I would like. Not sure how quiet these amps are supposed to be.

I have to check the pilot light on my 5E3 to be sure it's turned on. 
60 Hz ? Are you sure ?
Doesn't it sound more like stg between a low A# or B on your axe ? If so, you have 120 Hz hum, & stg is certainly wrong with your grounding arrangement.
Actually I fear that you have sveral chassis grounds (when looking at your pics), hence interferences with the currents causing ground loops. For instance, I see that your artificial center tap (2 x 100Rs) is tied to the ground (soldered acually) on the pilot lamp holder, whereas the HT center tap is bolted to the chassis near the PT (BTW, how about the heater -transformer- center tap, is it tied to the chassis as well ?)
You must have a one-and-only connection to be made between the circuit ground and chassis.

[olgoat]

I tried to use Doug's grounding recommendations instead of the ceriatone

-Pots and Jacks grounded to the chassis through contact.
-cathode ground to PT ground lug
-power cord ground to PT ground lug (problem identified there. Thanks TG
-PT center tap to PT ground lug
-heater simulated center tap Resistor to PT ground lug.

The board layout combines the grounds for the preamp and screen caps.  Is this what you are referring to as unacceptable?

Thanks

I'd say that Ceriatone grounding scheme is unacceptable !

BTW, the speaker ground ought to be connected to the power amp cathode resistor ground point.

[TubeGeek]

This indeed can get confusing.  I remember sorting through it all when trying to grasp it all.

In the 5e3, simply separate the preamp grounds from the power section grounds.  It's generally a good idea to have the preamp grounding point as close to the input jacks as possible.

The preamp grounds will be the input jacks, cathode cap grounds, first filter cap ground, and pot grounds.

The power section grounds will be the pt centre tap, green yellow power cord, power tube cathode grounds, speaker grounds, artificial filament ct.

[Willabe]

A 5Y3 has a directectly heated cathode so you can tap the B+ from either pin 2 or 8. But other rec. tubes, (like 5V4 and 5AR4/GZ34) can have an indirectly heated cathode with the actual cathode pin out on pin 8.

If you have your amp wired with pin 2 as the B+ tap and put in a 5V4 all the B+ current for the whole amp will be pulled from/through the rec. tubes 5v heater instead of it's cathode.  The heater can't take this.  

Because of this it's best to always use pin 8 as the B+ take off point. That way you can pop in other rec. tubes with out worry of burning up the tubes heater.


                     Brad        

[olgoat]

Just noticed the ceriatone layout I posted is not the exact one I used.  I just noticed they have resistors across 4 & 5 and 6 & 7 on the rectifier. My layout did not have those.  I got a hardcopy layout and didn't find the one I posted until I was done with the build.

[TubeGeek]

Just noticed the ceriatone layout I posted is not the exact one I used.  I just noticed they have resistors across 4 & 5 and 6 & 7 on the rectifier. My layout did not have those.  I got a hardcopy layout and didn't find the one I posted until I was done with the build.

You mean diodes right?  These aren't necessary for operation.  They are for protection if the 5y3 shorts out.

[TubeGeek]

The board layout combines the grounds for the preamp and screen caps.  Is this what you are referring to as unacceptable?

On your layout you see that the furthest to the right filter cap and middle filter cap grounds are connected.  Separate these grounds.  The furthest right filter cap is the plate supply ground for the preamp section.  This cap ground should connect to the preamp grounding point.

The middle filter cap ground is the screen grid supply ground, this should be connected to the same point as the pt ct and green yellow ac cord grounding wire.

[Willabe]

How did this ever work!!! I forgot to wire all the tabs on the terminal strips connected to the power supply bolt.

It'll work, it's just that you didn't have the safty ground hooked up.    

Your doing fine, it's gonna be a great sounding/playing amp.  


                         Brad      

[olgoat]

TG.  Thanks. All very mysterious.  I can't believe it worked at all.

I am confused by the terms cathode cap grounds, first filter cap ground  versus the power tube cathode grounds

The power tube cathode should be the 22uf cap going to pin 8 on the 6v6 so that is the board ground at the upper left of the ceriatone layout right above the 22uf cap (22 uf cap and left most 16 uf cap).  The next ground to the right is the ground for the 2-16 uf screen grid caps as well as the preamp caps.  Sounds like I need to break the ground at the top of the third 16uf cap from the left where the 56K resister and black wire come in from the right?  Sorry if that sounds confusing.

Thanks for you recommendations.  

This indeed can get confusing.  I remember sorting through it all when trying to grasp it all.

