Remove feedback in Zen V4

SIMONLEE · 4th June 2004, 08:43 PM

Has anybody tried to remove feedback network in Zen V4? (The 221K resistor and the 5pf Cap). What's the sound difference?

Will the length of feedback path influnce the sound? the shorter the better?

I appreciate somebody can give me an idea.

Nelson Pass · 5th June 2004, 12:51 AM

Of course the gain shoots way up and the damping factor
goes away. If you use an adequate amount of Source
resistance on Q1 to tame the gain and have a well damped
load with a flat impedance, you might just like it. The
overall distortion is higher, but the spectral presentation
is a little more even. Most people would not be able to get
past the damping factor, but it would make a great tweeter
amp, for example.

SIMONLEE · 5th June 2004, 02:19 AM

Thanks, Nelson.

I have built the Zen original, without feedback, It sounds excellent(I am not saying the bass, but it's enough for me). The damping factor is about 8.

The Zen V2 and V4 is quite similiar with original zen + BOZ except the current source. and with feedback. The damping factor is around 40, if I am right.

Would the Zen V2 work similiar as the original one if the feedback (3k resistor) is removed? How is the damping factor? I wonder if it's good enough used with high efficiency full range speakers.

Nelson Pass · 7th June 2004, 06:53 PM

The original Zen does use feedback - that's how it gets
the DF of 8, otherwise it would have none to speak of.

4th June 2004, 08:43 PM	#1
SIMONLEE diyAudio Member Join Date: May 2004 Location: Toronto	Remove feedback in Zen V4 Has anybody tried to remove feedback network in Zen V4? (The 221K resistor and the 5pf Cap). What's the sound difference? Will the length of feedback path influnce the sound? the shorter the better? I appreciate somebody can give me an idea.

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5th June 2004, 12:51 AM	#2
Nelson Pass The one and only Join Date: Mar 2001	Of course the gain shoots way up and the damping factor goes away. If you use an adequate amount of Source resistance on Q1 to tame the gain and have a well damped load with a flat impedance, you might just like it. The overall distortion is higher, but the spectral presentation is a little more even. Most people would not be able to get past the damping factor, but it would make a great tweeter amp, for example.

5th June 2004, 02:19 AM	#3
SIMONLEE diyAudio Member Join Date: May 2004 Location: Toronto	Thanks, Nelson. I have built the Zen original, without feedback, It sounds excellent(I am not saying the bass, but it's enough for me). The damping factor is about 8. The Zen V2 and V4 is quite similiar with original zen + BOZ except the current source. and with feedback. The damping factor is around 40, if I am right. Would the Zen V2 work similiar as the original one if the feedback (3k resistor) is removed? How is the damping factor? I wonder if it's good enough used with high efficiency full range speakers.

7th June 2004, 06:53 PM	#4
Nelson Pass The one and only Join Date: Mar 2001	The original Zen does use feedback - that's how it gets the DF of 8, otherwise it would have none to speak of.

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