Nice to hear about such confirmations. As we can see, it is quite different how this trick works, as one`s particular DAC setup, used chip, and so on... In my configurations this effect appear using a few hundred pF in between DAC phases, active I/V (OPA1632), and straight to output without any other filtering.
I was a little bit sceptic to publish some snap shots of my preliminary measurements (not very detailed or accurate), because it were taken using a 1792 chip. While we are here in a thread which is about something else...
But anyway, for the subject in discussion now it will be acceptable I suppose...
So, first (double picture) shows a well working set up. I used a cap value which it just were working, but not fine tuned for the best result.
There is to be seen on 20Khz a quite special quality of the sine signal, due to the remaining HF noises on a non filtering precessing. Even though, and very surprising for my self too, the audio output is only amazing.
There is another picture which shows a very nice square HF noise out of the (amplified - RCA) 1792 DAC outputs. The setup for the I/V and final it were tuned for the best and largest bandwidth. This very nice noise is not acceptable for an audio processor, so it have to be degraded, attenuated in one way, to minimize its negative impact for the audio/sound.
The third picture shows the worse case scenario, where a capacity (between DAC`s phases), over the critical value is used in a well working analogue post DAC processing set up. Everything become very bad...The degradation of the audio signal is obvious.
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Agreed, nice to see confirmation by somebody who just did it rather than argue against it without trying.
It sure is not subtle. And you nail the description right on.
I um'd and ah'd whether to put this out there - I remember what happened when I suggested SAW oscillator for Sabre DAC (and even in this is an Oppo forum, I don't mind references to other DACs as this is a conversation that needs to be had).
I am curious where you ended up response wise @ 20KHz relative to 1KHz.
Thanks again.
Cheers, Joe
PS: I don't claim to be a digital engineer, I am basically an analogue guy with a loudspeaker and amplifier background, and when I need to, I ask Terry questions. It is not that I am dumb when it comes to these matters, but I defer to those who are better qualified. I am very keen to get answers to what we have here, the mechanism at work - but the analogue in me says this is a noise issue.
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Straightforward NOS
Tom,
Assuming that I correctly understand how your DAC is configured, I suggest that you begin your experiment with a single 3.3nF standard value cap. (per channel) placed directly across the balanced AD1865 outputs. That value should produce about -0.5dB @ 20KHz, which is the point where I first begin to detect the effect. Use 10nF caps. to try the -1.3dB @ 20KHz response that Joe recommends, at which point the effect should clearly be audible.
However, I wouldn't be surprised if you do not obtain the effect through your NOS DAC. I currently suspect that the effect depends on a digital filter. In other words, the technique may enable digital filter based DACs to gain much of the sound quality of NOS DACs. Which might explain why the effect takes place via sigma-delta audio DACs, all of which feature integrated digital filters. However, this certainly could be an incorrect hypothesis on my part, so, definitely do tell us what you discover via your NOS DAC.
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Thanks Ken - so solder a single 3.3nF capacitor from pin 2 to pin 3 on each of the xlr outputs, leaving pin 1 untouched?
What type of capacitor is suitable?
Joe,
While the threshold point at which I can first detect the effect seems to be about -0.5dB @ 20KHz, I'm still experimenting and not at all settled that it's optimum. In fact, your recommendation of -1.3dB does seem to produce a better subjective overall effect than does -0.5dB, however, I'm not sure I'm satisfied with the treble balance just yet. I need to listen to more violin and brass recordings to better assess whether I'm noticeably missing musically accurate treble, or simply free of digital glare and brightness.
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Yes, assuming that those pins are wired directly to the AD1865's current output pin and it's respective 75 ohm I/V resistor. Merely tack solder the filter caps. in place so to make it easier to swap them out as you try different values. For experimentation purposes, you can likely get away with simply mechanically clamping them in place using only contact pressure.
The caps. I'm using for my experiments are Wima FKP-2 (film and foil) units. These are transparent sounding, at least to my ears, and inexpensive in these small values. I bought units for around 50 cents each through Mouser.com here in the U.S.
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<<< New Oppo BDP-105D >>>
Once in a while it cannot hurt.
1. The new Oppo BDP-105D now uses the new Darbee Visual Presence Darblet Video Enhancer (HDMI-1 output).
2. And the new digital USB Asynchronous DAC input now supports DSD128 or DSD 2x.
- I thought that some members here would be interested to know this latest and freshest news from just couple days ago or so.
Once in a while it cannot hurt.
1. The new Oppo BDP-105D now uses the new Darbee Visual Presence Darblet Video Enhancer (HDMI-1 output).
2. And the new digital USB Asynchronous DAC input now supports DSD128 or DSD 2x.
- I thought that some members here would be interested to know this latest and freshest news from just couple days ago or so.
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Once in a while it cannot hurt.
1. The new Oppo BDP-105D now uses the new Darbee Visual Presence Darblet Video Enhancer.
2. And the new digital USB input supports DSD128 - X2 DSD.
Ahah, they had indicated earlier that DSDX2 would come out with a "new" model. There is, as far as I can tell, no reason why a firmware upgrade to 103/105 would not do the same, right?
Cheers, Joe R
PS: These 'local contrast enhancement" algorithms has been available for still (digital) photography for some time. This is a "post-processing" chip in a similar manner, maybe does it frame by frame on the fly or looks for differences and processes that for speed? But not really new technology, just a newer application. I am surmising.
