Hapa Audio Aero Cu Coax (S/PDIF RCA)

Zuman

Active Member
Feb 25, 2023
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I recently moved my primary system from a built-in shelving-and-cabinet arrangement in our living room to a freestanding rack in a lower-level recreation room. Moving from the constraints of the built-ins to a Solidsteel S-Series rack allowed me to be more selective in both my speaker cables and interconnects, choosing shorter runs and having much better access for switching cables and components in and out.
In its simplest form, I have a NAD Masters Series M50.2 digital vault/player connected directly to a NAD Masters M32 integrated digital amp (the M32 not only includes preamp functions and a DAC, but also has an MM phono input, which immediately converts the phono signal to digital before performing any other operations with it). The M32 is particularly noted for extremely short signal paths. I also have a modified Rega table, but I didn't use that in the listening I'm writing about here. My speakers are CSS Criton 2TD-X MTMs with the upgraded crossovers, on Isoacoustics GAIA II feet, sitting on sand-filled Pangea stands, and connected by Audio Art SC-5 ePlus Cryo cables.
I decided to compare the few digital interconnect cables I have on-hand with Hapa Audio's digital RCA copper coax with the aerogel dielectric. Given aerogel's unprecedentedly-low material-to-air ratio, I was interested in whether I could actually hear any difference between that construction and a more traditional dielectric.
I asked Jason Wong of Hapa Audio for two of those interconnects to audition because I'd also just purchased a miniDSP SHD streamer/Dirac processor, and with that inserted into the system, I'd need to run one digital coax from the M50.2 to the miniDSP and another out from the miniDSP to the M32 (without the miniDSP, I could use just one digital interconnect between the M50.2 and the M32). Jason graciously responded and shipped two 0.75m cables out to me.
My first listening was conducted without the miniDSP. Because I already own an Audioquest Coffee AES/EBU cable, I could easily compare the Coffee AES cable with an S/PDIF coax by having them simultaneously connected and just switching inputs back and forth using the M32's remote control.
To have a comparison point, I first compared the Coffee AES with an Audioquest Cinnamon S/PDIF RCA interconnect. There was a clear difference when switching between the two, and because I could do so instantly I could tell every time which was which. The overall volume levels matched (according to my meter), but the Coffee AES sounded much smoother, rounder, and fuller than the Cinnamon S/PDIF, which was more "etched" sounding, especially in the mids. I thought that the Coffee AES might have been a little shy in the highs, but assumed that could be related to my 70-year old ears... My preference, however, was consistently for the Coffee AES/EBU over the Cinnamon S/PDIF coax.
When it was time to try the Hapa cables, I first left the Coffee AES cable connected so I could use the remote again to quickly switch between the inputs and see if the Hapa S/PDIF cable had the same contrast with it that the Cinnamon had demonstrated. Of course, up to that point I didn't know if the difference I had heard when switching inputs was due to any AES/EBU vs S/PDIF interface difference rather than cable performance.
Nope.
Once again, the AES input sounded quite different from the S/PDIF input, but this time the S/PDIF sounded better. The Coffee AES still sounded smooth and full, but the Hapa Digital Aero Cu Coax also sounded smooth and full, and with much more engaging mids and highs. While the Cinnamon coax was harsh in the mids and highs, the Hapa coax was airy and open without being grating. I really love when you can hear the bow across the strings of a bass, cello, or violin, but I don't appreciate when it sounds scratchy or scraping. Similarly, hearing a singer's breathing is so intimate, but sometimes that comes at the expense of top-end shrillness. The Hapa Digital Aero Cu Coax got it right. I suppose that my simplest explanation for my preference is that the AES/EBU cable sounded, to me, full, mature, but a bit boring. The Hapa Aero Cu Coax, however, sounded full, mature, but athletic and engaging without being brash.
After deciding that the Hapa cable wasn't doing anything I didn't want it to do, I put the miniDSP into the chain and did a Dirac calibration. I was surprised that Dirac didn't find a lot of things to correct, but it did fill in a few holes and remove a little low-mid bloom. It also made the soundstage more convincing and realistic. While I'm not a big fan of "Jazz at the Pawnshop" musically, the recording does reveal a lot, and it was pretty darned compelling. Keith Jarrett's Standards I and II delivered an equally "you-are-there" experience. Pink Floyd's A Momentary Lapse of Reason was wonderfully silly and entertaining from subwoofer-level frequencies to beyond my hearing range.
Finally, my biggest test is whether Sir Malcolm Sargent thundering through Messiah with the Huddersfield Choral Society and the Royal Liverpool Philharmonic sounds like a dense and congested audio stew or if I can clearly hear the divisions in the chorus and particularly the strings. Yes! Even though it was clear that the microphones were regularly overdriven, it was gloriously enjoyable.
After a little less than two weeks with the Hapa Digital Aero Cu Coax interconnects, I contentedly sent Hapa Audio a PayPal payment. They are superbly competent cables that deliver a complete, engaging, and sophisticated high fidelity experience.
 
