Fi Primer 807

Klimon · 12th November 2007, 11:36 PM

A few questions about the 807 amp below: http://tinpan.fortunecity.com/saints/668/primer/

What does the circuit between the 807 grid leak resistors do (with bias pots etcetera) + where does the arrow go (I figure the one above is B+ and the other one is indicated "to other channel" which strikes me dumb).

Any thoughts?

Thanx

Simon

tubelab.com · 13th November 2007, 12:52 AM

These are the bias adjustment pots. The one on the left sets the output tube current for the channel shown. The pot on the right sets the tube current for the channel not shown in this schematic (the other channel). The wiper of this pot goes to the 2200 uF cap in the other channel. There is actually one pot per channel. The arrow above goes to the -100 volt supply shown at the bottom of the page.

Klimon · 13th November 2007, 07:58 AM

Negative grid bias, offcourse.

Cheers,

Simon

12th November 2007, 11:36 PM	#1
Klimon diyAudio Member Join Date: Apr 2005 Location: Leuven	Fi Primer 807 A few questions about the 807 amp below: http://tinpan.fortunecity.com/saints/668/primer/ What does the circuit between the 807 grid leak resistors do (with bias pots etcetera) + where does the arrow go (I figure the one above is B+ and the other one is indicated "to other channel" which strikes me dumb). Any thoughts? Thanx Simon

13th November 2007, 12:52 AM	#2
tubelab.com diyAudio Member Join Date: Jul 2005 Location: South Florida	These are the bias adjustment pots. The one on the left sets the output tube current for the channel shown. The pot on the right sets the tube current for the channel not shown in this schematic (the other channel). The wiper of this pot goes to the 2200 uF cap in the other channel. There is actually one pot per channel. The arrow above goes to the -100 volt supply shown at the bottom of the page. __________________ Too much power is almost enough! Turn it up till it explodes - then back up just a little.

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13th November 2007, 07:58 AM	#3
Klimon diyAudio Member Join Date: Apr 2005 Location: Leuven	Negative grid bias, offcourse. Cheers, Simon

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