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Firestone "Custom Cute" DAC review: galvanically isolated XMOS/WM8740 24/192 USB DAC

post #1 of 9
Thread Starter 

Hey guys, my local Firestone Audio reseller recently received the new 2013 models and after checking their website, I couldn't resist borrowing their new "Custom Cute" USB DAC and post impressions in here while I'm at it happy_face1.gif

 

 

 

Here's the official url: http://www.firestone-audio.com/fsa_firecute/fsa_firecute_customcute.html

 

I've never been too interested in "me too" products when after quite a lot of digging you can always manage to find innovating products that try to squeeze in the most proven-to-work current solutions and add "unseen before" features......and all this for a reasonable price.

 

New $1K DAC's are being constantly released, but the "Custom Cute" costs $299 and its SupplierHD PSU $189...That's a whole different story, especially if you have a cherished headamp and no use for a cheapish TPA6120 headamp in your DAC(or obsolete/technically inferior S/PDIF & AES-EBU inputs).

 

here are some internal pics of "Custom Cute":

 

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You'll notice the XMOS chipset, that only requires drivers on Windows(they also come with ASIO 2.2 capabilities) and it's not fed by two low jitter clocks this time but by the same PLL1707 audio clock as in the Firestone Bravo transport that provides "perfect" zero PPM clock signals...talk about accuracy!

 

Then the I²S signal extracted from the XMOS chipset goes through an ISO7240M digital isolator that will provide galvanic isolation between the <XMOS computer side and the >WM8740 DAC side. I have yet to see this kind of design anywhere else, let alone for $299 ph34r.gif

 

Sure there are ADuM4160 isolators out there but these are capped to 12Mbit/s USB, I²S isolation would very much appear as the best solution to noise-free computer audio. If you have a noisy laptop, look no further the future of computer audio is here(and it doesn't cost 5 grand either ^^).

 

Then the isolated I²S signal is fed to the world acclaimed WM8740 DAC chip, that won this subjective shoot-out FWIW: http://www.audiodesignguide.com/DAC_final/DacFinal.html

 

Being a voltage output DAC chip, it does require a dual opamp for low-pass filtering but Firestone Audio played smart again and provided two swappable single opamps instead of a dual chip, so they both get their own dedicated power rail/caps and no need to bother with soldering tiny single SOIC8 opamps onto DIP8 adapters anymore...just roll the usual suspects(AD797, LT1028, OPA627) et voilà ))

 

It comes stock with two OPA604 opamps, that would apparently be notorious for being hard to please: http://www.head-fi.org/t/501046/the-lovely-cube-headphone-amp-lehmann-black-cube-linear-clone/975#post_8136795

Quote:
If OPA604 (or OPA2604) is placed in good circuit, it will blow away OPA2132/2134 and lots more expensive opamps. But OPA604/2604 is like king. It needs the best treatment and it is very picky about capacitors, resistors and circuit topology. But when it really sings - then you see the difference.

 

Of course the SupplierHD linear regulated PSU and galvanic isolation both would very much apply as "best treatment" to me happy_face1.gif

 

 

I should also state that the XMOS chipset is USB powered(which is mandatory for galvanic isolation as both sides can't technically share the same PSU) so I tried my luck with a whole bunch of audiophile USB PSU's that only ended up making the sound muddy and unfocused....quite a surprise to me to say the least. Long story short, I guess Firestone do know how to properly filter the noisy computer 5V signal huh blink.gif

 

 

Now, for the SupplierHD PSU: http://www.firestone-audio.com/fsa_firecute/fsa_firecute_supplierhd.html

 

 

 

It's always been a great idea to run the PSU within a separate faraday enclosure so EMI/RFI pollution onto the audio circuit will never be anything to worry about, it's great to see that Firestone kept up with this approach =)

 

I've made a few internal shots:

 

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I can't tell much about it except that:

 

-the official link claims it to be an improved design over the previous Supplier PSU, providing two ±12.5V rails instead of a single ±24V

 

-it can simultaneously feed two FireCute serie units(the old one could only output 0.2A, the new one up to 0.6A)

 

-It comes with two mini-din DC power cables that are very stiff and appear strongly shielded, a far cry from the über-thin DC cables of the old Supplier PSU.

 

-there is a 110/220V jumper switch, which was not the case for the old Supplier PSU.

 

 

Here are some pictures of the CustomCute/SupplierHD combo:

 

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My reseller's demo unit came as a Christmas special edition, but the regular version won't have any mention of this.......just "Custom Cute".

 

The DAC itself comes with a front switch to either use the SupplierHD PSU or the stock wallwart/old Supplier PSU. On the back of the unit, you only get the USB input, RCA output, SupplierHD PSU mini-din input and wallwart/Supplier DC barrel input.

 

So now that I gave a good overview of what's in the shiny boxes, time for me to fire up the combo by pluggin it to the line-input of my DP1:

 

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2 minutes to install the XMOS drivers, setup foobar for ASIO et voilà.

 

Oh wow, Firestone's new sales pitch is the HD acronym.......well, they sure didn't lie biggrin.gif

 

I can also hear why many ppl rave so much about WM8740 because it really does provide a highly enjoyable SQ, not as refined as AK4396/AD1955 of course....more like a nice in-between the "sterile/clinical/boring" sound and the lofi yet euphonic SQ of NOS DAC's for instance. I've never had too much interest in R2R because I couldn't locate any fairly priced DAC unit embedding them together with a serious USB input, but WM8740 certainly sounds excellent in this DAC.

