http://focus.ti.com/docs/prod/folders/print/pcm2902.html
http://focus.ti.com/docs/prod/folders/print/pcm2702.html
You may do the comparison on your own.
http://focus.ti.com/docs/prod/folders/print/pcm2702.html
You may do the comparison on your own.
An externally hosted image should be here but it was not working when we last tested it.
KECES
korping_chang@pchome.com.tw <korping_chang@pchome.com.tw>
The difference between those chip can be made simple by one feature... SpctAct USB interface.
This is a rather interesting (and good) interface designed by BurrBrown Japan. Simply speaking, it allows very precise tracking of USB host clock (which itself is not very accurate) and greatly improves the sound quality. (I once saw the designer's note on the development of this chip... it is amazing the hoops he jumped through to get this chip working like it is.)
This feature combined with the other specs of this chip, makes it heads and shoulders above other chip with similar functions. Even other BB/Ti chips, including PCM 290x and PCM270x (excluding 2702 of course) series.
The Ti's datasheets made that quite clear.
This is a rather interesting (and good) interface designed by BurrBrown Japan. Simply speaking, it allows very precise tracking of USB host clock (which itself is not very accurate) and greatly improves the sound quality. (I once saw the designer's note on the development of this chip... it is amazing the hoops he jumped through to get this chip working like it is.)
This feature combined with the other specs of this chip, makes it heads and shoulders above other chip with similar functions. Even other BB/Ti chips, including PCM 290x and PCM270x (excluding 2702 of course) series.
The Ti's datasheets made that quite clear.
Ah, forgot to introduce myself. I'm the English language support staff of KECES. My e-mail (for now) is from my day job, but if you want to ask anything that's not quite apporiate here, you are free to e-mail me directly. Otherwise, post here and I'll try to check back as often as possible.
Thanks.
Thanks.
Maniac said:
Correction, it is SpAct Clock tracking, tracks the USB clock... Ti states it like the following:
"SpAct™ (Sampling Period Adaptive Controlled Tracking) system recovers a stable, low-jitter clock for internal PLL and DAC operation from the USB interface audio data."
From Ti Product info web page. This is one feature that I wouldn't do without with USB DAC products.
Chips with it does not automatically become great DAC, but an USB DAC chip is cripped without it.fmak said:
Well, Koping is not well versed with English... so I'm here to respond questions in English... Call me Maniac or David... whichever you prefer...
With Chinese support, you need to install the proper support in your system before you can see it. Otherwise all you will see is a bunch of garbled ASCII code... You need Traditional Chinese support to be exact. Simpilified Chinese uses different encoding, and thus cannot be used to view the page.
[With Chinese support, you need to install the proper support in your system before you can see it. Otherwise all you will see is a bunch of garbled ASCII code... You need Traditional Chinese support to be exact. Simpilified Chinese uses different encoding, and thus cannot be used to view the page. [/B][/QUOTE]
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I have traditional Chinese support; in fact I am Chinese and there are no problems with other TW sites.
What to do next?
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I have traditional Chinese support; in fact I am Chinese and there are no problems with other TW sites.
What to do next?
Re: Re: Re: Try this...
So, how does one overcome this please? Otherwise it's their loss. My impression of Taiwan sites very poor, works less often than sites in other countries. And this from the dominant hardware industry.
------------------------------------------------------------------------Maniac said:
Now I remember, it is likely an Apache desinger's smart a** related problem. Where they assumed that everyone in the world uses only one encoding method...
So, how does one overcome this please? Otherwise it's their loss. My impression of Taiwan sites very poor, works less often than sites in other countries. And this from the dominant hardware industry.
Re: Re: Re: Re: Try this...
I've checked his server... It's seems to be working correctly... As it isn't using the newer Apache 2.x series that is affected with that default setting.
You might want to check the browser's setting instead... Sometimes browsers also come with braindead default settings that makes it working incorrectly in certain cases.
fmak said:
------------------------------------------------------------------------
So, how does one overcome this please? Otherwise it's their loss. My impression of Taiwan sites very poor, works less often than sites in other countries. And this from the dominant hardware industry.
