A basic gear question
JIMV -- Sun, 11/02/2008 - 10:01
I am new to this forum so forgive me if this is not the right place to ask this question. I am upgrading my CD source for the fist time in 8 years. I have bought a used (2002) Benchmark DAC1 and am now looking at transports/CD players. The DAC has an upsample capability. How does that work? will it take data from a CD player that does not upsample and do the conversion in the DAC or does it simply recognize an already upsampled signal from the CD player?
I am not looking for opinion on the value of upsampling, more the mechanics of how a CD player outboard DAC works with upsampling. Do I need to buy a specific type of CD transport to take advantage of the DAC1's upsampling capability.
I realize this is a basic question, but I really do not understand the process and hookup. I figure I am asking a sort of 'evaluation' question
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The DAC will take the normal 16 bit 44.1khz signal from your CD players digital outputs and upsample it. I am not aware of a CD player that presents an already upsampled bitstream at the digital output jacks. In other words, any CD player that has a digital output will provide your Benchmark with what it needs.
rwortman wrote:The DAC will take the normal 16 bit 44.1khz signal from your CD players digital outputs and upsample it. I am not aware of a CD player that presents an already upsampled bitstream at the digital output jacks. In other words, any CD player that has a digital output will provide your Benchmark with what it needs.
The DAC1 has a variety of upsample options and no manner for the operator to influence the selection. Does the thing automaticaly select the optimum sample size?
I know this is basic but the owners manual speaks of the capability and says nothing about its operation???
I just took a quick look at the DAC1 owners manual on Benchmark's site. I see nothing in there about upsampling options.
rwortman wrote:I just took a quick look at the DAC1 owners manual on Benchmark's site. I see nothing in there about upsampling options.
The manual says, on the cover
"DAC1
Instruction Manual
2-Channel 24-bit 192-kHz
Audio Digital-to-Analog Converter"
My question was about that 24-Bit 192-khz advertising. I know little of how such things work but know the higher the rate, the better potential for good sound the DAC has.
The exact 'how' this upsamplng occurs was the issue. I have read some good information about what the 24/192 means and what it does to the signal. My question is far more basic. I was/am unclear as to when, where and how the upsamplng takes place.
It appears the DAC1 takes a standard 44.1/16 digital data stream from the digital out of a CD player or transport and then upsamples with one chip before passing on the more complex signal to the actual DAC in the Benchmark unit which converts the upsampled data to an analog signal.
I do still have questions though. I understand the data stream must come in via the Toslink input to upsample. I also understand the DAC1 works best at 100hz. If this is true, would not the unit be a 24/100 upsampler and not the larger number? How would it ever work at 192? All this processing seems to be automatic. If so under what circumstance would one ever get the beneits of a 24/192 sample rate?
Put another way, what do I as a user need to do to have the DAC1 operate at its peak sample rate?
I guess I am asking technical questions but need responses in tech baby talk to understand.
As far as operating at its best at 100hz, I have no idea what you are talking about. You might not either. ;) The unit can take an input signal of up to 24bit/192Khz. It does proprietary stuff to that and outputs a wonderful sounding analog signal to whatever you connect it to. That is all you need to know. It is going take the digital output of your CD or DVD player and do its magic. If you want to know more I suggest you do some Google searching for DAC and CD player theory. I don't have time to write the book you need to read. ;)
rwortman wrote:As far as operating at its best at 100hz, I have no idea what you are talking about. You might not either. ;) The unit can take an input signal of up to 24bit/192Khz. It does proprietary stuff to that and outputs a wonderful sounding analog signal to whatever you connect it to. That is all you need to know. It is going take the digital output of your CD or DVD player and do its magic. If you want to know more I suggest you do some Google searching for DAC and CD player theory. I don't have time to write the book you need to read. ;)
I got te 100HZ from note by John Atkinson. The rest of your post is off topic. As I noted, I am not interested in DAC and CD player theory but in the specific operation of a specific DAC. Your post implies that the input signal can vary from the CD standard up to 24/192 but that idea directly contradicts other info from other folk I have asked who state that all digital data streams from CD players and transports arrive at the DAC as 16/44.1.
Either they are right or you are and, so far in my quest for answers, you stand alone.
JIMV wrote:rwortman wrote:As far as operating at its best at 100hz, I have no idea what you are talking about. You might not either. ;) The unit can take an input signal of up to 24bit/192Khz. It does proprietary stuff to that and outputs a wonderful sounding analog signal to whatever you connect it to. That is all you need to know. It is going take the digital output of your CD or DVD player and do its magic. If you want to know more I suggest you do some Google searching for DAC and CD player theory. I don't have time to write the book you need to read. ;)
I got te 100HZ from note by John Atkinson. The rest of your post is off topic. As I noted, I am not interested in DAC and CD player theory but in the specific operation of a specific DAC. Your post implies that the input signal can vary from the CD standard up to 24/192 but that idea directly contradicts other info from other folk I have asked who state that all digital data streams from CD players and transports arrive at the DAC as 16/44.1.
