So, what'd I miss?
First off I'd like to thank ASR for the review. I am pleased that the HTP-1 is the best measuring AVP ASR has ever measured, even better than some offerings from bigger, more known brands. I also want to thank Marc for going to extra mile and measuring several of the processors in his possession. Marc and I had talked about doing that (since he seems to have all of them now, and yes, I'm jealous) and how interesting it would be long before the ASR review was published. Frankly, I was curious as to where the HTP-1 would stack up. As all can see from the myriad of measurements, the HTP-1 is certainly not a compromised product to hit a $3999 price point. Both cannot be true: The HTP-1 measures among or better than products that cost 3x-4x as much, and yet also be compromised to hit a much lower price point. There is absolutely nothing wrong with the core performance of the HTP-1.
A lot of the discussion has revealed and illustrated that there is confusion around the amp sensitivity feature, so we will be making a change to the software so this is more clear. This setting should never have accepted a 7V maximum as the maximum output of the HTP-1 hardware is just above 4V RMS. The next software release will change the UI to acknowledge this limit. Further, there was a half dB gain error in the calculation that left the 0dB voltage just under 4V. This will be corrected.
Early in development of the HTP-1, I made a statement that the output voltage would be 12V. This was completely factual at the time as early prototype boards were built this way, but when connected to real amplifiers it became clear that this capability raised the noise floor by nearly 20dB when connected to industry standard amplifiers like the Monolith series amps. The design was changed to better match the expectation of common, consumer grade amplifiers which are generally driven to clipping by signals less than 2V RMS. The HTP-1 is designed to drive amplifiers of this sort, and has been maximized to match perfectly with the Monolith amplifier gain structure (which a lot of other amplifiers follow too). I should have went back and corrected this as we were developing the product.
We could have left out the Amp Sense control and could have simply built it for a 4V RMS output, but for those with a 1.6V amplifier, this would have been an 8dB penalty. I decided it was best to give users the ability to align the HTP-1 with your amplifier.
Sorry for any confusion. We look forward to continued work on more substantial features.
I also think a fair criticism coming out of the ASR review and discussion is that we didn't publish specs of the HTP-1. Now why didn't I do that? I was more focused on the feature set and value for the $$, and not measurements. I will do a much better job in being transparent in the future. If the HTP-1 measurements are among the highest measured AVPs and products that cost 2x-4x as much, what were we hiding again? There is no conspiracy. Every production unit is measured for performance on every channel. By collecting all of the data, we are confident that the performance specifications that we release are accurate and representative of all units in the field. In fact, many of the units in the field will have slightly better performance than what we state officially.
Having said that, here are the specs, and I attached all the measurement graphs:
All measurements made on a representative production unit using an AP-585 with balanced outputs. Software version 1.3.1.
Frequency Response:
48kHz, HDMI input, 20Hz to -20kHz, +0.1 -0.2dB.
Total Harmonic Distortion and Noise at 1kHz:
48kHz, HDMI input, 1.8V output. (amplifier sensitivity 1.8V, output level 0dB)
0.00050% (106dB) *best
48kHz, HDMI input, 2.2V output. (amplifier sensitivity 2.0V, output level 0dB)
0.00051% (105.7dB)
48kHz, HDMI input, 4.0V output. (amplifier sensitivity 4.0V, output level 0dB)
0.0014% (97dB)
Signal To Noise Ratio/Dynamic Range:
48kHz, HDMI input, 2V output. (amplifier sensitivity 2.0V, output level 0dB)
114.8 dB A-weighted
111.1 dB CCIR-2k
48kHz, HDMI input, 4V output. (amplifier sensitivity 4.0V, output level 0dB)
116.1 dB A-weighted
112.2 dB CCIR-2k
Channel Separation:
48kHz, HDMI input, 2V output. (amplifier sensitivity 2.0V, output level 0dB)
Left channel driven. >110dB at 10kHz
Output Impedance: 180Ω
Maximum Output (balanced): 4.0 VRMS
I'm going to finish with saying something that many will find truly controversial and polarizing:
THE LAST JEDI is a masterpiece.