Hum when volume is turned down - Page 4

miguel2 · 11th March 2003, 08:14 AM

I am using solid core copper wire, a bit more thick than cat5 in all connections to the volume pot. I find it very difficult to solder, as the solder seems to not wet properly the surface of the wire. So I plan to change it. What kind of wire do you use?

Miguel

Tube_Dude · 11th March 2003, 06:25 PM

Quote:

What kind of wire do you use?

Solid core thin wire...

miguel2 · 12th March 2003, 08:36 AM

I will try to put there something thinner. I am worried about contact between solder and copper. Maybe my 25W iron is not enough...

Miguel

Pedja · 16th March 2003, 08:40 PM

Hello Miguel,

EF86 can be uninviting when it comes to layout. I know the problem you’re talking about and I can believe you don’t have ground loops and still have a hum. There are some tricky things there I did not figure. If you had a solution it is maybe best to go back to that. If you’re ready for experiments, try to wire shield (pins 2 and 7) in different ways. And take note at the changes when you move resistors physically. Anyway, this tube can work in given configuration without any hum, and without series resistor at the input. As I said already, I did not figure this story, but have one (PCB) solution that surely works. Send me an e-mail if you are interested for more info about it.

Pedja

miguel2 · 18th March 2003, 06:51 PM

Hi Pedja,

Thanks for your help but I don´t want to go into making pcb's

... I have everything p2p wired, with the tube bases bolted to chassis. The layout is quite nice now, as the circuit is simple. I will try to move things a bit inside to see what happens and do something with the shield pins

Miguel

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11th March 2003, 08:14 AM	#31
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	I am using solid core copper wire, a bit more thick than cat5 in all connections to the volume pot. I find it very difficult to solder, as the solder seems to not wet properly the surface of the wire. So I plan to change it. What kind of wire do you use? Miguel

12th March 2003, 08:36 AM	#33
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	I will try to put there something thinner. I am worried about contact between solder and copper. Maybe my 25W iron is not enough... Miguel

16th March 2003, 08:40 PM	#34
Pedja diyAudio Member Join Date: Jun 2002 Location: Serbia	Hello Miguel, EF86 can be uninviting when it comes to layout. I know the problem you’re talking about and I can believe you don’t have ground loops and still have a hum. There are some tricky things there I did not figure. If you had a solution it is maybe best to go back to that. If you’re ready for experiments, try to wire shield (pins 2 and 7) in different ways. And take note at the changes when you move resistors physically. Anyway, this tube can work in given configuration without any hum, and without series resistor at the input. As I said already, I did not figure this story, but have one (PCB) solution that surely works. Send me an e-mail if you are interested for more info about it. Pedja

18th March 2003, 06:51 PM	#35
miguel2 diyAudio Member Join Date: Jun 2002 Location: Portugal	Hi Pedja, Thanks for your help but I don´t want to go into making pcb's ... I have everything p2p wired, with the tube bases bolted to chassis. The layout is quite nice now, as the circuit is simple. I will try to move things a bit inside to see what happens and do something with the shield pins Miguel

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