Bypass input resistor and use a 20k pot instead?

newbie23 · 23rd February 2007, 07:38 PM

I was wondering if it would be possible to bypass the input resistor on the Charizle board and use a 20k pot such as the DACT in its place. It sounds like it would work in theory, but would it sound better? Thanks for your input guys.

Pano · 24th February 2007, 03:53 AM

I can't picture how that would work. The input resistor is part of the feedback loop on the inputs. It sets the gain along with the feedback resistor.

How were you thinking of connecting it?

Stanco · 11th June 2007, 01:24 PM

how it would play without feedback? mah....

Stanco · 11th June 2007, 05:34 PM

someone has tried to remove the feedback in input? ciao

xenob · 13th June 2007, 06:05 PM

it should be possible
look at this thread

http://www.41hz.com/Forums/topic.asp?TOPIC_ID=582

"Input Gain = - Rfdbk/Rin. With Rin=22K you can trim Rfdbk from 50K (gain=2.2) to 1K (gain=0.04).

In theory that could replace volume control."

Pano · 13th June 2007, 09:04 PM

I'd be careful with that!

The input stage of the amp is an opamp. Running an opamp at less than unity gain (gain=0.04) can cause all sorts of stablity problems.

23rd February 2007, 07:38 PM	#1
newbie23 Banned Join Date: Feb 2007 Location: Indiana	Bypass input resistor and use a 20k pot instead? I was wondering if it would be possible to bypass the input resistor on the Charizle board and use a 20k pot such as the DACT in its place. It sounds like it would work in theory, but would it sound better? Thanks for your input guys.

24th February 2007, 03:53 AM	#2
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	I can't picture how that would work. The input resistor is part of the feedback loop on the inputs. It sets the gain along with the feedback resistor. How were you thinking of connecting it? __________________ Take the Speaker Voltage Test!

13th June 2007, 09:04 PM	#6
Pano diyAudio Moderator Join Date: Oct 2004 Location: North Carolina Blog Entries: 4	I'd be careful with that! The input stage of the amp is an opamp. Running an opamp at less than unity gain (gain=0.04) can cause all sorts of stablity problems. __________________ Take the Speaker Voltage Test!

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11th June 2007, 01:24 PM	#3
Stanco diyAudio Member Join Date: Apr 2006 Location: Rome-Italy	how it would play without feedback? mah....

11th June 2007, 05:34 PM	#4
Stanco diyAudio Member Join Date: Apr 2006 Location: Rome-Italy	someone has tried to remove the feedback in input? ciao

13th June 2007, 06:05 PM	#5
xenob diyAudio Member Join Date: Jan 2006 Location: Vienna	it should be possible look at this thread http://www.41hz.com/Forums/topic.asp?TOPIC_ID=582 "Input Gain = - Rfdbk/Rin. With Rin=22K you can trim Rfdbk from 50K (gain=2.2) to 1K (gain=0.04). In theory that could replace volume control."

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