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Old 12th June 2011, 03:11 PM   #1
john65b is offline john65b  United States
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Default ICEPower 250A PS

Hey all, Got a quick question...I am planning on building a PS for a pair of Icepower 250A modules.

Is a full 500VA power supply justified for this stereo amp?

I find it hard to believe the actual SMPS on the 250ASP is a 500W - as it is able to run itself and another 250A module...does anyone really know what its capability really is?

I know its 250w@2.7 ohm, and 200W@4ohm...is 400W PS required to run a 4ohm speaker?

I see many 48V SMPS at 3A, 7.3A that I could use, or just a conventional Toroid / rectifier / caps arrangement...
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Old 12th June 2011, 10:03 PM   #2
Nisbeth is offline Nisbeth  Denmark
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The ASP power supply would be able to deliver all the current, but not indefinitely. If you look at the specs you will see that there is a thermal limitation so full output is limited in duration to something like a minute. Mind you, this is 100% power with a noise signal, not a music signal with 1/8-1/3 power which is the normal test condition. I have two 250As driven by a 300W industrial SMPS and I have never hit clipping or shutdown on the PSU. If you use a conventional PSU, 300VA should be OK and you can go lower as well if you want to/need to.

/U.
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Old 12th June 2011, 11:47 PM   #3
john65b is offline john65b  United States
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300VA - OK, will do...Makes sense. After looking at those 250ASP, they didn't look much over 300VA...

I have also heard it is important to have a diode in series with the +/- 12V - a 1N4002 if I remember correctly - which is not documented anywhere in the ICE development manual....
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Old 13th June 2011, 06:46 AM   #4
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Both class D module and SMPS are not suitable for DIY purpose. But, “plug and play” class D power amplifier is very suitable for DIY purpose, particularly for non-technical Diyer. Frankly speaking, go to Hypex or NewClassD for the best quality of sound or B&O Icepower for the best c/p value. I am now using 5~10% of time in design stage of preparing a dual mono (two chassis) class D power amplifier using B&O Icepower 250ASX2 plus a differential buffer I/O. No rush!
Don’t make it too complicate as DIY just for fun. Just use simple calculation to roughly estimate the power supply (i.e. you need to know the concept of RMS and Peak value).

1) Power Input (PI) x Efficiency = Power Output (PO)
2) Efficiency: Class A (less 30%), Class AB (50~75%), Class D (75~90%)

For this reason, higher power supply started from Class A and down to Class D. For B&O Icepower 250A, the power output is 250W with efficiency 93%, thus power supply 2500.93= 269VA is minimum with RMS/Peak conversion and safety factor, 300VA is correct as recommended by Nisbeth. For stereo power amplifier with a pair of class D module required, power supply of 600AV or higher is recommended. Nisbeth recommended you to choose B&O Icepower 250ASP with built-in SMSP. It is another good choice to eliminate power supply consideration for non-technical Diyer.

In field of audio DIY industry, people always consider sound quality or price to be the first priority. But, I encourage Diyer to think about product safety to be the first priority. Since B&O Icepower 250ASP is a “plug and play” class D module, you add a metal chassis and accessories to complete a power amplifier. Please note the following to select power push button with LED illuminated for safety consideration:

=>Maximum power output = 500W (Stereo amplifier with a pair of 250ASP in same metal chassis)
=>Efficiency = 83%
=>Aux. output = 12 VDC
=>Electricity rating = 120 VAC/60Hz (Canada/USA)

1) Power Input (PI) x Efficiency = Power Output (PO)
2) Power (P) = Voltage (V) x Current (I)

=>120 x I = 500 0.83
=>I = 5A

Thus, to use power push button with spec. at 10A/120VAC(Main) and 12VDC(Aux for LED). But, recommend you to make a dual mono (one class D module per metal chassis) for better sound with power push button with spec. at 5A/120VAC(Main) and 12VDC(Aux for LED).
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Old 13th June 2011, 06:58 AM   #5
john65b is offline john65b  United States
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alant4321 - Please re read Nisbeth reply.

