ICEPower 125ASX2 Class D Amplifier Review

[Matias]

This 125ASX2 was hugely popular, can't wait for ICEpower to refresh it with their latest and greatest tech to reduce noise and distortion even further, hopefully keeping the same board size and connections so that it becomes a plug n' play swap upgrade.

 

[Rainier939]

This 125ASX2 was hugely popular, can't wait for ICEpower to refresh it with their latest and greatest tech to reduce noise and distortion even further, hopefully keeping the same board size and connections so that it becomes a plug n' play swap upgrade.

Looking at the specsheet they might havedone that.
The specsheet looks a lot like a purify or hypex nilai.
The screen shot is from the BTL performance and I really want to try it as a BTL monoblock

 

[Matias]

@Rainier939 wow, you are right: these modules underwent a silent upgrade/revision!

I had the datasheet version 1.9 for comparison with your print of the current version 2.2. We can see how worst it was than now.

2.1 2024-03-15 RSM/PBM New amplifier topology (Not UL certified yet)

2.2 2024-05-14 RSM/PBM New amplifier topology (released)

"State-of-the-art, high efficiency ICEpower amplification stage based on the patent pending Conductor topology."

BTL mode on 230V, 1kHz into 4 ohms is 0.0007% THD+N which translates to SINAD 103 excellent.

 

[Rainier939]

@Rainier939 wow, you are right: these modules underwent a silent upgrade/revision!

Why they did this so silently baffles me. These compete with the best in class modules.
They only downside to these is the continious power output rating. It's only 70 watt btl into 4 ohm but 200 watt btl into 8 ohm.
The thermal headroom on the ICEpower products is their bottleneck still. These need active cooling adn plenty of it.

 

[Sokel]

It's years that they are over 100dB SINAD with 300a and such:


SE

BTL

But the point here with the new ASX ones is that one gets the added PSU+amp at a comparable price with the single amp (with maybe a little less power for the price)

Really well done.

 

[Matias]

But only recently they developed the Conductor tech to have low distortion on the treble as well, comparable to NCore.

 

[Matias]

For example, one can build a 2 x 125ASX2 power amp, each in BTL (450W @ 4 ohms), with a Ghent case for 125 USD + 2 modules 230 USD each = 585 USD total. Not bad at all.

 

[Rainier939]

Exactly the point i wanted to make. These things are super competitive with a douwnside being that there is no way to BTL with SE connections on these. But with ballanced output dacs starting at $150 now you have 450 watts of ultra low distortion for under a $1000. That's the price of a single purify monoblock over here.

 

[Sokel]

But only recently they developed the Conductor tech to have low distortion on the treble as well, comparable to NCore.

Not so recently,compared with NC and Purifis and measured at comparable gain (usually the 25dB of Hypex or Purifi) 300a's at their worst case ,(4 Ohm SE) are directly comparable at 6.67kHz.
The newer Conductor is way better at their article.

 

[Matias]

Exactly the point i wanted to make. These things are super competitive with a douwnside being that there is no way to BTL with SE connections on these. But with ballanced output dacs starting at $150 now you have 450 watts of ultra low distortion for under a $1000. That's the price of a single purify monoblock over here.

I think the dual BTL should be compared to an NC502MP based amp power and SINAD wise. It's a little cheaper but also a little lower power so it's competitive.

 

[andrewjohn007]

You can score these at Parts Express now for $229.98. PE routinely has sales throughout the year which could potentially put one of these units at your door for less than two Franklins,

 

[Rainier939]

I think the dual BTL should be compared to an NC502MP based amp power and SINAD wise. It's a little cheaper but also a little lower power so it's competitive.

That's fair. But ICEpower is in the confersation now. They really made up ground over the last few years. being at 0.0006% while purify is at 0.00015% is an achievement. With a included powersuply and at 60% of the price of a purify module. The NC502MP is only available in finished products not on it's own I believe but at a fair price at most places.

 

[Matias]

The problem with this silent revision is that it's hard for the end customer to know whether it is a new design or new old stock that he/she is buying. I went back and forth between the old datasheet 1.9 and the current 2.2 and there are no clear markings stating the new design, even the part number is the same.

AFAIK the only way to know whether it is a new Conductor version are the chips on the output stage. Because other components like caps or inductors they may change even with the old HCOM+MECC technologies.

 

[Matias]

That's fair. But ICEpower is in the confersation now. They really made up ground over the last few years. being at 0.0006% while purify is at 0.00015% is an achievement. With a included powersuply and at 60% of the price of a purify module. The NC502MP is only available in finished products not on it's own I believe but at a fair price at most places.

I just updated the spreadsheet and indeed in >300W and >450W it replaced the NC502MP as better values.

Amplifier SINAD list ASR + 3rd parties

docs.google.com

 

[mocenigo]

Exactly the point i wanted to make. These things are super competitive with a douwnside being that there is no way to BTL with SE connections on these. But with ballanced output dacs starting at $150 now you have 450 watts of ultra low distortion for under a $1000. That's the price of a single purify monoblock over here.

You can always add a balancing buffer…

 

[quattro98]

This is a link to the updated data sheet.

https://shop.icepoweraudio.com/wp-content/uploads/2024/05/ICEpower125ASX2_Datasheet_2.2.pdf

 

[AndreaB]

You can always add a balancing buffer…

But remember that in BTL it has a very low input impedance!
I used the SOA-2.V3 from this German manufacturer. Scroll down the page

Symmetrierverst�rker-Module

 

[mocenigo]

But remember that in BTL it has a very low input impedance!
I used the SOA-2.V3 from this German manufacturer. Scroll down the page

Symmetrierverst�rker-Module

Of course! Very good observation.
That thing has a 2MΩ input resistance! (5 for the V4) and a 25Ω output impedance. Impressive.

The neurochrome universal buffer has better noise and distortion values, lower input impedance and also lower output impedance: 0.1Ω.

But I guess than both 25Ω and 0.1Ω are fine into a BTL 125ASX2. The older version had a 26KΩ input impedance (270KΩ at DC) dropping to 6KΩ at 20Khz. Looking at the design of the input circuit in the updated data sheet it seems that it will be the same. Hence 3KΩ at 20KHz in BTL and possibly half that at 40KHz. 25Ω is definitely fine.

 

[AndreaB]

I have been to this company in Berlin.
Great technician, great expertise, and lots of tools.
Also Audio Precision. They really do the measurements.
I also bought the headphone amplifier module.
Impressive.

https://funk-tonstudiotechnik.de/LPA-2S-englisch-300.pdf

 

[mocenigo]

I have been to this company in Berlin.
Great technician, great expertise, and lots of tools.
Also Audio Precision. They really do the measurements.
I also bought the headphone amplifier module.
Impressive.

https://funk-tonstudiotechnik.de/LPA-2S-englisch-300.pdf

I have looked at his portfolio. He seems to have designed quite a few nice things! German engineering at its best!