Advice sought on Class.T Amp for HTPC

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Hi all,

I've been researching the last couple of weeks on how to put together a multi-channel amp for an HTPC source. This is to replace my existing (cheap) Sony A/V unit which powers the 5.1 satellite speakers and active woofer. I've seen this post which seems to be doing similar things to what I want, but there were a few more questions I wanted to ask. Before I do so however, a quick description of what I have now and what I'm looking to achieve.

I have a Linux driven HTPC which will act as my source for everything, music, Television and Movies etc. Sound is currently output via S/PDIF to a Sony A/V unit which powers a set of 5.1 Jamo home theatre speakers.

I'd like to get rid of the Sony A/V and replace it with a simple power amp (the Sony is quite simply huge and has to sit on it's side to fit in the same cabinet as the HTPC. Even then it is too deep and the back of the cabinet has had to be removed and the cabinet moved away from the wall). I'm currently looking at 2x 4x100W Sure Electronics’ TK2050 to provide the power amp with a suitable SMPS power supply. Audio will be output as analogue from the HTPC to the amp, with the HTPC controlling volume.

I'd also like to have a signal sensing auto power-on, so I'm looking at adding in the ESP Project 38 ahead of the amps, though I notice that the Sure AMPs have a low power mute, so I suspect that the ESP project could be adapted to take advantage of this.

Finally, I'm going with the 2 board 8-channel solution as this gives me the option of bi-amp'ing the front left, right and centre channels (I'm assuming that the SW can bypass the amp as it is a powered woofer, there'll be a question regarding that later).

Questions:


  • First off, given my current speaker set up (and the fact that I won’t be swapping them out for anything nicer for a while yet).
  • I expect that since the sub woofer is active I would bypass the amp entirely and simply connect the woofer directly to the PC's 3.5mm jack for the woofer?
  • Do I need to add a high-pass filter ahead of the amp? I’m assuming that until I get to a situation where I want to be bi-amp’ing the front channels the filter’s on the board should be sufficient.
  • Has anyone got any experience of rehashing the ESP signal-detection project with a Sure board? I’m guessing that instead of interrupting the Amp’s power supply, the relay can be used instead as a switch for the board’s mute function (the power for the auto-on board could come from the 5V regulator as well).
  • I’m looking at the following power supply from Sure, is one enough for both boards, or would two be required? If two are necessary, is there any way to get them running (safely) from a single mains point?
  • Looking at the spec sheet for the amp, I’m seeing that the amp is only 82% efficient (providing 46W) at 6ohms. Am I right in the assumption that this will mean the Amp will have to work harder (hotter) to make my satellites louder. Should I consider active cooling as this is the case? Is there anything I can do (short of getting 4/8ohm speakers) to improve this?
  • Would there be any benefit (and to what) to using a pre-amp (buffer)? I ask as I found this buffer valve pre-amp when checking out Arjen Helder's ebay page (apologies for posting an ebay link which will eventually expire). I'm intrigued by the blurb for the product, but I'm not sure what it'll add (well, it's not designed for the TA2050 chip, so it might well add nothing at all). I also see a Potentiometer on the board for adjusting the gain, so I’m getting more of the feeling that it won’t add much as the Sure amp has very little control over adjusting things.
  • If the pre-amp is a viable addition:
    • Would there be any benefit passing the SW through this?
    • Should I pre-amp before or after any high-pass filters for the bi-amp setup?
Thanks in advance for your help guys, it’s really appreciated.
~Dan
 
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