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My comment will apparently be on topic concerning built-in bass/sub amps in full range speakers. I am torn between purchasing a Von Schweikert passive versus their assisted powered woofer speaker. The latter is claimed to permit great leeway in setup so that the bass can be dialed in later as opposed to adjusting the speakers (perhaps endlessly). Or using subs. My former music room was 25X23X11.5 but my permanent new music room is only 20X15X10, however designed for superior acoustics (slightly live with built-in wall carbon bass filtering ala J. Gordon Holt's desire). Music genre doesn't matter as bass is either present and well recorded or not (hopefully not poorly recorded or mastered too loud or mushy). I considered the Orion but it is double my budget. Looking at a Von Schweikert instead, probably powered for ease of installation (permanently).

Did anyone consider active or assisted bass speakers here before their decision? I don't want subs in a medium size room. I heard subs in big/huge rooms and they worked great.
 
My comment will apparently be on topic concerning built-in bass/sub amps in full range speakers. I am torn between purchasing a Von Schweikert passive versus their assisted powered woofer speaker. The latter is claimed to permit great leeway in setup so that the bass can be dialed in later as opposed to adjusting the speakers (perhaps endlessly). Or using subs. My former music room was 25X23X11.5 but my permanent new music room is only 20X15X10, however designed for superior acoustics (slightly live with built-in wall carbon bass filtering ala J. Gordon Holt's desire). Music genre doesn't matter as bass is either present and well recorded or not (hopefully not poorly recorded or mastered too loud or mushy). I considered the Orion but it is double my budget. Looking at a Von Schweikert instead, probably powered for ease of installation (permanently).

Did anyone consider active or assisted bass speakers here before their decision? I don't want subs in a medium size room. I heard subs in big/huge rooms and they worked great.
I purchased the VS VR9 SE MK2 with new Foundation amps (bass assist). Even cold (literally), transported, new jumper and power cables, it sounds GREAT! Mostly flat with a few adjustments for Bass Gain (reduction=2' from reflective front wall) crossover (+1 db) and tweeters and it sounds fabulous. Extremely open soundstage (depth and width), colorful, out of the box sound with great separation of performers. This with older high end tube gear (analog and digital but new DAC). The setup took only 1.5 hours as my room is extremely accommodating to speakers. Distance from side walls and between speakers was within 2 inches of the Signature IIIs.
 
I purchased the VS VR9 SE MK2 with new Foundation amps (bass assist). Even cold (literally), transported, new jumper and power cables, it sounds GREAT! Mostly flat with a few adjustments for Bass Gain (reduction=2' from reflective front wall) crossover (+1 db) and tweeters and it sounds fabulous. Extremely open soundstage (depth and width), colorful, out of the box sound with great separation of performers. This with older high end tube gear (analog and digital but new DAC). The setup took only 1.5 hours as my room is extremely accommodating to speakers. Distance from side walls and between speakers was within 2 inches of the Signature IIIs.
The only MAJOR improvement since installation was to dial the subwoofer bass phase from 0 to 180 degrees (out of phase). That eliminated the one octave hole in the mids and made the sound linear from top to bottom. The subs are too close to the rear wall. I never needed subs as I had either 6 12" or 6 10" woofers that went down low as well which were in passive speakers.
 

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