lead dressing

[sniffyduke]

Also posted under tech disc.

hi all,

I have a question. I have been looking at alot of inside pics of alot off different amps.

I specifically have been paying attention to the dressing of the BLk
and Red heater wires. that go to the tubes.

I recently built a Dumble clone and made sure the blk and red lead wires were tucked against the back wall. I was in belief that tis eliminates noice ect. But to be honest I really have no clue on that subject.

When I looked at pics inside of real Dumbles and various Trainwrecks
I notice this isn't the case.

In the pics of Larry Carlton's Dumble, I notice the dressing is directly over the tubes.

On V1 and V2 I also noticed that the cathode, is moved far away from heater wire except on PI.

Can some one explain to me the reasons for tucking your heater wires against back and placing them close or over tube sockets.

Is there a reason for these methods.

Thank you

[Structo]

Either method is acceptable.
Historically, Fender ran the heater wires over head of the tubes while Marshall ran them in the back corner of the chassis.
Mr. Dumble is known to run the cathode and plate wires close to each other on V1 and V2, some think it adds to the tone of an ODS amp.

[Normster]

The routing of heater wires depends on the lead dress from the board to the tubes. The objective is to keep heater wiring from introducing hum into the signal circuit. Many ways to do this, as you have discovered by looking at different amp circuits. Notice that Dumble runs his signal wires against the chassis. By running heater wiring above the tubes, he keeps them as far from the chassis and signal wiring as possible. Marshall, on the other hand, runs heater wiring into the back corner of the chassis, but keeps signal wiring above the chassis and tubes to eliminate and AC-induced hum.

[sniffyduke]

thanks, i'm still learning.

on the dumble, what do you mean by signal wires?

his heaters are close to tube and board wires.
what are signal wires?

thank you.

[sniffyduke]

The routing of heater wires depends on the lead dress from the board to the tubes. The objective is to keep heater wiring from introducing hum into the signal circuit. Many ways to do this, as you have discovered by looking at different amp circuits. Notice that Dumble runs his signal wires against the chassis. By running heater wiring above the tubes, he keeps them as far from the chassis and signal wiring as possible. Marshall, on the other hand, runs heater wiring into the back corner of the chassis, but keeps signal wiring above the chassis and tubes to eliminate and AC-induced hum.

oh, ok, you mean the signal wires are coming from boards to tube
and are flush with botom of amp. The heater wires are above the tubes
therfore away from signal wires. Is this correct?

So there are two schools of placement.

1. Heater wires pushed to back of chassis and signal wires raised and not flush against bottom of chassis (Marshall style)

2. Then there is Fender, Dumble style where heater wires are above tubes
and signal (tube) wires are plush against bottom of chassis,

Is this correct.

Are there any tonal benifits between the two or is it just two different meathods?

Thanks for your help guys
Im still trying to learn as much as I can.

I have had help from friends. And Nik at Ceriatone has been the most helpfull. Im new to this and that guy has gone out of his wayy to try to help me understand. But there are also alot of professionals like you guy's
that I am sure have alot off knowledge.

Thanl you very much for your responses.

So what gives the Trainwreck it's famous sustain, is it lead dressing placement?

[talbany]

Twisting the heater wires generates smallest possible, residual fields due to the canceling effect of the twisting.
Heater wires near the chassis are stitched down to the chassis by capacitive connections.. This connection method helps eat the capacitive radiation from the wire.
Chassis that are made of steel, and high current wires near the chassis have much of their magnetic radiation shorted by the ferromagnetic steel...this is why both methods work.. Twist em and fly them or loop them and lay them like Ken did in his wrecks..
You can go all out and twist em and lay em... But don't think that's necessary as one or the other works...

Tony

[erwin_ve]

Keeping signal wires away from the heater wires is not only to reduce hum.
If signal wire is too close to the heater wires, the magnetics from the heater wire "disturb" the signal in the signal wire and therefore killing your tone( even when there's no audible hum).

[sniffyduke]

Twisting the heater wires generates smallest possible, residual fields due to the canceling effect of the twisting.
Heater wires near the chassis are stitched down to the chassis by capacitive connections.. This connection method helps eat the capacitive radiation from the wire.
Chassis that are made of steel, and high current wires near the chassis have much of their magnetic radiation shorted by the ferromagnetic steel...this is why both methods work.. Twist em and fly them or loop them and lay them like Ken did in his wrecks..
You can go all out and twist em and lay em... But don't think that's necessary as one or the other works...



Wow, thanks for the great explanation.

[Structo]

To add to this, when I had initially built my D'Lite 44 I wired the heaters the Marshall way, which is on the floor in the rear corner.

I did this mainly because I installed a Ironsounds FX loop which is a solid state FX loop and it sits over V1 and V2, so I was afraid if I wired the heaters overhead it would induce hum due to the close proximity of the heater wires to the loop pcb.

When I recently re-wired my amp, I re-did my heater wiring and this time I ran them overhead.
It seemed to make it easier to keep the heater wires away from signal wires.

Tony raised a valid point as well, if the chassis is aluminum you are not going to get the ferrous metal shielding that a steel chassis affords.

Marshall initially used steel chassis and for the most part still use them.
This may be the reason they ran the heater wires on the floor in the rear.

Fender used steel chassis as well but Leo may have just copied what was out there at the time and stuck with that method.

So to summarize, I liked the heater wires overhead better and since that is the way Mr. Dumble did it, it should be done this way on a clone.