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Old 14th September 2008, 04:27 PM   #1001
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Quote:
Originally posted by fmak


Actually regardless of the SW4 setting, the lock light flickers on sometimes and produces a series of pops.

I've got something similar. I use a PC for a source. When set to 96KHz, the lock light goes out, though it sometimes flickers. However when I actually play a file at 96KHz, it locks properly and plays as it should. Then the track finishes and lock disappears a gain ... weird.

Not a big problem, and needs futher investigation, but I thought I'd mention it in case it helps shed some light on things.
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Old 14th September 2008, 05:24 PM   #1002
matejS is offline matejS  Slovenia
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Standard oscillator, FPGA... it I2S locks on whatever I've tried.
For SPDIF I tried 44k1, 48k, 96kHz it worked flawlessly.
However, when I was playing with FPGA/I2S (trying weird stuff) I managed to get DAC "stuck" on non-zero value (non 1.6V). So be caucus when playing with FPGA/I2S not to blow speakers (if having DC-coupled system w/o protection)!

Cheers,
Matej
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Old 14th September 2008, 05:43 PM   #1003
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Cheers Matej, and thanks for describing you I/V experiences earlier.
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Old 15th September 2008, 07:34 AM   #1004
DUC985 is offline DUC985  Germany
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Default D1 as I/V ?

since i was lucky and will receive the DAC hopefully soon. I would like to ask if somebody has tried the DAC with an D1 stage as I/V ?
Or if they would be any theoratical concerns using the D1 with the DAC.

And a second questions or confirmation. I also have a Denon 1920 which should be used as source.

For PCM i would use PIN :

PLRCK (51) - Left/Right clock
PBCK (50) - Bit Clock
PDATA1 (46) - PCM DATA

For DSD i would connect it through the vias at DBK,DSD1,DSD2
outlined by Russ.

Has anybody modified the power supply of the Denon already ? I'm still searching for a schematic of this player.

thx
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Old 15th September 2008, 09:05 AM   #1005
Yunick is offline Yunick  Sweden
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I will try the D1 as soon as Zei's PCB's arrive. I have the buffalo from the last sale, but haven't tried it yet .. There will be sometime before I can post results thou..

The source will be sqeezebox.,

Edit; spelling...
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Old 24th September 2008, 06:52 PM   #1006
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Default Sabre Sonics (lawng post)

The story so far: Have been listening to and modding the Sabre/Buffalo, and am now concluding that the Sabre passes what I call the chameleon test: every time I think it has a character, I find it was something else in the chain or something with the implementation of it. It is the first delta-sigma (or sigma-delta) DAC I have warmed up to.

The reference systems include: Yamaha C5 Concert Grand Piano. Denon PMAS1, Lavardin IS Ref, and custom Triode amps. Fried M7 and Newform ribbon speakers, Stax headphones. Heavily modded Sonic Frontiers T3/P3 and custom PCM63 DACs as digital sources. Decent cables, clean AC, carbon fibre shelving.

The Sabre chip is very context sensitive, ie power supplies need to be clean and quiet, and although it has excellent jitter rejection, one can still hear changes upstream, and the jitter rejection improves with better power supplies. Less interaction between sections. Reason #44100 why spdif is still evil. Each improvement supports the others, but one alone might not be enough, ie one might not hear diferent clocks if the analog supply is derived from the digital one, but it is clearly audible in tandem.

In stock form, the Buffalo has potential: good prat, solid L/R imaging, but horrible rendition of space, and an irritating digital character: initially sounds clean, but quickly becomes fatigueing(sp?). Tipped up tonal balance, threadbare rather than neutral, not warm, liquid, rich. A decent implementation, but suffering from the classic pitfalls of digital: no involvement, needs garlic. Slightly smoother, better with the soft filter setting. Frankly, it would be a waste of time to be concerned with the pros and cons of various I/V schemes for current output mode when the basic foundation of clean power and clock is not in place. Voltage out through good iron is quite sufficient. Good iron being key here. I will repeat the gentle suggestion for a B2 (the riboflavin?) with maybe $30 extra in regs/caps.

For those who are impressed with the sonics of the demo board or the Buffalo, you ain't heard nuttin yet. For those doing their own layouts, do indeed pay close attention to clean power. Gordon at Wavelength is spot on with 8 something discrete regulators. For the rest of us, integrated solutions are still quite good, and easily within reach.

Buffalo specifics: The analog power being derived from the digital supply, while not jar-jar bad, needs to go. The 1.2V core supply reg hanging off the 3.3V digital supply reg is a no-no. The clock needs it's own reg, not just hanging off the digital supply. The spdif comparitor hanging off the digital supply needs to be ****canned. Use i2s input mode, with something off board to process spdif.

