Hi,
I'm just trying to decide whether to try a non-OS DAC.
What are the opinions on how low the residual 44.1KHz can be made without impacting on the audio passband (ripple, group delay etc)?
What is a feasible figure in dB below operating level, or better below dBF?
TIA
Cheers,
I'm just trying to decide whether to try a non-OS DAC.
What are the opinions on how low the residual 44.1KHz can be made without impacting on the audio passband (ripple, group delay etc)?
What is a feasible figure in dB below operating level, or better below dBF?
TIA
Cheers,
Koinichiwa,
First, any Image up to around 40KHz is caused by frequencies normally piped to the tweeter and due to the sinc rolloff already notably down, as this rolloff reaches -3db @ 20KHz and is > -8db @ 30KHz. I have aspreadsheet to calculate the sinc curve for any funloving sample rate, but sadly even zipped it is > 3MB.
If the output waveform of the DAC is a propper ideal staircase than 40KHz as result of the sinc function will be down by 20db. However this "ideal" sinc curve will be blurred by non-ideal staircase (non-zero settling time of DAC) output.
Now, if you add my favoured "peaking" 3rd order lowpass you get an offset of the -3db @ 20KHz at the price of 90 degree Phaselag at 20KHz and a 3rd order rolloff above that, making 40KHz including the sinc function around -20db to -30db depending how fast the DAC settles.
IN MY PERSONAL VIEW such a level of attenuation of the first image suffices if well designed equipment is used. I'd even go as far as saying that the simpler LCR resonant Anti Sinc Circuit previously discussed with a 1st order LPF @ 44KHz combined with the sinc rolloff should be enough....
Sayonara
dhaen said:
First, any Image up to around 40KHz is caused by frequencies normally piped to the tweeter and due to the sinc rolloff already notably down, as this rolloff reaches -3db @ 20KHz and is > -8db @ 30KHz. I have aspreadsheet to calculate the sinc curve for any funloving sample rate, but sadly even zipped it is > 3MB.
If the output waveform of the DAC is a propper ideal staircase than 40KHz as result of the sinc function will be down by 20db. However this "ideal" sinc curve will be blurred by non-ideal staircase (non-zero settling time of DAC) output.
Now, if you add my favoured "peaking" 3rd order lowpass you get an offset of the -3db @ 20KHz at the price of 90 degree Phaselag at 20KHz and a 3rd order rolloff above that, making 40KHz including the sinc function around -20db to -30db depending how fast the DAC settles.
IN MY PERSONAL VIEW such a level of attenuation of the first image suffices if well designed equipment is used. I'd even go as far as saying that the simpler LCR resonant Anti Sinc Circuit previously discussed with a 1st order LPF @ 44KHz combined with the sinc rolloff should be enough....
Sayonara
Kuei Yang Wang said:
KYW,
If you email it to the webmaster account I might be able to put it on the server for you.
Or rather - you don't have mail
Koinichiwa Webmeister San,
The mail failed.....
<p.....10@////.com>:
17.250.248.49 failed after I sent the message.
Remote host said: 552 5.2.3 Message exceeds maximum fixed size (3145727)
(the e-mail addy was altered to throw off spambots....)
I uploaded the zip to here for temprary parking:
http://groups.yahoo.com/group/Thunderstone_audiophile/files/SINC.zip
Sayonara
Koinichiwa Webmeister San,
The mail failed.....
<p.....10@////.com>:
17.250.248.49 failed after I sent the message.
Remote host said: 552 5.2.3 Message exceeds maximum fixed size (3145727)
(the e-mail addy was altered to throw off spambots....)
I uploaded the zip to here for temprary parking:
http://groups.yahoo.com/group/Thunderstone_audiophile/files/SINC.zip
Sayonara
Good home found..
KYW,
If it's alright, I've put it here:
http://www.dhaen.org.uk/kyw/kyw.htm
I'll provide a more elegant link later.. e&oe
Jo mata
KYW,
If it's alright, I've put it here:
http://www.dhaen.org.uk/kyw/kyw.htm
I'll provide a more elegant link later.. e&oe
Jo mata
Re: Good home found..
Koinichiwa,
Yeah, that's cool. I simply wrote this on the quick a while back as I wanted to know "exact" values for a few thing in the context. As I could not find anything easy to use I made me one. Put it into the public domain...
Sayonara
Koinichiwa,
dhaen said:
Yeah, that's cool. I simply wrote this on the quick a while back as I wanted to know "exact" values for a few thing in the context. As I could not find anything easy to use I made me one. Put it into the public domain...
Sayonara
KYW,
I must say, the problem seems less than I'd thought.
The levels you quoted: were they below operating level? If so, which one 😉 Please tell me in dBF.