In the 5e3, simply separate the preamp grounds from the power section grounds.  It's generally a good idea to have the preamp grounding point as close to the input jacks as possible.

The preamp grounds will be the input jacks, cathode cap grounds, first filter cap ground, and pot grounds.

The power section grounds will be the pt centre tap, green yellow power cord, power tube cathode grounds, speaker grounds, artificial filament ct.

[olgoat]

I think I see what you are saying.  So for the three 16 uf caps, break the ground between # 2 and #3 from the left at the top of the board and run the ground from #3 to the pot ground.  Sound right?

THanks

The board layout combines the grounds for the preamp and screen caps.  Is this what you are referring to as unacceptable?

On your layout you see that the furthest to the right filter cap and middle filter cap grounds are connected.  Separate these grounds.  The furthest right filter cap is the plate supply ground for the preamp section.  This cap ground should connect to the preamp grounding point.

The middle filter cap ground is the screen grid supply ground, this should be connected to the same point as the pt ct and green yellow ac cord grounding wire.

[TubeGeek]

this help...?

[olgoat]

HA!!   And he's a graphic artist to Boot.  You BET it helps!   Thanks a bunch.  Warming up the iron now.

this help...?

[TubeGeek]

A 5Y3 has a directectly heated cathode so you can tap the B+ from either pin 2 or 8. But other rec. tubes, (like 5V4 and 5AR4/GZ34) can have an indirectly heated cathode with the actual cathode pin out on pin 8.

If you have your amp wired with pin 2 as the B+ tap and put in a 5V4 all the B+ current for the whole amp will be pulled from/through the rec. tubes 5v heater instead of it's cathode.  The heater can't take this.  

Because of this it's best to always use pin 8 as the B+ take off point. That way you can pop in other rec. tubes with out worry of burning up the tubes heater.


                     Brad        

I agree with Brad.  Use pin 8.

[archaos]

Doug's grounding recommendations seem to indicate multiple ground points on the chassis.  I would assume that what he refers to as star grounding is a single ground point for all chassis components.  He says star grounding is a no-no so I avoided it.

Actually try avoiding as much as possible either star grounding as a single ground point or multiple ground points on the chassis : they can be a real curse causing unwanted noise(s) or hum...
This : http://valvewizard2.webs.com/Grounding.pdf is correct.

On the Ceriatone layout posted by TG, the left smoothing cap is the reservoir cap supplying the anodes (it shouldn't be connected on it's ground side to the cathode bypass cap + resistor), the middle one should be the screens/cathodes smoothing cap (whereas it's the previous cap which is firstly connected to the cathode ground) & the last one is the preamp stages smoothing cap.

[TubeGeek]

Edited.

[olgoat]

That is very interesting.  I would not have thought there would be any difference between grounding  the left most 16uf cap directly as opposed to a common ground with the cahtode cap.   Thanks much for the updated diagram.   Going to get to work on it right now. 

TWC

Edited.

[Willabe]

I guess there's at least a few ways to do this, but the way I interpret KOC and Merlins wired ground schem is ;

Run the B+ CT directly to the negitive end of the 1'st B+ filter cap, OT CT feed to output power tubes, this is the first ground star, then from there run a single wire back to the common juntion of the power tubes cathode R and bypass cap and the screen grid filter caps negitive end ground and OT ground, second ground star. Then run a wire to the PI's R's/C's (3'rd) ground star, then to the next ground star and so forth.

(KOC likes to tap the 1 chassis ground from some where around the PI's star?)

Here's how I did mine.

                                     Brad      

 

[TubeGeek]

I guess there's at least a few ways to do this, but the way I interpret KOC and Merlins wired ground schem is ;

Run the B+ CT directly to the negitive end of the 1'st B+ filter cap, OT CT feed to output power tubes, this is the first ground star, then from there run a single wire back to the common juntion of the power tubes cathode R and bypass cap and the screen grid filter caps negitive end ground and OT ground, second ground star. Then run a wire to the PI's R's/C's (3'rd) ground star, then to the next ground star and so forth.

(KOC likes to tap the 1 chassis ground from some where around the PI's star?)

Here's how I did mine.

                                     Brad      

 

Nice job! Very logical layout.

[Willabe]

Thanks TG.

It makes it much easier using modern small radial filter caps.    

[archaos]

KOC likes to tap the 1 chassis ground from some where around the PI's star?

Yes he does when he uses a ground lift, otherwise he connects the ground system right at the very input jack near the main Earth bond.

The Ceriatone layout unfortunately uses the chassis as a ground plane, that's a great shame.

