"Raymond Koonce" wrote in message
news
Iain Churches wrote:
"Raymond Koonce" wrote in message
...
Hi RATs,
Here's a link to a project I've had on the bench for a while and got
finished today. I learned quite a bit on this one.
http://www.timebanditaudio.com/47%20Amp/Carmen47.html
It sounds as good as it looks.
Comments, questions?
Hello Raymond.
Congratulations, a beautiful job:-)
I would be interested to know the level of feedback you
finally arrive at, and also the output impedance too.
Do you have any performance figs?
I am just taking my first steps in SET after being
very impressed indeed with a Russian built Resnekov
SET owned by a professional cellist that I know.
Thanks :-) I sure enjoyed building this amp.
I don't have any performance specs except for the output power, about 2.7
WPC in pentode, less in triode. I have no idea how to calculate the
amount of feedback. Tips?
Hi Raymond.
It is so refreshing to see a thread on RAT
by someone who has actually *built* something
(and makes such a nice contrast to the voluminous
posts from some of those whose presence here
is an enigma - their sole purpose seems to be to
pour derision on thermionic audio)
This is a sad state of affairs, because it keeps
away so many good people who have an interest in
tube audio but their lack of knowledge and
experience prevents them from posting here for
fear of ridicule.
I have a simple method for measuring the feedback.
Firstly with a standard 8 Ohm (50W) dummy load
connected I disconnect the feedback loop with the
level of the source generator low. I then increase
the level to give me a reasonable output level across
the 8 Ohm Load. You can use any value you choose
I use 8.94V which equates to 10W (V2/R)
Call this V1.
Then I switch off the amp, and reconnect the
feedback loop. Power up again, and with the
source at the same level measure the output
voltage again. Call this new value V2.
Using the formula 20log(V1/V2) you can
work out the feedback in dB.So if you get
8.94V open loop and 4.47V closed loop
then you have 6dB of feedback.
Easy and fun:-)
I think you 'll be impressed with a properly built triode amp. I put my
McIntosh amps away after I built my first triode amp, a 45 SE stereo.
Yes. My only regret is that it has taken me so
long to become interested in SET. I would be
interested to know more about the 45 SE
which you build.
Congratulations once again on a fine project:-)
Iain