HTPC direct to active speakers/power amp and passive speakers

[rpo83]

Hi,

I am trying to find out if you can connect the discrete line level outputs of a sound card directly to active speakers. I see a number of sound cards that now have DD and DTS chips on board, so it seems stupid to only connect via SPDIF/optical to a HT processor! and introduce another component into the mix. I don't see why the PC can't also be a pre-amp, i have done previous systems using USB outboard cards for stereo and they worked great, but there doesn't seem to be any discussion on getting rid of the AV receiver.

I design high end home theatre systems and i don't think it will be very long before we can replace our Lexicon/Theta/Meridian type processors with a quality PC, these processors are virtually PC's anyway, but dont have the agility that a HTPC has, any thoughts would be welcome. I am in the process of designing our stand for CEDIA this year and would love to use a HTPC as we will be running a 2.35:1 constant image height screen and it would be great to run HD straight from the PC. The projector we will use accepts 1080p/24Hz and we hope to have a PS3 with its latet firmware outputting 1080p/24Hz,

I have spoken to a couple of the companies who promote and sell HTPC's and it was useless!!!

Cheers

Steve

[MSurge]

rpo83 - Yes I agree but people seem obsessed with having a digital output that feeds an amp to process the signal that then outputs an analogue signal to the speakers anyway.

You are thinking along the same lines as myself as my mainboard does onboard 7.1 which I figure I can take straight from the analogue outputs on the back of the case and use power-amps (or active speakers). Audio is not my "area" of knowledge but going this way keeps a neater looking system (ie one box up front with amps hidden etc).

My mainboard puts out reasonable specs for sound though there are many dedicated cards that would provide the higher levels of processing etc if it needed to be taken to the next step.

The biggest advantage is that using power amps means that an upgrade in sound processing for the next latest and greatest surround thingy means you just upgrade a card.

If find it interesting that digital is seen to be the ultimate but with my Yamaha 5.1 amplifier I get a small amount of noise still when it turned right up (with no input signal) when it's on Dolby surround but when turn off surround processing (ie plain stereo) there is no noise/buzz at all. This amp was second from top when I bought it and is connected to a set of Richter speaker so it's not like it's a cheapo setup but obviously the processing is adding noise even with no signal (or wires, leads) connected to digital or analogue.

My dilema has been to try and find a reasonable set of power-amps that I can use between my HTPC and my existing speakers. For now I can use my 5.1 Yamaha amp as an amp only by connecting the HTPC signal through the amp inputs and just amplifying each without processing but it seems a waste as my HTPC has newer dolby 7.1 (Dolby EX something-or-other?).

I have been in the drawn out process of rearranging the lounge layout to give a better layout so for now I have only connected the HTPC in stereo (no surround) through the amp so far and I would ideally like to swap my current 5.1 amp out for a few power-amps when I get it all how I want it arranged.

If you're more on the audio side of things could you suggest a cost effective way of achieving this? Any suggestions on power-amps or other alternatives? I no longer have a DVD or CD player with the amp since the HTPC does all music, TV and DVD duties now so volume etc will all be through the HTPC.

If you are "high-end audio" then perhaps you should keep in mind that I'm not after audiophile level gear.

Edit: Just a note to be careful with your double-posting on topics.

[merovingian]

I also looked into the HTPC-direct-into-power-amp option when getting my gear. It was difficult to find many/any people who have done it and were satisfied. OTOH, there were no shortage of the-audio-quality-will-never-be-there naysayers. The thing that was the clincher for me was this: power amps tend to be at the high end of the market and therefore don't come cheap. So it's not like I could have saved money by getting a power amp instead of a receiver. Furthermore, power amps don't generally come with a volume control, so you are putting a lot of faith in the soft volume control of your Media Centre.

As it stands, my receiver can take analog inputs, so it's pre-amp stage can be bypassed. In that sense my options for the future are still open. Nonetheless, the simple elegance of plugging a power amp straight into the HTPC is appealing to me.

[MSurge]

Sure you can pick up a decent (non audiophile here) amp for a reasonable price compared to power amps but then as new processing and sound "systems" come out over time then you will be up for bigger replacement costs for a new amp compared to a new PCI card couple with a few power amps that will last for a long time.

I consider it a bit like my MCE. It cost me a fair amount compared to a standard DVD recorder or PVR type machine and it's greater functionality aside, when it comes to upgrade (eg blu-ray etc) then it's probably a matter of swapping out some harware

[rpo83]

Hi guys thanks for the input.

The naysayers really confuse me.... don't they realise that if you look at a modern multi million dollar recording studio, it is typically a win98 or XP based digital format colsole or pro tools running on MAC G5's...

I spend alot of time traing my dealers about the speaker room interface as it is the most critical aspect of audio performance by many magnitudes of order, if we typically take for instance the usual placing of the front speaker baffle at about 90cm - 100cm from the wall behind the speaker we will see a major cancellation in the 85Hz - 95Hz reigon, how bad this cancellation will be is dependant upon the density of the rear wall, but even in a weatherboard or brick veneer home it would be typical to see a 10dB notch. see attached frequency response plot, this was a demonstration to one of my dealers about how placing speakers incorrectly has MAJOR issues, this plot shows a 2 octave 10dB hole in th fq, i don't care if you are running SACD from a $10,000 cd player with $2,000 cables into very high end equipment the differences in the performance benefit will never solve the room speaker interface...

I was demoing some products a couple of years ago, i was using my old pentium 90 with soundblaster 16 playing MP3 files ripped at 256K into a well set up pair of $10,000 speakers. The speakers were connected directly to the PC (using a DSE 3.5stereo to 2 RCA lead worth about $9.00) and the amount of positive comments from people who have sold audiophile products was huge, it wasn't until i told them what they were listening to did the stigma's of their old thought process take over their initial beliefs.

