Forums
New posts
Search forums
What's new
New posts
Latest activity
Members
Registered members
Current visitors
Log in
Register
What's new
Search
Search
Search titles only
By:
New posts
Search forums
Menu
Log in
Register
Install the app
Install
Audio and Video Talk
Valves / Vacuum Tubes
Single Ended 807 amplifier
JavaScript is disabled. For a better experience, please enable JavaScript in your browser before proceeding.
You are using an out of date browser. It may not display this or other websites correctly.
You should upgrade or use an
alternative browser
.
Reply to thread
Help Support AVForums:
This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Message
<blockquote data-quote="handsome" data-source="post: 898433" data-attributes="member: 772"><p>Have you tried not paralleling the 12AT7? As the text points out the higher the driver tube's impedance the more effective the feedback loop - basically you increase the feedback - by paralleling the tube you are halving it's impedance. Also as Ampdog pointed out by not bypassing the screen to either cathode or ground you are running the 807 as a (sort of) triode if you were to run it as a pentode its impedance would increase and the 12AT7-807 feedback loop would compensate. THis is what the designer talks about achieving - lowering the impedance of the output tube but not using global feedback to do so.....strange then that he operated the 807 that way....</p></blockquote><p></p>
[QUOTE="handsome, post: 898433, member: 772"] Have you tried not paralleling the 12AT7? As the text points out the higher the driver tube's impedance the more effective the feedback loop - basically you increase the feedback - by paralleling the tube you are halving it's impedance. Also as Ampdog pointed out by not bypassing the screen to either cathode or ground you are running the 807 as a (sort of) triode if you were to run it as a pentode its impedance would increase and the 12AT7-807 feedback loop would compensate. THis is what the designer talks about achieving - lowering the impedance of the output tube but not using global feedback to do so.....strange then that he operated the 807 that way.... [/QUOTE]
Insert quotes…
Verification
Post reply
Audio and Video Talk
Valves / Vacuum Tubes
Single Ended 807 amplifier
Top