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Thread: BOSC - HiFi Monoblock Class-D Amp

  1. #11
    Join Date: Mar 2017

    Location: London N2

    Posts: 1,530
    I'm Edward.

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    Quote Originally Posted by orchardaudio View Post
    If you are really interested in this product and would like to be one of the first people to get it at a reduced price, reserve now for $1. Only 55 spots available:
    https://orchardaudio.com/shop?olsPag...ts%2Fbsc-mplfr
    Does a reservation imply an obligation to purchase? If so what is the purchase price please?

    Is $1 for a pair of monoblocks or just for one amp?
    Main: Tidal/Roon > MiniITX > Metrum Hex > LDR > either Radford STA25 V or Trilogy 968 > Tannoy (Eaton or Berkeley).
    2nd: Tidal/Roon > Roopio on Pi > Chevron Paradox > Firebottle Buffer > Sugden Masterclass 2018 spec > Kudos Cardea


  2. #12
    Join Date: Mar 2019

    Location: New Jersey, USA

    Posts: 116
    I'm Leo.

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    Quote Originally Posted by Edward View Post
    Does a reservation imply an obligation to purchase? If so what is the purchase price please?

    Is $1 for a pair of monoblocks or just for one amp?
    $1 is for a two amplifiers. If you only need 1 we can work something out.

    There is no obligation to purchase with the reservation.

    Full pricing and updated specs here:
    https://orchardaudio.com/bosc

  3. #13
    Join Date: Feb 2010

    Location: Berkshire, UK

    Posts: 3,911
    I'm Tom.

    Default BOSC - HiFi Monoblock Class-D Amp

    Ok so long as there’s no obligation I paid my $1. Curious about these as a bit of a class d fan but will need more info before proceding.
    Main: Speakers 'RFC' Tannoy Canterburys / custom crossovers with Tannoy ST50 supertweeters; Amp - Silvercore 833C monoblocks; preamp TBA watch this space; Vinyl: Schopper'd Thorens TD124 MkII + Ikeda IT345-CR1 9 inch and Ikeda IT-407 12 inch tonearms; Cartridges Stereo - Miyajima Madake, Miyajima Takumi, Ikeda 9TT, vintage Ortofon SPU GE; Mono - Miyajimas - Zero 0.7, Premium 1.0, Miyajima/Edison '78' 4.0 conical, and Shure M44 strapped for mono with several Expert Stylus conicals for different eras of 78s; Phono stage Allnic H7000V used with Miyajima ETR-Mono and ETR-Stereo SUTs; Digital: Audio Note CDT2/II transport, heavily enhanced AN DAC based on kit but aspiring to DAC5 spec.

    Study: Speakers - Tannoy DC6; Amp: Marantz PM-4; Digital: CDP Sony CDP-X3000ES & Arcam rBlink; Vinyl: Garrard 401 with AT 1503 MkI broadcast arm, Ortofon SPU Classic GM, Ortofon 2-15k SUT and Puresound Tenuto platter mat

  4. #14
    Join Date: Mar 2019

    Location: New Jersey, USA

    Posts: 116
    I'm Leo.

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    Quote Originally Posted by montesquieu View Post
    Ok so long as there’s no obligation I paid my $1. Curious about these as a bit of a class d fan but will need more info before proceding.
    What info are you looking for?

  5. #15
    Join Date: Feb 2010

    Location: Berkshire, UK

    Posts: 3,911
    I'm Tom.

    Default BOSC - HiFi Monoblock Class-D Amp

    Lots of questions. Are these just class d only? Any input stage? Damping factor? What’s the current delivery like? Pics/specs of the power supply? More to the point how do they sound with various types of speakers? (Subjective obviously but even informal reviews on forum can provide valuable info).

    If you look at the info provided on design approach and topology for the NuPime ST10 and STA9 amps - both excellent class d amps, but also a good example of how to sell class d. They have class a input stages btw.
    Main: Speakers 'RFC' Tannoy Canterburys / custom crossovers with Tannoy ST50 supertweeters; Amp - Silvercore 833C monoblocks; preamp TBA watch this space; Vinyl: Schopper'd Thorens TD124 MkII + Ikeda IT345-CR1 9 inch and Ikeda IT-407 12 inch tonearms; Cartridges Stereo - Miyajima Madake, Miyajima Takumi, Ikeda 9TT, vintage Ortofon SPU GE; Mono - Miyajimas - Zero 0.7, Premium 1.0, Miyajima/Edison '78' 4.0 conical, and Shure M44 strapped for mono with several Expert Stylus conicals for different eras of 78s; Phono stage Allnic H7000V used with Miyajima ETR-Mono and ETR-Stereo SUTs; Digital: Audio Note CDT2/II transport, heavily enhanced AN DAC based on kit but aspiring to DAC5 spec.

    Study: Speakers - Tannoy DC6; Amp: Marantz PM-4; Digital: CDP Sony CDP-X3000ES & Arcam rBlink; Vinyl: Garrard 401 with AT 1503 MkI broadcast arm, Ortofon SPU Classic GM, Ortofon 2-15k SUT and Puresound Tenuto platter mat

  6. #16
    Join Date: Mar 2019

    Location: New Jersey, USA

    Posts: 116
    I'm Leo.

