JCAT Femto USB Card

I would like bring awareness to something that has drastically changed my computer audio experience: the JCAT Femto USB card.

The USB was very easy to install specially since Win 10 Pro recognizes the card without installing a driver - true plug-n-play. I was initially unimpressed with the sound and decided to burn in the card by continuously feeding signal through it for a week. OK, now I'm impressed. The imaging is so surefooted/solid and are emerging from a black background that I'm now experiencing my system in a way I have not experienced before. Even bass and midbass produces a solid image. The soundstage has become well layered and has grown a bit in height possibly due to increased midrange clarity. I thought my computer setup was excellent which is why I did not anticipate such a great improvement. My system is very revealing and all components have been modified with upgrades such as capacitors, resistors, diodes, fuse swaps, etc. This upgrade is a large step toward realism and allows my system to show off it's capabilities. The JCAT USB Femto card is highly recommended.

I ordered from the highend-audiopc website and had a positive purchasing experience.

It's good to see new products in the small PC audio market. Hopefully, in time, we'll see better competition and prices.

I've been using the original JCAT USB PCie card with its own power supply, with the JCAT 2 into 1 USB cable for 3 years now. It feeds into my Antelope Platinum DAC (+Rubidium Clock) and the music is as good as you can get. I use HD-800 phones so I can hear all the music issues as I convert each.

I convert my own music to WAV 24/196 and use the JCAT setup to vet each recording before sending to my NAS storage. I have been considering changing to the Femto card but they are expensive. Heck all our gear is expensive!


Thanks for sharing your impressions. I’m glad you’re enjoying my product.
If you connect a linear PSU to the card, it will get even better. 

Best regards,
JPLAY & JCAT Founder

I'm definitely considering a linear PSU for the JCAT USB card once I complete a speaker project that is underway. 

I look forward to the increase in sound quality but I don't look forward to adding another component that I have to turn on and off when I use my system. 

Mojo Audio has an internal voltage regulator that is powered by a molex cable. I would have loved to use this with the USB card but Mojo does not have the aluminum plates and can only sell the bare circuit board leaving the customer to find an aluminum plate / heat sink. 

Would it be possible for you to develop a component similar to Mojo Audio's internal regulator module? That would be very convenient to someone like me who prefers less components connected to the wall or power conditioner. 

The internal regulator from Mojo provides a nice improvement, even when combined with a linear PSU (I've tested it). But like you said, there is the heat issue - it must be installed on a large heatsink otherwise it gets extremely hot. 

I have no plans to develop such a product in the near future. Hope you can find an alternative solution

Best regards,
I installed the Mojo Audio voltage regulator inside the PC using a heat sink purchased from Mouser that fit the regulator almost perfectly (Mouser #: 436-F-DA50D). I used leftover thermal grease from my CPU/cooler project to couple the regulator plate and heat sink together.

So far so good. The regulator provided a bit of focus to the already great soundstage and removed grit from the sound. Mojo's regulator is definitely a worthwhile upgrade to a revealing system.
I forgot to mention that I used a pair of #8 x 1/2 inch screws + nuts to fasten the heatsink and regulator plate together.

The following links are photos of the installation. I posted a typo in the previous message: The correct screw size is 8-32 x 1/2".

You’ll notice a smaller heat sink in the photos. It’s the same size except the fins are much shorter. I used the shorter heat sink but I opted for the larger heat sink for good measure.

I almost used an entire container of 3.5 grams of Arctic Silver 5. I consider it an upgrade for the sake of thermal management.







@marcin_gps  I finally bought a linear power supply for the USB card. The jumper was set to "no filter". The soundstage is way more spacious and layered, digital glare is gone, detail is more realistic yet smooth, and bass is abundant and solid. It is imperative for the JCAT USB card to use an LPS. The power supply that I'm using is the UltraCap LPS 1.2 which was purchased directly from Uptone Audio. I regret not having purchased an LPS sooner.

I have a question about the,  JCAT Femto USB card.

I am wondering if using this card would improve the sound quality of my very entry level system?

Here is my equipment:

- HTPC (built it myself)
- Questyle CMA400i DAC
- Vincent Audio SV-500 Integrated Amp
- Martin Logan Motion 40 Speakers
- Jriver Software

I have also read that getting a better USB cable could also improve sound quality.

From my computer, I listen to the following formats of music: DSD, Qobuz and ripped CD's (FLAC).

I would say everything sound pretty good but am wondering if combo of the  JCAT Femto USB card. + better quality USB cable could produce significant improvements?

Would I need anything else? I was also reading about a power supply?

Is that a optional power supply that connects to the USB card and is it necessary?

And final question, I am assuming I would need to configure Jriver to work with the USB card, is that correct?

If anyone is interested you will get even better sound by getting yourself a JCat Femto Network card and your streaming will sound wonderful.
@jay73 There's no doubt that my system cannot sound the same without the JCAT Femto USB card. It's sound quality is at least 70% of the improvement that the Pass XA25 provided to my system and only a 5th of the price when you also include the price of a linear power supply.  

It's imperative that you use an LPS with the USB card. I cannot recommend the USB card without it. 

@jim204 I don't have a home network to stream music from one room to another. I don't my system will benefit from the network card. Let's see if @marcin_gps can chime in on this topic. 
@c_avila1    I have to say that anyone will notice a difference if they are using a wired network to stream music and I do agree that an LPS is mandatory. I use both cards with one and can really recomend them as they have made an incredible difference to the sound from my PC.
I purchased a JCAT and Mojo Audio voltage regulator.  I can say that the voltage regulator runs exceptionally cool, and after having it on for some time it is only mildly warm to the touch... .

While the difference with these two devices is noticeable (fuller, more dynamic and detailed sound), I think it is highly system dependent.  Compared to the new asus motherboard USB running off a Seasonic fanless titanium 600w power supply, with a relatively revealing front end (Lampizator Amber 3->Pass XA25-> Accuton Cell based speakers), I'd say its a somewhat worthwhile but very expensive difference to pay for.  Compared to the optical out of my TV, or the usb of a 10 year old Lenovo laptop, the difference is staggering and equals that of a major component change and is a relative bargain.  In other words, having heard the difference in my system I won't be going back to the motherboard USB... but if I had known in advance, I might have decided to address other weaknesses first.
@npdang You're not experiencing what the JCAT is capable of because you're not using a linear power supply. You can buy a budget LPS from Ebay which ship from China or get a high end power supply like the Illuminati V3 from Mojo Audio or a Farad Super3.

I also highly recommend that you purchase or make a high quality DC cable. Cerious Technologies made me an excellent Graphene Matrix DC cable. Zenwave and Verastarr can make custom DC cables as well.
I forgot to mention I am using a HDplex LPS in addition to the Mojo.  Compared to new tubes, speaker cables, etc. I just didn't experience the same level of improvement for the money, but as I mentioned before it was enough that I can't possibly go back :P
@npdang                      Just reading about your experience With the HD Plex supply. If I can give you some advice it would be to ditch the cables you received from HP Plex and and replace them with better ones. I now have silver core cables feeding my J Cat cards and it is a huge difference,give it a try you will be pleasantly surprised.
@npdang A single USB output on the JCAT cannot be powered by the Mojo voltage regulator via molex connector and LPS simultaneously. Disconnect the molex cable from the USB card and make sure that the jumper on the USB card is set to the appropriate position to feed power through the external linear power supply. 

This bears repeating: Disconnect the molex connector from the JCAT USB card and feed it 5 volts from the LPS.