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Thread: New DAC from Allo is coming soon

  1. #21
    Join Date: May 2016

    Location: Notts

    Posts: 1,430
    I'm Geoff.

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    Quote Originally Posted by The Black Adder View Post
    Hi Geoff.

    I think they have something on their website with an attenuator control.
    Thanks, I will check it out.

    Geoff

  2. #22
    Join Date: Aug 2016

    Location: France

    Posts: 169
    I'm Andre.

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    Quote Originally Posted by Sherwood View Post
    Hmmm?

    Are the XLR outputs fully balanced, and will it be possible to control the volume through software to the XLR's. I would like to feed the signal direct to my monoblock power amps without the need for a pre-amp.

    Alternatively, is there an option for a stepped attenuator with this design?

    Geoff

    hi Geoff,

    i am not sure what "fully balanced" means...
    they are balanced as mentioned before.

    yes you can control through software...
    we also sell a 24 position stepped attenuator.

    or even a relay attenuator.

    regards
    Andre

  3. #23
    Join Date: Aug 2016

    Location: France

    Posts: 169
    I'm Andre.

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    hi to all,

    as many of you heard , we have been working on a new DAC .


    We asked ourselves how its possible to bring true HIFI sound to the RPI. We wanted a price point thats accessible to everyone while blowing away any DAC made by anyone under 1000$ .
    Lets see if we succeeded

    1. DAC IC

    First we chose a very capable IC , the ess9038q2m . This IC has excellent specs (theoretical THD+N at -120) and the analog stage (output) is left to the designer (more on analog stage below). One extra advantage of the ess9038q2m is DOP
    Of course we used super caps and everything in audio path is film caps and thin film R.

    2. Clocks

    Any delta sigma IC is very sensitive to the clocks (jitter). We used the "ultra low jitter clocks from NDK NZ2520SDA http://www.ndk.com/en/products/searc...0972_1433.html. We also made sure that power was filtered by 2 LDOs in series along with a HF filter. Noise tested is in uV. Of course we also used buffers (that also has its power filtered 3 times..)
    What we achieved is the lowest jitter ever (390fs)

    3. Analog stage

    There are 2 kinds of analog stages , transfos and opamps. A lot of people swear by trans (with good reason) and others chose specific monolithic opamps. Still the consensus is that transfos are better as far as sound quality (but very expensive and bulky) and that opamps are better as far as THD+N numbers . If Opamps are used the quality of the PSU (opamps need dual rail 15V) is very important .

    Still we felt that opamps CAN be better than transfos..

    We concentrated a lot of efforts in this analog stage . You see , monolithic (integrated circuits) opamps suffer from the fact that not enough real estate is available on the silicon die .( excellent article https://sparkoslabs.com/audio-op-amp...eek-bandwidth/ )

    So our choice was ultimately to build a discreet opamp (with IV stage we got 6 of them) while feeding it from a DC/DC convertor that has filters on input (+ LDO) and filters on output (+ LDOs) and of a course a common mode choke (each rail has independent filtering) for a total noise thats lower than 1mV

    However building an opamp is not a trivial task . What we did is partner with Sparkoslabs.com and used his excellent design (thx you Andrew the wizard) . One review of those opamps https://www.monoandstereo.com/2014/0...s-review.htmll .

    Each board is then hand trimmed (individually ) for DC offset (when board is warm to simulate conditions of a board that been running for at least 45 min)) and then programmed for THD+N compensation .



    So in essence Katana dac is an excellent implementation of the Ess9038q2m in Master Mode (we are the first to do so) , with a discreet stage made by 6 opamps running in class A amplification . THD+N numbers (1Khz , 0 dbfs , a weighted ) at -112.75 !!!
    Pricing at 249$ (US) and 259Eur (tax included) Release date 17 of Julykatana.jpg
    Last edited by ALLO.com; 11-07-2018 at 07:22.

  4. #24
    Join Date: Sep 2009

    Location: Derbyshire

    Posts: 7,721
    I'm Josie.

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    Hi Andre...

    Can't wait... sounds really very interesting

  5. #25
    Join Date: May 2016

    Location: Notts

    Posts: 1,430
    I'm Geoff.

    Default

    Quote Originally Posted by ALLO.com View Post
    hi to all,

    as many of you heard , we have been working on a new DAC .


    We asked ourselves how its possible to bring true HIFI sound to the RPI. We wanted a price point thats accessible to everyone while blowing away any DAC made by anyone under 1000$ .
    Lets see if we succeeded

    1. DAC IC

    First we chose a very capable IC , the ess9038q2m . This IC has excellent specs (theoretical THD+N at -120) and the analog stage (output) is left to the designer (more on analog stage below). One extra advantage of the ess9038q2m is DOP
    Of course we used super caps and everything in audio path is film caps and thin film R.

