'Build a Better Audio Computer'
The following is from the FAQ section at Item Audio's online shop. Mark has put together a guide to self-build a computer audio transport that he puts together and sells.
This knowledge obviously has taken a while to put in writing, but that's nothing compared with the time and effort (and expense) that must have gone into gaining this experience. I like the fact he is sharing this with the wider audio community, that he puts his ideals where his mouth is and is pushing computer audio forward.
He has already posted the same thing at pfm, and it got a pretty heated response from those who can see no good motive or sound logic here. "Bits are bits, all computers are good enough", etc. However, while I cannot comment on whether this approach has merit due to my own lack of experience, it still seems a generous step to publish instructions on how to build your own audio computer, based on the Item T1 computer transport.
Hopefully the benefits of this approach will come full circle; more people will engage with a controversial subject, more people try it for themselves, knowledge increases, audio quality may increase also. Computer audio is the future, so why not smooth the way a little? Mark is definitely to be applauded for this step in my opinion, and though he may lose a few sales of built units he hopefully will make up for that in component sales as newbies have a go. Although I am still to finish modifying my Apple mini, I am very interested in following the T1 recipe next year, which has superseded the CAPS as my preference for a self build.
This knowledge obviously has taken a while to put in writing, but that's nothing compared with the time and effort (and expense) that must have gone into gaining this experience. I like the fact he is sharing this with the wider audio community, that he puts his ideals where his mouth is and is pushing computer audio forward.
He has already posted the same thing at pfm, and it got a pretty heated response from those who can see no good motive or sound logic here. "Bits are bits, all computers are good enough", etc. However, while I cannot comment on whether this approach has merit due to my own lack of experience, it still seems a generous step to publish instructions on how to build your own audio computer, based on the Item T1 computer transport.
Hopefully the benefits of this approach will come full circle; more people will engage with a controversial subject, more people try it for themselves, knowledge increases, audio quality may increase also. Computer audio is the future, so why not smooth the way a little? Mark is definitely to be applauded for this step in my opinion, and though he may lose a few sales of built units he hopefully will make up for that in component sales as newbies have a go. Although I am still to finish modifying my Apple mini, I am very interested in following the T1 recipe next year, which has superseded the CAPS as my preference for a self build.
Comments
From Item's FAQ section:
Our Second Generation recipes, dating from late 2009, proved
extremely successful in extracting the best possible performance from
Atom-based motherboards, culminating in the award-winning DAT1 with its
tri-linear power supply. We remain committed to advancing the quality of
computer audio playback, and are happy to announce our Third Generation
recipes enabling customers to build their own versions of our 2012
T-Series computer transports.
So what's new? Well, the Third Generation recipes focus squarely on
the computer as a USB device, in step with the groundswell of movement
toward asynchronous hi-res USB DACs. For the first time, we also move
away entirely from the low-power Atom platform: leveraging Intel's new
32nm 500-Series Celeron processors in the Model 1 transports, and even
lower-powered systems in the Model Zero transports. More on this, and
the Model 2 transports later. Crucially, also we're pleased to announce
the availability of the world's first commercially-available computer
transport featuring full fibre-optic PCIe isolation - solving many of
the problems arising from the plethora of noisy regulators populating
modern motherboards. We have retained the operational cornerstones of
the first and second gen transports: silent, upgradeable,
tablet-operated, and only ever primary linear power. We now also have a
recommended Linux solution that runs from a very small footprint as an
alternative to Windows XP, which remains our OS of choice - although we
do now recommend the combination of JPlay + Windows 8.
The use of the Adnaco fibre-optic PCIe/USB system in particular makes
possible the use of one machine as a high end USB transport, and a
BluRay and HD home theatre system with up to 9Gb on-board storage. For
the first time, the requirements of audio and video players can be
combined without compromise.
The advance from Atom to Celeron offers no penalty in terms of power
consumption, but brings major improvements in processing power (see
below) which has significnatly reduced 'software jitter' and DPC
latency: we're now effortlessly achieving baseline figures in the 2-5
microsecond range - even with Gigabit ethernet in play.
Also, for the first time, we've made available all the parts needed
to build your own T1 as a complete kit to which you can add your choice
of case and further optimisations. The core components are are follows:
INGREDIENTS
Intel DH61DL Mini ITX motherboard: £65
Intel Celeron G550T processor: £39Not only
is it one of the cheapest Mini ITX / socket 1155 boards you can buy, it
is one of the simplest and cleanest-running: drawing less than 1.25A
idling (including processor and RAM). The Intel SATA drivers (although
limited to 3Gb) are very stable and do not affect latency – an issue
that plagues many SATA6 implementations. It's USB3 port is driven by the
Renesas chipset which has proved to be one of the best-sounding
implementations available. The mini PCIe slot allows for the ultimate
energy efficient and high speed startup drive (mSATA) to be installed -
but it also has a PCIe 2.0 4x slot which is essential for the Adnaco and
SOtM add-ins. There is a DVI digital video port for high quality
monitor connection. Tucked away inside is an SPDIF header waiting to be
tapped. It has a proper 24+4 pin ATX input and, perhaps most crucially
of all, it plays nicely with dumb multi-rail linear PSUs. At the time of
writing, we believe there is no better board for an audio build.