[olgoat]

Thanks for all the help and suggestions yesterday.  I redid and corrected the grounding scheme and the hum is much reduced.  I can't say I don't know the amp is on but it is at a tolerable level.  The hum is a bit more than my Deluxe Reverb.  I think the amp sounds better as well.  A bit smoother with the ES345 than it did before. 

I think I got everyones concerns addressed.  Kind of like doing a graduate thesis by committee 

You guys are awesome.  But you all knew that already, didn't you?

[Willabe]

All Right! Nice Job!    

One more thing, looks like a small blob of solder is hanging over very close to the frame of the pilot light from the back conection of 1 of the heater wires and 100R. The frame is grounded to the chassis so this could short out the heaters.    

Also the 6V6's cathode R (250R/5w) looks like it's touching/laying right up against the cathode bypass cap? That will cook that cap if it is and take the life out of it. Just move them apart a little, 1/4" at least, a little more is better.
                      

                                Brad      

[TubeGeek]

Cool, glad we could help!

[Willabe]

I can't really see but did you run a green wire from the speaker jacks to the terminal strip? If you did and your speaker jacks are not insulated/isolated then you just made a ground loop with some of the highest current in the amp.

There's no need to run that ground over to the terminal strip _unless_ the jacks are insulated from the chassis as they are already grounded to the chassis.

I can see a wire going from the left side of the terminal strip to the center lug, but I don't see a wire going from the right side to center.

Unless it's on the back?

                    Brad      

[olgoat]

TG has said "The power section grounds will be the pt centre tap, green yellow power cord, power tube cathode grounds, speaker grounds, artificial filament ct.".  Hoffman grounding scheme I think calls for the Speaker ground to the OT bolt ground.  I followed what TG has said.  I'll lift the speaker ground to see if has any affect on the hum.

I will checkout the solder blob too.  I need to replace that pilot anyways, it's not machined right and the bulb does not go in properly.

Thanks for checking it out.

I can't really see but did you run a green wire from the speaker jacks to the terminal strip? If you did and your speaker jacks are not insulated/isolated then you just made a ground loop with some of the highest current in the amp.

There's no need to run that ground over to the terminal strip _unless_ the jacks are insulated from the chassis as they are already grounded to the chassis.

I can see a wire going from the left side of the terminal strip to the center lug, but I don't see a wire going from the right side to center.

Unless it's on the back?

                    Brad      

[olgoat]

Oh and sorry forgot.  On the terminal strips I solderd some bare wire thru the eyelets below the lugs so that all the lugs are common to the terminal strip mounting.  There is continuity across all lugs.  I removed the other terminal strip off the OT screw that I originally had the pots and the speaker grounded to.

I can't really see but did you run a green wire from the speaker jacks to the terminal strip? If you did and your speaker jacks are not insulated/isolated then you just made a ground loop with some of the highest current in the amp.

There's no need to run that ground over to the terminal strip _unless_ the jacks are insulated from the chassis as they are already grounded to the chassis.

I can see a wire going from the left side of the terminal strip to the center lug, but I don't see a wire going from the right side to center.

Unless it's on the back?

                    Brad      

[olgoat]

This has been the most productive thread I have ever started on any forum.   Thank you all very much.

[Willabe]

TG has said "The power section grounds will be the pt centre tap, green yellow power cord, power tube cathode grounds, speaker grounds, artificial filament ct.".  Hoffman grounding scheme I think calls for the Speaker ground to the OT bolt ground.  I followed what TG has said.  I'll lift the speaker ground to see if has any affect on the hum.

Yes but, if the speaker jack is _not_ a plastic type(Marshall) that has it's ground isolated from the chassis or you're _not_ using plastic shoulder washers with a Switchcraft type jack to isolate the jacks ground from the chassis, then the jack with the OT ground wire soldered to it's ground terminal is _already_ grounded at the chassis when you fasten it to the chassis.

Now the OT ground has 2 paths to choose from and this  _is_  a ground loop. 1 path from jack through the chassis and the second from the jack through the wire to the terminal strip to chassis ground. It has 2 places where it connects to chassis ground, it should only have 1 place where it connects to chassis ground.

In one of Gerald Weber's books (IIRC) he wrote that when a component, in this case has 2 paths to chassis ground it wants to take the path of least resistance. But in 1 split second it will/can see 1 path as the least resistance, then it will/can see the 2'nd path as the least resistive and if this happens it will keep flip/flopping back and forth, forward then backward, push/pull in the 2 paths/wires. Now we have an ac signal riding on the dc ground, the speed of which this is happening sets the frequency of this ac signal, causing the ground signal to modulate, ie, ground noise.

Someone else might be able to explain this better then me, please do if/where I've got this wrong, but I think it's pretty close, if not on the mark.

