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Old 23rd July 2008, 09:38 AM   #21
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There was nothing above a few KHz, no treble what so ever, only bass and some midrange but no treble.

The icepower amp got what it deserved, for the years i had it, it never got to see more than 200Hz, nowdays its replaced with a modified class d caramp that doesent need any cooling.
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Old 23rd July 2008, 10:25 AM   #22
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Maybe its satisfactory use depends a lot on the efficiency of the speakers it's used with? If they are eg 95 db, it'll barely be working, if 85 dB, the roll-off will kick in early & easily??
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Old 23rd July 2008, 11:10 AM   #23
Eva is offline Eva  Spain
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I think that the oldest versions of the bigger "1000" modules were for midbass only and they were extended to full range operation later.
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Old 23rd July 2008, 11:18 AM   #24
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Trust me , there is nothing "weak" about these amps. It measures in one way, and sounds in one - try to audition a set before buying them is usually a good strategy!

good luck / J
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Old 23rd July 2008, 11:30 AM   #25
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Quote:
Originally posted by Eva


Stone-age class-D amplifiers rely on a dummy RC load to achieve output filter damping and stability with high negative feedback. As a result, they suffer from a shortage in high frequency power that depends on the size of the dummy resistor.

Particularly, ICEpower is a design full of compromises due to the size. The damper resistors employed are not very big.

However, there are a few newer designs, like self-oscillating ones (UcD and derivatives), that achieve output filter damping and low THD in other ways resulting in no power shortages at all.
UCD is little newer than this, it's just the superior concept, but not because it's self oscillating, they both are that, rather because of the stable post filter feedback that many examples of self oscillating amps lack. There aren't any known derivatives worth the title other than everyone plugging their own copies, where most lacked the vision in preserving the qualities that made it what it is.

I'd commend IcePower for at least having a fairly complete datasheet which doesn't hide these aspects of its performance, if people took the time to read it.

The graph is more the equivalent of a somewhat falsly imposed SOA by the filter's snubber's resistor that better designs don't even need. With real music, in real loads, at typical levels and even high levels for short duration, the limiting should rarely ever if at all come into play.

The protection does not shut down but rather limits the input signal, and I doubt you'd be able to tell when it's active with an amp like this short of a visual indicator.

Such a penny pinched commercial implementation is never a good sign of a healthy amplifier though. As soon as a manufacturer starts relying on the "music power" argument, it starts to stink in terms of ultimacy, and becomes merely just adequate at best. Or at least I like to think so, but when you see the junk people actually listen to and mistake for high quality sound it becomes a moot point. See tripath in the included graphs below. IcePower is a semi respectable turnkey commercial brick, not the ultimate in high end by far.

While the use of such a bandaid snubber isn't in itself detrimental to the sound, the deeper issue is the very need of it being a screaming indicator of truly detrimental to quality design issues. Pre filter or as in this case mixed mode feedback notoriously suffers a lack of load immunity and poor group delay, effects which audibly detract from accuracy in a big way.

While less than accurate the load peaking can be somewhat euphonic though, leading to comments for other similarly "high tech" synthesizers as "this amp plays music!!", rather than reproducing it. Others still will claim that they all sound the same provided they're all equally implemented ( poorly! ).

Speaking of which, otto88, wrapping the internals with ERS paper is an audiophool method of implementation that isn't going to save a flawed concept or an ignorant implementation- nor could it help a good amplifier in any way. Save the money and ignore such examples of ignorance, for their only redeeming quality is that the increased heat will kill them off sooner than later.

In terms of generalizing comments about all class d behavior, it would again be useful to see some actual measurements. Even without a grasp of the language you can easily make sense of the graphs.

Note that while IcePower falls short of ideal it is surprisingly respectable compared to others like Tripath that are simply laughable. However the load dependancy shown, while slight compared to most others, hints at a gross group delay that you'd have to look elsewhere to see, perhaps even in the datasheet.

http://www.hypex.nl/docs/classeD_393_lores.pdf
http://www.hypex.nl/docs/classeD_394_lores.pdf

Note how UCD performs with respect to a well behaved linear amp.

If you prefer euphonic assault of noise rather than accurately reproduced music then I guess the choice is open to interpretation but if you seek real, repeatable, dependable accuracy it's a rare and clear choice. It may be more involved than plugging in a few wires on an anemic commercial turnkey brick, but not by much, and the information required to do it right is easily found.