Either they are right or you are and, so far in my quest for answers, you stand alone.
100hz is just above wall frequency and has nothing to do with the much higher frequencies used for audio digital data transmission. I have no idea what JA meant. Perhaps you misread it. Perhaps he is powering it from a synthesized AC source at 100hz. ( I doubt it) As far as the DAC accepting inputs up to 24/192 that is right from your owners manual. CD players and transports are not the only sources that can be attached to your new toy. DVD audio can be up to 24/192 as can other high res sources used in the recording industry. Benchmark is a pro audio company. All you have to do is plug the blasted thing in and use it. There is no way to select anything other than its standard processing. It will lock onto whatever the input data rate is and do its thing. If your pals are such experts, why not just ask one of them to hook the thing up for you? If you want a fuller understanding of what the thing does, then go find some reading material. You might start with a thorough reading of the manual.
rwortman wrote:JIMV wrote:rwortman wrote:As far as operating at its best at 100hz, I have no idea what you are talking about. You might not either. ;) The unit can take an input signal of up to 24bit/192Khz. It does proprietary stuff to that and outputs a wonderful sounding analog signal to whatever you connect it to. That is all you need to know. It is going take the digital output of your CD or DVD player and do its magic. If you want to know more I suggest you do some Google searching for DAC and CD player theory. I don't have time to write the book you need to read. ;)
I got te 100HZ from note by John Atkinson. The rest of your post is off topic. As I noted, I am not interested in DAC and CD player theory but in the specific operation of a specific DAC. Your post implies that the input signal can vary from the CD standard up to 24/192 but that idea directly contradicts other info from other folk I have asked who state that all digital data streams from CD players and transports arrive at the DAC as 16/44.1.
Either they are right or you are and, so far in my quest for answers, you stand alone.
100hz is just above wall frequency and has nothing to do with the much higher frequencies used for audio digital data transmission. I have no idea what JA meant. Perhaps you misread it. Perhaps he is powering it from a synthesized AC source at 100hz. ( I doubt it) As far as the DAC accepting inputs up to 24/192 that is right from your owners manual. CD players and transports are not the only sources that can be attached to your new toy. DVD audio can be up to 24/192 as can other high res sources used in the recording industry. Benchmark is a pro audio company. All you have to do is plug the blasted thing in and use it. There is no way to select anything other than its standard processing. It will lock onto whatever the input data rate is and do its thing. If your pals are such experts, why not just ask one of them to hook the thing up for you? If you want a fuller understanding of what the thing does, then go find some reading material. You might start with a thorough reading of the manual.
I am obviously not being clear. The DAC, the actual chip, works best at 100HZ, per JA. It is completely possible I am misunderstanding but what I have understood makes sense to me. The 16/44.1 signal comes into the DAC, goes to an upsampling chip and is converted to an optimal 100hz signal which goes to the actual DAC and then off as an analog signal. The folk I have been communicating with have simply answered my questions with more clarity and grace than you. That I still have questions is simply a reflection of my desire to understand how my unit works, not any reflection of anyone else.
Why you bother to spend any time on an audio forum while suffering from severe ass-hole syndrom is beyond me. Save your supercilious attempts at superiority for someone who actually believes you are more than an idiot savant, one who has an understanding of a single subject, in this case audio, and lacks all skills in about everything else including basic civility. I asked a valid question, you responded like the late marie Antoinete, but with less grace.
The signal coming from your CD player is 16 bits at 44.1 kilohertz. You are saying that somehow you need to set your DAC to convert that down to 100 hz, a frequency that is around 500 times slower than the input. This not only not how your machine works, it couldn't possibly work. If the sampling frequency was 100hz the highest frequency of audio you could decode would be 50Hz. I doubt you want to listen to nothing but deep bass hum. You came in here asking a question that revealed that you either have not read your manual or lack sufficient background to understand it. I read your manual for you, told you how your machine worked and suggested you read up on CD playback theory. You accused me of not knowing what I am talking about and straying from the topic. I have gone out of my way to try to help you and now you call me an asshole. If one of us is acting like an asshole, it would be you. If you don't want to learn more about how it works, then just hook the damn thing up, start listening and take your attitude and your questions to someone else.