Although rated
at 35W, in reality, this 'T' designated G550 draws no more power than a
dual-core Atom. The closely-related G530 is currently ranked by CPU Benchmark as the second best value processor (performance v tray cost)
currently available. Despite the previous stigma attached to the Celeron
brand, the latest 32nm G500 series are outstanding examples of
low-cost, high efficiency design. Basically, OOE trumps HyperThreading.
But as well as Atom's failure to handle out-of-order execution, the
DH61/Celeron platform offers a number of key advantages over the Atom
architecture - even the latest and most powerful D2700:
Bus speed - Atom: 2.5 GT/s | Celeron: 5GT/s
Cache - Atom: 1Mb L2 | Celeron: 2Mb SmartCache
Memory type - Atom: single channel DDR3/1066MHz | Celeron: dual channel DDR3/1333MHz
Memory bandwidth - Atom: 6.4GB/s | Celeron: 17GB/s
Max memory - Atom: 4Gb | Celeron: 32Gb
To reiterate: these benefits, specifically those targeted at improved
memory performance (important given that chosen apps use memory
playback) come without meaningful power or cost penalties. Despite
Intel's conservative rating, in reality this board/processor pairing
draws no more current than any other integrated Atom board – many of
which are more expensive. The additional horsepower of the 2.2GHz dual
core Celeron enables - for the first time - the same platform to be used
for a low-power Linux appliance, as well as a high-demand JPlay/Windows
OS system.
This processor includes integrated Intel HD graphics which has proved
to be more smoother and more reliable when handling video sources up to
720p - including Flash and BBC iPlayer HD. It will cope with 1080p but
only when using VNC, and not without the occasional stutter. However,
this platform is a much more capable multimedia companion that the
second generation models, and of course has a full-spec PCIe 2.0 slot
for the addition of upgraded graphics.
Pico PSU 80W (yellow) ATX DC-DC converter with 12V input: £27
Still
the cheapest and best value way to tackle the primary supply problem.
The cheapest - and silent - 80W Dc-DC converter version is actually the
best, with lower noise figures and less tampering with the 12V rail to
be supplied by a linear bench PSU. However, please note that if your PSU
cannot be fettled to deliver less than 12.5V, you will need the red WI
(wide input) version for an extra £10 or so.
Linear Bench Power Supply: from £40
There are
many suitable models to choose from. Mandatories are: quiet transformer;
passively cooled; low ripple and sufficient capacity. You will never go
wrong by choosing an over-rated PSU: the lower its output relative to
its maximum, the less noise it will generate. However, the Pico PSU is
only capable of handling 7.5A at 12V, so don't go crazy. The basic model
supplied in the T1 kit has a continuous capacity of 45W, and is capable
of handling peak demand of 70W - and has a very low peak-peak ripple
figure of 3mV. However, a system comprising of a single SSD or HD, with
no attached USB peripherals other than a DAC or converter, should draw
no more than 18W idle, and peak at around 30W when playing full-screen
video. Bear in mind that every attached USB device requires up to 500mA
at 5V, and that HDs draw up to 1A, whereas SSDs typically only require
500mA. Most supplies of this type are designated as 13.8V, but have
internal pots to bring the voltage down within range of the Pico PSu
80W. All bench supplies we supply are preset to 12.2V. If you use a
variable supply, set the voltage to precisely 12.0V.
DC Cable: DIY from £15
Terminate shotgun coaxial
satellite cable having at least 1mm solid core connectors with good
quality banana plugs at one end. At the other, strip the coax cable
desolder the black and white power connectors from the Pico PSU (taking
careful note of polarity) and solder the 1mm internal connector only
(not the shield) to the freshly vacated input connector cups. This gives
you an inexpensive, fully shielded, minimal connector DC lead direct to
the PSU. Alternatively (easier, but worse) connect the 2.5mm input
connector of the Pico PSU to a 2.5mm DC cable terminated with bare-wire
or banana-plugs at the PC end. The T1 kit comes with a 1m length of
suitable cable and high quality banana plugs.