 

The clean PSU, galvanic isolation and single opamps all pay in cash SQ-wise to my ears.....signal path is short, clean, SQ is uncompromising and the SS 3D'ness sounds as real as it's gonna get. I also didn't notice any harshness and I can only acclaim Firestone for putting together this HD sounding little unit. This kind of SQ for a bit less than $500 makes this combo a serious contender to feed a discrete/tube headamp I think, so you can benefit from a very clean DAC output and color it however you fancy afterwards.

 

I also had fun rolling opamps of course:

 

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They both kind of tamed down the clarity of the stock OPA604 opamps but I wouldn't say that they sounded "better".......but more like less "focused" and more "relaxed", which might or might not be what you are looking for. OTOH, opamp rolling is meant to allow you to find the SQ color YOU want to hear in your rig.....so it will all depend on your headamp, the quality of your source files, your phone and more than anything else your personal taste. AD797 and OPA627 would be worth a try, too bad I didn't have any of them aroundpopcorn.gif


Edited by leeperry - 5/30/13 at 6:55pm
post #2 of 9

399$ ? Found at 299$

 

http://www.hideflifestyle.com/firestone-audio-custom-cute-headphone-amplifier.html

 

http://www.avhifi.com/shop/firestone-audio-custom-cute-usb-dac.html

 

So it's even better for the price ^^

post #3 of 9
Thread Starter 

Oops yah, my mistake! Fixedbeerchug.gif

post #4 of 9

So are you saying it sounds better than our Eximus DP1 s? ;)

You might as well compare them.

post #5 of 9
Thread Starter 

Hah, well the DP1 is notorious for its sweet, forgiving yet very detailed "live sounding" 3D SS......It also requires a serious USB PSU in order to sound its best IME(the 6moons owner also tried every kind he could put his hands on) so that's $3K + $250 basically. 

 

The Custom Cute doesn't sound sweet or forgiving, it sounds "straight to the point" with a lot more details and an equally impressive 3D SS for a DAC, it would only require a more relaxed headamp IMHO, and possibly something hybrid or discrete in order to add a more euphonic character to the sound. That's where I wasn't too fond of rolling opamps when feeding the DP1 headamp because the latter also sounds pretty colored.....but if you are using a clear sounding headamp then rolling "darker" opamps such as OPA627 might be a great idea.

 

I'm still very impressed by what $500 can buy you these days...and again I have yet to hear of a galvanically isolated XMOS based DAC, FSA really did a "coup de maître" IMO as you are not forced to make do with S/PDIF isolation anymore. That's the major added value of this DAC IMO.

 

"better" is so subjective, I've owned the DP1 for +1 year now, I've heard a good share of high bang/bucks DAC's in the meantime but the DP1 stays wink_face.gif


Edited by leeperry - 5/8/13 at 3:05pm
post #6 of 9

got one last week as my ILTW is dead

 

the highs are very good. better than the ILTW.

 

mid low and lows are mediocre. male voice and kick drums not very natural.

 

will swap the opa604ap to opa627bp to see if there is any improvement

 

as i play this little bugger near my monitor i had to disable the illuminated top by taking out the upper board

 

previously was using asio4all via mediamonkey. now i had to use the custom cute asio which is very good.

 

no indication of the input sample rates like ILTW is a minus.  direct connect with USB2 instead of ILTW direct connect to USB1 and pressing the little button at the back every time when switch on computer is a plus

 

for around $300 this is a good item.


Edited by cpu8088 - 7/6/13 at 8:32pm
post #7 of 9
Thread Starter 

Oh yeah, I forgot to mention the illuminating upper board but who cares about it tbh...all it really does is decrease the cooling capability of the aluminium enclosure and opamps are well known to provide better specs as temperature decreases.

 

Genuine OPA627BP's are pretty pricey(cheap ones are more than likely fake), you could also try OPA1641's on adapters. That's a really great sounding chip and it's cheap too.

 

There is no question that the XMOS 32bit ASIO sounds far better than ASIO4ALL ever will IME.

 

It's indeed a really great "bang for bucks" DAC if you really only need a USB input and a RCA out, the nice added value is that even the noisiest laptops will never cause any ground loop.

 

Of course if you want a more elaborated output stage(than a voltage output DAC chip through two single opamps as LPF), a headphones output or sample rate front led indicators then this is not the right unit....compromises again happy_face1.gif

 

The ILTW is using the TE8802L USB chip which is a terrible solution IMO, mostly bastardized at the last minute over the ubiquitous isochronous TE7022L, together with horrific ASIO drivers and poor real-world performance(there's only so much you can get from PLL clock synthesis) .


Edited by leeperry - 7/7/13 at 3:26pm
post #8 of 9

just swapped the 2 opamps with Burr Brown opa627bp.

 

the highs are more solid and less prominent than before, making the bass with more attacks. mids are very smooth and silky. very listenable.

 

got them cheap from ebay. about half the price than from farnell.

post #9 of 9

the opa627bp is a worthwhile mod

 

that lead me thinking firestone audio should use that as stock instead of the cheap and inferior  opa

 

to maintain the same price:

 

1) skip the exotic packaging

 

2) do without the free interconnect rca cables

 

3) get rid of the board with light showing the firestone logo and print the FSA logo on front plate

 

having some means to show input sample rates would be nicer. either by indicator lights or icons in task bar will do

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