450 Pound Monobloc Amplifier

Mitch4T, the short answer is that M725 and M625 produce a not inconsiderable amount of heat.... Yes, I have M725 in my system, and M625 runs even a little hotter than M725. And yes, their interiors are relatively crowded, particularly M625 stereo... Just do not ask me what they look inside.... I am blind and do not enjoy rooting inside chassis and zapping myself by fondling undischarged capacitors.

While M725 contain some interesting technical solutions, like 4-pole capacitors for post rectification current smoothing, and ceramic boards, it will be fascinating to assess how these, and other relatively traditional designs, will stack up against the upcoming stream of new generation class D amps, regardless of weight, heat dissipation, inside crowdedness, or... cooling fins inventiveness.

After all, like Igor Stravinsky said.... We judge a tree by its fruits, not by its roots.
G.

That's great news! Now all that's missing is some ineffecient multi driver speakers with wicked phase angles to make things complete.

I am very interested to see, over the next 2-10 years, how the established big names in high-end audio react to the already very serious threat that class d amplifiers represent. From my perspective, the writing is on the wall as far as the future direction of high-end technology for power amplification:

1. The current class A, A/B and tube amps are large, heavy, expensive, inefficient(20-55% efficient) devices that emit copious amounts of heat. This 450 lb Boulder monobloc amp may merely be the latest epitome of this group. These amps are probably nearing the end of their life cycle.

2. The current class D amps are small, light, inexpensive or relatively so,highly efficient (approx.90% efficient) devices that emit very low amounts of heat. These amps are at the onset of their life cycle and future improvements are likely.

If you owned a high-end amplifier company, which technology would you stake your future on?
Mapman made a very good point earlier in pointing out that the leaders in class D will probably be newer, less established companies. There are a few amp manufacturers, like Rowland, Rogue and ARC for example, that have read the writing on the wall and have begun offering class D amps of their own recently. I would not be suprised if a few others venture into class D,too.
But, as we all know, in the end it will come down to which ones sound the best. I'm going to refrain from commenting on this since we will all be voting on this soon enough with our ears and our wallets. But I will say that it looks like the class D train is just pulling away from the station.
Just my 2 cents.

Thanks,
Tim

im betting the 450 lp amps will toast the 15 lp amps' what would you rather have running you speakers, a v12 1000 cubic inch engine with 300 hp or a 4 cylinda 90 cubic inch engine with 300 hp?? think of who would last longer

Mitch4t, the size and weight of the heat sinks on the Rowland 625 and 725 series amps are used to dissipate heat from the power output devices and are necessary due to their operation in a high bias Class A/B design. It is a common misconception that all amps using switched mode power supplies are Class D, while the type of power supply design and the bias/operation of the output stages are two completely separate design choices. A power amp with a switching output stage (also called Class D) is a highly efficient design that does not generally require large heat sinks for the switching output devices. When an amp design uses a Class A or A/B output stage large heat sinks are generally needed to dissipate heat from the output devices, regardless of the power supply design type. Hopefully this helps to clarify the issue. Good listening to all!