ICEPower 125ASX2 Input Buffer?

lxmyers · 31st October 2011, 02:07 AM

Hello All,
I am trying to put together a Power Amplifier to use with my PC and have got hold of a B&O ICEPower 125ASX2 Module which seems perfect for the application.

I am having a bit of trouble with the concept of an Input Buffer, apparently the Amplifier has a Low Impedance Input... Does this mean an Input Buffer required between my PC and the AMP?

The Desinger's Manual has a conceptual schematic (attached below) for a basic Input Buffer and I was wondering if it would be suitable?

I apologise if the question isn't clear, I'm quite new to this sort of thing and not really sure where to start.
Thank you all for your help in advance.

Kind Regards,
Alex

mravlca · 31st October 2011, 11:06 AM

Hello Alex,

You can use your 125ASX2 connected directly to your PC soundcard, but you have to use software for volume regulation. If you will use potentiometer between soundcard and 125ASX2 you will change frequency response of the amplifier.

I am using BUF634T buffer and I must say it works very well with my 125ASX2, but I am unable to show any test results.

Best Regards,
Ales

Nisbeth · 31st October 2011, 05:25 PM

That schematic shows a completely standard op-amp buffer - you can basically use the schematic from the CMoy headphone amplifier (google that). The only thing you need to look closer at here is the 10R resistor in the power supply to the opamp. These are required if you want to power the buffer from the AUX supply of the 125ASX. If you use a small external supply for the buffer then these resitors are not necessary.

/U.

StigErik · 31st October 2011, 07:21 PM

A buffer is not required at all if you can plug your source signal directly into the 125ASX2.

lxmyers · 2nd November 2011, 12:20 AM

Thank you all for your replies, they have all been very helpful.

Just to confirm (incase I missed something), a Buffer is not really needed if the 125ASX2 is directly connected to the PC (source) and volume is controlled through the software.
However, if there is a something (Pre-Amp) between the Source and Power-Amp, some sort of Buffer would be recommended?

A lot of people seem to recommend the Burr-Brown OPA627 as a good choice for the OP-AMP, the CMoy Headphone Amp or the BUF634 Buffer using the OPA627 would both need ±15VDC.

If I use the AUX Supply of the 125ASX2, would it be wise to use a LM7815T and LM7915T (or similar) to regulate the supply down to ±15VDC?

Thank you all again.
Kind Regards,
Alex

31st October 2011, 07:21 PM	#4
StigErik diyAudio Member Join Date: Feb 2008	A buffer is not required at all if you can plug your source signal directly into the 125ASX2. __________________ dipoles dipoles dipoles dipoles dipoles dipoles dipoles dipoles and dipoles

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31st October 2011, 11:06 AM	#2
mravlca diyAudio Member Join Date: Jul 2009 Location: Ljubljana	Hello Alex, You can use your 125ASX2 connected directly to your PC soundcard, but you have to use software for volume regulation. If you will use potentiometer between soundcard and 125ASX2 you will change frequency response of the amplifier. I am using BUF634T buffer and I must say it works very well with my 125ASX2, but I am unable to show any test results. Best Regards, Ales

31st October 2011, 05:25 PM	#3
Nisbeth diyAudio Member Join Date: Jan 2001 Location: Denmark	That schematic shows a completely standard op-amp buffer - you can basically use the schematic from the CMoy headphone amplifier (google that). The only thing you need to look closer at here is the 10R resistor in the power supply to the opamp. These are required if you want to power the buffer from the AUX supply of the 125ASX. If you use a small external supply for the buffer then these resitors are not necessary. /U.

2nd November 2011, 12:20 AM	#5
lxmyers diyAudio Member Join Date: Oct 2011	Thank you all for your replies, they have all been very helpful. Just to confirm (incase I missed something), a Buffer is not really needed if the 125ASX2 is directly connected to the PC (source) and volume is controlled through the software. However, if there is a something (Pre-Amp) between the Source and Power-Amp, some sort of Buffer would be recommended? A lot of people seem to recommend the Burr-Brown OPA627 as a good choice for the OP-AMP, the CMoy Headphone Amp or the BUF634 Buffer using the OPA627 would both need ±15VDC. If I use the AUX Supply of the 125ASX2, would it be wise to use a LM7815T and LM7915T (or similar) to regulate the supply down to ±15VDC? Thank you all again. Kind Regards, Alex

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