Endplate Experiments & RCA Jacks for ODAC

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CNC Experiments

Nick has spent the past three weeks making noise, breaking drill bits, and splashing super fun blue coolant all over the office. Most people don’t pick up mechanical engineering and machining as new “skills” in just three weeks, but we do what we have to here.

First batch of reasonable test parts, despite artwork mistakes and over-sized screw holes

With the basics of CNC’ing out of the way, our attention has turned back to the reason we bought the CNC in the the first place. We want brilliant quality, and we want our parts now.

We’ve specified brushed aluminum on our endplates since they were first designed. It turns out that most aluminum suppliers do not offer brushing. The process is a time consuming and challenging task even for most machine shops. That was a disappointing discovery!

Our endplates will still be brushed, but this sourcing realization led us to experiment with the aluminum. The test pieces shown above were machined at our shop on Friday afternoon, then plated on Monday morning in downtown St. Louis. Clear alodine and black anodizing finishes both look fantastic. And it was all done in under 2 business days. 🙂

O2+ODAC Rear Panel with 3.5mm Output

Rear B2-080BK endplate with 3.5mm ODAC output

Although we don’t recommend that you install a 3.5mm output jack on your O2+ODAC, some customers have requested to do so anyway. This is for you: Machined O2+ODAC Endplate w/3.5mm output. These are made from stock endplates included with the Box B2-080 cases, thus, the price is lower than other endplates.

RCA Jacks for ODAC

RCA jack on an O2 Endplate. Hey, it fits!

Okay, this isn’t an ODAC or even a reasonable device. But it is a proof of concept for our Standalone ODAC w/RCA outputs.

We’ve avoided RCA outputs on the Standalone ODAC for several reasons. RCA jacks take longer to assemble and cost more than a 3.5mm jack, but this has been irrelevant to our decision.

We haven’t offered RCA jacks on the ODAC due to virtually identical performance: Why complicate a product with multiple variations and increased build cost at no benefit? The 3.5mm jack on the ODAC circuit board is wired to the same line output header as used by RCA jacks. Some customers have asked, “Aren’t 3.5mm cables more lossy than RCA?”. As NwAvGuy has stated, characteristic impedance is a non-issue in unbalanced audio systems. There are no impedance mismatches to be concerned with, and there are no significant losses resulting from the use of a 3.5mm cable. Crosstalk might change negligibly (1-3dB), but overall, it’s a myth that RCA cables are less lossy than 3.5mm cords. Case in point, why would NwAvGuy (an audio benchmark and measurement fanatic) have designed the ODAC with a 3.5mm jack if it were “lossy”? He wouldn’t have! I’m sure NwAvGuy can provide benchmarks if badgered.

3.5mm to RCA Cable
3.5mm to RCA Cable

Moreover, you can use a common 3.5mm to RCA cable for direct connection of a 3.5mm device to an RCA device.

With all of that said, it’s easier to build products customers want, than to convince everyone that what we’re building is the best solution.

So last week we set out to fit RCA jacks into our Standalone ODAC enclosure. I had briefly collaborated with Stefan of Head ‘n’ HiFi earlier this year on the Standalone ODAC case. We’d been asked by NwAvGuy’s contractor to lead the design and distribution of a standardized ODAC case for the DIY community. I wanted ultimate enclosure quality, and was willing to wait until late July for a custom case fabricated in the USA.

However, Stefan wanted cases immediately, and didn’t think he could fit RCA jacks into our thin case, with only 10mm to work with (a typical RCA jack is 9.5mm). Stefan’s a nice guy, but we had to agree to disagree on our design goals. Product excellence is more important than expedited delivery and cost, especially when a product will stick around for years to come.

Despite the tiny clearance, we’ve managed to design ODAC endplates that will accept 2x RCA jacks and still fit into our thin ODAC enclosure, without losing ground isolation. This is only possible due to a beautiful, black anodized finish. More pictures are coming soon. For now, imagine the gold RCA jack pictured above on our Standalone ODAC.

ODACs are scheduled to arrive July 19-25. All Standalone ODACs will ship by the end of July.

14 thoughts on “Endplate Experiments & RCA Jacks for ODAC”

  1. Hey JDSLabs,

    It’s great to see so much progress! I love the options to engrave the new amps, as well as the black endplates. Do you think you could make black endplates for the C421 and 3.5mm ODAC as well? Lots of people would probably be interested. Fantastic work though!


    1. Thanks, Tony. Yes, we’ll offer black endplates for all of our products. It shouldn’t take long after we knock out ODAC orders. Lots and lots of endplates to make for those…

      1. I just saw your pictures on Facebook and they look fantastic. The smaller case is beautiful. Great work again!

  2. Hey JDSLabs,

    Are you guys going to continue using the oversized c421 case for the ODAC or considering changing to a smaller case? I am a pleased customer with a O2 and would like to purchase an ODAC from JDSLabs, except I find that the case makes it less aesthetically pleasing when stacked on top or beneath the O2.



