There seems to be interest in the IcePower boards provided by Bang & Olufsen, many of which are available to consumers now. In the USA, Parts Express will sell you many different models, but if you go on ebay you can find others - in particular is the 125asx2, which is a two channel amplifier with a power supply built in, promising 125 watts per channel. It can also be bridged for I think 500W, although this requires a purpose built input stage. Seems like a great amplifier for home use.
See the datasheet here:
https://www.parts-express.com/pedocs/specs/minidsp-icepower-125asx2-data-sheet.pdf
I reviewed the distortion and output of the different models, and while their isn't much deviation, some had a little less distortion and some had a bit more output. The 125asx2 distortion graphs for 115 operation can be seen below:
As you can see, into an 8ohm load the unit stays below .02% distortion, and for much of the bandwidth of the speaker you're at .005% or less. Distortion starts to go up at 50 watts at 8 ohms, or 80 watts into 4 ohms.
I'm currently designing a speaker with a fairly robust high xmax 8" woofer, and 50 watts into that driver is around the excursion limit in a bass reflex cabinet tuned to 30hz, at which point you're looking at 97db at a distance of 6', which is louder than I personally listen. So, for a pair of bookshelf speakers or moderate 3 ways, this thing may give you what you need. If not, I highly recommend the 500asx models, which are more expensive but offer quite a bit of power. The 500asx and 125asx models seemed to be the sweet spots in the line to me.
Speaking of expense, I built this for a small second system I am making, which is why I wanted to try the icepower module instead of hypex nCore. The 125asx2 module came from ebay, shipped from California, for about 125 dollars. The case and wiring harness came from Ghent audio in China, and cost 90 dollars (I believe shipping was free?). All told, this amplifier cost me under $220.
See this page for pictures of the case:
https://www.ghentaudio.com/kit/asx125-sr.html
If you wanted to make a pair of 500W monoblocks, it would cost you $912. There are also 1000W icePower boards used in Rowland amplifiers, and 200W modules. These modules are available on Parts express. These modules are all mono, but parts express sells a 200W module without power supply that can be powered from another 200W module without a power supply. Ghent sells a case for precisely this configuration.
My impressions of the building experience: the case from Ghent looks good enough, although the case for the ncore units has nicer branding (this has none on the front.) The proportions with the included feet are appealing to me. The input and outputs are of nice enough quality, although the iec plug was very hard to insert. The speaker terminals are quite heavy duty so soldering to them requires patience. The LED is not overly bright. The wiring harnesses are quite nice - the output wires are heavy gauge, and the inputs are nice slinky silicone coated wires.
Importantly - the case comes with no instructions, so you will need to use your deduction skills to figure out what standoffs and screws to use where. To wire the unit up, refer to the icePower datasheet. Here are some tips if you're doing this:
1. This one is important - there is a blue wire jumper which can be placed on two different locations on the board, one location for 115v operation and one for 230v. Mine came in the 230v position, which would have possibly damaged the amplifier if I didn't check it and move it to 115v. The datasheet clearly shows the locations of these terminals but isn't explicit about how to set them so I will be - put the jumper on the voltage that corresponds the voltage in your locale.
2. One of the screws for the feet is silver, not black. This is the grounding screw - use it for the foot which goes near the power input. Ghent has scraped away the paint around this screwhole to make good contact.
2. The standoffs for the switch and amp module are all nylon, except for one which is brass. I assumed, hopefully correctly, that this was supposed to go to a grounding point on the IcePower board. The hole for this standoff also has the paint removed around it, and the corresponding hole on the icepower module has a flat tinned area.
3. The switch is hard to screw in, you'll want a good slender shaft screwdriver
That's it I think. It took me maybe 40 minutes to assemble and 40 to solder the connections. Unlike some electronics projects, the case is pretty big and easy to work in.
The sound? Well it sounds like an amplifier, nothing jumps out at me. So far I've only checked it to see if it worked. It's certainly powerful enough for my use. I'm going to send it to Amir to hopefully get characterized soon. The SINAD chart for amplifiers uses a 1khz tone at 5W into a 4 ohm load - according to our datasheet we can expect .002% distortion, which comes out to a best case SINAD of -94db, but who knows if we'll get there.
