What is better sounding I/V con. ?

Gasho · 12th July 2005, 04:32 PM

What I/V conversion on BB PCM63K gives more natural , and transparent sound .

Active (AD847) , or passive with high quality , precision resistor (100ohm) connected from current output of DAC to ground?

Charles Hansen · 13th July 2005, 04:39 AM

Passive.

Gasho · 13th July 2005, 05:12 AM

Or transformer coupled.?

Gasho · 13th July 2005, 05:26 AM

OK , my player is made with PDM100 HDCD dekoder , and it have some kind of relay (S301) . I don´t know is it some kind of gain switch or emphasisi filter or.......

zinsula · 13th July 2005, 08:30 AM

If you want to go with opamps, try this very inventive implementation of the AD844 (common base), which avoids the drawbacks of "standard" opamp I/V's:
http://users.verat.net/~rogic/1541/1...ev1_1b_sch.pdf

Read also all explanations on that website. Be aware that you can only use AD844 (and _very_ few others) with such an implementation. Not all current feedback opamps give access to the required circuit nodes.

And you'll need to make some mods, AFAIK PCM63 has not the asymmetric current range as TDA1541.
(I believe the circuit will be simpler in the PCM63 case)

Tino

mpopovics · 14th July 2005, 07:29 AM

Gasho!

I would give a try to Pass D1 output (Pass uses PCM63 too...)

Regards,
Milan

Gasho · 14th July 2005, 07:30 AM

I am going to do it passive. I will try 100ohm as reference , and +/- 10ohm variations. After that I will put a passive 6db/okt low pass filter (20KHz) than pass that signal to OP (output stage with gain).

mpopovics · 14th July 2005, 07:58 AM

I think, it is something with filter characteristics (probably)...
Would need mre time to study the schematics

Gasho · 14th July 2005, 09:02 AM

Quote:

Originally posted by mpopovics
Gasho!

I would give a try to Pass D1 output (Pass uses PCM63 too...)

Regards,
Milan

Hmm , I can´t find the data about that type of I/V conversion.

Probably that sistem work only if two DACs per channel works in balanced mode (on one DAC the signal is phase reversed in digital domain).

Joseph K · 14th July 2005, 09:05 AM

Gasho,

That switch is the normal /hdcd mode filter. When HDCD is not active, you have to apply 6dB attenuation, which can be done internally in the pmd100, but You loose resolution, or externally in an analogic way, which can be seen on the schematics. [this is the proper, good solution]

By the way, thanks for the schematics!

Did You notice the tricky I/V solution applied here by Rotel? I have noticed that when I peeked into my one, and have a certain respect for it. Maybe it would worth a bit deeper digging into..
And, if You decide to go passive, your output resistance is just there, 100 ohm

Ciao, George

12th July 2005, 04:32 PM	#1
Gasho diyAudio Member Join Date: Nov 2004 Location: Zagreb	What is better sounding I/V con. ? What I/V conversion on BB PCM63K gives more natural , and transparent sound . Active (AD847) , or passive with high quality , precision resistor (100ohm) connected from current output of DAC to ground?

14th July 2005, 07:29 AM	#6
mpopovics diyAudio Member Join Date: Apr 2002 Location: Hungary	PCM63K Gasho! I would give a try to Pass D1 output (Pass uses PCM63 too...) Regards, Milan

14th July 2005, 07:58 AM	#8
mpopovics diyAudio Member Join Date: Apr 2002 Location: Hungary	S301 I think, it is something with filter characteristics (probably)... Would need mre time to study the schematics

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Best sounding DIY SS amp	trespasser_guy	Solid State	69	2nd November 2007 06:07 PM
Better sounding ECL86's	Robyn_E	Tubes / Valves	2	9th August 2007 04:05 PM


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

13th July 2005, 04:39 AM	#2
Charles Hansen diyAudio Member Join Date: May 2003 Location: Colorado	Passive.

13th July 2005, 05:12 AM	#3
Gasho diyAudio Member Join Date: Nov 2004 Location: Zagreb	Or transformer coupled.?

13th July 2005, 08:30 AM	#5
zinsula diyAudio Member Join Date: Mar 2004	If you want to go with opamps, try this very inventive implementation of the AD844 (common base), which avoids the drawbacks of "standard" opamp I/V's: http://users.verat.net/~rogic/1541/1...ev1_1b_sch.pdf Read also all explanations on that website. Be aware that you can only use AD844 (and _very_ few others) with such an implementation. Not all current feedback opamps give access to the required circuit nodes. And you'll need to make some mods, AFAIK PCM63 has not the asymmetric current range as TDA1541. (I believe the circuit will be simpler in the PCM63 case) Tino

14th July 2005, 07:30 AM	#7
Gasho diyAudio Member Join Date: Nov 2004 Location: Zagreb	I am going to do it passive. I will try 100ohm as reference , and +/- 10ohm variations. After that I will put a passive 6db/okt low pass filter (20KHz) than pass that signal to OP (output stage with gain).

14th July 2005, 09:05 AM	#10
Joseph K diyAudio Member Join Date: Dec 2004 Location: gran sasso	Gasho, That switch is the normal /hdcd mode filter. When HDCD is not active, you have to apply 6dB attenuation, which can be done internally in the pmd100, but You loose resolution, or externally in an analogic way, which can be seen on the schematics. [this is the proper, good solution] By the way, thanks for the schematics! Did You notice the tricky I/V solution applied here by Rotel? I have noticed that when I peeked into my one, and have a certain respect for it. Maybe it would worth a bit deeper digging into.. And, if You decide to go passive, your output resistance is just there, 100 ohm Ciao, George

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read