Extreme HTPC

[Synthesis]

Hi folks,

I've just finished up a HTPC that's both silent for movies yet still has the grunt to do gaming justice. Its also compact for such a powerful and silent machine.

I needed a fair bit of graphics processing power as I try to game at my 52" Samsung native res of 1920x1080 so have gone with dual ATI 3870 in crossfire. These cards are great because they're silent at idle ie. watching movies or desktop work. When gaming you can hear a faint hum from the fans but its still quieter than Antec P180 which is fully tricked out with acoustic treatment and 'quiet' 120mm fans. The 3Ghz E6850 CPU is entirely passively cooled using 8 heatpipes connected to the huge heatsink integrated into the case. The X38 based motherboard is also passively cooled. The noise from hard drives is a real problem when your dealing with a silent machine so the two 750Gb Samsung F1's are mounted in Xilence coolers and these are configured in a RAID 0 array.
PSU is a 620w Nesteq ASM semi passive model and is attached to the left case heatsink for additional cooling. I'm running a fairly power hungry setup and the fan never kicks in whilst on the desktop or watching movies. When gaming I can just hear it start up every few minutes for about 15 seconds, even so its still quieter than the Seasonic M12 I have in the Antec P180.

Everything is stock with no overclocking. CPU temps are 39c idle and 61c load after 40 minutes of folding. GFX hover around 60c idle and 85c load.

Overall extremely happy.

System spec is:

Case: mCubed HFX classic with Imon VFD and remote
Mobo: Gigabyte X38-DS5
CPU: Intel E6850 3Ghz
RAM: 4Gb OcUK DDR2 1066Mhz
HDD: 2x Samsung F1 750Mb 32Mb cache (raid0)
Optical: Pioneer Bluray
PSU: Nesteq 620w ASM Semi fanless
Graphics: 2x HIS 3870xt in crossfire

Monitor: 52" Samsung LE52M87

 

[jaykay]

Man that case is a giant heatsink.

 

[BillytheImpaler]

Nice work! How much did it all cost you?

 

[Synthesis]

Nice work! How much did it all cost you?

Thanks

All in the PC cost just over £1500. However the case took up £400 of that and the silent components such as the HD caddies and PSU are always over priced and again they were about £200. So a fair premium has been paid silence.

Having heard it though its totally worth the extra expense. Unless your gaming you don't even know the PC is on and that's important to me for movies and general work.

 

[gt_junkie]

What speakers are those? Are they ribbon tweeters in there too?!!!

They look seriously expensive!

Nice HTPC by the way.

gt

 

[RJC]

That does look good, the cpu heatsink is the case .

Rob

 

[Synthesis]

What speakers are those? Are they ribbon tweeters in there too?!!!

They look seriously expensive!

Nice HTPC by the way.

gt

Cheers mate.

I'm proud to say the speakers are all my own creation from initial design right through to the spray job and crossover.

And a couple of construction shots:

 

[Synthesis]

In case you wondering, the speakers aren't just a pretty face. Here's the performance of the crossovers and loudspeaker in general:

Frequency Response showing +0.5dB / -1dB (1/24th octave smoothing)

Overall view individual driver responses and overall response (1/24th octave smoothing). Note that measurement is only valid from 200hz up as bass measurement was omitted.

Step response at the listening position:

CSD showing decay behaviour at the listening position within the 1st second after signal excitation.

Without bass traps and digital driver/room correction:

With bass traps and digital driver/room correction:

 

[WarBird]

that is rather class now man

 

[gt_junkie]

Wow... that is my only response!

You should go into production with those.

I love my wharfedale floorstanders but those thing's are simply awesome!

Are you in the industry or was it just a major labour of love? The workmanship and complexity is very impressive matey!

Gonna get 5 stars for the thread but also for the speakers!!!

gt

 

[Raikiri]

Great HTPC system, strange choice graphics wise though (I would have probably gone for the new 512mb 8800GTS with a passive cooler).

Also have to say those speakers are brilliantly done, what drivers/tweeter did you use and how long did you put into building them?

 

[Synthesis]

Are you in the industry or was it just a major labour of love? The workmanship and complexity is very impressive matey!

Thanks again. T'was my pleasure to show the pics.

I'm not in the industry, just an audio nut who can't afford £20,000+ speakers so built my own. I've had an interest in this for many years and have built a few speakers now. The design in this thread took me over a year to do but a quick listen will tell you it was time very well spent.

Here's a couple of the others I've built:

And a couple of Subs:

 

[Synthesis]

Great HTPC system, strange choice graphics wise though (I would have probably gone for the new 512mb 8800GTS with a passive cooler).

I bought the 3870's just when they were released back in the middle of last month. In hindsight I wish I'd waited a little longer and gone with a single more powerful card instead of crossfire. In fact I did buy a Leadtek 8800GT to compare with the 3870's but its stock cooler was horrible and the HTPC case I'm using wouldn't allow the height for something like the thermalright coolers and definitely not the accelero S1.

In the end the 3870's are silent when idle and quiet when gaming. They also pack a potent punch if whatever your playing supports crossfire.

I'm really waiting on the new D9E from nvidia.

Also have to say those speakers are brilliantly done, what drivers/tweeter did you use and how long did you put into building them?

