Prior to whatever tuning changes the AD36 revision would undergo, it too combined a Powersoft module then 4th-order passive filter following the DSP. Kenaz's combination of DSP and passive filters is shared with Poland's Fram Audio who likewise prefer analog to DSP xovers. But it's not a solution one meets a lot. Once DSP is on hand, most designers execute all necessary filter functions in the digital domain. Does that make the AD36 a hybrid?
This screen shot of an older YouTube video shows the relative sizing between AD15 and AD36. The latter is significantly larger. No wonder that for his first English review, Train wanted to submit that. It'll be appropriate for bigger rooms than the AD15 especially when, as I favor, the speakers sit well clear of the front wall to stage deeper and minimize boundary gain. My Cen.Grand DSDAC 1.0 Deluxe runs analog R2R on-chip volume by way of a Muses opamp. My Sonnet Pasithea DAC from Dutch auteur Cees Ruijtenberg runs remote-controlled variable reference voltage on its R2R resistor ladders and is another balanced design. I had two variable downstairs sources to front the review speakers.
On my desktop, iFi's iDSD Pro Signature DAC is fully balanced also with analog volume while a legacy Auralic Vega uses Sabre's digital code. Upstairs I'd use an icOn 4Pro autoformer volume control. I had three scenarios to drop the Taiwanese visitors into. Six months after I penned this intro, Train was back. "The latest AD36 is finished and ready to ship. Please let me know when you're available." I was so I did. Basic specs are 94dB sensitivity, 40Hz-18kHz bandwidth, dimensions of 24.6 x 37 x 38.8cm WxDxH and weight of 14.6kg. The internal DSP runs once more at 96kHz.
"Our website is currently being updated. We're still working on it but should be done soon." In the interim Train sent me a flickr album link to see his new finish. Now that was ready for prime time. So was the price: €11'500/pr. Purists who flare their collective nostrils at redundant A/D conversion upon entry will prefer the 'pro-audio' option of AES/EBU. Even in our sector they can find a few digital transports with built-in remote volume like for example Auralic. I simply had none of their rare kind. I'd step into impurity by entering analog. Here common sense tabulates gains and losses. Should A/D conversion incur a 1% loss but the DSP which it enables create a 30% gain in linearity, time alignment, bass extension, dynamics with built-in overdrive protection and more… only the math-challenged would cry over the one percent. On how the current AD36 deviates from the original, "the obvious and biggest difference is cosmetic. Besides this I also adjusted the cab's internal structure but this change wasn't that impactful. It was mainly for assembly efficiency and I could tune out this tiny difference with the built-in DSP to recapture the exact sound I had originally designed for this model."
I had more questions. "Could you explain your concept for venting both woofer and coax? From the drawing it looks like some air vents being more for depressurization of the back wave than classic port resonance gain." "Of course. First, I picked a coaxial main driver which in active guise is rare and typically suffers insufficient bass. Adding a standard woofer would enlarge the cabinet and involve either a classic ported or transmission-line design. Now the speaker's overall size would become a bit unwieldy. My past experience and inspiration from some PA systems then pointed the way forward to an internal angled woofer. If you calculate my cabinet, it looks like utter nonsense. It should cause real issues for all the drivers. But I'm using high-quality PA parts known for their accuracy and high power handling at low distortion. This creates sound of crystalline clarity which is a total disaster to the average audiophile. So I added some air vents on the top and front. They release air pressure on the coax to let it breathe; and inject a kind of 'dirtiness' which reverts the squeaky-clean sound back to audiophile normal. My small woofer is typically a mid-bass driver but being a PA part, robust enough to allow me to sink very high power into it to perform like a subwoofer. I use a 700-watt power module on this driver. The overlapping active crossover then pushes the coax's efficiency to the next level. The exact details of this are a bit complicated. All I'll say is that it's our own solution on how to tune the EQ, power and efficiency in a balanced way. I think that the result is a rare active speaker without any true equivalent in today's market. It's quite a complex system actually."
Next I asked Train what had him prefer a passive filter on the coax preceded by DSP; and an active on the woofer. "The reason why the coax uses a passive crossover is that my power amp and DSP are 2-channel only yet this is a 3-way. I had to reduce one channel to match the electronics. My solution is somewhat tricky in that the passive filter allows me to combine two channels into one. Yet I use no resistive elements in it to match tweeter and woofer sensitivities. I pre-correct for this in DSP instead to avoid padding resistors which compromise treble performance. Technically this is still a 3-way active speaker; just with a wrinkle. Top-tier German PA brand d&b use it too and their line-array systems consistently require just half the power typically needed for a given number of drivers. They also combine multiple channels with DSP pre-processing." Right after Taiwan's annual Dragon Boat festival, my samples would ship with a temporary importation or ATA carnet to circumvent customs/VAT hassles as well as not land Train re-importation fees back home.
An intermediary Irish shipping agent emailed me the carnet well before the speakers left Taiwan. I was asked to check its accuracy. Everything was spot on; except being good for a full year. I explained to the agent that I wouldn't need these samples longer than 3 weeks; and to expect my request for return pickup accordingly. While I waited for international freight to do its thing, I return you to one of the more amusing bits of hifi chat I've come across: "…sound of such crystalline clarity is a total disaster to the average audiophile. So I added some air vents on the top and front. They release air pressure on the coax to let it breathe; and inject a kind of 'dirtiness' which reverts the squeaky-clean sound back to audiophile normal." Audiophilia as a pro engineer's poor whipping boy? Wondering about Train's "dirtiness", I imagined small time blur from delayed rear energies mixing with direct emissions across the coax's bandwidth; perhaps even some comb filtering and anti-phase cancellation effects off axis. Whatever it was, I thought it wicked that the high-end at large promotes ever more resolution and 'an open window on the music' while Train implies that our kind can't stand the squeaky-clean truth to need some dirt on our windows.
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