Question about lead dress

[12AX7]

I have always just had the board to tube socket wires all over the place but being sure they are not close or parallel to each other and cross at 90 degrees. But it looks sloppy like that. I also try and make them short as possible, but i'm thinking maybe it's better to go longer so i can route them better. Can someone point to a pic of what is a generally accepted good way of doing it? Also, i've seen some where they are all laid flat against the chassis. I assume this is so the chassis acts as a shield to more of an extent?  Anyways, some good pics would be appreciated, thanks.

[SILVERGUN]

Sluckey has done some beautiful work, and a great job of documenting it, and if you haven't see his site yet,,you should before he takes it down

If it's good enough for him,,,it's good enough for me....and I take a lot of my inspiration to build from this site:
http://home.comcast.net/~seluckey/amps/index.htm

Doug does some super clean wiring as well, and when I sit down with the iron out it's a great "goal" to shoot for:

[12AX7]

Hard to tell from the pics, but are the wires all laid down against the chassis? Thats one thing i'm wondering most about.  Whether thats the generally accepted as the better method rather than having them raised to keep them as far apart as possible. 

[Willabe]

See how the socket wires on Sluckeys exit the turret board from underneath and Dougs come off the top?

It's the grid wire that's the most concern.


             Brad     

[firemedic]

This may help. If you bundle together the wires from an individual stage (plate, grid & cathode) they can be parallel since the plate signal will be out of phase with the cathode. It's not "negative feedback" as such but the idea is the same. If each individual stage is bundled this way & separated from the bundles of other stages, that can go a long way towards preventing oscillation.

Personally I use shielded wire a lot for the grids that connect to pots, long runs, etc. & you can run that however you like.

I forget who posted his/her build pics that had the heater wires up in the air over the sockets, but what a great idea! I use that method and my builds are pretty quiet considering how messy they are.   

[Willabe]

I forget who posted his/her build pics that had the heater wires up in the air over the sockets, but what a great idea!

That's standard on Fender BF/SF amps.


              Brad     

[SILVERGUN]

The "Hoffman Layout" puts the components for each stage in order, and in turn attempts to keep wire lengths short and direct,, without stages crossing over (where possible)

I don't think that 'against the chassis or not' is the biggest concern

It's more about tweaking your layout to minimze long or crossed wires where possible....take a good hard look at the info on this site about the "Hoffman Layout".....I think Doug did it for good reasons 

Not sure if I believe the 'chassis as a shield' theory,,,simply because it serves as a common ground point, and the goal is to keep your power supply ground out of your preamp signal....

I'm no expert, but that's my take on it

[HotBluePlates]

Sometimes you have to be creative and change physical layout, or use 3-D space rather than 2-D to get excellent lead dress. See the internals of the vacuum-tube Tek scope below. The sockets are in between parallel ceramic strips, which have components spanning across them, and also have components from a strip down to the related tube socket pin. This gives the ultimate in short lead length where it is critical. Most of the time, you don't need to do it like this (though I kind of approximated this in my Standel build, just cause I wanted to).

Most of the time, excellent lead dress is not important in audio circuits, but it is critically important in radio frequency and video circuits. So in audio, you might be able to get away with less-than-perfect lead dress if it helps serviceability.

Often, you can't predict when slop is tolerable, and have to go with your experience to guide you as to how careful you need to be.

[HotBluePlates]

Different angle of a similar scope.

[SILVERGUN]

I don't spend much time on other forums but this is one of my favorite threads to just browse through....

Talk about 1000 ways to skin a cat 

http://www.thegearpage.net/board/showthread.php?t=334977

[HotBluePlates]

I forget who posted his/her build pics that had the heater wires up in the air over the sockets, but what a great idea!

That's standard on Fender BF/SF amps.

What's interesting is people do the tweed Fenders wrong. The heaters are laid in first, and dressed into the corner of the chassis lip, closest to the open side of the chassis. That keeps the heaters the furthest from the preamp components, and routing the other wires at right angles to the heaters isn't difficult.

Often, grid wires are then dress up into the air to stay away from the heater and other wires.

[12AX7]

Wow, that gear page thread is fantastic. Gave me ideas plus made me realize mine ain't so bad ! But i'm putting all new wiring, board and board components in mine in a week or so, so i wanted to get some ideas on what to consider. Grouping each stage together sounds like the best advice. I'll take lots of time planning every run. The amp has no noise or oscillation as it is now, but I want to be sure no issues arise.

[tubeswell]

Those tubes look like a real bastard to change.

[HotBluePlates]

Look at the 2nd picture. The tubes are accessible from large open areas on the other side of the scope.

Tek scopes generally had 2 side covers, left and right, which covered the whole vertical side plus half of the top. There was a third cover on the bottom of the case that gave access to the circuitry for tube mounted upright. It's actually quite easy to change all tubes and access any part of the electronics.