I've checked his server... It's seems to be working correctly... As it isn't using the newer Apache 2.x series that is affected with that default setting.
You might want to check the browser's setting instead... Sometimes browsers also come with braindead default settings that makes it working incorrectly in certain cases.
Re: Re: Re: Re: Re: Try this...
You might want to check the browser's setting instead... Sometimes browsers also come with braindead default settings that makes it working incorrectly in certain cases. [/B][/QUOTE]
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Just did; nothing wrong to me. Reads other trad Chinese sites. May be the link is brain dead.
You might want to check the browser's setting instead... Sometimes browsers also come with braindead default settings that makes it working incorrectly in certain cases.
[/B][/QUOTE]--------------------------------------------------------------
Just did; nothing wrong to me. Reads other trad Chinese sites. May be the link is brain dead.
Maniac said:
From what i read from the datasheets each of the USB chips use SPACT clock recovery. Is it done differently in the 2702?
The way i see it though is that the 2702 is meant for more hifi apps. While the rest of the chips such as the 270x and 290x are meant for more cheap USB headphones with mics for game playing, chatting and so on. Not for your average audiophile by no means. However the power supply can be made nice and clean and i would bet on all the chips sounding pretty good with quality comaparable to the average comsumer portable CD player.
One thought to this is taking on of the chips with SPDIF output and using a SPDIF reciever such as the DIR1701 or DIR1703 then interfacing that to a DAC of your choice. With that youve got SPACT in the USB interface and IN the SPDIF reciever giving you a nice low jitter interface and a the ability to use virtually any DAC you wish. The one draw back though is the inability to support anything higher than a 48khz 16bit sample.
Another thought would be to get one of these http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=3452144533&category=31534 and use that to send the audio format of your choice to the reciever and DAC. But i would bet that sending anything other than 16 bit 44.1khz or 48khz will require some rewritting of the drivers for that unit.
sorry to rant but i hope i insprired someone
Benjlv said:
IIRC only the 270x series have SpAct feature...290x series not only have lesser spec than 2702, but don't have SpAct.
Benjlv said:
Indeed, 2704/5/6/7's spec is much lower than the original 2702. Not to mention 290x series. If I remember correctly, ALL of them were designed for inexpensive audio applications. Tho 2702's audio quality was high enough for other more demanding applications as well. (take a look at that MSRP USD $1600 USB DAC with tube output circuit)
Benjlv said:
Well, I've talked to Koping about it, and it is kind of a hard choice. Are you going to give up high quality audio? or are you going to give up SPDIF and a very simple output circuit? (2704/5/6/7's output circuit is very simple, and you can easily bolt on a powerOp for direct to speaker capability.)
I'm personally leaning toward 2702, for the higher quality of sound.
Benjlv said:
People I knew had already gotten their hand on that USB box... And they took it apart... You can see it in the link below, they even had two RMAA test report for it. However, VIA's CODEC is something that I'd avoid like plague. Simply speaking, it STINKS.
http://www.dearhoney.idv.tw/Audio/Justlink/
IMHO, you might want to check out the Spec of that USB interface chip for what it can support... I haven't and would do that in a bit... Kinda busy at office today.
personally im just going to add a SPDIF DAC after a 2706. I hope to be able to add functionallity of the track change buttons and volume buttons in my design.
as far as that expensive Tube preamp goes...well i think its neat, but i see it as more of a easily implimented novelty in that application.
something like this would have been more in order
http://www.overclockers.com.au/~mwp/dac3/
but instead a higher end DAC with perhaps tube based I/V converters if its possible.
as far as that expensive Tube preamp goes...well i think its neat, but i see it as more of a easily implimented novelty in that application.
something like this would have been more in order
http://www.overclockers.com.au/~mwp/dac3/
but instead a higher end DAC with perhaps tube based I/V converters if its possible.
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