|
Audio Asylum Thread Printer Get a view of an entire thread on one page |
For Sale Ads |
173.174.66.72
In Reply to: RE: Spring time posted by 6AS7_6SN7 on May 17, 2015 at 04:40:52
Thanks for the links. Unfortunately, I can't read most of the text. What value did you use for the output transformers (plate-to-plate Z)? I seem to remember that these tubes might need about 6K-7K when operated with two in parallel.
--------------------------
Buy Chinese. Bury freedom.
Follow Ups:
In order to make a long story short, I used the same 2X115V-2X6V 50Hz/50W toroidal power transformers.
In the case of one GI-30 tube per channel (or GI-30/829B/7E29), one 50W toroidal transformer per channel.
In case of two GI-30 parallel tubes per channel, two toroidal 50W transformers per channel.
I hope this (and the schematics) will suffice to get the message.
ecc230
I'm having difficulty putting it together. What is the winding ratio from the anodes to the load, and what is the load Z?
--------------------------
Buy Chinese. Bury freedom.
With reference to the enlarged picture:
Transformers 2X110V/2X6V 50W-50Hz (toroids): T1, T2
Primary T1: L12, L13
Primary T2: L10, L8
Secondary T1: L15, L14
Secondary T2: L11, L9
Wound up auxiliary (manually added) for NFB: T1 L17, T2 L16
[voltage ratio of each auxiliary winding = 110/9 = 12.2 = SQRT (6/0.04)]
In sim world (within class A operation and with NFB), 140V of plate voltage variation corresponds to 23 mA of current variation (140/0.023 = 6086 Ohm).
The basic plate impedance corresponding to 110/6 V ratio (@ 8 Ohm load) is (110/6)*(110/6)*8 = 2688 Ohm.
As T1 and T2 primaries are in series, the theoretical impedance would be 5.4K, which is consistent with the above 6.1K 'measured' in sim world when NFB is applied.
ecc230
Thanks, that's in line with my estimate for a PP pair. I think these are capable of roughly 80-100W output in AB1. Someday I'll get everything together for my own version of this... :)
--------------------------
Buy Chinese. Bury freedom.
In this picture the auxiliary windings for NFB can be seen.
I made those windings because the 560V HT comes from direct 220V AC line rectification.
http://db.audioasylum.com/mhtml/m.html?forum=tubediy&n=190208&highlight=construction+hints+6AS7_6SN7&search_url=%2Fcgi%2Fsearch.mpl%3Fauthor%3DSal%26user_id%3D6472%26forum%3DALL%26sortRank%3DNone%26sort%3Ddate%26sortOrder%3DDESC
ecc230
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: