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stax · September 4th, 2006, 11:40 AM

Just finished 5f1 build which sounds great through a 2x12 greenback cab, but
there is a little too much background noise for my liking.
I used the old original layout which used a single wire for the heaters,then ground pins1and 2 on power tube and 9 on pre amp.
Would i of been better off running a twisted pair?
Also there is no centre tap on transformer heater secondary
Thanks in advance to all you champ experts

JohnnyCrash · September 4th, 2006, 10:15 PM

1. Don't ground the pins.
2. Create an artificial center tap by wiring each 6.3v wire to a 100 ohm resistor, then the other end of BOTH resistors to ground.

Number 2 can be done at the jewel lap, on the board, or at the first tube socket.

Be sure to put a 25uF/25v cap on the first resistor (cathode bypass cap) - it's not on the original '50s layout.

The center tap will remove a lot of noise, but if you need more noise remioved, use shielded wire on the input jack (including the connections to and from the board and 12AX7).

Move all of the preamp wires as far away from the rest of the wires, if possible and also check your preamp solders.

September 4th, 2006, 11:40 AM	#1 (permalink)
stax Tele-Meister Join Date: Jul 2006 Location: Brentwood U.K. Age: 53 Posts: 407 9 Photos	champ noise Just finished 5f1 build which sounds great through a 2x12 greenback cab, but there is a little too much background noise for my liking. I used the old original layout which used a single wire for the heaters,then ground pins1and 2 on power tube and 9 on pre amp. Would i of been better off running a twisted pair? Also there is no centre tap on transformer heater secondary Thanks in advance to all you champ experts

September 4th, 2006, 10:15 PM	#2 (permalink)
JohnnyCrash Poster Extraordinaire Join Date: Mar 2005 Location: Fullerton, CA Posts: 8,743	1. Don't ground the pins. 2. Create an artificial center tap by wiring each 6.3v wire to a 100 ohm resistor, then the other end of BOTH resistors to ground. Number 2 can be done at the jewel lap, on the board, or at the first tube socket. Be sure to put a 25uF/25v cap on the first resistor (cathode bypass cap) - it's not on the original '50s layout. The center tap will remove a lot of noise, but if you need more noise remioved, use shielded wire on the input jack (including the connections to and from the board and 12AX7). Move all of the preamp wires as far away from the rest of the wires, if possible and also check your preamp solders. __________________ -- I constantly have to remind myself I'm a grownup and it's just the internet.

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