Strange splitter in the Audio Research D4

ray_moth · 16th August 2008, 04:26 AM

Has anyone seen the AR D4 schematic? It's an all-balanced design that uses as a phase inverter a "preamp" to one side of the PP input stage. I've never seen anything like it before. It's too big to post here, it will have to be a link. It's that scruffy-looking ECC81 (12AT7) that's squeezed into the bottom left corner.

reinhard · 16th August 2008, 05:31 AM

That is only a phase inverter with a gain of one.

Reinhard

kenpeter · 16th August 2008, 06:57 AM

At first glance, I thought it might be a 4th circuit inverter.
But its nothing so glorious.

1st half Y1 (ECC83) tries to -multiply input by Mu of 100
2nd half Y2 (ECC81) tries to cathode follow that Mu.

But the input and output feed together op-amp style
through the 301K and 316K resisistors to a unity (-1)
local loop gain.

Allen Wright · 16th August 2008, 07:40 AM

Audio Research strikes again!

Thisi s absolutely nothing new, and about as complex and excessive as you can get.

KISS in reverse seems to be A-Rs claim to fame...

Regards, Allen

richwalters · 17th August 2008, 03:48 PM

Looks like another clone of the Worthen phase splitter. It may provide good balance once set up with the right tube, otherwise a replacement will require test equipment to re setup. A major disadvantage. Not my ideas.

richj

16th August 2008, 04:26 AM	#1
ray_moth diyAudio Moderator Emeritus Join Date: Jan 2004 Location: Jakarta	Strange splitter in the Audio Research D4 Has anyone seen the AR D4 schematic? It's an all-balanced design that uses as a phase inverter a "preamp" to one side of the PP input stage. I've never seen anything like it before. It's too big to post here, it will have to be a link. It's that scruffy-looking ECC81 (12AT7) that's squeezed into the bottom left corner.

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16th August 2008, 05:31 AM	#2
reinhard diyAudio Member Join Date: Dec 2000 Location: Germany	That is only a phase inverter with a gain of one. Reinhard

16th August 2008, 06:57 AM	#3
kenpeter diyAudio Member Join Date: Nov 2007 Location: Dallas	At first glance, I thought it might be a 4th circuit inverter. But its nothing so glorious. 1st half Y1 (ECC83) tries to -multiply input by Mu of 100 2nd half Y2 (ECC81) tries to cathode follow that Mu. But the input and output feed together op-amp style through the 301K and 316K resisistors to a unity (-1) local loop gain.

16th August 2008, 07:40 AM	#4
Allen Wright R.I.P. Join Date: Dec 2001 Location: Schaffhausen Switzerland	Audio Research strikes again! Thisi s absolutely nothing new, and about as complex and excessive as you can get. KISS in reverse seems to be A-Rs claim to fame... Regards, Allen

17th August 2008, 03:48 PM	#5
richwalters diyAudio Member Join Date: Sep 2003 Location: Alps:Tube amp designs over 150W, SMPS guru.	Looks like another clone of the Worthen phase splitter. It may provide good balance once set up with the right tube, otherwise a replacement will require test equipment to re setup. A major disadvantage. Not my ideas. richj