Regarding your idiot savant charge: I am not the one that came in here triumphantly brandishing his vocabulary, confusing the length of the words with the weight of the argument, whilst being apparently unable to comprehend the owners manual for the audio device he just purchased. I, on the other hand, can understand both your pompous post and your owners manual. Whose understanding is more narrowly focussed?
Here I am being a sucker and still trying to help. I just read an Atkinson review over at the S'phile webpage. Might this be what you are referring to?:
"The datastream selected by the front-panel switch is sent to an asynchronous sample-rate converter chip, an Analog Devices AD1896, which, regardless of the original sample rate of the data, converts it to a datastream sampled at 110kHz. As well as isolating the DAC stage from word-clock jitter on the incoming signal, this sample-rate conversion allows the DAC to run at its optimal sample rate. Benchmark's John Siau explains that "the trade-off of a small amount of SRC distortion far outweighs the more significant distortion and noise of the D/A chip operating at sample-rates other than its most efficient rate....[110kHz] is the highest frequency to maintain the full oversampling of the D/A chip."
This is an explanation of what the DAC1 does internally to convert bits to audio. It does not describe anything you can select or change. It is saying that the input data is sample rate converted to 110 kilohertz (not 100 hertz) to optimize the noise and distortion performance of the internal DAC chips. As the writer explains, they are trading a bit of increased distortion caused by the sample rate conversion for increased accuracy of the DAC chip by running it at its optimum frequency. It would appear to me that any input data rate above 96khz would be, as you suspected, a waste of bandwidth. Interesting, but nothing you need to know or understand to operate your DAC1.
rwortman wrote:The signal coming from your CD player is 16 bits at 44.1 kilohertz. You are saying that somehow you need to set your DAC to convert that down to 100 hz, a frequency that is around 500 times slower than the input. This not only not how your machine works, it couldn't possibly work. If the sampling frequency was 100hz the highest frequency of audio you could decode would be 50Hz. I doubt you want to listen to nothing but deep bass hum. You came in here asking a question that revealed that you either have not read your manual or lack sufficient background to understand it. I read your manual for you, told you how your machine worked and suggested you read up on CD playback theory. You accused me of not knowing what I am talking about and straying from the topic. I have gone out of my way to try to help you and now you call me an asshole. If one of us is acting like an asshole, it would be you. If you don't want to learn more about how it works, then just hook the damn thing up, start listening and take your attitude and your questions to someone else.
Regarding your idiot savant charge: I am not the one that came in here triumphantly brandishing his vocabulary, confusing the length of the words with the weight of the argument, whilst being apparently unable to comprehend the owners manual for the audio device he just purchased. I, on the other hand, can understand both your pompous post and your owners manual. Whose understanding is more narrowly focussed?
Alas..I have a few posting problems, most notably an inability to type...not 100hz but 100khz....
My fault.
That you understand the technical aspects of the hobby does not imply either social skills or any knowledge of any other issue or skill. I politely asked a question and admitted my lack of knowledge on the issue up front. Your response was snotty and to a large extent, off topic.
I'd bet you voted Obama :shock:
Please read the edit above for a further attempt to answer your question. Who I support for president is irrelevant to this discussion but you are wrong. I am an intensely curious person with a engineering background and have read widely about a large variety of interests. I am an expert on a few things and have a decent knowledge of a whole bunch of things. Just about the opposite of an idiot savant. I do have a tendency to get annoyed when someone asks a question and then, when my answer differs from their preconception, accuses me of not knowing what I am talking about. My ego is larger than it should be. I apologize for the sarcastic air that crept into my subsequent posts. If you have further tech questions that I can help with, please feel free to email me at rwortman2 [at] charter [dot] net
Have a nice day and enjoy your new DAC. I am thoroughly enjoying the Cambridge Audio DacMagic that I just purchased
bump
rwortman wrote:Please read the edit above for a further attempt to answer your question. Who I support for president is irrelevant to this discussion but you are wrong. I am an intensely curious person with a engineering background and have read widely about a large variety of interests. I am an expert on a few things and have a decent knowledge of a whole bunch of things. Just about the opposite of an idiot savant. I do have a tendency to get annoyed when someone asks a question and then, when my answer differs from their preconception, accuses me of not knowing what I am talking about. My ego is larger than it should be. I apologize for the sarcastic air that crept into my subsequent posts. If you have further tech questions that I can help with, please feel free to email me at rwortman2 [at] charter [dot] net
Have a nice day and enjoy your new DAC. I am thoroughly enjoying the Cambridge Audio DacMagic that I just purchased
And I apologize as well. I was also out of line. I have found audio folk to be generally pretty decent folk always eager to help a novice on an issue. As to 110khz, I got that from a topic specific post on another forum from JA, where he stated 100khz. Your latest edit does answer my question. Thank you.