Analog filter for NOS DAC

Marlowe · 6th September 2005, 08:36 PM

I've built a non-oversampling TDA1541A DAC with Pedja's PCB for year. After several tweaking and modification, I replaced the AD844 I/V output stage with resistor I/V conversion and 6922 SRPP output stage.
And then, I found the main schematic of Audio Note DAC 1.1 Kit from the site http://audionotekits.espyderweb.net/
Although the other NOS DAC manufacture 47Labs declare they don't place any analog filter in their DAC, AN use a slight filter (a 12mH inductor and a 10nF cap) after the output of AD1865.
Because it is hard to get good inductors (Solen's are good, but they're huge and expensive for 12mH), I just clone the AN's analog filter with a samll and cheapo ferrite style inductor. However, the result is positive - the sound now is relaxed and sweeter, and more musical than without filters.
I've read so much discussions about varieties of I/V conversion of NOS DAC, but the discussions about analog filters are rare. What do you think of the analog filter for NOS DAC?

rfbrw · 6th September 2005, 08:47 PM

The latest upgrade removes the analogue filter.

http://www.audionote.co.uk/dacs/dac_level_1.html

garbage · 7th September 2005, 09:07 AM

zanden uses analog filters.

6moons review of the 5000mk2 dac.

rfbrw · 7th September 2005, 11:05 AM

Marlowe, if you are interested in the Zanden filter then this thread may be of interest to you.

Zanden Parallel DAC Questions

Post number 22 has a link to the UK patent office for the Zanden patent. It also links to the US version of the patent which may not have been available at the time the thread was started.

X.G. · 7th September 2005, 03:20 PM

you will find the the correct theory
http://pdfserv.maxim-ic.com/en/an/A4903.pdf

this is my experience:
http://www.diyaudio.com/forums/showt...ht=#post672387

this is the respone of NOS DAC in normal.......

this is my calculation in the respone of NOS DAC.

6th September 2005, 08:36 PM	#1
Marlowe diyAudio Member Join Date: Feb 2003	Analog filter for NOS DAC I've built a non-oversampling TDA1541A DAC with Pedja's PCB for year. After several tweaking and modification, I replaced the AD844 I/V output stage with resistor I/V conversion and 6922 SRPP output stage. And then, I found the main schematic of Audio Note DAC 1.1 Kit from the site http://audionotekits.espyderweb.net/ Although the other NOS DAC manufacture 47Labs declare they don't place any analog filter in their DAC, AN use a slight filter (a 12mH inductor and a 10nF cap) after the output of AD1865. Because it is hard to get good inductors (Solen's are good, but they're huge and expensive for 12mH), I just clone the AN's analog filter with a samll and cheapo ferrite style inductor. However, the result is positive - the sound now is relaxed and sweeter, and more musical than without filters. I've read so much discussions about varieties of I/V conversion of NOS DAC, but the discussions about analog filters are rare. What do you think of the analog filter for NOS DAC? __________________ Here's looking at you, kid.

7th September 2005, 03:20 PM	#5
X.G. diyAudio Member Join Date: Sep 2003 Location: GuangDong China	Zanden's theory is wrong! you will find the the correct theory http://pdfserv.maxim-ic.com/en/an/A4903.pdf this is my experience: http://www.diyaudio.com/forums/showt...ht=#post672387 this is the respone of NOS DAC in normal....... this is my calculation in the respone of NOS DAC.

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6th September 2005, 08:47 PM	#2
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	The latest upgrade removes the analogue filter. http://www.audionote.co.uk/dacs/dac_level_1.html

7th September 2005, 09:07 AM	#3
garbage diyAudio Member Join Date: Apr 2004 Location: Singapore	zanden uses analog filters. 6moons review of the 5000mk2 dac.

7th September 2005, 11:05 AM	#4
rfbrw diyAudio Member Join Date: Oct 2001 Location: .	Marlowe, if you are interested in the Zanden filter then this thread may be of interest to you. Zanden Parallel DAC Questions Post number 22 has a link to the UK patent office for the Zanden patent. It also links to the US version of the patent which may not have been available at the time the thread was started.

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