Okagesama-de,
John
(Nihon-go wa honto omoshiroi desu-ne)
I must say, the problem seems less than I'd thought.
The levels you quoted: were they below operating level? If so, which one 😉 Please tell me in dBF.
Okagesama-de,
John
(Nihon-go wa honto omoshiroi desu-ne)
Hello Dhaen,
Check these pages, show the effectiveness of a few non-o/s filtering approaches (four are multiple notches, one is 3rd order low pass).
Pedja
Try it, of course.dhaen said:
In fact it is impossible.dhaen said:
Depends on what is the goal. Digital filters are at least 60dB (some the whole 120dB) effective and they attenuate practically immediately after the audio band. You can not achieve this by the analog means unless you destroy the sound completely. Fortunately, with decent rest of the gear, you actually do not need a filtering.dhaen said:
Check these pages, show the effectiveness of a few non-o/s filtering approaches (four are multiple notches, one is 3rd order low pass).
Pedja
Pedja,
Impressive information on your site 🙂 thank you for the link.
I shall study it.
I'm sure I will need filtering: I use SET. (But it's decent 😉 )
I'll be back 😎
Cheers,
Impressive information on your site 🙂 thank you for the link.
I shall study it.
I'm sure I will need filtering: I use SET. (But it's decent 😉 )
I'll be back 😎
Cheers,
Koinichiwa,
Well, if your signal is 0dbfs the the quoted figures of -20...-30db refer to 0dbfs. If your signal is @ -60dbfs the -20...-30db refer to that.
I used the originla Kusonoki DAC (4 X TDA1543, 1st order LPF @ 50KHz) for quite a few years, I never had problems with what I'd chalk up to the high level of ultrasonic noice. Amps during this time where any, from solid state to PP and SE Valves.
Sayonara
dhaen said:
Well, if your signal is 0dbfs the the quoted figures of -20...-30db refer to 0dbfs. If your signal is @ -60dbfs the -20...-30db refer to that.
dhaen said:
I used the originla Kusonoki DAC (4 X TDA1543, 1st order LPF @ 50KHz) for quite a few years, I never had problems with what I'd chalk up to the high level of ultrasonic noice. Amps during this time where any, from solid state to PP and SE Valves.
Sayonara
Kuei Yang Wang said:
Ah so you are talking about the level of the image here, which must be the same level as the signal at any moment in time...
So-desu-ka
John
Hall Of Mirrors
John,
These are the spectral contents of 1kHz, 5kHz, 10kHz and 20kHz unfiltered sinewaves sampled by 44.1kHz. Essentially these diagrams do not show anything more than Thorsten’s spreadsheet, but it might be easier to follow the situation with particular freqs. In these diagrams Y axis is 60dB tall.
I updated my site with info about the correct values of the levels in dB (Y axis) in the FFT diagrams (there is a mistake in the original graphs since sample and hold function is not modeled).
Pedja
John,
These are the spectral contents of 1kHz, 5kHz, 10kHz and 20kHz unfiltered sinewaves sampled by 44.1kHz. Essentially these diagrams do not show anything more than Thorsten’s spreadsheet, but it might be easier to follow the situation with particular freqs. In these diagrams Y axis is 60dB tall.
I updated my site with info about the correct values of the levels in dB (Y axis) in the FFT diagrams (there is a mistake in the original graphs since sample and hold function is not modeled).
Pedja
Attachments
Hall of nightmares!
Pedja,
Thank you for the clarification. I had not considered there to be quite so many out-of-band components. If I don't filter them, the will have a field-day in my output stage, mixing to produce in-band components. These may well be the same frequencies and amplitudes as the music, but I bet their phase will differ....
I'm still not convinced about non-OS 🙄
Cheers,
Pedja,
Thank you for the clarification. I had not considered there to be quite so many out-of-band components. If I don't filter them, the will have a field-day in my output stage, mixing to produce in-band components. These may well be the same frequencies and amplitudes as the music, but I bet their phase will differ....
I'm still not convinced about non-OS 🙄
Cheers,
Re: Hall of nightmares!
Koinichiwa,
BUT THEY MUST BE. It's a fundamental point of and byproduct of sampling, hence the (supposed) need for a reconstruction filter.
Now to filter these components out you need a filter that drops some 60...100db in the band between around 20 & 24KHz....
That will entierly depend upon your outputstage...
You always trade one thing for another. Ask yourself what is the worst bargain:
1) A system that (seems to) violate causality (Digital Filter)
2) An extermely high order analogue filter
3) A little noise in the supersonic range
(Hint, if a little supersonic noise bothers DO NOT EVER play SACD, DVD-A or LP)....
Sayonara
Koinichiwa,
dhaen said:
BUT THEY MUST BE. It's a fundamental point of and byproduct of sampling, hence the (supposed) need for a reconstruction filter.
