ICE amps need cooling?

It is not standby power. Smaller module 200ASC has FTC power listed as 55W (standby is about 10W). Icepower cannot run with maximum power for a long time but you don't need it because "average music power" is in single percents of peak power. Also B&O spects are very conservative - please read what I found on another forum:

"Originally posted by dmfraser
I operated a sample 1000ASP on the bench delivering 350W average of pink noise into a 4 ohm load for over one hour with no additional heatsink and the metal case stayed below 55°C.

However, higher levels would make the power supply voltage go down to act as a thermal compensation. Much nicer than just shutting down.

However, with 1214W of sine wave, partly into clipping, after about 35 seconds, the output level would drop to about 600W by the protection circuitry. Remember this is with no additional heatsink.

The 200ASC, I was able to operate with sine wave at 100W into 4 ohms continuously. Turning it up, with sine wave, the module would shut down at about 214W.

However, with pink noise at 100Waverage and a 6 db crest factor, the 200ASC would run all day without shut down, until I was tired of tying up one of my Audio Precisions with it. It would also run all day with music, driven hard where the output limiter was set to a peak limit of 210W maximum. That is, the limiter would allow small amounts of clipping. Driven so the limit light in our external optical limiter was on essentially continuously."

Icepower has even more serious limitation of maximum power at higher frequencies (to protect output chokes) but again it's not important since high frequencies in music carry very little power and the tweeter (and your ears) cannot take more than 10% of the speakers maximum power anyway.

Muralman1 - SMPS are regulated (line and load) while linear power supplies are not. They also operate at non-audible frequency that is easy to filter out while 120Hz is not. They also respond faster to load demands than linear supplies because of inductance of huge electrolytic caps (unless you use expensive slit foil caps). In fact class D is controlled SMPS. Reviewers of icepower amps like Bel Canto S300 (SMPS on board) praised behavior at max power and heavy orchestral pieces (holding coherence, imaging etc).

Size of power supply is not an indication of its quality. Small 1" Dia toroidal transformer in SMPS can cary at 100kHz as much power as huge toroidal transformer at 60Hz.

As for your statement:

"It is a proven fact that the digital power supply ICE modules are not good for
high audio use. They are instituted in mass productions of popular electronics."

- I like to mention that highly praised Jeff Rowland's Capri preamp has switching power supply.

"Your "analog" power supply also switches power on and off."

"Also, this being a low frequency switching one may believe that it would be much more audible than the much quicker switching of the digital PS ICE module."

Exactly. That was the reason for Jeff Rowland to put switching power supply in Capri preamp (efficiency not needed here) and using batteries previously.

Jeff Rowland's Continuum 500 is one of the best integrated amps and it has SMPS - certainly not "mass production of popular electronics" - just look at the price tag.

I think that technical reasoning and showing examples won't make any difference. H2O owned by Muralman1 has linear power supply and he believes that's the only solution. If his H20 would use switching power supply he would claim just the opposite. It is not a criticism - just observation.

Muralman1 - I don't know what context was that. You stated that digital power supply ICE modules are instituted in mass production of popular electronics - could you provide us with example of popular mass produced electronics with ICE module in it? (I don't know of any). The smallest ICEpower I know with built in switching power supply 200ASC has great reviews in products such as Rowland model 102, Bel Canto S300, M300 etc. I also mentioned before that great sounding Jeff Rowland Continuum 500 has switching power supplies as well as Capri preamp. Reading your post one would thing that serious electronics has linear power supplies and mass production has switchers because they, as you stated, "are not suitable for audio". How do you know that? Do you know something that Jeff Rowland doesn't? Could you clarify what was the context of your statement - maybe I'm missing something.

Muralman1 - I don't recognize this module. It is probably made by B&O for car market and not the home audio. In addition it is in application that always uses switching power supplies - no linear to compare with.

