Lundahl+EL84 PP+concertina+input stage - Page 7

trifidmaster · 19th April 2007, 09:41 PM

Update:
After applying feedback, the max amplification became not enough.
Originally the preamp and the splitter were in 2 separate envelopes/channel.

Now, in the 2nd topology the the preamp + splitter are moved into one envelope. Doing so, one full tube (6922) became free/per channel. And as a next step this free tube was used as extra preamp + current source, and the amplifiaction is now more than enough.

Playing with the feedback (feedback resistor value + feedback topology) the sound starts to be "acceptable" with many different music including classical music.

The BEAUTIFUL sound of the 6922 is audible.

Stefan.

trifidmaster · 2nd January 2008, 10:29 AM

And finally the speakers are ready for the amp.

The sound is very "impressive". The speakers are in closed box, and still bass comes out from them. Highly recommended!

trif.

trifidmaster · 2nd January 2008, 10:38 AM

Here is the enclosure design - currently in "production"

trif.

trifidmaster · 21st December 2008, 12:50 PM

This projects start to live again - After many months I have decided: the current FE127E single drivers are NOT enough for my room/needs.

I am thinking into direction of using the FE207E from Fostex.
As soon as the speakers are built - new set of test will start. I hope that my "simple" PP will be able to drive these bigger speaker.

trif.

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19th April 2007, 09:41 PM	#61
trifidmaster diyAudio Member Join Date: Apr 2006 Location: Belgium	Update: After applying feedback, the max amplification became not enough. Originally the preamp and the splitter were in 2 separate envelopes/channel. Now, in the 2nd topology the the preamp + splitter are moved into one envelope. Doing so, one full tube (6922) became free/per channel. And as a next step this free tube was used as extra preamp + current source, and the amplifiaction is now more than enough. Playing with the feedback (feedback resistor value + feedback topology) the sound starts to be "acceptable" with many different music including classical music. The BEAUTIFUL sound of the 6922 is audible. Stefan.

21st December 2008, 12:50 PM	#64
trifidmaster diyAudio Member Join Date: Apr 2006 Location: Belgium	This projects start to live again - After many months I have decided: the current FE127E single drivers are NOT enough for my room/needs. I am thinking into direction of using the FE207E from Fostex. As soon as the speakers are built - new set of test will start. I hope that my "simple" PP will be able to drive these bigger speaker. trif.

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