Now to filter these components out you need a filter that drops some 60...100db in the band between around 20 & 24KHz....
dhaen said:
That will entierly depend upon your outputstage...
dhaen said:
You always trade one thing for another. Ask yourself what is the worst bargain:
1) A system that (seems to) violate causality (Digital Filter)
2) An extermely high order analogue filter
3) A little noise in the supersonic range
(Hint, if a little supersonic noise bothers DO NOT EVER play SACD, DVD-A or LP)....
Sayonara
The impossible question...
Pedja and Thorsten,
OK, I'll try😉* So please can you answer the following:
What's a good non-OS DAC chip (I've only done oversamplers before).
Preferably a thru-hole type, 'cause the old boys eyes are not like they were
Cost? Less than 50 Euro per pair.
Capable of interface with the CS8412, 'cause I use them.
Preferably with differential output, but not essential.
Available without too much digging.
*In fact I have a cunning plan to fit both types of DAC 😎
Cheers,
Pedja and Thorsten,
OK, I'll try😉* So please can you answer the following:
What's a good non-OS DAC chip (I've only done oversamplers before).
Preferably a thru-hole type, 'cause the old boys eyes are not like they were
Cost? Less than 50 Euro per pair.
Capable of interface with the CS8412, 'cause I use them.
Preferably with differential output, but not essential.
Available without too much digging.
*In fact I have a cunning plan to fit both types of DAC 😎
Cheers,
Re: The impossible question...
Koinichiwa,
For simplicity of use and also sound I like the older Philips Types well. They can interface directly to the CS8412/14 etc., no glue logic needed. In order of MY personal sonic preference:
TDA1541
TDA1545
TDA1543
HOWEVER, the TDA1543 is easiest to work with and gets the quickests results. Kusonoki used that one and I also started with a simple copy of the Kusonoki DAC from MJ, 4 X parallel TDA1543, passive "direct output" IV, +8V supply to the TDA.
The TDA1541 has the highests sonic potential. It is still one of the tree or four sonically absolute best DAC chips for CD (it is only 16-Bit). It has a very "analogue" sound - Naim had them for a long time in all their CDP's and for good reasons, Marantz put it into their flagship CD7. The acclaimed Zanden DAC also uses this chip.
It also is hardest to implement well as it predates well arranged ground & supply pins (meaning next to each other for short decoupling loops), requires for best perfomance a galvanically seperate -15V supply for "analogue" side, well starwired (to the analogue ground) 14pcs "filter" caps that provide the references for the "continous calibration" operation of the DAC and so on.
Other DAC's I liked NOS are PCM63 (I suspect PCM1702/1704 will do well too), but you need gluelogic that replaces the digital filter and splits the datstream and all. I listend to the AD Chips in the AN DAC's and liked them less than PCM63 & TDA1541, so I never bothered trying them in my own stuff.
Of course, ANY delta sigma Chip is out and not to be used....
Sayonara
Koinichiwa,
dhaen said:
For simplicity of use and also sound I like the older Philips Types well. They can interface directly to the CS8412/14 etc., no glue logic needed. In order of MY personal sonic preference:
TDA1541
TDA1545
TDA1543
HOWEVER, the TDA1543 is easiest to work with and gets the quickests results. Kusonoki used that one and I also started with a simple copy of the Kusonoki DAC from MJ, 4 X parallel TDA1543, passive "direct output" IV, +8V supply to the TDA.
The TDA1541 has the highests sonic potential. It is still one of the tree or four sonically absolute best DAC chips for CD (it is only 16-Bit). It has a very "analogue" sound - Naim had them for a long time in all their CDP's and for good reasons, Marantz put it into their flagship CD7. The acclaimed Zanden DAC also uses this chip.
It also is hardest to implement well as it predates well arranged ground & supply pins (meaning next to each other for short decoupling loops), requires for best perfomance a galvanically seperate -15V supply for "analogue" side, well starwired (to the analogue ground) 14pcs "filter" caps that provide the references for the "continous calibration" operation of the DAC and so on.
Other DAC's I liked NOS are PCM63 (I suspect PCM1702/1704 will do well too), but you need gluelogic that replaces the digital filter and splits the datstream and all. I listend to the AD Chips in the AN DAC's and liked them less than PCM63 & TDA1541, so I never bothered trying them in my own stuff.
Of course, ANY delta sigma Chip is out and not to be used....
Sayonara
I'm being led...
Hi,
The TDA1541 looks interesting. Can it still be sourced in the UK, or Europe?
Cheers,
BTW, please get your "pairs of fish" sorted out from your greetings😉
Hi,
The TDA1541 looks interesting. Can it still be sourced in the UK, or Europe?
Cheers,
😉 I've never used anything else...
BTW, please get your "pairs of fish" sorted out from your greetings😉
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