On a frame by frame basis, yes. ...And not everywhere on the picture but only "a certains endroits". ...Most needed?
It's kind of a sharpness/contrast control enhancer in one.
* Firmware upgrade to enable DSD 2x (DSD128) from the 103 and 105? ...Why? ...When they can make more money from people selling them older players and upgrading to the newer ones, like the 105D ($1,299).
It's kind of a sharpness/contrast control enhancer in one.
* Firmware upgrade to enable DSD 2x (DSD128) from the 103 and 105? ...Why? ...When they can make more money from people selling them older players and upgrading to the newer ones, like the 105D ($1,299).
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Do we as yet have a name for this effect?
Given Joe and Ken are the proponents of a newly discovered audio phenomen, shall we coin it the "Joeken Effect". If anyone doesn't believe us, they have their joke already lined up
Do we as yet have a name for this effect?
Given Joe and Ken are the proponents of a newly discovered audio phenomen, shall we coin it the "Joeken Effect". If anyone doesn't believe us, they have their joke already lined up
Tom, thanks, but no. Joe deserves all the credit for publishing this observation. I suggest naming it the 'Rasmussen Effect'.
I can confirm that Joe was the first one who refer it to this "behaviour/effect" in a earlier PM to me. So he deserve well the honour. Else one may look back in the thread to see the Joe`s posts about this. Ken was in the last, the third one who confirmed publicly the results of implementing this kind of filtering...
But Rasmunssen Effect it may be a too long name... It take too much time to write it down.
JR Effect it may be a better choice in my opinion...
But Rasmunssen Effect it may be a too long name... It take too much time to write it down.
JR Effect it may be a better choice in my opinion...
I fully agree also with Joe about the few/small improvements in the "new" BP105D device.
As one who have experimented quite a lot with these last two players models, I may say that I wonder very much about why Oppo have chosen to invest more to implement a video Darbee system in its players. Darbee is an improvement for picture, but it happen altering the original video signal by extra (software) processing, rendering and filtering. Really unnecessary in case of Oppo players!. These machines have already a good video processor in QDEO chip. What for extra filtering and improvement in the video stage?
Big improvements in video (as audio stage) it come only from few simple (low cost) improvements in the clock system (and/or power system) of the player, as using a higher quality oscillators. Such small improvements (for the clock system) may even cause a lowering of the total production costs for this player model, and leads to quite dramatic improvements for both picture and sound.
Using an extra processor chips, pay licenses to Darbee, and increasing the computing power in the machine with side effects (heat generating and more power needed), are in my opinion unreasonable measures.
As I have said many times before, Oppo`s player concept it may be a real breakthrough in the marked, for even lower production costs, if some small reasonable design measures it should be taken when about some details...
But anyway, what the modders are then for, if the things it should be made very right from the very beginning?
I think that more exciting (for us as audio people) it may be the new coming and a really new Oppo product: Headphone Amplifier, with included asynchronous ES9018 USB DAC in stereo set up. Quite sure we will have to mod something there too...
As one who have experimented quite a lot with these last two players models, I may say that I wonder very much about why Oppo have chosen to invest more to implement a video Darbee system in its players. Darbee is an improvement for picture, but it happen altering the original video signal by extra (software) processing, rendering and filtering. Really unnecessary in case of Oppo players!. These machines have already a good video processor in QDEO chip. What for extra filtering and improvement in the video stage?
Big improvements in video (as audio stage) it come only from few simple (low cost) improvements in the clock system (and/or power system) of the player, as using a higher quality oscillators. Such small improvements (for the clock system) may even cause a lowering of the total production costs for this player model, and leads to quite dramatic improvements for both picture and sound.
Using an extra processor chips, pay licenses to Darbee, and increasing the computing power in the machine with side effects (heat generating and more power needed), are in my opinion unreasonable measures.
As I have said many times before, Oppo`s player concept it may be a real breakthrough in the marked, for even lower production costs, if some small reasonable design measures it should be taken when about some details...
But anyway, what the modders are then for, if the things it should be made very right from the very beginning?
I think that more exciting (for us as audio people) it may be the new coming and a really new Oppo product: Headphone Amplifier, with included asynchronous ES9018 USB DAC in stereo set up. Quite sure we will have to mod something there too...
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My true questions for you gentlemen of this thread:
Can the original Oppo BDP-105 be modified better than the 105 ModWright one (best top grade tubes and separate power supply - PS 9.1)?
...Roughly four grands all together.
And question two: How the 105 top Modwright version compares to the Trinity DAC?
...Or the dCS Da Vinci digital five-box system? ...Or is it four? ... dCS Scarlatti is.
ESS DAC, or Ring DAC (custom)?
Can the original Oppo BDP-105 be modified better than the 105 ModWright one (best top grade tubes and separate power supply - PS 9.1)?
...Roughly four grands all together.
And question two: How the 105 top Modwright version compares to the Trinity DAC?
...Or the dCS Da Vinci digital five-box system? ...Or is it four? ... dCS Scarlatti is.
ESS DAC, or Ring DAC (custom)?
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...Sound wise (measurably, and auditory). But! How many members here at diyAudio had the unique opportunity to do so?