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FS: ICEPower 125ASX2 module

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#82
MrSlim said:
Anywhere in the audio device chain, (in the analog realm anyway) the output impedance of the source device needs to be lower (and much lower is better) than the input impedance of the device following it. The lower impedance of the output device is better able to "control" the input stage of the following device(follow the signal more precisely). That is often the reason that "pure" passive preamps(no electronic components) tend to "soften" the sound of a system, and now even "passive" preamps have some kind of unity (x1) gain buffer following the switching/volume control. The buffer provides a low output impedance, so that the amplifier following does not "see" the impedance of the volume control.

Oh, and yes, driving directly from the Squeezebox or Ipod is a better bet.



The DCB1 is the most popular variant of the Pass B1 buffer. Since it has no gain (ie unity or a gain of 1), it isn't technically a preamplifier, since it doesn't amplify the signal, but what it does do is offer a low output impedance to the amplifier it is feeding, and thus is able to make the amp do what it is told to do with more conviction.. 😉

Since most audio sources are now line level, and don't need a preamp(unlike a turntable which does), a DCB1 with some source switching and a volume control in front of it can make a very nice "preamp", for the lack of a better word.



The DCB1 is probably the best one to build (I have one in process myself), since it is the most popular, you will be able to get lots of support building it. You could build it on a perf board, but the easiest way is to get in on one of the Group Buys for boards.
This is the most recent group buy thread. It's probably the best place to start asking about how to get a board (that's what I did)

http://www.diyaudio.com/forums/group-buys/147075-gb-dc-coupled-b1-buffer-shunt-psus.html
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Thank you very much.
 
#87
Simes123 said:
Ghent, is it possible to buy just a front panel (silver) without volume control? I've changed my mind about the volume control now! Thanks.
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To be honestly, we have only silver front panel with volume knob in stock now, I hadn't expected that so much friends like case without volume konb😀

Whatever, there is possible to make some extra silver front panels, I will keep you posted in time here, please wait a few days.

By the way, we have 30pcs Black cases in stock again, welcome to order the Combo of 125ASX2 + Diy-suite case.

Best Regards,
Ghent
 
#89
Guys
I have had the same amp from a different builder. Really fantastic sound. If anyone purchases this amp they will be pleased I am sure.
To address the 10k input impedance: You want a low output impedance source and if you are using a passive pre you need it to be very low. I have used a 3k and 7k input impedance passive with it. Not sure what output impedance of those passives were as I never measured but they are equal to 3k and 7k pots. They sounded fantastic. I would hesitate to use a 100k pot however it WILL work it will just not have that crisp transparency that you may or may not be looking for. The higher the passives value goes the more of a 'tubey' sound you are going to get and the lower you go, as long as your source can drive the passive, the more crisp and transparent the sound will become.
Fantastic value Ghent is offering here. Amazing value and a wonderful amp.
Impedances: you want to have something vaguely resembling this
Source =A
Pre =B
Amp =C
A=X (X is whatever the source output impedance is)
B=10X
C=10B when B=10X
Anytime that A<(B/10) is good
Anytime that C>10B is good
Anytime that B>10A AND 10B<C is wonderful
 
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#91
Hi Guys,

The latest prices are the following:
* 125ASX2 module: USD160/pc (Free Shipping)
* Diy-Suite case: USD 80/pc (Free Shipping)
* Combo of 125ASX2 + Diy-Suite case: USD230/pc (Free Shipping)
* Completed Amp: USD260 (free shipping, we assembly/test in advance)

The above are free shipping via postal air parcel, about 3 weeks.
We could provide EMS express about one week with extra shipping cost.

Best Regards,
Ghent
 
#92
I'm really excited by this solution! My project is to eliminate hum and noise by getting the amp as close to the speaker as possible and using balanced signal cables, so this seems perfect - I have already sent an email to ghentxu asking about the silver cases without volume knob.

However, I had thought about getting a 50ASX2 module for each of my back speakers (to save money and space). Would anyone else be interested in requesting a smaller version of the package??
 
#95
Just for reference.
If you refer to the datasheet of B&O Icepower (download from website) and website of Hypex UcD for input buffer design, the input buffer of B&O Icepower which is based on analog filter is wrong. But, the input buffer of Hypex UcD which is based on differential I/O by Bruno Putzuys is correct. It may be one of reason to cause difference in sonic performance between them.
 
#98
alant4321 said:
Just for reference.
If you refer to the datasheet of B&O Icepower (download from website) and website of Hypex UcD for input buffer design, the input buffer of B&O Icepower which is based on analog filter is wrong. But, the input buffer of Hypex UcD which is based on differential I/O by Bruno Putzuys is correct. It may be one of reason to cause difference in sonic performance between them.
Click to expand...

Do you have any links to this info?
 
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