See the datasheet here:
https://www.parts-express.com/pedocs/specs/minidsp-icepower-125asx2-data-sheet.pdf
I reviewed the distortion and output of the different models, and while their isn't much deviation, some had a little less distortion and some had a bit more output. The 125asx2 distortion graphs for 115 operation can be seen below:
As you can see, into an 8ohm load the unit stays below .02% distortion, and for much of the bandwidth of the speaker you're at .005% or less. Distortion starts to go up at 50 watts at 8 ohms, or 80 watts into 4 ohms.
I'm currently designing a speaker with a fairly robust high xmax 8" woofer, and 50 watts into that driver is around the excursion limit in a bass reflex cabinet tuned to 30hz, at which point you're looking at 97db at a distance of 6', which is louder than I personally listen. So, for a pair of bookshelf speakers or moderate 3 ways, this thing may give you what you need. If not, I highly recommend the 500asx models, which are more expensive but offer quite a bit of power. The 500asx and 125asx models seemed to be the sweet spots in the line to me.
Speaking of expense, I built this for a small second system I am making, which is why I wanted to try the icepower module instead of hypex nCore. The 125asx2 module came from ebay, shipped from California, for about 125 dollars. The case and wiring harness came from Ghent audio in China, and cost 90 dollars (I believe shipping was free?). All told, this amplifier cost me under $220.
See this page for pictures of the case:
https://www.ghentaudio.com/kit/asx125-sr.html
If you wanted to make a pair of 500W monoblocks, it would cost you $912. There are also 1000W icePower boards used in Rowland amplifiers, and 200W modules. These modules are available on Parts express. These modules are all mono, but parts express sells a 200W module without power supply that can be powered from another 200W module without a power supply. Ghent sells a case for precisely this configuration.
My impressions of the building experience: the case from Ghent looks good enough, although the case for the ncore units has nicer branding (this has none on the front.) The proportions with the included feet are appealing to me. The input and outputs are of nice enough quality, although the iec plug was very hard to insert. The speaker terminals are quite heavy duty so soldering to them requires patience. The LED is not overly bright. The wiring harnesses are quite nice - the output wires are heavy gauge, and the inputs are nice slinky silicone coated wires.
Importantly - the case comes with no instructions, so you will need to use your deduction skills to figure out what standoffs and screws to use where. To wire the unit up, refer to the icePower datasheet. Here are some tips if you're doing this:
1. This one is important - there is a blue wire jumper which can be placed on two different locations on the board, one location for 115v operation and one for 230v. Mine came in the 230v position, which would have possibly damaged the amplifier if I didn't check it and move it to 115v. The datasheet clearly shows the locations of these terminals but isn't explicit about how to set them so I will be - put the jumper on the voltage that corresponds the voltage in your locale.
2. One of the screws for the feet is silver, not black. This is the grounding screw - use it for the foot which goes near the power input. Ghent has scraped away the paint around this screwhole to make good contact.
2. The standoffs for the switch and amp module are all nylon, except for one which is brass. I assumed, hopefully correctly, that this was supposed to go to a grounding point on the IcePower board. The hole for this standoff also has the paint removed around it, and the corresponding hole on the icepower module has a flat tinned area.
3. The switch is hard to screw in, you'll want a good slender shaft screwdriver
That's it I think. It took me maybe 40 minutes to assemble and 40 to solder the connections. Unlike some electronics projects, the case is pretty big and easy to work in.
The sound? Well it sounds like an amplifier, nothing jumps out at me. So far I've only checked it to see if it worked. It's certainly powerful enough for my use. I'm going to send it to Amir to hopefully get characterized soon. The SINAD chart for amplifiers uses a 1khz tone at 5W into a 4 ohm load - according to our datasheet we can expect .002% distortion, which comes out to a best case SINAD of -94db, but who knows if we'll get there.