    1. John,

      Custom length ODAC cases are in production and will be available around the same time the second batch of ODAC boards arrive. Length is 49mm (versus the 95mm c421 case length).

      If you have an unshipped ODAC preorder/backorder, you may request the 49mm case by email. If placing a new order, make your special request in the order notes. We’ll add more information to the store page as soon as we have cases in stock. 49mm cases will become the standard.

  3. Hey JDSlabs! I’ve been faithfully waiting for a new update to no avail.

    Could you guys post some pictures of the different options available sometime when you get free time?

    It would just be great to see all the finished product options, such as the 49mm case vs 95 mm case, black faceplaces vs silver faceplates, and rca vs 3.5mm

      1. The new cases look awesome. I have a bare ODAC board that has been waiting for this case for a while…. Please let me know how to order the case.

        1. Cases and endplates will be posted to our store as soon as we establish extra inventory. Backorders are the #1 priority this coming week.

  4. Hi JDS Labs,
    I want to thank you for getting out my C421 when I called at the last minute late in the day on a Friday back in early December.

    I have finally had some time to sit down and really put some attention on the finer aspects of the unit. I am using the C421 with the new V-MODA Crossfade M-100 headphones, a set of V-MODA Remix 4S IEM’s, and also a set of Shure SE425 IEM’s. All of them recent acquisitions, except for the Remix 4S.

    I also purchased a FiiO Andes (E07K) Portable USB DAC and Headphone Amplifier round the same time for my son. The FiiO E07K is their latest offering and considered one of their two best portable amplifiers. For my source I have a couple of iPod 160GB Classics and an iPhone4 32GB. My music is all either 320k fixed rate ripped directly of my CD’s or Apple lossless .M4a format.

    I have been playing a wide variety of music from all three completely full units and listening direct from the sources and through both amplifiers via a FiiO L11 Line Out Dock (LOD) Connector and a Nuforce Transient High Performance 3.5mm Cable.

    Here is what I found.
    Prior to using the exceptional headphones and external amplifiers I never realized a difference in the fidelity of the iPhone4 and the iPod Classic 6th gen (original and 2nd revision). The iPod Classics are definitely better to my ear.

    Both amplifiers offer considerably enhanced fidelity over the raw sources. Details and soundstage are dramatically improved by both amps. The music, which was already pretty darned good with just the two exceptional headphones came alive even more with the external amps.

    Some music sounded comparably worse than I had remembered in the past (with lower quality headphones). I believe this is because the amps bring out so much subtle detail that the imperfections become apparent. With these “lower quality” recordings I seemed to be able to draw out a finer quality result using the FiiO E07K amp with its bass & treble controls used to bring out or balance out the mix. I found maybe 5% of my recordings fell into this category

    Fortunately, most of my music is top quality stuff and with this music the clear winner is the stunning clarity and subtlety of the C421. At first listen when I got the C421 and tried it out I initially though “Hmm, I can hear a difference, but not a $185 difference”. This was standing up, playing a track and listening to 30 seconds, trying it with and without the amp listening to the same 30 seconds. Now that I have been able to lay back and calmly listen to entire tracks and albums with both amps, or without any external amps, the difference to me now is nothing short of stunning. The C421 is a work of art, visually and especially aurally. The FiiO Andes E07K is a wonderful amplifier, and at $89 is a real steal IMO, but the C421 just adds a measure of fidelity that is hard to put into words. It’s as if you can see the electrons flowing through the circuit being nurtured and pampered at every junction (OK, I’m an engineer). The bass boost adds a perfect amount of boost for the Shure SE425’s, while the V-MODAs are so adept at playing bass they don’t. need it. The quality of the bass is clean and crisp right on target with a nice punch without ever overdoing it. Crisp is not a word I would typically use to describe bass, but that is what it is. The Crossfade M-100’s play a huge role here as they have amazing bass, but the C421 amp takes it even one step better than the FiiO E07K.

    Like I said earlier, there is some music that benefits from the separate bass and treble controls of the FiiO Andes E07K, and it is a very fine amp to do that job. In the perfect world I would have the progeny of the C421 that would add the bass and treble control without sacrificing any of the electron pampering of the C421. It would just coerce them a bit more if needed.

    If I might add a suggestion, which may not be practical due to the layout inside the unit. It is a real hassle to use the unit when it is all wired up. I have two USB wires for power to the source and the amp, a wire from the source to the amp, and a headphone wire. With everything attached it is difficult to stick a finger in there to adjust the volume or flip the bass boost switch, especially in the dark. I would like to see the power switch, volume control, and bass boost all on the one side, with all the connections on the other. Gain switch can go wherever it works best. I realize there may some implication for the fidelity and/or space with the battery in there, but it’s just a thought.

    Thank you JDS Labs for a really fine amp. It brings out even more enjoyment from my fine equipment and music.

    1. Dan,

      Nick has experimented with this. Bluetooth isn’t recognized as an audiophile grade method of audio transmission, so no solid plans…

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