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    Quote Originally Posted by montesquieu View Post
    Lots of questions. Are these just class d only? Any input stage? Damping factor? What’s the current delivery like? Pics/specs of the power supply? More to the point how do they sound with various types of speakers? (Subjective obviously but even informal reviews on forum can provide valuable info).

    If you look at the info provided on design approach and topology for the NuPime ST10 and STA9 amps - both excellent class d amps, but also a good example of how to sell class d. They have class a input stages btw.
    It is a full class-d amplifier using gallium nitride (GaN) output devices in a full-bridge configuration (fully balanced output). The modulator is fully custom and proprietary. It is not based on any modules like nCore or ICE.

    I just measured the damping factor at 1kHz to be 425, so for the specs I will say >400. More importantly BOSC allows you to suspend the amp from the back of the speaker eliminating long cables which can hurt a great damping factor (see picture below).

    The input stage is a Texas Instruments OPA1612 which in my opinion is the best audio monolithic op amp currently available.

    The Power supply is a 56V 250W swithing power supply - All tests and specs are performed and measured with this power supply. (see picture below)

    I am not able to comment on how they sound, but I can say that they will have no issues with driving any kind of speakers. A review will be out shortly. Also a member of this forum has agreed to try them and post findings. That will be a few weeks.


    Attached Images Attached Images

  7. #17
    Join Date: Feb 2010

    Location: Berkshire, UK

    Posts: 3,911
    I'm Tom.

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    Quote Originally Posted by orchardaudio View Post
    It is a full class-d amplifier using gallium nitride (GaN) output devices in a full-bridge configuration (fully balanced output). The modulator is fully custom and proprietary. It is not based on any modules like nCore or ICE.

    I just measured the damping factor at 1kHz to be 425, so for the specs I will say >400. More importantly BOSC allows you to suspend the amp from the back of the speaker eliminating long cables which can hurt a great damping factor (see picture below).

    The input stage is a Texas Instruments OPA1612 which in my opinion is the best audio monolithic op amp currently available.

    The Power supply is a 56V 250W swithing power supply - All tests and specs are performed and measured with this power supply. (see picture below)

    I am not able to comment on how they sound, but I can say that they will have no issues with driving any kind of speakers. A review will be out shortly. Also a member of this forum has agreed to try them and post findings. That will be a few weeks.


    Thanks that's all very useful info, thanks. I see the pic shows balanced input which could be handy in many cases.

    It seems to be quite the thing at the moment for Class D manufacturers to add a discrete input stage, sometimes single ended, sometimes tweaked in some way (in some cases I believe even by digital singnal processing) to give a small amount of first and second harmonic associated with tubes, with the stated intent of giving a warmer/more triodey feel to whatever Class D main board is in use. It's interesting that you have opted to stick with an op amp - no doubt for the distortion specs and so on you mention.
    Main: Speakers 'RFC' Tannoy Canterburys / custom crossovers with Tannoy ST50 supertweeters; Amp - Silvercore 833C monoblocks; preamp TBA watch this space; Vinyl: Schopper'd Thorens TD124 MkII + Ikeda IT345-CR1 9 inch and Ikeda IT-407 12 inch tonearms; Cartridges Stereo - Miyajima Madake, Miyajima Takumi, Ikeda 9TT, vintage Ortofon SPU GE; Mono - Miyajimas - Zero 0.7, Premium 1.0, Miyajima/Edison '78' 4.0 conical, and Shure M44 strapped for mono with several Expert Stylus conicals for different eras of 78s; Phono stage Allnic H7000V used with Miyajima ETR-Mono and ETR-Stereo SUTs; Digital: Audio Note CDT2/II transport, heavily enhanced AN DAC based on kit but aspiring to DAC5 spec.

    Study: Speakers - Tannoy DC6; Amp: Marantz PM-4; Digital: CDP Sony CDP-X3000ES & Arcam rBlink; Vinyl: Garrard 401 with AT 1503 MkI broadcast arm, Ortofon SPU Classic GM, Ortofon 2-15k SUT and Puresound Tenuto platter mat

  8. #18
    Join Date: Mar 2019

    Location: New Jersey, USA

    Posts: 116
    I'm Leo.

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    The AMP has a true balanced input, but also comes with an RCA to XLR adapter for those that would need it.

  9. #19
    Join Date: Jan 2009

    Location: Essex

    Posts: 20,725
    I'm openingabottleofwine.

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    How well do these amplifiers perform when used with electrostatic speakers? I would consider using them with my Quad '57s.

    Thanks
    Barry

  10. #20
    Join Date: Mar 2019

    Location: New Jersey, USA

    Posts: 116
    I'm Leo.

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    Quote Originally Posted by Barry View Post
    How well do these amplifiers perform when used with electrostatic speakers? I would consider using them with my Quad '57s.

    Thanks
    I do not have this type of speaker. I don't see any issue with it. The performance will still be very good as long as the load presented to the amplifier is in the 4 to 8 ohm range.

    Where are you located I can potentially send you sample units to try in 3 to 4 weeks.

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