Also your OT ground wire has a lot of current flowing through it and is running right through/past/over/along side of the 6V6's wires, this may or may not induce hum into these (power tube socket) wires and may or may not be injecting this noise into the 6V6 tubes to be amplified, but if it is being injecting into the power tubes......      

Yes the power tubes are less sensitive to this than say preamp tubes, but still it can be a problem.

If you look at the drawings I posted of my 5E3 you will see I used isolated jacks and then ran the screen grid B+ filter caps ground, 6V6's cathode R/bypass C, 6V6's grid return R's and OT ground wire to a single ground "star" point then ran this star to the B+ ground buss.

I'm _NOT_ saying this is the only way to run a grounding system in an amp as this is only my interpretation of what I've read from KOC and Merlin. Just that IMHO you should not have the OT grounded in more than 1 place or have the OT ground wire close to the any sensitive wires that could inject this current/noise into any tube to be amplified.

I hope this is helpfull to you olgoat, as a wired ground layout and lead dress is/can be real head scratcher, at least for me.          


                       Brad        

[olgoat]

Brad thanks for the comments and explanation. This is my first go around and your layout looked very alien to me.  I was having a hard time seeing where the grounding was other than the power cord.  I will have another look.   I barely have any concept of what my layout is actually doing.  But I do appreciate the concerns.

I am not sure what the options are for the OT wires to the speaker jacks as far as routing.  It pretty much comes into the chassis right in the middle of all the preamp tube wiring. Other than elevating it over the top and to the jacks and trying to not pick anything up from the elevated heater wires, not sure where else it could go.  Maybe more twisting is in order.  I'll look at that when I try to lift the ground wire from the speaker jacks to see what that does.

Tim

TG has said "The power section grounds will be the pt centre tap, green yellow power cord, power tube cathode grounds, speaker grounds, artificial filament ct.".  Hoffman grounding scheme I think calls for the Speaker ground to the OT bolt ground.  I followed what TG has said.  I'll lift the speaker ground to see if has any affect on the hum.

Yes but, if the speaker jack is _not_ a plastic type(Marshall) that has it's ground isolated from the chassis or you're _not_ using plastic shoulder washers with a Switchcraft type jack to isolate the jacks ground from the chassis, then the jack with the OT ground wire soldered to it's ground terminal is _already_ grounded at the chassis when you fasten it to the chassis.

Now the OT ground has 2 paths to choose from and this  _is_  a ground loop. 1 path from jack through the chassis and the second from the jack through the wire to the terminal strip to chassis ground. It has 2 places where it connects to chassis ground, it should only have 1 place where it connects to chassis ground.

In one of Gerald Weber's books (IIRC) he wrote that when a component, in this case has 2 paths to chassis ground it wants to take the path of least resistance. But in 1 split second it will/can see 1 path as the least resistance, then it will/can see the 2'nd path as the least resistive and if this happens it will keep flip/flopping back and forth, forward then backward, push/pull in the 2 paths/wires. Now we have an ac signal riding on the dc ground, the speed of which this is happening sets the frequency of this ac signal, causing the ground signal to modulate, ie, ground noise.

Someone else might be able to explain this better then me, please do if/where I've got this wrong, but I think it's pretty close, if not on the mark.

Also your OT ground wire has a lot of current flowing through it and is running right through/past/over/along side of the 6V6's wires, this may or may not induce hum into these (power tube socket) wires and may or may not be injecting this noise into the 6V6 tubes to be amplified, but if it is being injecting into the power tubes......      

Yes the power tubes are less sensitive to this than say preamp tubes, but still it can be a problem.

If you look at the drawings I posted of my 5E3 you will see I used isolated jacks and then ran the screen grid B+ filter caps ground, 6V6's cathode R/bypass C, 6V6's grid return R's and OT ground wire to a single ground "star" point then ran this star to the B+ ground buss.

I'm _NOT_ saying this is the only way to run a grounding system in an amp as this is only my interpretation of what I've read from KOC and Merlin. Just that IMHO you should not have the OT grounded in more than 1 place or have the OT ground wire close to the any sensitive wires that could inject this current/noise into any tube to be amplified.

I hope this is helpfull to you olgoat, as a wired ground layout and lead dress is/can be real head scratcher, at least for me.          


                       Brad        

[Willabe]

This is my first go around and your layout looked very alien to me.  I was having a hard time seeing where the grounding was other than the power cord. I barely have any concept of what my layout is actually doing.

When I get a chance I'll try to re-post the 5E3 layout with the B+ ground buss colored in green for clarity.

