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Thread: Thinking about building a class-D amp

  1. #1
    Join Date: Sep 2017

    Location: Dublin

    Posts: 506
    I'm Pavel.

    Default Thinking about building a class-D amp

    I'm thinking about building a class D amp, and would like to use this thread as a means of collecting various bits of info in one place and hopefully fostering useful discussion :-)

    We have a quiet time at work right now, so I spent the last week reading diyaudio.com and figuring out what class-D boards/modules would be most appropriate for my needs.

    What I want in an amplifier:

    • audiophile quality;
    • enough power to drive my current speakers (Usher S520; their sensitivity is just 84.5 dB and apparently they need quite a bit of juice to make them sing);
    • reasonable requirements in terms of power consumption / heatsinks / size and weight;
    • it should be relatively straightforward to hook up and configure.


    I think the following three options (mostly) meet my needs:

    1. Eastern Audio Technology (Hifimediy) T4: https://hifimediy.com/amplifiers/diy...dorf-amplifier

    This board is based on TK2050/STA516 combo.

    Pros:

    • very well-reviewed;
    • uses high quality components (capacitors, inductors, etc);
    • this board is basically self-contained and only a handful of components are needed to build a functional amplifier (a case, a transformer, connectors and wiring).


    What I don't like about this board is the lack of info and technical documentation. For example, the manufacturer states that it provides 2x180W @ 8 Ohm, but doesn't provide THD at full power. I suspect that the rated output power is at 10% THD. It means that it probably outputs about 50-70 Wpc while keeping distortion reasonable.

    2. Connex IRS2092 Stereo: http://connexelectronic.com/product/...reo-amplifier/

    This board is based on the IRS2092 controller chip and IR power MOSFETs.

    Pros:

    • well-reviewed;
    • uses high quality components;
    • provides all the power I will ever need;
    • very low parts count if used with its matching power supply;
    • excellent documentation;
    • best in class protection against fault conditions if used with its matching power supply.


    However, there are some things that I don't like about this board. First of all, I'm a bit suspicious about IRS2092 which was initially pitched for PA and automotive applications. On this particular board the output filter, apparently, is not included in the feedback loop, which means that some loads could interact with the filter and adversely affect the sound. The input impedance is very low, so a buffer is needed to provide maximum compatibility with different sources.

    3. Hypex UcD180HG-HxR: https://www.diyclassd.com/product/ucd180hg-with-hxr/5

    This board is produced by Hypex and uses their proprietary technology. Two boards are needed to build a stereo amp.

    Pros:
    • widely considered to be among the best class-D amps available at the moment;
    • uses high-quality components;
    • low parts count if used with its matching power supply;
    • excellent protection if used with its matching power supply;
    • balanced input;
    • excellent documentation.


    What I don't like about this board: rated power output at 8 Ohm is 120 W at 1% THD and just 60 W at 0.1% THD (similar to Hifimediy T4). Expensive. No single-ended inputs.


    At this point I'm inclined to go with the Hypex simply because it's guaranteed to be good, even if the resulting amplifier would be rather expensive.

  2. #2
    Join Date: May 2016

    Location: Notts

    Posts: 2,734
    I'm Geoff.

    Default

    Have a look at this new product.

    http://www.nuprimeaudio.com/product/...v=79cba1185463

    I have a pair of the more powerful STA-9 which output almost 300w in bridged mode. They are exceptional for the price. I think that either one STA-9 or a pair of STA-6 as monoblocks would suit you well, budget permitting.

    Geoff

  3. #3
    Join Date: Sep 2017

    Location: Dublin

    Posts: 506
    I'm Pavel.

    Default

    Thanks, I know about NuPrime products and actually used IDA-8 in my home system before moving to Ireland.

    Are there any European dealers? I can’t find their stuff for sale anywhere.

    And also building something with my own hands is better for my soul...

  4. #4
    Join Date: May 2016

    Location: Notts

    Posts: 2,734
    I'm Geoff.

    Default

    Quote Originally Posted by Shovel_Knight View Post
    Thanks, I know about NuPrime products and actually used IDA-8 in my home system before moving to Ireland.