Quote:
I have two 250As driven by a 300W industrial SMPS
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Old 13th June 2011, 07:22 AM   #6
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Quote:
Originally Posted by john65b View Post
alant4321 - Please re read Nisbeth reply.
Neglect Nisbeth's saying. B&O is from Denmark, but Nisbeth is realy from Denmark? My recommendation is:

1) Use at least 300VA power supply for each 250A B&O Icepower class D module
2) Don't use industrial grade SMPS such as in electrical appliance. Use high-end audio grade SMPS such as suppliers from Hypex, Coldamp, Audio Power, CAD Audio, Connectronics, etc...
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Old 13th June 2011, 10:30 AM   #7
Nisbeth is offline Nisbeth  Denmark
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Thank you for that vote of confidence in my abilities Alan

As you probably know, normal "commercial" audio testing is done with sinewaves/noise at 1/8th power for consumer level equipment to simulate that you are normally playing music with a high PAR(peak-average ratio)/crest factor. For PA-use, you would normally go to 1/3rd power to simulate heavy use but that it is - the DIY'ers massively oversized PSUs with 1000VA for a 2*100W class AB amp isn't required here.

For a linear PSU, that means the "real" power requirement is then between ((2*250W)/0,93)/8 = 67W and ((2*250W)/0,93)/3 = 179W not counting transformer losses. For normal home use you could therefore go to 160VA with a bit of safety margin and even a 225VA transformer should be adequately sized. The key thing to remember is that while the average power may only be what is described above, the peak power/peak current requirements are still corresponding to (2*250W)/0,93) = 537W. For a linear supply this isn't much of a problem, the transformer will just be a little bit hotter. What you have to remember in this that the catch with an industrial SMPS is that it is not designed for audio, meaning that once you get to 100% load it will current limit to protect it, but on the other hand an industrial 300W PSU is designed to run at 300W output throughout its entire lifetime. Here, you would normally have to look at the peak current requirements of the amp instead of average power to ensure that you do not hit current clipping (which sounds really bad).

This is why I wrote that the PSU in the 250ASP is sized with a thermal limitation - it will deliver the peak power you need but if you try to run it continuously at that level it will overheat after a fairly short time because it is not required. Many DIY'ers will say that this is lying/cheating/misrepresentation of the product, but what it actually is is good engineering because 99+% of all real-world requirements are met!

I am not saying there is no benefit to oversizing the PSU in an amplifier, I am just saying that calculating how much you really need can be a useful reality check to avoid paying more that you actually need. Now if you think that any transformer under 2kVA is unsuitable for powering anything bigger than a three-tone doorbell then by all means go ahead and spend your money, but for the rest of us with limited means for this hobby I think it is very useful to check before spending the money.

I hope this helps explain my thinking

/U.

PS: Oh and by the way, not only am I actually from Denmark, I also used to work for ICEpower...
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Old 13th June 2011, 11:55 AM   #8
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Quote:
Originally Posted by Nisbeth View Post
PS: Oh and by the way, not only am I actually from Denmark, I also used to work for ICEpower...
Dear Nisbeth,

1) For Diyer explanation, try to explain as simple as possible. My explanation is simple and no secret. Oversized PSU is no harm and safety, but pay more money. For precise and advanced calculation, keep it as secret for your commercial use. I start my career in R&D, I hate to copy.
2) If you are now really working for B&O in Denmark, then please response to all B&O issues to Diyer. I have no business relationship with B&O and speak it in free of charge.
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Old 13th June 2011, 12:21 PM   #9
Nisbeth is offline Nisbeth  Denmark
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I said I used to work for ICEpower (some years back), not that I do it now - please read what I write. I was just trying to correct what you wrote as I do not believe it was correct or accurate. I don't believe that DIY'ers should ignore how things are being designed by professionals, at least not without knowing the consequences.

Also to clarify: My day job now is being an IT consultant for a brewery, so I have no commercial interest in being here whatsoever. If you check more user profile you can see I have been registered on diyaudio for more than 10 years now because I enjoy this as a hobby, not because there is any commercial interest for me at all.

/U.

PS: John, apologies for having to clutter up your thread with this stuff
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Old 13th June 2011, 12:30 PM   #10
pdul is offline pdul  Denmark
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Quote:
Originally Posted by alant4321 View Post
Dear Nisbeth,

1) For Diyer explanation, try to explain as simple as possible. My explanation is simple and no secret. Oversized PSU is no harm and safety, but pay more money. For precise and advanced calculation, keep it as secret for your commercial use. I start my career in R&D, I hate to copy.
2) If you are now really working for B&O in Denmark, then please response to all B&O issues to Diyer. I have no business relationship with B&O and speak it in free of charge.
Who would you charge anyway
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