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Discussion Starter · #1 ·
If I'm going to build a pure digital HTPC where everything is going through the PC, it would seem that the traditional receiver/amp is a bit of overkill. There is no need for video or audio switching. Is there a simpler amp that takes digital out of the PC, powers a 5.1, 6.1 or 7.1 speaker arrangement and has some way to drive volume and balance (via serial or network, not IR)?
 

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Why not use the digital volume of the PC soundcard to drive a normal multi-channel amp?
 

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Discussion Starter · #3 ·
oh, and on/off :) it would be nice to automate/script this without all the messy ir cabling/repeaters and other paraphernalia of the analog world.


i've never used the spdif or toslink out of a pc sound card so i was not aware that the volume controlled that. i thought it was an unmodified raw digital stream. wouldn't digital volume control cause distortion or loss of sound quality at low volumes?
 

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Note that no amp will take digital inputs . . . digital signals require decoding: dolby digital, etc., etc. An amp will take inputs only for each individual channel, usually either RCA inputs or balanced xlr inputs.


I can strongly recommend Bryston ( www.bryston.ca ) -- hand-made, 20-year warranty, but very expensive.
 

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mrallen

I meant to use the digital volume of the PC to control the analog output of the PC to the amplifier.
 

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Quote:
I meant to use the digital volume of the PC to control the analog output of the PC to the amplifier.
I did exactly that, only to later find out, that with a dedicated pre amp, I was able to drive my amp 17 dB louder (!!). It could be that my amp expects a very strong signal, anyway, you should check out these things, before settling on your sound card as a pre amp for your amp.
 

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Yeah, I don't expect all sound cards would have the right amount of gain right out of the box but there are some folks over in the HTPC section who are now using the M-Audio Revolution with just an amp.
 

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Quote:
Yeah, I don't expect all sound cards would have the right amount of gain right out of the box but there are some folks over in the HTPC section who are now using the M-Audio Revolution with just an amp.
LoL, I was one of them.
 

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Discussion Starter · #9 ·
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Originally posted by mdryja

Note that no amp will take digital inputs . . . digital signals require decoding: dolby digital, etc., etc. An amp will take inputs only for each individual channel, usually either RCA inputs or balanced xlr inputs.

This statement confuses me. What about amps/receivers that have spdif/toslink inputs and claim to support dolby digital, dts, etc? Here's an inexpensive example .
 

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Quote:
Originally posted by mdryja
Note that no amp will take digital inputs . . . digital signals require decoding: dolby digital, etc., etc. An amp will take inputs only for each individual channel, usually either RCA inputs or balanced xlr inputs.
there is one amp that will take digital inputs:

Tact Millenium


'course, it's only stereo, so you'd need a couple of these plus a digital DD/DTS decoder. and, yeah, it's expensive too. very interesting, innovative product though.



mrallen:


i believe mdryja is referring to power amplifiers. a receiver is a combination of a processor, preamp and power amp. so yes, these accept a digital signal through the pre-amp, process the DD/DTS signal, perform D/A conversion, and send the now-analog signal to the power amp, which drives your speakers.


also, AFAIK, analog volume control is preferable to digital, as digital volume is "stepped", i.e., there are x many discrete volume levels from silent to full-blast, whereas analog is continuous throughout that range.
 

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gongzero

That's certainly debatable. I have some components with stepped attenuators that sound far better than pots do (or rather, they have far less sound of their own). The real disadvantage to digital volume is that it loses some of the resolution. Nonetheless, companies like Wadia employ digital volume and swear by it. *shrug*


I can't think of any small analog preamps that do multi-channel, unfortunately.
 

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rtype, it certainly is debatable, and i won't step into the ring to debate the unquantifiable. your post brings up some very good points. i was only pointing out the limitation of digital volume control over an analog pot... perhaps i shouldn't have used the word "preferable".
 

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gongzero

No no, you're very right to say there are limitations and what I mentioned about the stepped attenuators is irrelevent other than to say that despite having a stepped volume, they're superior in performance. Heh, you know, I've never seen a multichannel pre/pro with all stepped attenuators.
 

