450 Pound Monobloc Amplifier

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!

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Hey Tim, I think you are right on the money. I believe with a decent amount of money thrown at R&D, the switching amp could be to linear amps what digital cameras did to film cameras.

Bill, thanks for the explanation.
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@ Tomtab,good point with your post 3-16-13,I believe class D amps is essentually the same to me as sacd technology,it came,it was good,it went the way as vhs video tapes!gone!,class D amps may be good,I do not doubt that!,I am saying,however,That it may be a passing fad,we all seen alot of technologys over the years that were quite good!,they slowly faded away!cheers!

03-16-13: Tomtab
"I'm 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."

Tomtab,
You may be right, the 450lb class A amp might 'toast' the 15lb class D amp, but only if you placed the class D close enough to the class A so that it's within the amp's 'toasting' heat radius.
I'm not understanding why you think most people would prefer a gas/electricity guzzling V12 1,000 cubic inch motor to drive their speakers over a gas/electricity sipping 4 cylinder motor, especially if they both produce the same 300 horsepower.
I knew there would be oppossing opinions to my viewpoint. But, if your statements represent the best reasoning in support of class A,A/B and tube amps, then these old technologies may be in worst shape than I thought.

It is worth pointing out that not all class D amplifiers run necessarily as cool as cukes...
There is in my opinion the possibility that as design elaboration of amplifiers based on new generation class D technology increases, some future -- and totally hypothetical implementations -- from any number of manufacturers -- may potentially generate fair amounts of heat, and therefore benefit from hefty chassis, fins or other heat dissipation mechanisms.

Even in retrospective, we can find examples of heat generaating class D amplifiers. For example, the withdrawn Rowland Continuum 500 integrated, a 44 Lbs midrange class D design based on the ICEpower 1000ASP module, generates a considerable amount of heat, and runs quite toasty to the touch.... And no, the device has regretably no cooling fins.

In this particular case, I conjecture that two circuit elements in C500 may be major contributors to heat generation... a bunch of bulk output capacitors, and a 1500W PFC-based current rectifier.

As usual, only time will tell what the future brings... Oops, I suspect I just spewed out a repetitively redundant tautology... I meant... Oh well, never mind *sigh!*

G.