Yes you'll find switchers in every piece of modern mass market electronics but you'll also find linear supplies there. Should I conclude that linear supplies are not suitable for audio? It is important to understand that class D amp including your H2O is switching mode power supply with varying reference voltage. Do you really thing that B&O would put mass market power supply "not suitable for audio" in their best amps or you believe that good SMPS cannot be designed for audio? Again your H2O is switching power supply.

Switching power supplies have improved over the years as much as class D amps (because it's the same thing). They operate at zero-voltage, zero-current switching with very little noise that is non audible and easy to filter out. Many manufacturers are still sticking to old fashion "no brain needed to design" linear power supply probably believing that switchers are worse but it is really funny that they produce class D amps.

Jeff Rowland switched all his production to class D with switching power supplies. He even uses switchers in preamps and he released only great products in over 20 years. Maybe your audio experience or expectations are higher than mine but if it's good enough for Jeff Rowland is good enough for me.

Muralman1 - I said it's funny because they think power supply should not switch but the amp itself should - and both of them are the same thing.

On the other hand I don't think they are THAT stupid and have some purpose in mind. The obvious one is that a lot of buyers, like you, still believes in linear power supplies.

If you can come up with any technical reason against using switching power supplies in audio - please let me know.

Muralman - I don't know how many times I have to repeat that - CLASS D IS SWITCHING POWER SUPPLY. Switching itself does not make class D or SMPS digital. Both of them are exactly the same thing.

There is very little noise in properly designed SMPS (my Rowland 102 has 110dB S/N).
Noise is at non audible frequency
This frequency is easy to filter out (that's why Rowland uses it in preamps instead of linear

AS for linear power supply - it is not class A. Class A is an active regulated supply while linear PS in neither active nor regulated (line and load). It produces 120Hz ripple in-spite of huge number of capacitors. There are good and bad realization of each technology but the fact is that linear one is unregulated.

Muralman1 - yes it is pretty much the same. I have no idea why you call switching power supplies digital and amplifier analog. Both of them are analog (no discrete values) and both operate with PWM and feedbacks. Modulation process might be different but purpose of power supply is different - input value is constant and feedback keeps output constant. The issue that you raised was noise. Since both operate at the same principle (pulse width modulation) and the same power - noise product of both is the same and very easy to filter out.

Icepower doesn't even bother to filter amplifier's switching noise completely and leaves about 1% on speaker wires. This noise is not audible and can modulate the sound only on non-linear element. Tweeter is potentially one but only if membrane moves (it cannot at such high frequencies). It cannot radiate because it needs hundreds of feet of wire to create 1/4 wave antenna.

There is quite few amps built with 1000ASP module that includes built in SMPS (40 Amperes) and very good reviews.

Let me repeat again - SMPS are regulated (line and load) and can deliver a lot of current - each of 1000ASP modules have its own 40A SMPS.

B&O guys are audio freaks and would never design substandard SMPS to their Icepower modules. I would be happy to discuss it with them if they would find my statements "insulting" or "hilarious". I design electronics (including SMPS) and am familiar with Karsten Nielsen doctorate work.

As for Henry Ho - he might get very low ripple by using a lot of capacitors but you're paying for that and power supply is still completely unregulated same way it was designed more than 50 years ago. Class D was invented during demonstration of response of SMPS. Engineers claimed that SMPS was so fast that it could even play music. Since then SMPS got highly specialized as well as class D. Requirements are different since SMPS is unidirectional and holds constant output voltage but they both got quite sophisticated with a lot of high quality ICs released in recent years.

Muralman1 - I still don't understand why you keep calling switching power supplies "digital". As for them being suitable only for mass market and not for the audio (your original statement) your Henry Ho (H2O) released two amps with Icepower modules with built-in switching power supplies M250S and M500S. Alleluja!!!

The only other circuitry in my Rowland Icepower amp is tiny input board with differential amp THAT1200. If there are any modds to original Icepower they are probably done at factory level (modds void B&O warranty) and reflect desired "house sound".

Eldartford - Rowland was widely using batteries in preamps and wrote a lot of FAQ about it. Now he switched to SMPS (Capri). If there is any switching noise it would not be able to hide well since Capri's bandwidth is 350kHz.