Hello
I may be new on this forum but i'm not new to audio and electronics. I'll keep this short for the first time. I want to build a tube output DAC based on Analog Devices (or maybe BurrBrown) DAC. I decided to go that way becouse I do not want to copy or recreate an existing design based on many times described TDA1541(A) and TDA1543(A). Tube output is a "must be" for me.
Anybody can create a bad sounding DAC based on any chip so i asked myself why not try to build a good one with the newest technology available.
Q: Any suggestion on the DAC selection (as mentioned earlier AD or BB maybe Cirrus) with Delta-Sigma OS 24(?) bit.
Thank you in advance,
Jernej
PS: Please don't mind my bad english
I may be new on this forum but i'm not new to audio and electronics. I'll keep this short for the first time. I want to build a tube output DAC based on Analog Devices (or maybe BurrBrown) DAC. I decided to go that way becouse I do not want to copy or recreate an existing design based on many times described TDA1541(A) and TDA1543(A). Tube output is a "must be" for me.
Anybody can create a bad sounding DAC based on any chip so i asked myself why not try to build a good one with the newest technology available.Q: Any suggestion on the DAC selection (as mentioned earlier AD or BB maybe Cirrus) with Delta-Sigma OS 24(?) bit.
Thank you in advance,
Jernej
PS: Please don't mind my bad english
ssstromar said:Hello
Q: Any suggestion on the DAC selection (as mentioned earlier AD or BB maybe Cirrus) with Delta-Sigma OS 24(?) bit.
Thank you in advance,
Jernej
PS: Please don't mind my bad english
The AD1853 from AD seems to be popular amongst the makers of expensive dacs and though that is not necessarily a good reason to use them, it is as good as any other reason. The AD1852 which has a voltage output would make the use of valves a little easier. You might also want to consider the dual differential example given in the AD1852 datasheet.
AD1852
The basic idea for the project is to use as few as possible components on the analog outputs. We all heard some of very good sounding CDP with directly connected outputs. No analog filters used, no buffers (OP-AMPS).
I would use only simple RC filtering on the output and a cathode coupled diferential pair of maybe ECC83 valves. Valves operate only in theory well above 100kHz or even less so they are natural filters. For the analog section I would definetly use P2P with silver coated OFC (UPC) solid core wire.
AD1852 has voltage outputs so it is the first choice for the project. AD1853 has the same arcitecture but it's a I-DAC so scratch that (or do I ?).
What benefits have mono design compared to single chip conversion for both chanels.
The basic idea for the project is to use as few as possible components on the analog outputs. We all heard some of very good sounding CDP with directly connected outputs. No analog filters used, no buffers (OP-AMPS).
I would use only simple RC filtering on the output and a cathode coupled diferential pair of maybe ECC83 valves. Valves operate only in theory well above 100kHz or even less so they are natural filters. For the analog section I would definetly use P2P with silver coated OFC (UPC) solid core wire.
AD1852 has voltage outputs so it is the first choice for the project. AD1853 has the same arcitecture but it's a I-DAC so scratch that (or do I ?).
What benefits have mono design compared to single chip conversion for both chanels.
balanced or SE
As we know AD1852 and others have diferential outputs which are in 95% used only to be summed up with an OP-AMP output stage. OK some CDPs have balanced outputs as well but many users simply connect them to SE input stages of amplifiers via interconect cables which only propagate positive signal and ground.
So, come to think of it that my idea of diferential pair of valves in theory isn't that bad, DAC outputs will be evenly loaded so can be valve outputs regardless of SE or balanced load.
Or in theory why not use only one DAC diferential output becouse all of benefits which come with diferential pairs are only used to the OPAMP, beyond that is SE.
CS8414 seems to be the most common choice for the input reciever.
Will consider in further development.
As we know AD1852 and others have diferential outputs which are in 95% used only to be summed up with an OP-AMP output stage. OK some CDPs have balanced outputs as well but many users simply connect them to SE input stages of amplifiers via interconect cables which only propagate positive signal and ground.
So, come to think of it that my idea of diferential pair of valves in theory isn't that bad, DAC outputs will be evenly loaded so can be valve outputs regardless of SE or balanced load.
Or in theory why not use only one DAC diferential output becouse all of benefits which come with diferential pairs are only used to the OPAMP, beyond that is SE.
CS8414 seems to be the most common choice for the input reciever.
moderation
Im still under moderation so my posts appear few hours later and seem out of place.
). Tell you a little secret, you really don't need analog filters for valve output stage .
Im still under moderation so my posts appear few hours later and seem out of place.
