Home > DIY HiFi > How Good is ES9018 in Voltage Mode? (Part II)

How Good is ES9018 in Voltage Mode? (Part II)

Another data point (by Andrea Ciuffoli and QuangHao) showing that voltage mode output of the Sabre DAC is quite good [link]

This evening I have tested the following configurations with a my friend with lot of experience on audio reproduction and recording.

  1. Actual op-amp module (balanced with passive IV 10ohm)
  2. Satri design (balanced not suggested because it does not work good on balanced circuit)
  3. Raleigh Audio Line Stage clone with K & K Audio Basic CCS modules (balanced current mode with passive IV 10ohm)
  4. Un-balanced direct connection in voltage mode with only 2.2uF Z-Cap capacitor (0.1uF bypass MKP1837 as option)
  5. Lundahl LL1684 (balanced in voltage mode with OS-CON)

The last is the best.

(Transformer 1:1 configuration with center 10K // 2.2 – 22uF Sanyo OS-CON as described in the old Glass Audio article of Stefano Perugini: http://digilander.libero.it/paeng/a_24_bit_dac_full_article.htm)


Perhaps using the Lundahl transformer to convert balanced to single ended beats the unbalanced v-out mode (#4 and #5 above) because the balanced to unbalanced conversion gives you twice the voltage swing.

Seems that straight balanced output should be the same or even better than unbalanced output through a transformer because in the first case there is nothing in the signal path that can color the signal. I use the DAC in balanced voltage-out mode since my amp (UCD180HG) has balanced inputs.

Same author makes this claim in his blog [link]


It is possible to use the voltage output and after some listening tests with my friends I consider this configuration as the best.

In this case the output stage can be a transformer.

The last firmware allow to get an un-balanced signal output but you get only 1Vrms at 0dB.

You can read the previous post on this subject here: [link]

Both of my operating ES9018 DACs are used in voltage mode differential outputs to UCD180HG amp modules (connected with Cat5E patch cables)





To my knowledge, QuangHao and Andrea are the first “manufacturers” that have given a serious look at voltage mode output. As people start receiving their DAC, some are starting to compare V-out vs I-out modes. Here is one that praises the sonics of the V-out mode: [link]

FYI – I finally assembled my unit this weekend, and I must say that anyone who has not tried running the op-amps modules in voltage mode is doing themselves a rather large disservice. It seems to sound much livelier in voltage mode to me.

The Bass is the best that I have ever heard on my system. The soundstage is very large. Both Voltage and Current modes sound great. But I find that in voltage mode, the sound is just subjectively more “alive” sounding. I haven’t performed any measurements yet, so I don’t know if this is simply the result of possibly preferring higher distortion by running in voltage mode or not.

I just find that there is more of an emotional connection to the music in voltage mode using my op-amp modules. Plus there is amazing impact on transients such as bass drum.

Another V-out report [link]


I haven’t tried the opamp output stages yet but the LL1684 sounds so good that I wonder if I ever will get to it
Especially with high resolution recordings it’s remarkable, it’s the first DAC that I hear pianos playing like real pianos.

I use Foobar configured as here.

The Smashing Pumpkins have a reissue of “Mellon Collie And The Infinite Sadness” that’s available in 24bit/96kHz and some songs are very good



According to Dustin Forman, the designer of the ES9018 DAC,

… The current mode is simply when the current going in and out the pin of the chip is being sensed. This mode has the benefit of cancelling 2nd and 3rd harmonics of some of the internal analog circuitry.

The “voltage mode” is when the pin of the chip has a voltage that is being sensed. While this has the 2nd and 3rd harmonics (at the -100dB level or so), some people have even claimed this mode is more “tube-like”. It is all personal preference. [link]

Is it really just “personal preference”?


