Home > General > Interesting details of Weiss Implementation of ES9018

Interesting details of Weiss Implementation of ES9018

January 20, 2012 Leave a comment Go to comments


The photos below shows the inside of the Weiss 202DAC. Notice that there is no local oscillator, the location/pads where the oscillator should be located is empty.

(photos taken from different sites in the internet. Japanese sites have the best pics)

I would suspect that the clock is provided by the audio interface chip (DICE chip) which derives its clock from its local oscillator as shown below

According to the specification of the DICE chip, the crystal frequency shall by 24.576MHz (section  This frequency multiplied by 4 results in a frequency of 98.304MHz. According to Enjoy the Music, this frequency is what is used to “drive” the ES9018 chip.

According to Russ White [link],

The best thing to do if you desired a synchronous clock is simply to supply one that is an exact multiple of the incoming bit clock. But if you do both 44.1khz and 48khz based multiples that is going to mean two master clocks. The way to do this is to use the same master clock that is actually used to generate the bit clock (by division). I have implemented this using my XMOS proto board. It works quite well, but you still want a fairly high speed clock.

Operating like this allows the DPLL to basically free wheel. It does not even have to try to maintain a lock. 🙂

This seems to imply that sample rates may be resampled to 192K  (an even division of 24.576) and then sent to the DAC

People at diyaudio have been experimenting with synchronous clocking with great results. The other message here is that the forthcoming XMOS interface from TPA will allow this kind of synchronous clock interface which is favored by the likes of Weiss


I think the batch number means week 52 of year 2009. Notice also the location of the Buffalo II DAC and compare to the Weiss implementation.


I have been trying to access the programmable feature of the ESS DAC without any success. According to the review at Enjoy the Music,

1. About Filter A and B. These are stated to be “upsampling filters,” but no real detail is given in the manual. Are they similar to other manufacturers upsampling filters, i.e. one is for say 96kHz and the other for 192kHz Upsampling? Does this mean DAC202 cannot be set to bypass upsampling (44.1kHz native playback with oversampling only?).

Answer: The A and B filters are the ones used in the ES9018 DAC chip, i.e. the “factory presets” so to speak. In the ES9018 all input signals (independent of their sampling rate) are upsampled to about 1.5MHz. The B filter has a softer transition band than the A filter. We plan to add more filters to those two.

This leads me to think that even industry-leading edge people like ESS have not been able to use the programmable filter feature of the DAC. Weiss does say that they “plan to add more filters”, but right now it seems that feature is not available.

In any case, Stereophile published the response of the two built-in filters (left is the sharp filter)


The relays are Panasonic TN relays.

The DAC202 has four selectable coarse analog settings and provide 1.06, 2.12, 4.15, and 8.15v at the analog outputs. These are related to the gain resistors at the output stage. The relays are there to select the appropriate resistor for the desired gain. In addition, there may be relays selecting the appropriate input pins for I2S and SPDIF (although you could permanently wire and switch between I2S and 3 other SPDIF inputs just by programming the registers in the DAC chip as detailed here [link])

  1. Russ White
    January 20, 2012 at 22:48

    The programmable filter feature of the ES9018 works perfectly well, I have used several custom filters.

    You must load the filters as per the datasheet, but the filter design (matlab work) part is a bit more tricky, but by no means impossible. 🙂 There is some information you must know which I am not sure is public. At least I don’t see it in the datasheet. That is why I have not given many details.

    Cheers(And happy new year)!

    • BlogGeanDo
      January 21, 2012 at 00:59

      Hi Russ, thanks for chiming in…
      Well, it is then an undocumented feature (only available to a few lucky people like you :-))
      The only es9018 based I know that has multiple filter is the Audiolab MDAC with 7 selectable filters, but I’m not sure if they are implemented in the ESS chip. They have a minimum phase filter and that would require non-symmetric filter and the ESS DAC assumes that the filters are symmetric (This was shared with me by another diyer). In any case, I am just looking for hints as to how to program those filters and that is just for fun…

      Regarding the upcoming Xmos interface, can you send the master clocks (x4 their frequency) to the DAC? for synchronous clocking?

  2. Russ White
    January 21, 2012 at 01:13

    I am not the only one who knows how to do it because I have compared notes with at least 3 other people.

    In slow roll off you can have completely custom coeffieicnts. Can implement any coefficients in this mode. (even asymmetrical, phase warped(for those who want no “pre-ringing”) Downside is there is only 64 taps. This is a 4x oversampling filter. The first coefficient MUST be 0, the rest are up to you. 🙂

    The USB module design does allow for synchronous clocking.

    I am not sure what you mean by X4 their frequency. Synchronous only requires that the master clock be some multiple of the bit clock. That does not need to be 4 times. 🙂

    • BlogGeanDo
      January 21, 2012 at 01:26

      I think I read you are planning to use the 24.576 clock. If you multiply by 4 you get to the sweet spot that can support 352K sample rates with OSF on.

      As I said, you are one of the few lucky people :-). So how do end-users get the undocumented specifications?

  3. Russ White
    January 21, 2012 at 02:00

    We will be using faster clocks than that. 🙂

    We will be using any type of clock multiplier or PLL either.

  4. Russ White
    January 21, 2012 at 02:04

    Oops I meant to will not be using any type of clock multiplier or PLL.

  5. Bunpei
    January 21, 2012 at 11:42

    Other than oscillators by Crystech or NDK for 90 MHz range, Si590 of Silicon Laboratories is easy to order on Digi-key. Specified frequencies are available within one week because they are programmable at the timing of shipping.
    However, I am not sure whether its phase noise feature is low enough or not.

    • BlogGeanDo
      January 21, 2012 at 18:52

      Yeah, I suppose Russ will divide down the higher frequencies for the XMOS rather than use the new crystek audio frequency clocks and multiply up for the Sabre DAC. But then they are a big customer of Crystek and may be able to order custom frequencies…

  6. TaxiDriver
    January 21, 2012 at 21:55

    The measured performance of Weiss 202 is out of this world (check last month’s Stereophile).
    I wonder how a Buffalo would compare measurement-wise.

    • Russ White
      January 21, 2012 at 22:59

      Stereophile can build one of their own and find out. I Would suggest with the Legato 3,1 output stage. 🙂 I certainly do not posses their testing gear, or I would do it myself. I am just an amateur.

  7. BlogGeanDo
    January 21, 2012 at 23:46

    There are some measurements here:
    “This measure is a Textronix AM700, is worse than a Audioprecisión and may be in poor condition. But compared to other DAC is the best I’ve ever measured.”

    Not apples to apples, but the parties involved are “very happy” with the measurements 🙂

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