denon dv-2910 output cap

Marcelinho · 30th December 2008, 10:45 PM

http://nas.nijkerk.nl/pub/output.pdf

Above a representation of the output of one channel of a Denon DV-2910 cd/dvd/saccd player just after the last opamp.

I want to replace the dc blocking cap (elco 50v/100uF) with a mcp-type of about 10uF.

I want to connect the cap directly to the cinch connector and bypass all those smd muting transistors.

The datasheet of the preceding opamp (njm2068) states that it is advisable to add a 50-ohms serie resistor at the output to prevent oscilation with a capacitive load. Did Denon forget one?

What is the function of the 30K ohm to ground after the dc blocking cap. Can I do without?

jitter · 31st December 2008, 08:58 AM

Your link doesn't work.

I'm no designer but I guess Denon may have omitted the 50R resistor on purpose knowing that the combination of the DC-blocking cap, 30k resistor and (typical) input impedance of amp connected to it won't lead to oscillations. You will probably change the output impedance of the DVD-player by substituting the blocking cap. Just putting in a different cap of arbitrarily chosen value might therefore not be an improvement.

Marcelinho · 31st December 2008, 12:38 PM

Oeps my mistake must be a ftp site

ftp://nas.nijkerk.nl/pub/output.pdf

Extreme_Boky · 1st January 2009, 07:37 AM

Quote:

Originally posted by Marcelinho
[B]http://nas.nijkerk.nl/pub/output.pdf

Above a representation of the output of one channel of a Denon DV-2910 cd/dvd/saccd player just after the last opamp.

I want to replace the dc blocking cap (elco 50v/100uF) with a mcp-type of about 10uF.

try different types of around 4.7 to 10uF. I suggest Auricap or silver in oil.

Quote:

I want to connect the cap directly to the cinch connector and bypass all those smd muting transistors.

...and tracks capacitance as well!!!

Quote:

The datasheet of the preceding opamp (njm2068) states that it is advisable to add a 50-ohms serie resistor at the output to prevent oscilation with a capacitive load. Did Denon forget one?

they did not... it is not crucial to put this series resistor with 2068 OP

Quote:

What is the function of the 30K ohm to ground after the dc blocking cap. Can I do without?

loads the OP if nothing is connected to the player... solder 30K resistor at the cinch connector.

Boky

Marcelinho · 1st January 2009, 10:54 AM

Ok, that makes sense to me. I've done that before with a cd-player.
The 10uF with 30K resistor and the input impedance of the amp must give a low enough -3dB point. Just have to look up the formula's again.

So if i run the opamp in class-a by connecting the output with a 10K resistor to +v or -v (before the cap), does that change my -3dB calculations?

Extreme_Boky · 1st January 2009, 07:37 PM

I call that OP rape. They are already biased in class A...

Boky

30th December 2008, 10:45 PM	#1
Marcelinho diyAudio Member Join Date: Oct 2005	denon dv-2910 output cap http://nas.nijkerk.nl/pub/output.pdf Above a representation of the output of one channel of a Denon DV-2910 cd/dvd/saccd player just after the last opamp. I want to replace the dc blocking cap (elco 50v/100uF) with a mcp-type of about 10uF. I want to connect the cap directly to the cinch connector and bypass all those smd muting transistors. The datasheet of the preceding opamp (njm2068) states that it is advisable to add a 50-ohms serie resistor at the output to prevent oscilation with a capacitive load. Did Denon forget one? What is the function of the 30K ohm to ground after the dc blocking cap. Can I do without?

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31st December 2008, 08:58 AM	#2
jitter diyAudio Member Join Date: Aug 2004 Location: Eindhoven, The Netherlands	Your link doesn't work. I'm no designer but I guess Denon may have omitted the 50R resistor on purpose knowing that the combination of the DC-blocking cap, 30k resistor and (typical) input impedance of amp connected to it won't lead to oscillations. You will probably change the output impedance of the DVD-player by substituting the blocking cap. Just putting in a different cap of arbitrarily chosen value might therefore not be an improvement.

31st December 2008, 12:38 PM	#3
Marcelinho diyAudio Member Join Date: Oct 2005	Oeps my mistake must be a ftp site ftp://nas.nijkerk.nl/pub/output.pdf

1st January 2009, 10:54 AM	#5
Marcelinho diyAudio Member Join Date: Oct 2005	Ok, that makes sense to me. I've done that before with a cd-player. The 10uF with 30K resistor and the input impedance of the amp must give a low enough -3dB point. Just have to look up the formula's again. So if i run the opamp in class-a by connecting the output with a 10K resistor to +v or -v (before the cap), does that change my -3dB calculations?

1st January 2009, 07:37 PM	#6
Extreme_Boky diyAudio Member Join Date: Dec 2003 Location: Sydney	I call that OP rape. They are already biased in class A... Boky

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