K&K Audio / Lundahl Transformers

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K&K Audio / Lundahl Transformers

Newbie, need help. Parafeed line preamp. ll1930,ll1667

182.55.169.217

acdc211300@yahoo.com.sg

Hi All,
I am a newbie in this hobby. Please help.

I am doing a parafeed line preamp using the ll1667 as plate choke, wired in parallel. Using 6DJ8 as the tube. Using one triode for one side. The line output trans is ll1930. B+ about 180V, after the ll1667, about 80V, connecting with a 4.7uf capacitor in between the plate and primary of the ll1930. ll1930 is wired as 5.8:1 configuration. Signal pass through 100k volume pot,in series with 1.2k ohm resistor to screen of 6DJ8. Cathode to ground ,passing through 200 ohm resistor in series with 47uf capacitor. Measured about 1.2V.

Currently, got no sound when connected to power amp, need help. Where did I go wrong, please advise. Thank You very much.

Follow Ups:

RE: Newbie, need help. Parafeed line preamp. ll1930,ll1667 - KevinC 11:00:08 09/28/14 (0)
This won't solve your no sound problem, but if you connect the "-" side of the LL1930 primary to the cathode of the 6DJ8, you don't need the cathode bypass cap.

It's not obvious, other than the "200 ohm resistor in series with 47uF capacitor" typo, what you've done that would result in lost sound isn't obvious to me.

Kevin Carter
K&K Audio
www.kandkaudio.com
RE: Newbie, need help. Parafeed line preamp. ll1930,ll1667 - Dave Davenport 08:56:20 09/28/14 (2)
You said:
"Cathode to ground ,passing through 200 ohm resistor in series with 47uf capacitor."

This may have been a typo mistake, but the capacitor should be in parallel with the resistor.

Dave
- RE: Newbie, need help. Parafeed line preamp. ll1930,ll1667 - acdc211300@yahoo.com.sg 23:26:18 09/28/14 (1)
  Sorry for the confusion, the 47uf is parallel to the 200 ohm. Dave is right. Kevin, should I connect the ll1930 Primary's -ve to before the 200 ohm or to the ground. Please advise.
  - RE: Newbie, need help. Parafeed line preamp. ll1930,ll1667 - KevinC 06:17:12 09/29/14 (0)
    Connect the -ve to the junction of the tube cathode and the 200R resistor.
    
    Kevin Carter
    K&K Audio
    www.kandkaudio.com

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