It's also worth noting that the use of UCD modules is fully supported by the manufacturer, unlike IcePower, where should something go wrong you'll be left to your own devices entirely.

That said, for the price YFW is dumping these for, I suppose you could do worse, but expect to get little more than you paid for.
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Old 23rd July 2008, 11:41 AM   #26
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Berns,

Thank you for an extremely informative post.
(And enlightenment on ERS paper)

The attraction of the ICEpower is not just YFW's low price, but 'turnkey' for the time poor or who have other diy priorities (eg speakers).

I don't know of an equivalent UCD turnkey board is there one?
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Old 23rd July 2008, 12:47 PM   #27
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My ICE-Power module was a 250A which was supposed to have a wider range than the 500 and 1000W brothers as well as the ASP series.
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Old 23rd July 2008, 12:56 PM   #28
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If these perform better than the "laughable" Tripath as Berns says, then I should be pleased with my purchase.

The main thing that attracted me to these amps is the integrated power supply. I have many many other class-d amp modules I'm not using because I have no motivation to buy/build power supplies for them.
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Old 23rd July 2008, 02:33 PM   #29
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Quote:
Originally posted by otto88
Berns,

Thank you for an extremely informative post.
(And enlightenment on ERS paper)

The attraction of the ICEpower is not just YFW's low price, but 'turnkey' for the time poor or who have other diy priorities (eg speakers).

I don't know of an equivalent UCD turnkey board is there one?

Equivalent? I sure hope not. Seriously though they do offer completed very high quality unregulated power supplies and a soon to be released SMPS that will deliver where these things fall flat. What's a few extra wires? It falls to your needs, expectations and budget, but do your research for certain.

I'd like to point out some confusion with TNT's commentary here. He seems to be the very proud owner of the 1000ASP version. He first quoted from its datasheet which stated how it features input limiting circuitry as protection for the discussed frequency dependent thermal issue.

Later stating:
"As I understand it, you never experiance a "roll off" as in experianced reduced level of high freq. energy but rather, the amp shut down really. Something that never happend me despite of neighbour war levels."

His amplifier version never would shutdown from this as the ASP versions offer input limiting as protection against it. While ASC versions don't offer such limiting and do simply shut down, and that you will surely notice. There's a difference in cost between the two by several orders of magnitude X2. You do get what you pay for, and you can't in good faith comment on the robustness of a 200ASC through the eyes of a 1000ASP, one is weak and the other handicapped.

I find greater issue in lack of thermal mass in general.

"Note that long-term high power levels may be limited by other
safety circuits before the HF long-term power limit is reached."

"Thermal Protection
The ICEpower1000ASP is equipped with two thermal protection circuits. The first monitors the temperature of
the power supply and attenuates the output voltage if the temperature exceeds the limit. The other protection
circuit monitors the amplifier temperature and shuts down the amplifier if the temperature becomes too high.
Both protection circuits are self-resetting once the temperature has dropped to an acceptable level."

PT Continuous output power8) without
thermal shutdown.
Thermal stab. @ Ta = 25 OC.
4, no external heatsink. - 85 - W
PT Continuous output power8) without
thermal shutdown.
Thermal stab. @ Ta = 50 OC.
4, no external heatsink.- 40 - W

That's in free air.. for the 1000ASP. Slap it in a "very tigth shielded and closed box" and watch it ride the limiting all its life. Sorry to say it but I don't think I'd consider TNT's described implementation successful.

PT Continuous output power4) without
thermal shutdown. 0 - 8kHz5)
Thermal stab. @ Ta = 25 OC. - 40 - W
PT Continuous output power4) without
thermal shutdown. 0 - 8kHz5)
Thermal stab. @ Ta = 50 OC. - 25 - W

That's for the 200ASC.

Goes to show you the level of cheap we're talking about here, engineered to the final penny, geared towards PMPO.
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Old 23rd July 2008, 02:49 PM   #30
TNT is offline TNT  Sweden
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The ASPs backside is screwed to the box via heatsink grease so in fact, the whole box is the heatsink and the box istelf is just bearly varm to the touch. 85 watts continous power - ... do you use your amps like that - your judgment may be blurred trying to hear through your tinitus.

I wish You could hear my system

/

re: "200ASC through the eyes of a 1000ASP" - absolutley, my statements are only valid for 1000SAP !
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