I have spent 25 years selling the worlds best audiophile equipment, (SOTA, Krell, Mark Levinson, Apogee, ect) Now i am involved in the pro world and it is a major wake up call from the "Audiophile way of thinking" of trying to find a sound that you like, but having no way to analyse your results. I hope it wont be very long before consumers find out the real questions to ask instead of the usual "how many watts?"

The parallels between the PC and AV worlds are very strong, reinforced by the amount of forums for both, and quickly consumers will start to get a feel for what is important, a systematic way of thinking is reinforced and that is the key.

Anyway enough ranting from me..

Cheers

Steve

[MSurge]

Steve,

Your comments are appreciated as I've never understood the whole optical digital obsession but never had the technical knowledge to argue the point. I've only had what I can hear to go on and I've heard some attrocious sounding optically connected systems and my own (cheap by your standards) Richter speakers are very nice connected to digital or analogue, even with you average bit-rate MP3 source.

I'm sure there are systems and setups where it does make a difference but these would be very high end but for the average mug user with a "normal" daily use system I don't think the acoustics of the rest of the environment would really justify it all.

So could you point me in the direction of how/where for some reasonable power amps. What options do I have or is it all pretty much power amps that suit the high end audio that are around?

[rpo83]

Hi MSurge,

As i tried to point out in my post, your main concern should be the placement of your speakers in your room, in regards to walls and your listening position. As a recommendation we believe all speakers should be at least 1.2 metres off the floor. Most hifi people obsess about the location of the tweeter but in reality it is the bass driver you should be woorying about as the wavelengths of bass frequencies are long 20Hz is 17metres long and as frequency doubles the length halves. As high frequencies are relatively tiny 20kHz is 17mm long we can simply point the speaker both horizontally and vertically to the main listening position. In a lot of my installs where i have physical and asthetic requirments i will invert the speaker, keeping the tweeter close to ear level but increasing the distance of the bass driver to the floor. Bad floor reflections typically occur in the 150Hz - 300Hz reigon.

In regards to cost effective power amplifiers i would recommend you look at the NAD, Rotel, AMC type amplifier, they have typically large toroidial power supplies can handle large current and have good damping factor. Power amplifiers are very rugged and pretty much bullet proof, speakers and power amps are B chain products which mean thay are specified for the application at hand and won't change over the life of a room- i usually include projection screens as well. The A chain products, the products that deliver the content change with alarming frequency, these products are DVD/CD players surround sound processors, projectors/LCD/DLP/Lycos. So i would recommend that if you are on a tight budget Ebay is your friend, there are a couple of great amps on there at the moment for very little money.

Cheers

Steve

[MSurge]

I'll take your word on the speaker location and I know this can make a difference but my main speakers are floor standing Richters so I'm not about to suspend these off the wall. The surround speakers (when I get around to installing them) will be up near ceiling height, and while I'm sure these locations can be improved the rest of the room doesn't lend itself to good acoustics so I'm less concerned. When it's set up in a room with better acoustics then I'd get more worried about it.

Given that for a 7.1 system I'd be looking at four stereo amps to cover it all I think you might be aiming a bit higher with these amps than I had in mind but I would appreciate some pointers or web links that you might be able to put together. PM me with anything that you don't want to post in the forum if you want.

This is a very basic question but I assume a normal power-amp will work fine with the analogue signal from the PC outputs?

Edit : Also just thinking how much of a pain it would be to mount my sub 1.2m off the floor. Nah can't be bothered for now.

[merovingian]

Originally Posted by MSurge

I'll take your word on the speaker location and I know this can make a difference but my main speakers are floor standing Richters so I'm not about to suspend these off the wall. The surround speakers (when I get around to installing them) will be up near ceiling height, and while I'm sure these locations can be improved the rest of the room doesn't lend itself to good acoustics so I'm less concerned. When it's set up in a room with better acoustics then I'd get more worried about it.

Given that for a 7.1 system I'd be looking at four stereo amps to cover it all I think you might be aiming a bit higher with these amps than I had in mind but I would appreciate some pointers or web links that you might be able to put together. PM me with anything that you don't want to post in the forum if you want.

Four stereo power amps? You can get multi-channel power amplifiers. For example:

http://europe.rotel.com/products/mul...amplifiers.htm

So just one power amp to cover it all.

I have my rear speakers mounted close to ceiling height. It's reasonably OK, but I would do my best to avoid it if doing another room from scratch. I presume that you are looking to position them this high because, like me, you have your seating against the back wall? If so, I personally don't see that 7.1 is going to be of benefit. You really need to have your seating off the wall so you can build a good soundstage behind the seating. Also, 7.1 is really only going to come into it's own with the new HD formats. IMO, you will struggle to get much benefit out of these formats if your room acoustics are poor, as you've mentioned, or your speaker placement is far from optimal.

[logifuse]

Apologies if I missed this point being mentioned, but one reason for a receiver is the flexibility if offers. What if you want AM radio or to play with a games console, or watch something using the Tv's inbuilt tuner with good sound? How are you going to connect them to your active set up?

I guess it comes down to quality - if you're happy with the audio quality, then go for it. Me - I prefer to listen to CDs played in a quality Rotel CD player. It's even better when used as a transport to an Audionote valve DAC...... I know I'm drifting in to (mild) audiophile territory, but you can't get that kind of warmth or depth from a PC. But then you wouldn't be listening to mp3s either.

Also, if I were using the connections from a sound card to feed amps, I'd want better connectors - you don't need 3 figure priced cables, but at least you have more of a choice for plain RCA connectors compared to 3.5mm jacks.

BTW, yes, your sound card should be out-putting at line level, so it can be connected directly to a power amp/active speaker.

Justin