Hi All,
My first post here.
I recently build an 12AX7 tube preamp, got it working quite well. I am very pleased with the sound of it.
Did the star grounding and all cabling is done properly. I run the tubes at 250VDC.
I have one question though, I want to wire the Noval sockets to be chassis mount, so I got sockets and I tried to wire the sockets with wires (around 15cm) and got hum and buzz, although the proper pin connections were made, wires are 0.5mm sq.
Is there any specific way to wire / group wires in order to cancel the hum?
Regards,
Matyin
My first post here.
I recently build an 12AX7 tube preamp, got it working quite well. I am very pleased with the sound of it.
Did the star grounding and all cabling is done properly. I run the tubes at 250VDC.
I have one question though, I want to wire the Noval sockets to be chassis mount, so I got sockets and I tried to wire the sockets with wires (around 15cm) and got hum and buzz, although the proper pin connections were made, wires are 0.5mm sq.
Is there any specific way to wire / group wires in order to cancel the hum?
Regards,
Matyin
Thank you for your reply.
My wiring is properly done, no hum when I have the tubes in the pcb sockets. I would like to have the tubes mounted on chassis sockets and with wires connected to the main pcb.
My wiring is properly done, no hum when I have the tubes in the pcb sockets. I would like to have the tubes mounted on chassis sockets and with wires connected to the main pcb.
The wires must be inside the chassis or they will catch all the hum and buzz and wifi in the room.
Maybe post a picture? There are many ways someone could implement "have the tubes mounted on chassis sockets".
Maybe post a picture? There are many ways someone could implement "have the tubes mounted on chassis sockets".
The first picture is of the sockets I want to mount on the top of my enclosure.
The second one is how the tubes are mounted now.
Out of option is just to raise the PCB to the top of my enclosure. Hence, the wiring from pcb to sockets question.
I did preliminary wiring with non twisted wires but i got quite a lot of hum/buzz.
My thoughts are:
twist and group the wires
i.e.
pin 1 and pin 6 (both anodes)
pin 2 and pin 7 (grids)
pin 3 and pin 8 (cathodes)
pin 4,5 and pin 9 (heaters and common)
each are a separate groups of twisted wires going from pcb to noval socket.
Do I need to have shielded cables?
Also only the tubes will protrude out of the chassis top. All cabling is inside.
Thank You.
Attachments
The usual method is like in the first photo, with the board mounted on the underside of the top panel,
sockets up, with tubes protruding through holes in the top panel. No extension wires needed.
sockets up, with tubes protruding through holes in the top panel. No extension wires needed.
I know but now i need to rework the whole enclosure, the design i'd like to do try is to wire up the sockets to the enclosure.
Any suggestions on that part?
Regards
Martin
Bad idea. There's a reason why most do it the way they do, because it works.
Form follows function.
Form follows function.
Your Noval socket is meant for point to point wiring. Yours is a PCB. Just punch or drill holes in the top panel , and mount the PCB with standoffs. Simple. You said that you don't want to rework the entire enclosure. Can we see a picture of the enclosure?
One technique I have done is to attach a piece of sheet metal on the top panel covering the Noval sockets, then punch properly spaced holes for your PCB. In my project, I added sheet metal covering the entire top panel, of an amp, and then punched all the holes where I wanted. I suck at chassis work, but it wasn't that difficult.
One technique I have done is to attach a piece of sheet metal on the top panel covering the Noval sockets, then punch properly spaced holes for your PCB. In my project, I added sheet metal covering the entire top panel, of an amp, and then punched all the holes where I wanted. I suck at chassis work, but it wasn't that difficult.
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pic #6 incredible , just have to match position on metal ,, you grouping plus with plus , usualy plus and minus like professional interconnect cable guarranted no rfi
Here are some pictures that might be helpful. I used the chassis and output transformer from an Eico HF-20. The sockets are all chassis mount, but it will work for punched or drilled holes for your PCB.
Original Eico HF-20
Modified monoblock amp. Sheet metal (clear coated brass in this case) screwed at the four corners. Holes were punched with the top plate attached, through both the brass and the top panel of the amp.
If you only need to cover the Noval holes, you could have the sheet metal cut just to that size.
Original Eico HF-20
Modified monoblock amp. Sheet metal (clear coated brass in this case) screwed at the four corners. Holes were punched with the top plate attached, through both the brass and the top panel of the amp.
If you only need to cover the Noval holes, you could have the sheet metal cut just to that size.
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