Xigmatek Loki tower cooler: from £18 (case permitting)
Our
third generation recipes places greater stress on lower operating
temperatures on the motherboard: cooler = less noise. Our preferred
cooler on a budget is Xigmatek Loki which combines true copper
heatpipes, good quality construction and excellent passive cooling
properties at a bargain basement price. There are better coolers at
higher prices that are easy recommendations, but we know of nothing that
offers better value. The cooler comes with a fan – remove it. The Loki
measures 134mmin height - a midget among tower coolers - but still
requiring significant headroom – hence our case recommendations below.
Corsair M4 Solid State Drive: from £35
Many
brands of SSD have poorly implemented drivers of firmware that create
significant spikes in DPC latency and hard pagefaults. The Corsair M4
has been the most reliable we've tested. The Intel DH61DL has a Mini
PCIe slot that can be used to house an M4 mSATA drive if you're using a
very small footprint case, or are on the tightest budget. However, the
increased bandwidth and option to use a SATA filter makes our preferred
choice a conventional 2.5" filtered SSD drive.
SOtM SATA filter II: £45
Each drive should be
fitted with an SOtM SATA filters: even SSDs generate noise injected back
into the signal path (see product page for details). The Mark II model
contains several improvements over the Mark I.
2Gb DDR 1333MHz memory: £12
Use the lowest
latency memory you can find or afford. For a Linux, JRiver or
Foobar-based install a single stick of 2Gb DDR3 will suffice. For
JRiver, Signalist or Phasure running under Windows 8, 2x 4Gb is
recommended.
Stillpoints fabric or better: from £30 per sheet
The
case is already a pretty good screen: and gaps in the screen are
necessary for ventilation. The aim here is to absorb reflections that
would otherwise radiate back into the case, and shield critical parts of
the signal path. Place patches underneath the CPU and graphics
chipsets; above, below and to the side of the ATX socket, and around the
USB output socket. The absorption characteristic of Stillpoints fabric
are not hugely impressive: a number of specialised (thicker) materials
are available that are considerably more effective - and expensive:
starting at around £100 for an A4 sheet.
Chassis: from £39
Operating System: from £0Ideal low-end cases for the T1
include the Coolermaster Elite 200 and CIT MTX003B: both are 'shuttle'
format HTPC cases designed for Mini ITX boards. Both also accommodate
higher quality full size optical drives and a full-sized expansion slot
for PCIe cards (ie, Adnaco, SOtM or HDMI video). Crucially, both cases
have headroom for the 134mm Xigmatek Loki cooler. If this format doesn't
appeal (it's hardly a looker) the Streacom FC5, FC8, FC9 and FC10
chassis are highly recommended: in this case, you don't need the
Xigmatek cooler: all cases have integral heatpipe cooling - effective
turning the whole aluminium chassis into a heatsink - like our Mac Mini
modification. The Plex cases offer similar functionality, but aren't as
attractive, don't have full-size expansion slots (horizontally disposed
on a PCIe riser) - and are more expensive.
Windows XP remains our
OS of choice: it is compatible with every DAC, and always comes up with
the goods via ASIO or Kernel Streaming. Our pre-stripped and optimised
XP build, complete with authentic hologrammed licence pack is available
for £40 as an option with the T1 kit. During JRiver playback, and
running Task Manager and full network services, the OS is reduced to
fewer than 140 active threads. Alternately, we can supply or recommend
Linux MPD which works perfectly on the T1 platform. Dual-booting with
XBMCbuntu gives a neat and fully-featured multimedia platform.
OPTIONS & UPGRADES
Adnaco USB: £375
We strongly recommend the Adnaco
PCIe/USB system for USB3 output. It effectively firewalls all residual
gavanic noise behind a battery or linear-powered USB socket. For further
details, please see the product page.
SOtM USB: £299
The PCI-based USB 2.0 output that
formed the centrepiece of the DAT1 and second generation recipes has now
been upgraded to PCIe and USB 3.0. In certain instances, this may
outperform the Adnaco system: if in doubt, try before you buy in our
free home loan programme.
SPDIF output: from £150
The highest performing
on-board SPDIF solution currently available is the new PCIe version of
the stalwart ESI Juli@ card. It benefits significantly from two minor
modifications: first, tapping the PCIe connection to inject a clean
linear-generated supply and, second, hardwiring a BNC or RCA digital
interconnect directly to its output - bypassing the DIN multi-connector.
Full instructions are available to anyone purchasing this card from us.
