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Icepower 1200AS1 custom monoblock amp custom build

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#1
Hello All,

Did an Icepower 1200AS1 Amp custom build as a pair of monoblocks. All good until I completed the project. The problem is that the power supply transformers vibrate at 60Hz. There is a clear hum if you put your ear near the amps. This does not propagate to the output. However, this, in my view, is a serious quality issue with IcePower and they have not acknowledged the issue nor replaced the boards.

I also have a pair of Nord NC500 monoblocks and they are dead quiet, dark as night and my A/B comparison vial listening is that there is no difference sound-wise, but I will definitely not recommend IcePower as their quality is suspect and any board with transformer mechanical vibration and hum is totally unacceptable. I am flabbergasted at the lack of such basic quality control. It would seem to me, based on my experience, that Hypex is far superior in their quality and build.

I have attached a couple of pictures.

Thank you
 

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strat_80
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Thread Starter #3
Sorry boss - that does not make sense to me. It has AC mains power.

If you mean a superimposed DC signal on the AC mains, then I have no clue as the power company may know. I also don;t have the instruments to measure and analyze the input mains power.

I can also say the NC-500 Nord monoblocks I have are dead as night and silent. They draw from the same AC mains power.
 

tmtomh

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#4
Sorry boss - that does not make sense to me. It has AC mains power.

If you mean a superimposed DC signal on the AC mains, then I have no clue as the power company may know. I also don;t have the instruments to measure and analyze the input mains power.

I can also say the NC-500 Nord monoblocks I have are dead as night and silent. They draw from the same AC mains power.
DC on the AC line is very common, and it does not affect all equipment. What you are describing is the amp's power transformer physically vibrating because of the DC going into it from the AC line. This mechanical vibration is very annoying - but it is not a sign of poor build quality. In fact, the very large, often very expensive and well-built toroidal transformers one sees in some very high quality equipment are usually the most susceptible to this. (I know your units don't have toroidals - just saying those are the most commonly affected by this issue.) It's also an issue that does not vary just from model to model or brand to brand - it can vary from individual unit to unit.

If your Nords are not affected by this, that's great, especially since the Hypex amp modules in the Nord units are better spec'd than the ICEPower modules anyway.

If you want to keep your ICE units, I suggest a DC blocker. You can make one yourself for probably $20-30 in parts, but if you are like me you will just want to buy a commercial product. I have this one and it works great:

https://avahifi.com/products/humdinger-dc-line-blocker

Normal line conditioners, surge protectors, and voltage regulators will not address this issue - you need a DC blocker. Conversely, DC blockers will only address that one issue - they do not address sound coming through the speakers.

Good luck!
 
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strat_80
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Thread Starter #5
Hi tmtomh,

Thanks for the very informative note. I suspected that it is what you meant - DC in the AC power source. Yes - it is mechanical as it does not propagate into the audio output, which is fine.

I built the Icepower monoblocks because they are rated at higher power. See picture if anybody is interested. Looks beautiful.

One other minor annoyance is an extremely low ground loop. The ground loop is from a couple of SVS SB-2000 subs that I also use to crossover and send the high-pass signal to the amp. If I remove the subs, the ground loop is gone. Again, the Nord's are not susceptible to this. I concluded that the Hypex power supply, which is a separate board, may have blockers built in.
 

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egellings

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#6
Would it be possible to shock mount the power xfmrs on rubber bushings in the amplifiers to reduce the noise?
 
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strat_80
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Thread Starter #8
Thanks Ironhorse128,
I was able to get Ghent Xu to get a pair of his regular Al cases anodized to that color. The covid hit and it was six months later he was able to get it done. But he got it done. I had to do the build myself and it is a bit of work. Far easier to buy assembled. But most affordable shops only sell silver or black.

If it is DC in the AC line, then I assume shock mounting will do nothing. I contacted Icepower and they seem to be aware of the issue and have a revised board that they will ship me and will see how that goes. Maybe they put a DC blocker in - I am not sure.
 
OP
strat_80
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Thread Starter #9
Hi tmtomh,

I purchased the humdinger and it is clear (as I earlier suspected) it is transformer hum, not DC int he mains. The humdinger does nothing. I consider it tuition for learning. I expect Icepower to replace the boards as they promised. As I may have mentioned, my Nord Hypex NC500 monoblocks are dead as night.

Also reply to egellings,

Unfortunately not, because the amp and supply are all on one board that Icepower supplies. The Hypex comes as two separate boards - power supply board and amp board.
 

tmtomh

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#10
Hi tmtomh,

I purchased the humdinger and it is clear (as I earlier suspected) it is transformer hum, not DC int he mains. The humdinger does nothing. I consider it tuition for learning. I expect Icepower to replace the boards as they promised. As I may have mentioned, my Nord Hypex NC500 monoblocks are dead as night.

Also reply to egellings,

Unfortunately not, because the amp and supply are all on one board that Icepower supplies. The Hypex comes as two separate boards - power supply board and amp board.
So sorry to hear the Humdinger didn't work, but I applaud your attitude about "tuition for learning." Hopefully Icepower will do the right thing.
 
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strat_80
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Thread Starter #11
The Humdinger was reasonably prices and so have no issue keeping it.

If anyone is interested, I also built an 18" passive subwoofer, powered by a Crown Audio XLS 2502. The driver is a Dayton Audio UM18-22 18" Ultimax DVC. Unfortunately, no DSP excursion controls. Preferred an external amp as I may have wrongly concluded that a plate amp might have its components inside rattled a bit. If I do it again, I will probably go with A 15 inch Rythmik with their servo control.
 

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