CS6A4689 Headphone amplifier project

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ammel68

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Joined 2009
tedkok said:
Actually, I was wondering if I put this amplifier to Kickstart, will
you guys be my honored supporters? If that's the case, what price range will you be willing to pay for it? say, assembled PCB, and assembled PCB with CNC AL case.
Click to expand...

First, what is Kickstart?

How can someone place a value on someone's project? You're the only one who knows what all the parts, case and labor costs.
 
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tedkok

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Joined 2015
The test result of the headphone amplifier is excellent, but we find a bug...when the battery voltage drop but not low enough, the DC-DC converter will still struggle to pump the +/-10V output for the amplifier, which results in not enough current to supply to the amplifier IC, and in some case, one power rail (either + or - supply rail) will drop to a lower voltage while the other still functioning properly. In this case, the IC will not be powered properly, and the close loop design will make the output stage of the IC to drift to one side, and create high output current drive for the failed power rail. Eventually, the output will shut down, but the IC will also burn out. To avoid this situation, we have added a watch dog IC CS7P61C-22 which will output a low when the input voltage (the battery voltage) is lower than 2.2V to the circuit. This output will directly tied to the power on delay circuit, and hence stopped the power on circuit from working and turn off the whole headphone. To indicate the lower battery condition, a NMOS M2 is added to turn on a LED to tell the user that the system cannot turn on because of low battery voltage.

Attached is the modification of the power on delay circuit
 

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tedkok

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Joined 2015
Thanks ammel68 for pointing out that it should be Kickstarter
instead of kickstart......

Concerning about the pricing issue, it's common for marketing to gather information before pricing a particular item. It's true that the public won't exactly the FOB price of a product, and so is the manufacturer won't know exactly what's the acceptable price in the market. I am just trying to pick the brain of the reader of this thread to get some idea about how much are they willing to pay for such a fine headphone amplifier, such as to determine if it is a profitable business, or something that will lose money.
 
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tjstyle

Member
Joined 2015
tedkok said:
From a 3.7V Li-ion battery to +/-10V dual rail supply, we applied the CS7D651 DC-DC converter. A very low noise DC-DC converter with enough output current for the high performance CS6A4689 amplifier IC

Noted that a simple connection of the DC-DC output and the amplifier with do the job in raw.....but with power on pop....We shall show you how we resolve that problem in my next post
Click to expand...

Interested to test CS7D651, but there is no enough information for this chip and where to buy.
 
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tedkok

Member
Joined 2015
IV converter for the APTX BT module

The APTX BT module has balanced current output. An IV converter has to be performed to convert it to be compatible with the headphone amplifier. An opamp based IV converter can be constructed as
 

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