PCM1792 and DSD1792 with 132dB SNR

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#8
I'm all for higher voltage rails. If we get 9VRMS voltage outputs from the DAC, we have a much easier job of post-DAC filtering and line driving.

If it's 15V rails we can also use some canned superregulator circuits.
 
#10
1792 DAC

My sense is that this DAC is just an updated PCM 1738. I bet it will run on plus 3 and plus 5 volts and do current out. Also the references to voltage out are after the I-V converter. They are probalbly stating that if you raise the output voltage, you get better dynamic range. We shall see. I will be calling them Monday and will let everyone know what they say. I hope it is a direct replacement for the 1738 because you could just swap them and get (hopefully) better sound.

Ric Schultz
 
#11
PCM 1792

Just got the preliminary data sheet on the PCM 1792 from TI. It is not pin compatable with the PCM 1738. It is however, like I thought. It runs on 3 volts digital, 5 volts analog and has balanced current outs (all like the 1738). However, it outputs much more current, has separate power supply feeds for both left and right analog supplies, has a better digital filter and 10 db better dynamic range. I cannot even get a sample yet. Looks like at least 3-6 months before products hit the streets with this chip. It looks like a killer DAC chip.
 
#13
Re: PCM 1792

Ric Schultz said:
Just got the preliminary data sheet on the PCM 1792 from TI. It is not pin compatable with the PCM 1738. It is however, like I thought. It runs on 3 volts digital, 5 volts analog and has balanced current outs (all like the 1738). However, it outputs much more current, has separate power supply feeds for both left and right analog supplies, has a better digital filter and 10 db better dynamic range. I cannot even get a sample yet. Looks like at least 3-6 months before products hit the streets with this chip. It looks like a killer DAC chip.
Click to expand...

Hi Ric,

Thanks for info, saw it myself from Stereophile
link. Yes looks very good. Just when you thought
123dB was good from AD1955 then wambo, another
9dB. That's not a small amount although THD at 0dB FS
is still pretty much same. Can we even hear this
improvement...

Did they say what specifically is better about DF?
This is an area I think the manufacturers
need to look at after listening to 0xOS.

How much current does it OP?

Regards,

Terry
 
#14
PCM 1792

Terry,
Stop band attenuation now 130db whereas the PCM1738 was 85. Ripple noise substantially less as well.

8 ma current out. Just like Analog Devices 1955.

I agree about non-oversampling systems. Cannot wait for pure multi-bit non oversampling ADCs and DACs running at 24/192 with no or little analog filtering.

It will come, you bet. The tweakers never stop!

Ric Schultz
 
#15
Interesting, but isnt this advanced segment dac like 1738, isnt sign magnitude better?
Did they discontinued to use sign magnitude technology? Why?
Click to expand...
Don't count on it. I had a meeting with TI apps engineers today, and I get the sense they are still developing the R2R DAC series. Why would they stop? This is their flagship lineup, favoured by the high-end market which wants to differentiate itself from lower cost consumer products. TI is probably the only player left in the R2R DAC game (ok, except possibly for the dCs ring DACs, but they're not quite the same thing). My $10 says PCM1706 (or whatever they call the successor to PCM1704) will appear on the market in the near future... maybe as early as CES, but hopefully by Q3/03. Apparently, they have some very good ADCs in the works which will be quite nice to see. I'll be watching closely to see what they display at CES.

TI has by now hired away many of the DAC engineers from Crystal. I think this is a major reason we are now seeing very good sigma-delta chips coming from the TI/BB group, although CS and AKM both still have some very good products.
 
#16
skaara said:
Interesting, but isnt this advanced segment dac like 1738, isnt sign magnitude better?
Did they discontinued to use sign magnitude technology? Why?
Click to expand...

R2R ladder DACs are very expensive to make compared to
sigma delta and advanced segment (1738).
They also appeared to hit a wall WRT measured performance
of R2R with DR112dB and THD 102dB (1704) being greatly surpassed now by others.

I would be surprised if we ever see another R2R DAC from
Ti.

Terry
 
#17
hifiZen said:
Don't count on it. I had a meeting with TI apps engineers today, and I get the sense they are still developing the R2R DAC series. Why would they stop?
Click to expand...

Cost mainly and measured performance. I'm not sure
how big a niche audiophile market is for ladder DACs
but it seems pretty small compared to the millions of
DVD players that are sold. However it would be nice if
you were right.



Apparently, they have some very good ADCs in the works which will be quite nice to see. I'll be watching closely to see what they display at CES.
Click to expand...

Good news. It seemed like AKM were the only ones pushing
envelope. Nice to see some competition in hi end ADC land.



TI has by now hired away many of the DAC engineers from Crystal. I think this is a major reason we are now seeing very good sigma-delta chips coming from the TI/BB group, although CS and AKM both still have some very good products.
Click to expand...

That makes sense. Crystal seemed to hit a wall of development
(or cost) after they did all the 120dB ADC's.

Terry
 
#19
Well, granted that R2R is expensive technology. I think it's mainly a prestige thing. TI has been known for occasionally producing some over-the-top products which ultimately prove to be too expensive for the market. They seem to enjoy demonstrating their engineering prowess by releasing something every now and then which totally beats the pants off everything else in the market. Marketing strategy I guess. (?)

Anyway, I'll put my money where my mouth is - I don't think we've seen the last of the R2R DACs just yet...
 
#20
They seem to enjoy demonstrating their engineering prowess by releasing something eve

HA HA HA HA HA HA. TI? Stop your hurting me! I guess nobody learned thie lesson with the distortion race in amps where many really bad sounding amps had the best distortion numbers.
Deja Vu all over again ...............
 
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