    Are there any European dealers? I can’t find their stuff for sale anywhere.

    And also building something with my own hands is better for my soul...
    Their website lists several European dealers under where to buy section.

    Geoff

  5. #5
    Join Date: Sep 2017

    Location: Dublin

    Posts: 506
    I'm Pavel.

    Default

    Somehow I’m not too keen on ordering from Romania or Italy, but I will keep this NuPrime amp in mind in case this DIY project turns out to be too expensive (my DIY projects sometimes can spiral out of control in terms of expenses ).

    In the meantime I’d like to think about power requirements and heat dissipation of my DIY project.

    The Connex IRS2092 power amp is likely to be the most power hungry of aforementioned options. It outputs 200 Wpc at 4 Ohm or 105 Wpc at 8 Ohm. Efficiency at full output is 92%, so worst case power consumption driving a pair of 4 Ohm speakers will be roughly 435 W. Worst case heat dissipation is going to be about 35 W and the onboard heatsink should take care of it nicely.

    A pair of Hypex UcD180 will output 180 Wpc max with 90% efficiency, worst case power consumption is going to be 396 W and worse case heat dissipation is going to be 36 W or 18 W per module. If I use an aluminium case, I can bolt the modules to side panels and it will be enough to cool them efficiently.

  6. #6
    Join Date: May 2016

    Location: Notts

    Posts: 2,734
    I'm Geoff.

    Default

    Quote Originally Posted by Shovel_Knight View Post
    Somehow I’m not too keen on ordering from Romania or Italy, but I will keep this NuPrime amp in mind in case this DIY project turns out to be too expensive (my DIY projects sometimes can spiral out of control in terms of expenses ).

    In the meantime I’d like to think about power requirements and heat dissipation of my DIY project.

    The Connex IRS2092 power amp is likely to be the most power hungry of aforementioned options. It outputs 200 Wpc at 4 Ohm or 105 Wpc at 8 Ohm. Efficiency at full output is 92%, so worst case power consumption driving a pair of 4 Ohm speakers will be roughly 435 W. Worst case heat dissipation is going to be about 35 W and the onboard heatsink should take care of it nicely.

    A pair of Hypex UcD180 will output 180 Wpc max with 90% efficiency, worst case power consumption is going to be 396 W and worse case heat dissipation is going to be 36 W or 18 W per module. If I use an aluminium case, I can bolt the modules to side panels and it will be enough to cool them efficiently.
    Why would you want to buy from those countries rather than Belgium, France, Germany or the Netherlands?

    Geoff

  7. #7
    Join Date: Sep 2017

    Location: Dublin

    Posts: 506
    I'm Pavel.

    Default

    Ideally, I’d like to buy from Ireland or U.K., but couldn’t find it for sale here ¯\_(ツ)_/¯

  8. #8
    Join Date: May 2016

    Location: Notts

    Posts: 2,734
    I'm Geoff.

    Default

    Quote Originally Posted by Shovel_Knight View Post
    Ideally, I’d like to buy from Ireland or U.K., but couldn’t find it for sale here ¯\_(ツ)_/¯
    True, not yet. I just wondered why you referenced those unlikely countries other than nearer ones.

    Geoff

  9. #9
    Join Date: Feb 2013

    Location: Switerland

    Posts: 1,199
    I'm rupert.

    Default looking forward

    I'm looking forward to your build

    I have a penchant towards the Connex products. I've put together some IRS2092 amps with good results. The latest one was a LJM L15 (with the old capacitors). They are pretty cheap, so I gave them a try. I preferred running them with a linear PSU as opposed to a SMPS.

    What I like with Connex (as with Hypex) is that all the components (SMPS/AMP) are meant to work together. I also think that the UcD / NCore amps are overpriced for the extra 0.1% in SQ you aparently get. I had a UcD with the regulators - but I couldn't say if it was that was much better than a well power-supplied IRS2092). What was obvious was the difference in price !

    Good luck with the build.

  10. #10
    Join Date: Sep 2017

    Location: Dublin

    Posts: 506
    I'm Pavel.

    Default

    Thanks! I hope it will be worth it :-)

    Next step is making the BOMs and calculating possible expenses.

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