Ah another man with fine taste Thanks for the qudos.

The 8" bass and 5" midrange drivers are from a Danish company called Audiotechnology. You probably better know them as the people who created Dynaudio and Scanspeak.
The ribbon tweeter is from a Serbian company called RAAL and is probably the finest ribbon tweeter on the planet.

5" Midrange:

8" Bass:

Tweeter:

 

[jak731]

nice setup you got there, when might the next strain of the upgrade virus strike?

have 5 stars btw

 

[gt_junkie]

Lovely!

Would be interested to hear how you got hold of those dynaudio drive units - was searching for those a couple of years ago.

Personally got a selection of wharfedale tweeters, mid and bass units to do something like this with a friend but unfortunately work and other commitments got in the way.

Did you get literature to help you with the design? I've searched for info on speaker design but it seems cabinet tuning, drive matching and crossover designing is an incredibly complex process!

gt

 

[Synthesis]

nice setup you got there, when might the next strain of the upgrade virus strike?

have 5 stars btw

The PC is safe but the audio system is never far off a change or swap around. Half the fun is the building and the other half is listening to it.

 

[gt_junkie]

The PC is safe but the audio system is never far off a change or swap around. Half the fun is the building and the other half is listening to it.

If you upgrade so often then please let me know when you plan to get rid of any of those speakers.

Some of those kind of remind me of JM Utopia and Revel Ultima's.

gt

 

[mdjmcnally]

Youv'e just answer my question for what PSU to stick in my case. These are pricy cases and accessories but well worth it to get a silent htpc

 

[badbob]

Why do you have Crossfire in a HTPC? I hope you're playing games on it otherwise it's just a waste. And it'll bee too loud.

 

[Synthesis]

Lovely!

Would be interested to hear how you got hold of those dynaudio drive units - was searching for those a couple of years ago.

Personally got a selection of wharfedale tweeters, mid and bass units to do something like this with a friend but unfortunately work and other commitments got in the way.

Did you get literature to help you with the design? I've searched for info on speaker design but it seems cabinet tuning, drive matching and crossover designing is an incredibly complex process!

gt

You never get anything with 99% of drivers. A few come with data sheets showing frequency response but that's about it.

Designing a loudspeaker and crossover is complicated, especially once you start to build 3.5 way designs such as the one here. But there's some key rules that all good speakers adhere to. Once your aware of these then you can build around these limitations. Driver selection is probably the most important thing. You need to use drivers that are optimised for a specific frequency band. No one driver can successfully cover the entire audible frequency range and offer good dispersion characteristics(think of this as how even the frequency response is offaxis) so its become the norm to use increasingly smaller radiating surfaces to deal out ever higher frequencies. This directivity of a driver is related to the diameter of its radiating surface. As frequencies get higher their wavelength becomes shorter and once the frequency wavelength starts to become aligned or exceed the cone diameter then beaming of the sound becomes prevalent causing a significant drop in output when listening offaxis.
Your probably thinking "yeah but I have the speakers pointed directly at me so who cares about what happens offaxis". Well it would appear that way until you realise that the uneven offaxis response is also part of the sound you hear and contributes towards something known as the 'reverberant sound field'. This reverberant field is audible and important. Much like you'd realise that a speaker with an uneven on axis response is flawed the same is true of a speaker who's off axis performance is all over the place.
So in summary use a 15" no further above 400hz and a 5" no more than 3Khz for optimal results. Small drivers such as 1" tweeters have no issues with high frequencies but then distortion with low frequencies becomes an issue so you must use a crossover to cut those out. It all a careful balancing act and there's far more than I can explain in a brief post but with experimentation things do become much clearer on what does and doesn't both measure and sound right.

Another key point is driver to driver spacing or the distance between drivers. Again this relates to frequency wavelengths and the center to center spacing of each driver. Basic rule of thumb is that spacing should be significantly less than the crossover frequency wavelength between the drivers. If you get the drivers as close as possible on the baffle then that's a good thing and try not to do something like like cross over an 8" driver to 1" dome at 4Khz.

Its impossible for me to go into crossover design here simply because its such a huge subject and each loudspeaker design warrants a totally unique perspective on what should and shouldn't be done. Quite often their isn't an exact science to crossover design and instead a collaboration between the ear, microphone and crossover CAD software work to best effect.

I personally use digtal finite impulse response crossover filters because these have no phase related artifacts and means they are time coherent in the electrical domain. On top of this I also use driver and room correction filters to make the speakers more accurate to the 'ideal'.

Here's a quick illustration of the whole crossover and correction stuff I just talked about. A picture speaks a thousand words and all that.

Crossover types are transient perfect Neville/Thiele 1st order. Also in the overlay is an actual unsmoothed mid driver measurement after correction. The black line shows the perfect summing of the filters.

Plots showing the impressive improvement after driver correction:

Frequency Response

Red = Filter Response
Green = Corrected Driver response(unsmoothed)
Brown = Uncorrected Driver Response(unsmoothed)

Step Response

Red = Filter Step Response
Green = Corrected Driver Step Response(unsmoothed)
Brown = Uncorrected Driver Step Response(unsmoothed)

Phase

Green = Filter Phase
Blue = Corrected Driver Phase(unsmoothed)
Black = Uncorrected Driver Phase(unsmoothed)