Sennheiser Q&A: HDV 820 Digital Amplifier

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  1. Sennheiser
    What DAC chip is used?
    [Grell, Axel] We have a tried many different DAC chips and had the best results when we listened to the ESS ES9018S.

    Is it using a Single or Dual DAC configuration?
    [Grell, Axel] We are using the “Single” DAC configuration! As the ES9018S is coming with 8 internal DACs this is already a quadruple solution for each channel. We did intense listening tests with the result that the PCB layout and the type of Op Amps used has a much higher impact than a second ES 9018. Extended clock wires to connect a second DAC chip have a much higher negative impact to the audio signal quality than using a single DAC chip instead of a dual DAC solution.

    But we don’t use it in the “standard” set-up where the outputs of the filter stage lead to a single ended differential stage. In the HDV 820 the 4 parallelized balanced outputs of each channel of the ES9018 are feeding a fully balanced circuit design. When the Pentaconn or XLR4 outputs are used, this balanced signal path terminates only in the headphone's speaker.

    What type of tuning or filters?
    [Grell, Axel] The whole circuit design is based on the original ESS filters. For sampling frequencies of 48 kHz and below we are using the sharp roll off characteristic. Above 48 kHz the soft roll off is used. Again: all these decisions were made according to the whole circuit design. They are not primarily based on measured data but on listening tests using several listeners and several types of headphones.

    In SPDIF mode sharp roll off filters are used at all sampling rates.

    "heck what's the power output?"
    [Grell, Axel] See attached graphics!

    HDV 820 Output Power .jpg
    HDV 820 Power Curve.jpg

    "I know it's designed with full-sized headphones in mind, but how does it perform with IEM's (Sennheiser IE 800 in particular)?... I've read as a general rule of thumb that you want the output impedance of your amp to be at least 1/8th that of your headphone's impedance. Even some full size headphones like the Fostex TH900 (25 Ω) and Focal Utopia (80 Ω) could be negatively affected."

    [Grell, Axel] There is no general rule for “the right output impedance” for a headphone amplifier. There are some high output impedance tube amplifiers that sound great, others don’t, some Zero- Ohms solid state amplifiers sound cold and harsh, others sound good. A headphone and a headphone amplifier is a complex system of impedances, amplifier feedback loops, amplifier current supply and so on. That could lead to typical distortions and dynamic changes of the amplifiers output parameters depending on the headphone impedance and the type of amplifier. Therefore we made listening tests with many different headphones (Sennheiser and other brands from 25 Ohms up to 600 Ohms) using different impedances at the output of the prototypes of HDV 820. The outcome of this listening tests are the output impedances of the HDV 820.

    As you can see from the attached curves a HDV 820 can drive a TH900 with 2.75 W. This should be enough.

    Once upon a time, the "standard output impedance" was 120 Ω. Generally speaking, don't lose sight of the forest because of focusing too much on one tree.

    Is there a plan to upgrade firmware later to support MQA "unfolding?"
    [Grell, Axel] This is under investigation.

    Is the power cable made in-house by Sennheiser, or is it a "Normal" IEC Cable?
    [Grell, Axel] The HDV 820 comes with a “Normal” IEC Cable. Due to its power supply design the HDV 820 should sound great already using this cable. As cables play a big role for audiophiles, customers are free to choose a mains cable that sounds best for them.

    That's it for now folks, thanks for awaiting a response from the source itself!
    Last edited: Feb 5, 2018
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    vrln and YesThisIs like this.
  2. Giraku
    Thank you for the detailed updates.
    I’m really interested in buying one. But one problem is that there is no US store has it in stock. The only place having this amplifier available for purchase is the Sennheiser online store.
    When will they become available through audio shops in US?
  3. Ginge
    Seconded, I very much want to buy this amp, but you can't find a US retailer that carries it.
    Giraku likes this.
  4. bugstone
    Sennheiser, Ginge and Giraku like this.
  5. Sennheiser
    Ok gentlemen!

    The HDV 820 is available right now for order from Sennheiser direct, with a 30-day Money Back Guarantee if you need to try it out. Our authorized retailer network should start getting inventory on November 1st

    Last edited: Oct 10, 2017
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  6. selvakumar
  7. Arniesb
    Dont be ridiculous. Burson is nothing impressive.
  8. Ginge
    That's a joke right? If not, you should educate your ears.
    selvakumar likes this.
  9. vrln
    Thanks for the Q&A, this was a very interesting read! I´m really glad you changed the 3-pin XLR outputs on the back to be variable level (= works with active monitors).

    Just got my HDV820 :) Now roll on HD 660 S - can´t wait to try them via the symmetrical pentaconn connection.
    Sennheiser and Giraku like this.
  10. selvakumar
    you are right both are made for different user
  11. Giraku
    Wow, you got HDV820 already!?
    Please share your impression as I’m on the fence of ordering one!!
  12. vrln
    Only had it for a few days now, but sure... In the past I used to have a HDV800, but I sold it in part due to it not having proper preamp XLR outputs (for desktop active monitors). Sound quality wise I didn´t have anything significant to complain about it, great product and in A/B tests at the store I preferred it to everything else they had at the time. So when this model finally added support for XLR preamp outputs it was an easy choice for me.

    Haven´t had the chance to run it via balanced outputs yet, but it already sounds good single ended with my HD 600. It only gets better from here. My overall impression is that there´s nothing about it (in design or sound) that bothers me. It just works. Just like Apple stuff. Took me a long time to realize it, but in my experience that´s usually the best way to know something is good in high end audio. I´ve tried a lot of stuff during my voyage, but these days I´m no longer interested in the tinkering aspect of the hobby so I´m drawn to solutions like the HDV820 (= everything by same manufacturer*, one box solution).

    It´s not cheap, but it´s great if you just want something that you know will work great with all Sennheiser headphones plus looks good/neat on the desktop. No cable mess from separate components, no need to spend money trying to match headphone amplifiers with the optimal DAC. Holds resale value well. Something you can just buy, enjoy and then forget about gear except maybe new headphones :) (assuming you mainly use Sennheiser headphones)

    Going to primarily pair it with the new HD 660 S (still think the HD 600/650 are much better all rounders than the HD 800 lineup). Is there something "better" out there in the separates headphone amp/DAC world? Sure most likely, but in this price range the differences are for me too minimal to fuss about.

    * Preferably a large established company with deep R&D/engineering knowledge.
    Last edited: Oct 14, 2017
    AppleheadMay and Sennheiser like this.
  13. YesThisIs
    Just a quick and stupid question:

    What kind of box did your HDV 820 come with?
  14. vrln
    No such thing as a stupid question... Just a cardboard one with the unit, manuals and so on inside - no fancy packaging. I thought there would be another box inside it, but nope. Somewhat surprising for a high end flagship product actually. The HDV800 on the other hand had a standard Sennheiser style box like with their headphones. This unit is probably one of the first retail ones to leave the factory at Wedemark, Germany.
    YesThisIs likes this.
  15. YesThisIs
    Thanks! :)

    Yeah i did see this video from Facebook: And my reaction was "wut.... must be something retailers get for demoing or something..."

    It doesn't make the product any less good/valuable. But it's bit strange that HD800s come literally with silk box and also the HDVD 800 did come with a nicer box.... Oh well, at least it's protected decent enough.
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