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    Building, troubleshooting and testing of these amplifiers should only be
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6AS7G SE or P-P?

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artosalo

artosalo

Member
Joined 2010
What would you think, if somebody suggest SE because it sounds better than PP and somebody Else says opposite?
I once let my hifi-friends to test one of my triode SE-amplifier. One guy liked so much, that he immediately wanted to build this. The other said that this was one of the worst tube amplifier he has listened.
Which one was right?
 
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6

6A3sUMMER

Member
Joined 2016
There is SE, there is PP, and there is Totem Pole (one form of OTL).

I would not recommend OTL for a first project amplifier.
Others would recommend OTL (maybe they will build it for you, test it, fix it if needed, and test it again).

Power may not be important to the Original Poster, but loudspeaker minimum impedance is important, especially before deciding to build an OTL amplifier.

Measure the loudspeaker DCR. That is the minimum impedance of many loudspeakers.

Just my opinions
 
K

Koonw

Disabled Account
Joined 2013

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  • McProud-6AS7G-PP-1948-ed.png
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Ryssen

Ryssen

Member
Joined 2003
Thanks for the info!
One question ,in for exemplet "koonw's" first link theres an interstagetrafo used as a fase splitter.
I read that some People say that an IT trafo destroys yhe sound.
Or is it just what some People say and The other half dont?
 
K

Koonw

Disabled Account
Joined 2013
That was in 40's maybe other phase splitter didn't even exist.
I notice that is capacitor para-feed circuit, so may be even better than an air-gaped one, you probably can use PP type IT, so low DCR winding and non-cap coupling guarantee no DC blocking on power tube grid bias.
 
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K

Koonw

Disabled Account
Joined 2013
You mean idle current in primary OT? Ia is equal to Ik, where Ik=2.2k, Ia=Ik=125/(2200+500/2)= 51mA
Another way is to replace cathode resistor with constant current sink for each cathode, these do away with any need for adjustment.
https://www.diyaudio.com/community/threads/transformer-coupled-6as7-6080.91626/post-1098816
That is another improvement over McProud amp

Here is a video and schematic for another PP amp:
http://www.diyaudiovillage.net/index.php?topic=19132.60
http://upic.me/i/ab/6as7ppp.gif
 
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