F2a tube as pentode SE

[as_audio]

Please let us know the details.

 

[commstech]

View attachment 1198327
The left side is the old version and the right side is the new version

awesome build!!!

 

[hooman]

new f2a se amp is finished .,..😊👍

 

[hooman]

zero hum and noise.....prefect sound ..............full 10w Each output......protect expensive output tubes. one of best se tube amp for music listener.....

​

 

[Bigun]

ABSOLUTELY FREAKING AWSOME!

 

[as_audio]

Zero hum : Hum and noise voltage on speaker output taken
with millivoltmeter would be nice to know. In daily life there
is no "zero" - except in our wallet ..

 

[hooman]

zero feedback......
zero feedback means no feedback in amp circuit?
no ...there is feedback .

so...low hum = The user thinks will hear a low hum in speaker!! Let's see the real pictures of the scope in f2a amp .

out put speaker terminal of f2a amp . vol=min

 

[hooman]

10 khz

 

[hooman]

sin

 

[hooman]

1khz out put speaker terminal

 

[as_audio]

First picture : you can not check noise with a scope alone.

 

[bepone]

hooman great amp.. is it tetrode or triode wired? can you share something about tranformers? also on pm

 

[hooman]

to as_audio : I have built many amplifiers. And in all of them the scope helped in reducing hum noise. Sometimes it was difficult. If you know anything more , please share.

 

[hooman]

to bepone: thanks .... i will send in pm.

 

[as_audio]

Low levels of hum and noise cannot be displayed with a scope, you need a millivoltmeter with ac output as low noise amplifier.

 

[hooman]

When I assemble an tube amplifier, I need to see and monitoring the hum waveform. And I know I'm definitely see hum. so need oscilloscope first

​

.

 

[as_audio]

.. and additional amplification. Your trace in post 47 clearly shows that resolution / sensitivity is too low.

 

[hooman]

to as_audio: Have you ever built an amplifier? Please post a link.​

 

[as_audio]

Pretentious and off topic.

 

[hooman]

In previous posts, I wrote many times that we have many skilled professionals in this forum. And they should help others. I asked you if you have ever made something and shared it? But you gave a bad answer. I wish you would give links to your creations.