Northbridge cooling: from £10
The pre-built T1
comes with an upgrade Northbridge cooler and thermal paste that lowers
the operating temperature of this chipset by 8-10°. After the Xigmatek
or case heatpipe upgrade, the Northbridge chipset will be the hottest
point on the motherboard and therefore the weakest link with regard to
lowering temperature-related system noise
Power Supply
Upgrading the T1 to a tri-linear PSU
brings bigger gains than any other single upgrade. If you have
sufficient patience, we'll happily supply you 3m of shotgun coaxial
satellite cable, six banana plugs, ATX shells, a linear power supply and
full instructions for £299. Alternatively, we can supply a pre-built
loom with upgrade PSU and bus-bar ATX connector with breakouts for PCIe
and USB for £399. Taking it up another notch for serious modders, we
can supply the above with two dual-rail linear power supplies and
instructions for injecting a fourth 1.5V rail directly to the memory.
Alternatively, if you've opted for a silent Seasonic ATX supply, the
addition of Core Audio ATX filters is a very effective way of lowering
input noise on all rails, and breaks the 120W ceiling imposed by the
Pico PSU.
Optical Drive: from £40
A few home truths first:
slimline drives are generally fragile and unreliable. Full-sized optical
drives (DVD of BluRay) can draw as much current as the rest of a
well-specified PC put together and generate a larger EM field, as well
as greater acoustic disturbance than anything else in the system.
Furthermore the SM 'bricks' that power the external drives are typically
of very poor quality in terms of ripple noise. It pays, therefore, to
treat the administration of your music library as a different process to
playback of your music library. The simplest solution is to buy a high
quality Samsung or NEC drive, rip your discs, then unplug it. Or even to
rip your CDs on another machine and transfer them via ethernet or
sneakernet. Unless your machine is intended as a one box BluRay player
it's hard to find a good reason to include it in the same chassis as the
'transport'. Again, use of the Adnaco will mitigate some of these
objections: if you have to build in an optical drive, provide it with
its own PSU by cannibalising the SATA/PATA connector from an external
caddy and unplug it when not in use. On no account should the optical
drive be powered by the 12/5V section of a Pico PSU loom.
We tend to agree with the HiFi World review of a Mac Mini modded to the max (tweaked OS + Audirvana + SATA filter + SSD + Paul Hynes linear PSU + passive cooling conversion + de-wireless): sounds good (five stars, no less!), but not as good as the best Windows / Linux builds. I'm quite depressed about it, because I'm a lifelong Apple fanboy.
You and Dave (Uglymusic - resident Apple fanboy) should get together and weep into some latte at a posh coffee bar in your black roll-neck sweaters...
Is it the fun of trying different products or a belief that competition drives up standards that appeals?
I don't know iTunes very well. I use it to manage my iPhone and that's it really, so can't compare with JRiver.
Invent it Dave! manufacture it! Sell it! I will be there.
[-O<
There was an interesting comment on pfm by a chap who builds very high end audiopooters, to the end that IF you get all the hardware considerations right, then a Windows OS sounds better than Linux and OSX. Mark echoed the comment, and endorsed it by saying he knew many system builders who had found the same.
I doubt there are any absolute truths out there.
Keith.
As always keep an open mind and compare everything I your system to a known reference.
Keith.
I love JRiver though. It's a cracking piece of software that just keeps on giving!
That just about wraps it up for me. The new CAPS designs don't appear to offer much over & above (if anything) the Item design, and whichever road you go down, you need to throw a fair bit of dosh at it to do it 'properly'.
For context, it's worth remembering that for three years, the creator of the CAPS recipe claimed that the primary power supply made no difference. Now, suddenly, it's essential to have a £800 battery. I would recommend anyone interested in doing a DIY build to examine the T1, CAPS and cMP recipes carefully.
The beauty of the T1 is that you can start cheap and build on it, whereas the CAPS is a dead end. You can even switch approaches entirely from the standard, lean, XP-based version to the JPlay Way: adding memory, upgrading the processor and running W8: all on the same hardware platform. There's really no reason to use an Atom processor for audio in 2012, and especially 2013.
Some DAC manufacturers see it as a badge of dishonour to admit their products reveal any differences in input cabling or transport specification. Others, like Wadia, dCS, Perreaux, et al have recently changed their tune, acknowledging that such things matter.
A recent series of articles in HiFi Choice focused on differences between USB > SPDIF converters, and different versions of the Mac Mini - quite easily mapping measurable factors to audible outcomes. The DAC on which all their tests was based was the Weiss 202 . . .
There's plenty of controversy around this subject, but it's interesting!
When it comes to off-the-shelf linear PSUs there's a pretty strict cheap / good / WAF triangle to draw a line through: you can have good and cheap, but not pretty; if you want good and bling, it won't be cheap.
It's fairly easy to recase the innards of a lab PSU, and hardwire the DC outputs while you're at it. Or, you can step up to the Paul Hynes / Fidelity which (from us) ranges between £350-600 depending on capacity.