Yes it is alien!          FWIW, IMO, for a first go round you've done great. And you're now fine tuning it and it's getting even better.    

I used to think,       hum, well a ground is a ground, right? It all goes to the same place right, to ground? What's the big deal?      

And it took me a while (well a LOOONNGG time, bit by bit       ) also to read and study schematics and layout drawings to start to get it, most if not all will tell you the same thing.

Tim, I'm still trying to figure it out too, you'll get it, you olgoat you.         (Sorry I just could'nt resist   )

Take some time and read and then re-read and then re-re-read Merlins info, as our friend archaos posted the link earler for you (here it is again;  http://valvewizard2.webs.com/Grounding.pdf) and any other stuff you can till it makes scence to you, it's what we all do.

Bottom line is (to me anyway), it looks like your speaker jack is a metal Switchcraft type and if this is true, you don't need to run it's ground over to the main ground point, because it's _already_ grounded to/at the chassis. So nothing to worry about as far as where to rout it. Many amps including Fender grounded the OT at the speaker jack to the chassis. What the guys told you about where/how to ground the B+ filter caps is the bigger part, and you've already done that. It worked, so this is good.

Weber talk about the same B+ filter cap ground fixes for Fenders, that the guys have showed you, years ago in his books.

But I still think you should get rid of the ground wire that's running from the speaker jack (and is all tangled up with the power tube socket's wires), over to the main chassis ground point.

When you lift that ground wire, if it were me I'd lift _both ends and take it all the way out_ and then see if it makes a difference.

Gonna be a great sounding and playing amp when you're done Tim.     

                        
                                Brad        

[archaos]

Take some time and read and then re-read and then re-re-read Merlins info

Learn it by heart actually. 

[Willabe]

Hi Tim,

Here's my 5E3 layout with the wired ground high lighted in green.

The point I took the ac signal ground to chassis is high lighted in red.

I only have 2 chassis ground connections. 1 is the safety ground, 3'rd wire from ac power cord, 2 is the ac signal ground. All jacks are insulated/isolated from chassis.

The heater CT is grounded through the dc stand-off. So i put these components (R's, C's) close to the pilot light so I could twist the CT with the heater leads for noise rejection.   

Again, this is just my _ interpretation _  of what I've read from KOC's and Merlin's books.


                      Brad      

EDIT; Doh, I forgot the 2 @ 220K grid return R's for the 6V6's. I'll fix that and re post.

[archaos]

Here's my 5E3 layout with the wired ground high lighted in green.

I do like stuff like that ! 

[olgoat]

Thanks Brad.   Printing it out to have a close look.

Tim

Hi Tim,

Here's my 5E3 layout with the wired ground high lighted in green.

The point I took the ac signal ground to chassis is high lighted in red.

I only have 2 chassis ground connections. 1 is the safety ground, 3'rd wire from ac power cord, 2 is the ac signal ground. All jacks are insulated/isolated from chassis.

The heater CT is grounded through the dc stand-off. So i put these components (R's, C's) close to the pilot light so I could twist the CT with the heater leads for noise rejection.   

Again, this is just my _ interpretation _  of what I've read from KOC's and Merlin's books.


                      Brad      

EDIT; Doh, I forgot the 2 @ 220K grid return R's for the 6V6's. I'll fix that and re post.

[Willabe]

OK, I added the 2 @ 220K grid return R's for the 6V6's.

If you look at the drawing you see the ground "stars" that are brought together at 1 single point and go to the B+ supplies filter cap's ground that supplies that part of the ac signal circuit.

On the power tubes the PT CT goes directly to the plate supply node filter cap, and nothing else, ground star #1. Then ground star #2's filter cap's (screen grid supply node) ground side gets the 6V6's grid return R's, cathode R/C and the OTs ground. You can see I have the OTs ground wire routed away from the 6V6's socket wires this way. Then it goes down the line to ground star #3, and so forth.

Tying the grounds together like this, with their associated B+ supply node filter caps ground allows all the ground currents for each ground star to flow within itself without disturbing other parts of the circuit.

The heater CT is referenced to ground through the heaters dc stand-off 100K R back to ground star #4. See the BRN wire underlined in blue.

The next amp I build with a rectifier tube is going to have the B+ CT wire go to pin 5 on the rec. tube socket twisted with the B+ leads, then run the rectified B+ with the B+'s CT ground wire as a twisted pair to the power tubes plate supplies filter cap's  +/-  for better noise rejection of the PT's B+ power supply wires.  

                
                                 Brad      

EDIT; If this amp had a NFB loop to the PI, I would have grounded the OT at the PI's ground star.