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mrallen,


There are some amps that have rs-232 control. You could use the serial port of the computer to turn on/off the amp. Also, some amps have a remote trigger. This is a minijack input that, whe it receives 3-12V it automatically turns the amp on. Finally, some amps have an auto-sensing circuit, whereby, when they receive a signal, they will turn themselves on.


One of the best bang for the bucks amplifiers is the Outlawaudio amplifiers. They are of exceptional build quality and performance, yet are reasonably priced (100W X 7 all channels driven at 8ohms for $900).


I personally prefer to use the coax spdif output of my motherboard for my sound. This feeds my receiver. I feel that my receiver has better quality dacs than the m-audio cards and that there is less chance of my receiver picking up noise outside of my pc.


Russ
 

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Discussion Starter · #15 ·
thanks, Russ.


I've been looking at traditional receivers like the Denon 4802r. It just seems that most of that thing isn't going to be used since it will only have one input from the pc (spdif/toslink) and no video inputs (which will be direct PC DVI to projector).


Isn't there anything out ther which just does the digital/dolby conversion and amplification for speakers but is still discretely controllable without IR (preferrably serial)? If not, it seems like a bit of a gap in the HTPC market.
 

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mrallan,


Yes, there are products that decode DD and DTS signals then pass that signal on to an amplifier, they are called DD/DTS decoders. They take the spdif output of the computer and decode it to analog, then pass that signal on to the amplifier. Conversly you can get a pre-amp, a pre-amp does the DD/DTS decoding as well as component video switching etc, then sends the audio signal out to the amplifier. Outlaw audio also makes a very good preamp, the model 950 for $800, or you can get the pre-amp (950) and amp (7100) for $1600. The thing is, even the pre-amps have video inputs etc. You can hardly find any stand alone DD and DTS decoders, and the ones you do find cost a pretty penny.


Also, remember that you can buy a very nice audio card such as the M-audio or the like, that will have analog outputs that can then connect to an external amp. I have not used one, so I cannot comment on the quality, however, I still believe that the M-audio card will pick up more interference than a standard receiver. Also, when using a sound card, either the sound card or the software has to be able to decode all the surround formats you wish to listen to, whereas with spdif output, the receiver or pre-amp does all the decoding.


No, your best bet is to either get a receiver, or a pre-amp/amp combo (depending on how much cash you have).


Russ


P.S. why do you not want the "extras" of a receiver?
 

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Discussion Starter · #18 ·
Quote:
P.S. why do you not want the "extras" of a receiver? [/b]
It's a combination of size, weight, aesthetics and not buying junk I don't need. It's like not wanting a bunch of legacy ports on a PC that's never going to need them. Except in this case it's 39 legacy ports and 1 which will be used.


I guess I'll stick with the Denon since, price-wise, I'll be spending more to get individual components which then have to be lashed together with more ungainly cabling. Aesthetics out the window.


thanks!
 

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It really depends on what is in your Home Theater and what may be in your Home Theater in the future. Since I have a High Def satellite receiver and an X-Box in addition to my HTPC that I use quite frequently, a Receiver works well. The HPTC is used for 1) DVD Playback 2)Ripped CD Playback 3) Still picture and home movie viewing and 4) Home Automation. To me, there was no simple solution to routing the Satellite Receiver and X-box through the HTPC and using it as a switcher. However, If i had no need or want for satellite or the X-box, I would probabaly take the receiver out of the equation. Keep in mind that if you want to expand down the road to say a DVD-Audio player, DVHS or other media, you may be limited by not having a receiver. Drew
 

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mrallan,


I can definitely feel where you're coming from, paying for something you don't need. However, just remember that you will have a great deal of flexibility with the receiver that you would not have with the DD/DTS decoder or sound card.


Although, the 4802R is not inexpensive. You could easily move to separates, which, although require slightly more cabling, also provide much more power and clarity. Just a thought.


Russ
 
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