Welcome! Need support, you got it. Or share youe ideas and experiences.
Return to K&K Audio / Lundahl Transformers
99.178.170.55
In Reply to: RE: Filament Choke Questions and 4P1L Sources posted by Prospect on April 14, 2016 at 09:47:26
I don't know the configuration that Thomas Mayer is using either. You would have to contact him to understand his "LCL" implementation fully.
The common mode series connection offers the same degree of filtering that the simpler series connection does, but adds a degree of common mode filtering, removing "noise" that is common to both power supply leads. It is worth pursuing for the small, but significant sonic improvement that it brings.
My experience with buying tubes from Eastern European or Russian suppliers on eBay has been mostly very good. If the picture shows 4P1Ls wrapped in the original packing, then it's very likely that they are new. Naked individual tubes shown without the packaging visible are to be avoided. I have never seen a 4P1L that was manufactured by any other than the "Svetlana" (winged C) factory, although I suspect that they exist. I've heard really good sound from tubes produced in the 60s, 70s, 80s and early 90s.
Kevin Carter
K&K Audio
www.kandkaudio.com
Follow Ups:
Thanks, Kevin!
Your advice on sourcing the tubes sounds reasonable. I've had good luck on eBay (following careful, and hard-learned lessons).
After some searching I did find a schematic of Thomas's LCL filter. It does use just one filter bank (with 30k uF) and the last choke connects directly to the DHT. He uses the LL2733 choke.
If I'm calculating this right, a stereo implementation of his topology (4 chokes) would add about $400 to the project just for the filament supplies! The Coleman Regulators seems like a more feasible solution.
Thanks again for your help.
I suspect that the rationale for this is the relatively high audio impedance that the second choke represents.
Iron ain't cheap, but then, if used properly, they also don't sound cheap!
Kevin Carter
K&K Audio
www.kandkaudio.com
Post a Followup:
FAQ |
Post a Message! |
Forgot Password? |
|
||||||||||||||
|
This post is made possible by the generous support of people like you and our sponsors: