darTZeel NHB-108 Model One power amplifier Manufacturer's Comment
Editor: Not only I was delighted reading this review, I was also very glad that it was conducted by Wes Phillips, the very guy who qualified the Home Entertainment 2002 introduction of the NHB-108 in these words: "maybe the Cinderella of the show." Three years later, we are all proud at darTZeel that the "Cinderella's Pumpkin" grew that way. I think that WP truly described what all customers write us regularly. Yes, we do build this amp like a Swiss watch, and yes, it has a cost. We did not add any "gadget" to this machine, and every Swiss franc has been carefully—at least we tried it—invested. If the street price was only $100 less, the sound wouldn't be the same. For us, it is the sound that counts first. The best testimony is the one we can read in WP's article. Thank you very much, Wes, for this wonderful review.
Now, the technical side: Every single word John Atkinson wrote about the NHB-108 was dead right. The description of the circuit design is perfect, concise, and clear; I couldn't describe it better.
[About the "bang": The amp has power resistors in series with the AC mains, for soft starting purpose. These resistors are then shunted by a static relay (there are two static relays in the amp, one for the power on, the other for soft start; the main switch does not carry the power by itself).
In very earlier versions (only four samples made this way, none sold to end users), the circuit which feeds the static relay was powered by one of the two main power transformers. When you had one channel shut off by the crowbar circuit, the static relay was no more activated, and the power resistors saw full power, and literally exploded (they are in metallic-kind cans, and are true weapons when heated too quickly).
Current versions use a third, small separate transformer, located under the left power transformer platform, dedicated to the soft start circuit, so when only one channel is shut off, the static relay is still activated.]
Comparing the NHB-108 Model One to a Carol Shelby AC Cobra is quite revealing. I love this car—uncivilized and wild, but wow! The current version of the NHB-108 Model One, the version B, while having exactly the same look, now features (as JA noted) true floating balanced XLR inputs. Also, in order to render the machine a little bit more "recommendable on a general basis," we added a DC compensation circuit. But if the user prefers the pure, wild side, this circuit can be switched off. Now the machine is almost plug-and-play, provided that we use the right protection-fuse ratings. (Just joking, John; I know that you were sadder than I was.)
A last word about the heatsinks: Okay, they can get hot. In normal use, however-I mean when we play some music-they barely reach 60ºC. Hot to touch, but not hazardous. No chance of hard-boiling your breakfast eggs on them!—Hervé Delétraz, darTZeel Audio SA High End Audio Manufacture