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Old 18th June 2017, 04:34 AM   #61
sumotan is online now sumotan  Indonesia
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Technically speaking lowering esr & noise might be the way to go
with cap banks but I never found them to sound better then normal
caps approach if properly set up. Think the better way is to pre filter
the AC prior to main caps. Anyway lets leave that for another thread

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Old 19th June 2017, 07:38 AM   #62
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Quote:
Originally Posted by canvas View Post
According to someone, the Denafrips is a 31 seg. 5bit string + 11bit R2R design. However, it has considerable glitches. On low level signal, the glitches could be as high as 10mv.

Click the image to open in full size.

Here is the measurement about multibit monolithic LTC2642 on my board.
This is -60dBFS signal(0dBFS=2Vrms).Bandwidth is probably 10MHz because of 25MS/sample.You can see 2mV glitch when the signal across 6bits boundary.Maximum glitch of LTC2642 doesn't occur at the point between 0x7fff and 0x8000. It occurs every 6bits boundary.
tek00202.png

tek00181.png
Glitch is 0.216*2.26,almost 0.2nVsec.This has 20kHz LPF.Datasheet say 0.5nVsec,probably without LPF.
tek00182.png

If you decrease the bandwidth as low as 100kHz like this.Glitches will almost fade away.
tek00197.png
Another multibit pcm1704 is glitchless as long as I have tested.It is the most surprising thing for me about pcm1704.
tek00203.png
I think analog waveform is something subjective.What you can get from somewhat depends on your experience.But audio application is subjective issue, personal like and dislike.So,I like to use analog waveform.

By the way,It's better to use FFT objectively.
Here is the plot of without glitch of LTC2642. If you decrease the magnitude of signal by 2dB ,you can get glitch free condition.Because glich occurs every 6bit boundary.Below -60dbFS with some offset(0x1f) is glitch free area.
glitch1.jpg

This is the FFT of the first picture which has glitch.
glitch3.jpg
The difference between them comes from the difference of magnitude.THD of multibit mainly depends on the magnitude of signal.I think glitch has no influence below 40kHz region,which is already shown from analog waveform.
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Old 19th June 2017, 09:10 AM   #63
canvas is offline canvas  Taiwan
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Quote:
Originally Posted by xx3stksm View Post
Here is the measurement about multibit monolithic LTC2642 on my board.
Thanks for sharing your findings. The PCM1704 is advertised as 'glitch-free', so that's got to count for something. Did you try adding a ferrite bead after the output? I think they will help for certain degree.

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Old 19th June 2017, 10:40 AM   #64
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Quote:
Originally Posted by sumotan View Post
Technically speaking lowering esr & noise might be the way to go
with cap banks but I never found them to sound better then normal
caps approach if properly set up. Think the better way is to pre filter
the AC prior to main caps. Anyway lets leave that for another thread

Cheers
I agree with you from my experience.Though I have already retired,I use to run a small electric manufacture for video appliance. Video systems have much frequency range than audio.Noise from power is more critical.

When I had noise related troubles,the final choice was an additional capacitor as close as power pin. 150 microF OScon.This is the end.Another additional caps are not effective. Available space is also limited. One cap is totally adequate enough.

DIYers have time,space and money for their achievement.I think there is difference in degrees of enthusiasm.Mine is not so hot from my history.But I love to see them.
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Old 19th June 2017, 10:51 AM   #65
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Quote:
Originally Posted by canvas View Post
Thanks for sharing your findings. The PCM1704 is advertised as 'glitch-free', so that's got to count for something. Did you try adding a ferrite bead after the output? I think they will help for certain degree.

Poting
I don't have experience of adding ferrite bead. There are many characteristic beads.Some have impact on audio frequency range.Of cource,you can select suitable one for your application.

USB powered DAC sometimrs need ferrite.But as long as you carefully design the circuit,you usually don't need ferrite IMHO.
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Old 19th June 2017, 10:59 AM   #66
sumotan is online now sumotan  Indonesia
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Hi xx3
Meddle with some beads before results aren't
favorable for me. Yes it may sound quieter but
in terms of SQ it adds a constrain dark sound
which makes the music sound lifeless. As for your
comment of bypass at the pin, I prefer to use a 0.47 uf value instead but no oscons on analog
related location

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Old 20th June 2017, 02:02 PM   #67
canvas is offline canvas  Taiwan
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Well, I only place the beads after the I-out of a DAC. For voltage signal, I agree that it may not be a good idea.

R2R DAC has been researched decades ago. The engineers of AD & BB put a lot of effort into its design. It's not easy to beat their product unless we also know how to overcome these problems.
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Last edited by canvas; 20th June 2017 at 02:04 PM.
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Old 21st June 2017, 05:11 AM   #68
sumotan is online now sumotan  Indonesia
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Yes Canvas I agree. I use to think that the Ultra Analog dac was the best of the breed but after fiddling with Nos Tda 1541dac especially with
Pedja's AYA ll DS my thoughts have change somewhat. Seems like today's R2R even in discrete
form is missing something. Makes me think that
the Guru's of yesteryear knew things that the new
generation of designers don't or have overlooked

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Old 21st June 2017, 05:21 AM   #69
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I agree too canvas, the present-day implementers of R2R aren't as experienced DAC designers as those multibit engineers at Philips or BB or ADI.

When the designer of TotalDac was active on DIYA I asked him what the advantage was in going to a discrete R2R. I don't recall him giving me an answer. As far as I can see the advantage primarily is in marketing (discrete carries more kudos than IC) and also in not using no-longer-in-production chips.
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Old 21st June 2017, 05:52 AM   #70
sumotan is online now sumotan  Indonesia
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If I may Im gonna go off track a little. Lets forget high res
for a moment & just look at Red Book playback.
I dare say that a properly set up Cs 4328 dac will kill
any chips that being produce now. This lovely dac has
long been forgotten due to marketing hype.
For R2R TDA 1541 is really hard to beat

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