Yes, thank you, the datasheet provided for AD1852 or 3 is dated 1999 and 2000. Cirrus logic CS8414 is superseded by CS8416.
Precisely the idea. Actualy I prefer SE stage not balanced, but since i'm doing this from scratch paper can take anything (hope I got the phrase right
). Tell you a little secret, you really don't need analog filters for valve output stage .moderation
I'm still under moderation so my posts appear out of date. Hope that will pass soon.
. Valves it is, for output stage say I. Tell you a little secret you don't really need any filtering network for valve output.
I'll search the Tube section for output stage solutions. But by any means please post a thread if somebody came across a similar problem.
PS: I'm writing this the second time, first was lost by my mistake or some other factor. If my first post similar to this one appear accept my apologies, but read them both.
Jernej
I'm still under moderation so my posts appear out of date. Hope that will pass soon.
Thank you, the datasheets provided from AD for 1852/1853 are dated 1999/2000, and in the meen while CS8414 was superseded by CS8416.
Actualy I prefer SE but since I'm in developing stage building from scratch paper can take anything
. Valves it is, for output stage say I. Tell you a little secret you don't really need any filtering network for valve output.I'll search the Tube section for output stage solutions. But by any means please post a thread if somebody came across a similar problem.
PS: I'm writing this the second time, first was lost by my mistake or some other factor. If my first post similar to this one appear accept my apologies, but read them both.
Jernej
Re: moderation
Hi.
This would not be a bad place to start....
http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html
See also this thread....
http://www.diyaudio.com/forums/showthread.php?s=&postid=902341#post902341
The Thorsten output for differential DACs has been played with by members with good results.
For transistor / FET, try this:-
http://ultranalog.com/cdenhancer/sacdenhancer/
An all-FET version is also on the thread above.
andy
ssstromar said:I'm still under moderation so my posts appear out of date. Hope that will pass soon.
Thank you, the datasheets provided from AD for 1852/1853 are dated 1999/2000, and in the meen while CS8414 was superseded by CS8416.
Actualy I prefer SE but since I'm in developing stage building from scratch paper can take anything
I'll search the Tube section for output stage solutions. But by any means please post a thread if somebody came across a similar problem.
PS: I'm writing this the second time, first was lost by my mistake or some other factor. If my first post similar to this one appear accept my apologies, but read them both.
Jernej
Hi.
This would not be a bad place to start....
http://www.fortunecity.com/rivendell/xentar/1179/theory/vasfda/vasfda.html
See also this thread....
http://www.diyaudio.com/forums/showthread.php?s=&postid=902341#post902341
The Thorsten output for differential DACs has been played with by members with good results.
For transistor / FET, try this:-
http://ultranalog.com/cdenhancer/sacdenhancer/
An all-FET version is also on the thread above.
andy
SRPP
A thing to write in TUBES section acctualy.
As I was able to determine so far CS8416 and AD1852 and AD1853 have output / input modes: Right/Left Justified and I2S wich are the same according to timing diagram, so that makes things a little easier.
Q: Programmable volume control on DAC. Is it best just to set volume to max and leave it there, when performance is at question.
PS: previous article was posted twice, I don't know what happend with moderation, before there was allways a message "You are under moderation" but this time no sign of my article and in some time both appeared
This is very interesting stuff but both designs are SRPP. I don't want to use another SRPP stage in my DAC becousse I allready have one in preamp. To make things worse SRPP design have gain of 30dB or more so feedback loop is required and that will only downgrade the performance.
A thing to write in TUBES section acctualy.
As I was able to determine so far CS8416 and AD1852 and AD1853 have output / input modes: Right/Left Justified and I2S wich are the same according to timing diagram, so that makes things a little easier.
Q: Programmable volume control on DAC. Is it best just to set volume to max and leave it there, when performance is at question.
PS: previous article was posted twice, I don't know what happend with moderation, before there was allways a message "You are under moderation" but this time no sign of my article and in some time both appeared
Re: SRPP
Hi.
Have you found the stuff under the '63 thread ??
I converted the srpp to differential LTP and it works well as a bal-unbal.
The ultranalog circuit has been used in FET and bipolar and in FET mode is possibly better than tube !
Andy
ssstromar said:
This is very interesting stuff but both designs are SRPP. I don't want to use another SRPP stage in my DAC becousse I allready have one in preamp. To make things worse SRPP design have gain of 30dB or more so feedback loop is required and that will only downgrade the performance.
A thing to write in TUBES section acctualy.
Hi.
Have you found the stuff under the '63 thread ??
I converted the srpp to differential LTP and it works well as a bal-unbal.
The ultranalog circuit has been used in FET and bipolar and in FET mode is possibly better than tube !
Andy
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