Classe DR-2 vs Classe DR-3

I have, essentially, both. The DR-2 was Classe's first product. The DR-2 uses Motorola power Darlington transistors on the outputs and no driver transistors. The DR-3 uses Motorola power transistors with drivers. The DR-2 has regular 5-way binding posts while the DR-3 has monsterous silver or gold plated connectors that will accept bare wire or spades only. The DR-2 & DR-3 have big, thick bus bars for grounding, and both amps are dual-mono and bridgeable. The DR-2 is a simple, elegant circuit with a minimal amount of capacitor bypassing and tantalum input coupling caps. The DR-3 has alot of capacitor bypassing and film input coupling caps. The DR-3 is an all-out high-end design; there is nothing in the design and construction that has not been scrutinized and overbuilt. The DR-2 is a bit more humble, but still extremely well designed and well built.

Sound-wise, I can't exactly speak for the DR-2, but I can come close: The DR-2, like all of Dave Reich's designs, has a very natural, yet highly accurate sound. There is a touch of warmth, but not like tubes. The sound is extremely balanced with no frequency range standing out any more than another. The DR-3 has similar characteristics, but with even more detail and resolution. It is my opinion that the DR-3 does not have the same bass as the 2. The DR-3's bass is very relaxed and effortless, but seems a touch slow. I once described the DR-25's bass as "oozing out of the speakers with no sense of urgency", and I might describe the DR-3 the same way.

Now, please take my words with a grain of salt. I have never actually heard a DR-2, but I do own and use it's predecessor, the Eleson PCA-100. This looks exactly like a DR-2/3 without the big, engraved faceplate. This amp is the reason Classe came to be (Class A - Classe, get it?). There is no available schematic for the DR-2, but I recently found a picture of the inside of a DR-2 that confirms that the Eleson and Classe circuits are the same. The only major remaining difference between my Eleson and the DR-2 may be the transformers. FWIW, Dave Reich said that the Eleson could be considered a DR-1 when I spoke to him last October :-)

I purchased an early DR-3 (there was also a DR-3B) just last weekend, so I'm still comparing the two amplifiers. I'm presently using a pair of dynamic monitors (I have no planars or 'stats) so I do not have the full frequency range of larger speakers. I am also using a DR-5 preamp.

FWIW, I noticed that both of these amps have a high DC turn-on transient that will push your drivers out as far as they can go! I recommend being careful with smaller speakers as these amps can vaporize your vioce coils in a fraction of a second (ask me how I know). Also, these amps run hot - they're burning over 150 watts per channel at all times. Keep the amp ventilated, but do not use forced-air (fan) to cool the amp.

Cheers,
-JamesW-

Sorry, I have not seen this thread in some time.

To answer Nurxhunter: Forced air should not be used because it raises the bias current. The amplifier, by design, seeks to reach equalibrium between temperature and electrical operating point. If you've ever had to wait for an amplifer to "settle in" for it to sound its best, it is because of this. As it is, the bias current of these amplifiers is quite high because of genuine class A operation, forcing it to go higher will shorten the life of the output devices because they will try to run hotter even though forced air may seem to make it run cooler. It was designed to be perfect without forced air - the huge heatsinks take care of that just fine.

You may also note that these amplifiers run cooler the harder you push them (as opposed to class AB amplifiers which get hotter) - that's because some of the power that is otherwise dissipated by the heatsink at idle is now going into your load. In other words, these amps run hottest during idle.