    2. Clocks

    Any delta sigma IC is very sensitive to the clocks (jitter). We used the "ultra low jitter clocks from NDK NZ2520SDA http://www.ndk.com/en/products/searc...0972_1433.html. We also made sure that power was filtered by 2 LDOs in series along with a HF filter. Noise tested is in uV. Of course we also used buffers (that also has its power filtered 3 times..)
    What we achieved is the lowest jitter ever (390fs)

    3. Analog stage

    There are 2 kinds of analog stages , transfos and opamps. A lot of people swear by trans (with good reason) and others chose specific monolithic opamps. Still the consensus is that transfos are better as far as sound quality (but very expensive and bulky) and that opamps are better as far as THD+N numbers . If Opamps are used the quality of the PSU (opamps need dual rail 15V) is very important .

    Still we felt that opamps CAN be better than transfos..

    We concentrated a lot of efforts in this analog stage . You see , monolithic (integrated circuits) opamps suffer from the fact that not enough real estate is available on the silicon die .( excellent article https://sparkoslabs.com/audio-op-amp...eek-bandwidth/ )

    So our choice was ultimately to build a discreet opamp (with IV stage we got 6 of them) while feeding it from a DC/DC convertor that has filters on input (+ LDO) and filters on output (+ LDOs) and of a course a common mode choke (each rail has independent filtering) for a total noise thats lower than 1mV

    However building an opamp is not a trivial task . What we did is partner with Sparkoslabs.com and used his excellent design (thx you Andrew the wizard) . One review of those opamps https://www.monoandstereo.com/2014/0...s-review.htmll .

    Each board is then hand trimmed (individually ) for DC offset (when board is warm to simulate conditions of a board that been running for at least 45 min)) and then programmed for THD+N compensation .



    So in essence Katana dac is an excellent implementation of the Ess9038q2m in Master Mode (we are the first to do so) , with a discreet stage made by 6 opamps running in class A amplification . THD+N numbers (1Khz , 0 dbfs , a weighted ) at -112.75 !!!
    Pricing at 249$ (US) and 259Eur (tax included) Release date 17 of Julykatana.jpg
    Looks very interesting and probably exactly what I am looking for when I move overseas later this year. Two questions:

    a) Is it possible to fit a volume control, and which is the best in terms of sound quality?
    b) I understand this has XLR outputs. Is this an option or are they standard? Do xlrs replace the rca outputs?


    Geoff

  6. #26
    Join Date: Aug 2016

    Location: France

    Posts: 169
    I'm Andre.

    Default

    Geoff,

    the RCA connectors are mounted/soldered on the board, they are standard; but there are provisions (holes) where you can solder wires for XLR connectors.
    Its a small DIY project that allows you to have both outputs with little effort.

    for volume control, you can use our relay attenuator that can be used as stand alone.
    https://www.allo.com/sparky/relay-attenuator.html

    regards and let me know if you have any other questions.

    Andre

  7. #27
    Join Date: May 2016

    Location: Notts

    Posts: 1,430
    I'm Geoff.

    Default

    Quote Originally Posted by ALLO.com View Post
    Geoff,

    the RCA connectors are mounted/soldered on the board, they are standard; but there are provisions (holes) where you can solder wires for XLR connectors.
    Its a small DIY project that allows you to have both outputs with little effort.

    for volume control, you can use our relay attenuator that can be used as stand alone.
    https://www.allo.com/sparky/relay-attenuator.html

    regards and let me know if you have any other questions.

    Andre
    Andre,

    thanks for your prompt reply. Just a few follow on points.

    Will any case for the new DAC have cut outs for the XLRs, or will it be necessary to adapt the case?

    You say that the relay attenuator can be used stand alone. Not sure I understand this? Would that be in a separate box and if so how would it connect to the new DAC?

    Thanks

    Geoff

  8. #28
    Join Date: Aug 2016

    Location: France

    Posts: 169
    I'm Andre.

    Default

    hi agian,


    yes, the acrylic case will have openings for the XLR connecting wires.

    for the relay attenuator, let me get back to you on this by tomorrow after i confer with the team.
    regards,
    Andre

  9. #29
    Join Date: Aug 2016

    Location: France

    Posts: 169
    I'm Andre.

    Default

    hi again Geoff,

    for volume control here is what we can offer:
    1> stepped attenuator sitting between Katana and AMP. wil require RCA cables.
    we dont have a case for it, but its something we can do.

    2> relay attenuator . will require soldering for the I2S signaling.
    making a case for that will be harder.

    regards,
    Andre

  10. #30
    Join Date: May 2016

    Location: Notts

    Posts: 1,430
    I'm Geoff.

    Default

    Quote Originally Posted by ALLO.com View Post
    hi again Geoff,

    for volume control here is what we can offer:
    1> stepped attenuator sitting between Katana and AMP. wil require RCA cables.
    we dont have a case for it, but its something we can do.

    2> relay attenuator . will require soldering for the I2S signaling.
    making a case for that will be harder.

    regards,
    Andre
    Andre,

    thanks for the clarification.

    If I understand it, the relay attenuator operates in the digital domain and the stepped attenuator in the analogue domain.

    When do you expect to ship the first Katanas?

    Geoff

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