Two LT1963A 3.3 EST for 3.3V digital and clock. Different pinout from the 1117 series regs. 470uF to 1500uF bypass caps. Big bypass caps at the reg, small 1uF at the chip. The Crystek clock module is sufficient, but needs a separate reg. Separate 3.3 or 5 volt pre-reg for the 1.2 volt core reg. An LT1027 ref through a 5k/10k r/2r divider with 470uF cap at inputs of the opamps to get 3.33 volts for analog. The National LM4562 opamp buffers are decent, just need clean/quiet source, like the LT1027, and larger bypass at the outputs to keep impedance from spiking. 1500uF low ESR bypass caps work well. The LT1027 has a noise reduction pin, use it. A 27uF low esr low leakage cap works there. A single supply of 7.5V is sufficient feeding this arangement, an LT1431 with an LT1086 or LT317 *inside* the loop, with a 2r/r divider to give 7.5 V. Big bypass cap, of course.

Voltage out: Lundahl LL1676 amorphous core 2+2:1+1 with the two "2" windings in parallel across the diff analog outs of Sabre. A 4700pF cap also across the diff outs for more out of band filtering. The "1" windings can be series for balanced/single out, or parallel for single out. This gives an output impedance of a bit under 400 ohms balanced, and a bit under 100 ohms single ended, while letting the chip and tranny rip. The Sabre has vanishingly low residual offset, so the trannies can be DC coupled. Obviously, one gets quite good common mode rejection going the transformer route. Also, no extra bipolar power supplies needed, car audio...? The Sabre has apparently got quite good thermal matching through good (internal) layout, and the geometry of the devices likely has time constants short enough for sufficiently fast settling. If feeding a high impedance, low sensitivity amp, like one with glowing triodes, flip the trannies and go 1:2 for lots of voltage out with a still quite manageble 1600 ohm output Z.

More specifics: The wierd muckup of the bass with the Wolfson spdif appears to be a poor "match" of time constants between the Wolf dpll and the Sabre hyperstream jitter reduction. I suspect that the Wolf is curve fitting along the envelope to give nice wide eye patterns and low measured jitter at high frequencies at the expense of wobble at low frequencies. Reason # 44101 why spdif is still evil. The the caucasian filter: lacklustre pacing, can't dance. I hear this quite clearly comparing live to recorded Piano. It would be easy to miss if the reference was not live: a lot of recordings have this characteristic. I remember a chuckle from an audio show back in the nineties: high end A/V display played a video clip from the Eagles. First note, about half of the front row, myself included, stood up and left. At a hotel in California, we did not want to hear Hotel California. Anyhow, I alleviated the Wolf by removing the low freq rolloff at the spdif input with a differentiator feeding a pair of window comparitors feeding a S/R ff DC coupled to the spdif in. Not a purist approach for 75ohm matching, not a commercially viable solution, but it works for DIY. No schematic, as I did it on the fly. I am building a CS8416 spdif to i2s board, we shall see. With an ultrasonic jitter corner, the phase noise of the source will be dominant, and maybe we can let the Sabre's excellent jitter rejection shine.

Recap in honor of Mercury Retrograde: LT1963A for 3.3 volt regs, LT1027 5V ref padded to 3.3 for analog. Separate clock reg. Separate pre-reg for the 1.2V core reg. Phat bypass caps. Looped LT1431/LT1086 reg feeding the card. Lundahl LL1676 amorphous core parallel primaries, with 4700pF cap across them. Still evolving, looks like a Frankenstein with all the added parts...but day and night sonics so far. Layout when it settles sufficiently.
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Old 24th September 2008, 09:23 PM   #1007
rossl is offline rossl  United States
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Default Re: Sabre Sonics (lawng post)

Quote:
Originally posted by wildmonkeysects
The story so far: Have been listening to and modding the Sabre/Buffalo,

...

Two LT1963A 3.3 EST for 3.3V digital and clock. Different pinout from the 1117 series regs. 470uF to 1500uF bypass caps. Big bypass caps at the reg, small 1uF at the chip.
...


Thanks for the comments.

I am wondering how much improvment you see by giving the Sabre it's own quiet 3V3 digital supply, versus sharing the 3V3 digital with a few other digital logic ICs.

I thought the 3V3 digital was just for logic level interface of digital signals.

Other than that, I have somewhat implemented a lot of the other improvments you mention, but not exactly as you have done. Hundreds of caps on my PCB.
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Old 25th September 2008, 04:39 PM   #1008
TBM is offline TBM  Norway
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Default Re: Sabre Sonics (lawng post)

Quote:
Originally posted by wildmonkeysects
The story so far: Have been listening to and modding the Sabre/Buffalo, and............
Great to learn from your experiences.

Cheers,
Tom
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Old 26th September 2008, 02:12 AM   #1009
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Default Corrections I should of made a while ago

A few weeks back I posted a statement I wish to correct. I said the "Samsung was the first to have Sabre into production" While this is true for the ES9006 psrt (the 9008 little brother) I would like to point out that Twisted Pear's Buffalo, is really the first to have the 9008 in production. Just wanted to clear the air.

Thanks

Dustin


BTW, I love reading all the stuff about this chip. I hope to hear of things that could have been done better since I want to keep learning. I like the moments when I go "Damn, why didn't I think of that"
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Old 26th September 2008, 11:24 AM   #1010
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HI Russ

If I remember well there is 4 dac in ESS ,there is a idea to use as digital xover ?
ie 3 dac for up and one for bass ,is possible to implement in local sofware or add on pcb ??

if are viable solution can solve a lot problem in diyaudio......

thanks
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