HPA-NXA50L
I have built two mono blocks. Each has a 600 VA encapsulated transformer, a RCRC filter with 0,5 and 0,25 ohms resistors and 600.000uF electrolytic capacitors, inrush current limiter, a mains DC-filter and loudspeaker protection. The bias is adjusted to 2,85 A the heatsinks are about 50-51 degrees Celsius (125 F) when warming up from about 22 degrees Celsius is complete. This should leave headroom for use even during a hot Danish summer. But a lot of cooling IS recommended and cooling can hardly be overdone.
The sound is magnificent. No less. The soundstage is huge and very roomy, the tonal balance is very neutral.
Details are abundant and very natural sounding. They let you hear all the detail you could possibly wish for, in a way that sounds utterly right. The details are there, you can clearly hear them, yet they do not seem exaggerated, on the contrary, they blend in in a very naturally sounding way. This is easily among the most detailed and transparent I have heard, yet totally without being too bright or too focused on the detail. They are equally good at making the tonal textures a joy to listen to. Piano music, for example sounds very natural, and all stages of the sound from the hammer hitting the string to the final reverberation in the room evolve smoothly, and, the recording permitting, this amp lets you know that this is happening in a room.
Transients are delivered with power and attack. The bass is tight and well controlled. I thought I had a major low-frequency room resonance problem – and I probably have to some extent – but these amps have reduced this problem considerably, revealing what superb control in the low-end region can do to tighten up bass response.
Dynamics is excellent, even at low volume I was often surprised at how much weight they can give to instruments demanding it, even at low listening levels.
Best of all they are very musical: They let you connect directly with the music’s emotions – from sadness to joyful foot tapping.
They are utterly pleasurable to listen to with all kinds of music and I am extremely happy with them.
Ole Thomsen
Denmark
