ICEpower 50asx2 modules

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I have decided to give this board a try with some very efficient horns. I am undecided on whether I will need a buffer. The latest pdf file in a block diagram shows an input buffer. Page 21.

http://www.icepower.bang-olufsen.com/files/solutions/icepower50asx2.pdf

Does anyone know whether the board has been updated with a buffer for the front end from experience with this board? I have a FW B1 buffer to use if needed but was just curious to see what others say. The buffer described in the topic is pretty easy to build as well.
 
I have decided to give this board a try with some very efficient horns. I am undecided on whether I will need a buffer. The latest pdf file in a block diagram shows an input buffer. Page 21.

http://www.icepower.bang-olufsen.com/files/solutions/icepower50asx2.pdf

Does anyone know whether the board has been updated with a buffer for the front end from experience with this board? I have a FW B1 buffer to use if needed but was just curious to see what others say. The buffer described in the topic is pretty easy to build as well.

Hi wdecho,

There is no input buffer on 50ASX2 boards, and the input impedance go as low as 6k at 20 kHz, cf :

www.diyaudio.com/forums/class-d/192789-i...ods.html#post2642203

(50ASX2 and 125ASX2 modules probably share the same input stage design.)

I use this module connected to a Najda DSP and the buffer is required, the high section was muddy without.

I've used this design for the input buffer :

theslowdiyer.wordpress.com/2013/09/02/pr...cepower-asx-modules/

This combo is sounding very good IMHO.

BR,

Pascal
 
Another question. Reading the info you provided Pascal, Stokessd said "the amp needs a low output impedance source to drive it." What is considered a low output impedance? I have a number of preamps but my go to one now is a BA3 preamp and from what I found the output impedance of it is around 300 ohms. Is this considered low enough? I know I will find out when I try and use it with this amp but I am just curious. I will add a buffer if necessary but I am a believer in less is better.
 
From the literature provided;

"The single ended input buffer has an anti-aliasingfiltering and a DC capacitor. The input impedance of the signal input section is minimum 8kΩ over the audio bandwidth, which is an acceptable loading condition for pre-amps, active crossover outputs etc."

300 ohm source impedance will be fine. The rule of thumb is usually 10x so anything under 800 ohms shouldn't be loaded down too badly.
 
Hi wdecho,

I would be interrested by reading your listening impressions :)

I will post when I have built and listened to it for a few days. I think what all the talk of a buffer with this amp is what not to do, using just pots to adjust sound. A good pre or buffer is necessary or build the buffer described in the instructions of the board. I think what this board is designed for is in speaker placement or some other device such as television, etc. It should be plenty powerful enough for my 103db horns as a stand alone amplifier.
 
Hi wdecho,

I would be interrested by reading your listening impressions :)

It only took less than an hour to get this board working. My first impression is: It sounds way better than it should. I am going to wait a few days before saying anything more. I have learned it takes a few hours listening to a new amp and comparing it with some of my others before saying too much. The only other Class D I have played with is the TPA3116 and each time I have put it in my system I am at first impressed but then after about an hour of listening it begins to fatique me. This amp does not appear to do that.
 
Hi wdecho,

The only other Class D I have played with is the TPA3116
I've tested the Sure TPA3116 board with rails caps changed for Panasonic OSCON SEPF and I can tell you that the 50ASX2 is on another league.

Also flat response for the 50ASX2 and not the Sure board TPA3116 wich is about -1.25 db at 20 Khz :

FR2-_1.jpg
 
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Hello, I contacted a technician who claimed he was able to convert a SE version into a BTL version and put it to work on a Gallien Krueger MB200 mini head.
He said he resolded the jumper SE/BTL into the BTL position and he had to put the thermal sensor in the coil position, but I don´t know what this really means.

Anyone have any hint on it?
 
Hello, I contacted a technician who claimed he was able to convert a SE version into a BTL version and put it to work on a Gallien Krueger MB200 mini head.
He said he resolded the jumper SE/BTL into the BTL position and he had to put the thermal sensor in the coil position, but I don´t know what this really means.

Anyone have any hint on it?

Do they sell 2 different versions?
 
Do they sell 2 different versions?

Yes, one 2 channel and one 1 channel (bridge/BTL) version.
The BTL version lacks some hardware so it can only be used as one channel.
Big question is, if it is possible to bridge/BTL the 2 channel version so that it is similar to the BTL version.

As far as I know, it is not reccommended to bridge the two channel version the regular way. (like a class A/B amp)

Spec sheet; http://www.icepower.bang-olufsen.com/files/solutions/icepower50asx2.pdf
 
I haven't tried it myself, but it should be possible. IIRC, the only difference between the two (apart from the components omitted on the BTL version for cost-reasons) is the setting of the W4xx jumper in the bottom right corner. This jumper functions similar to the BTL-sync pin on the 125ASX and 250ASX to keep the channels aligned under load (see explanation in the 125ASX datasheet).

If anyone does try it, please report back (I'm out of modules so can't test it myself)

/U.
 
A question.

How I should connect ground? The manual is a bit unclear.

SP negative terminal x2 - Connect to Chassis?
Input ground x2 - float from Chassis?


Hi plasnu,

Speaker negative (and positive) terminal -> isolated from chassis
Input ground x2 -> isolated from chassis and both connected at the RCA side

Chassis MUST be connected to earth.

You may find the section Use Of Loop Breaker Circuits on this link useful if you want to connect the 0 volt line of the module to the chassis :

Earthing (Grounding) Your Hi-Fi - Tricks and Techniques
 
Hi plasnu,

Speaker negative (and positive) terminal -> isolated from chassis
Input ground x2 -> isolated from chassis and both connected at the RCA side

Chassis MUST be connected to earth.

You may find the section Use Of Loop Breaker Circuits on this link useful if you want to connect the 0 volt line of the module to the chassis :

Earthing (Grounding) Your Hi-Fi - Tricks and Techniques

I isolated the board's ground from the chassis as you had suggested, and it is working fine. Thanks a lot! :)
 
So, what would be the general conclusion ... can one modify SE to BTL version by re-soldering the jumper? (not sure what else needs to be done). I'm toying with the idea to build lower profile dual mono 50ASX2 amp as I could source SE cheaply and have some readily available RTX input buffers from Ghent Audio.
 
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