The only concern with voltage out is the filtering of high frequency noise. This can be mitigated in several ways:

Passive filtering First order RC filter

This is what I’ve been using. The attenuation is “minimal” but I cannot detect whether the high frequency noise causes a problem or not (since I have no other filter to compare). However, according to TI [link], using a fist order RC filter is a feasible solution for removing out of band noise and actual measurements comparing a second order low pass vs a passive RC low pass shows no degradation in performance.



Passive Filtering High order LC filter

Abraxalito has been sharing a lot of work on high order passive filtering for DACs. You can check his blog here [link], and here is an example of a balanced mode 7th order LC filter


I have not have a chance to build/try one of these filters…

DAC settings to reduce HF noise

High frequency noise can be reduced by adjusting the quantizer setting in the DAC. According to ESS [785],

The HF noise coming out of the DAC in 6bit mode is noticeably more than it is in 9 bit mode. DAC output seems to require less filtering. Running the analog section with a less aggressive filter has some nice benefits (better slew rate etc) to the final audio

In addition, a higher value quantizer setting seems to give better sonics [link]

Sonic difference, 9-bit vs 8-bit true differential (only register settings were changed)

Under 9-bit quantizer mode, the sound is less bold, and attacks are more solid, noises contained in recordings are more audible. Although those difference are very small amount and It required me repetitive comparison over and over.


Thus it seems that a pretty optimal configuration for the ESS DAC is:

  • Vout mode with a simple RC low pass
  • 9-bit quantizer setting
  • Higher sample rate input [link]
  1. Con
    July 16, 2013 at 07:58

    I just wonder who really want to have all that impedances and nF caps in the audio signal path (filter above)…
    Only try without no any filtering… to hear the sound…

  2. wktk_smile
    July 16, 2013 at 10:19

    the comparison between 9bit and 8bit quantizer mode was done while imitating true differential
    mode (under pseudo differential mode in register setting) experiment.

    9bit quantizer mode is work correctly only under pseudo differential mode as far as I know, and
    keep in mind it usually throw away the benefits of true differential mode.

  3. David Quayle
    July 16, 2013 at 11:01

    Have I got this right?
    I take the output directly from the BIII (balanced) output, to a Lundahl LL1684 transformer, & then straight to the SE RCA plug. Not forgetting the OS-CON & resistor, before the tranny.
    The guy I bought my IVY off a couple of years ago said he was using Lundahl transformers as the output stage & it was the best he had ever heard.

    • BlgGear
      July 16, 2013 at 18:00

      Yeah, that is the report. Since I don’t need to convert to SE mode, I don’t use anything

  4. David Quayle
    July 16, 2013 at 11:03

    Oh, I assume that means I would also have isolated outputs?

  5. David Quayle
    July 17, 2013 at 11:19

    BlgGear :
    Yeah, that is the report. Since I don’t need to convert to SE mode, I don’t use anything

    Not even a resistor in the signal path?

    • BlgGear
      July 18, 2013 at 01:15

      Well, yes. I have an RC low pass

      • Rob
        March 15, 2014 at 02:42

        Can I ask for the RC filter details you use ? I want to apply to 8 channel application – from 9018 in 8 channel voltage mode direct to Hypex amps.

      • BlgGear
      • Rob
        March 16, 2014 at 23:21

        Thanks, but I wonder if the output resistance needs to included in the RC filter calculation as I understand the ES9018 has 780 ohm output resistance in 8 channel mode or 195 ohm in 2 channel mode. ?

      • BlgGear
        March 17, 2014 at 18:21

        Hmmm, I am not sure about this. If this is the case, the effect of the series resistor would be much higher than in stereo. Can you measure out output response?

      • Rob
        March 17, 2014 at 22:14

        Sorry I cannot yet measure as I have yet to get the hardware, but if I am correct your low pass filter design in your link in comment #9 is in fact an R of 220+195 ohm and the filter F is closer to 38kHz rather then your design point of 74kHz. In 8 channel mode the R would be 220+780 ohm and the F would be around 16kHz…but again I may have this wrong!

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