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Did Redbook get it right?

I've always felt a tension between the narrative that a) the Redbook spec murdered music, probably in cahoots with greedy plastic vendors, and b) the great respect I've had for engineers I have worked with. I would think they knew what they were doing, considering the stakes and the state of their art at the time.

I leaned towards the murder/greed scenario, especially as my original Sony 520-ES CD player presented a fleshless corpse of Joni's Blue album, and the few high-end players of the time I tried, like the Enlightened Audio, seemed to fail at resurrection.

I've reconsidered. If I rip my CD's to FLAC, feed a Benchmark DAC over USB, and into my tube amplification, I am stunned by how good and satisfying many CD's sound. I have no desire to fire the Linn Sondek back up. I have no sense of things missing. Sure, there are many crap CD's, but is any of that stink coming from Redbook spec? Some newer CD's simply stun. I not into country, but something like the Mavericks' In Time CD is acoustically complete and fully fleshed.

I've been over to HDTracks and Acoustic Sounds to download hi-rez versions, and I can feel the pull to feed my rig the best I can buy. It's such a good story, easily embraced by the audiophile mind, but I'm increasingly wondering if it is all marketing razzle-dazzle...more, denser, higher...and in the end, Redbook got it right, and the new DACs finally do it justice.

Always with an open mind, and there's much better gear than mine, but I'm newly impressed by the original Spec.
electroslacker
georgehifi's avatar
georgehifi
10,312 posts
 

Correct, I/V stages going back in the days of R2R Ladder Multibit dacs, were opamps with negative feedback, no matter how good the opamp was, the negative feedback couldn't handle the very high frequency glitches noise and other rubbish that came out of them.

Today we now know to use active I/V stages that don't use feedback, and they then can make these old R2R Multibit dacs really come to life.

Passive I/V resistors for R2R Multibit are ok, but they kill the output too much, so the next stage has be amplified too much to get anywhere near 2v, trouble is that the noise and crap gets boosted along with it and you end up with it on the output.

The best Multibit dac with good I/V stage I've heard is the PCM1704 followed by the PCM1702 then the TDA1541

Cheers George
clio09
3,362 posts
 
George, what DACs that you know of use multibit chips and no negative feedback, old or new. I have two digital sources right now that use PCM 1704 but not sure whether or not they use negative feedback.

I too like the TDA 1541 and also the PCM-63PK.
georgehifi's avatar
georgehifi
10,312 posts
 
Hi Clio, I use a Cary 303/200 which has the 24bit R2R Ladder PCM1704K chips, and it also has the PMD-200 HDCD filter as well as (switchable) copy of the DF1704 in DSP form.

It also used OPA627 I/V which had feedback, but I completely gutted the I/V, filtering, buffer and XLR opamps.
And now I use the I/V stage that I started a thread for over here (linked). It was also used earlier but I believe not fully exploited and slightly differently by Peja Rojic of Audial and Charles Hansen of Ayre. I also implemented a golden oldie for the output buffer, a BUF03 pure class A zero feedback unity gain stage.
The whole setup is now dc coupled and feedback free from the PCM1704 dac's outputs to the output rca's of the cdp.

http://www.diyaudio.com/forums/digital-source/227677-using-ad844-i-v.html

Cheers George
chayro
3,016 posts
 
It's right if you get a good recording. I don't listen to much digital anymore, but this morning I was listening to MA Recordings Bach Cello Suites on my EAR Acute CD player and I was shaking my head on how good it sounded.
geoffkait's avatar
geoffkait
23,365 posts
 
Listen to a CD. Then listen to the same piece on cassette. Case closed.
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