Hi,
can someone tell me the resistance in Ohm at the earphone outlett - Sansa Clip 8GB?
Thanks Gambler
Approx. 10 Meg ohm per channel to common. Reading with Fluke 77 DVM. Note that the Clip uses a “phantom ground” output circuit, so there are no low ohm load resistors or output capacitors used. Google for phantom ground to get an explanation of the circuit compared to conventional amp output circuits.
Hi,
thanks for your answer, but it´s hard for me to believe that there are 10 MOhm… the phantomground is also called virtual ground. An other person answered the same question in general information there are 16 Ohm, and that happens with all sansas.
So what is wrong and what is right?
Greetings Gambler
Message Edited by Gambler on 09-01-2009 03:05 PM
You asked for measured resistance, not output impedance. The output impedance is rated at 16 ohm maximum load. You don’t want to use any earphones with less than 16 ohm impedance. Resistance is a DC measurement and impedance is an AC measurement. Amp output is AC driving an inductive load (speaker coils) and frequency will alter the impedance value.
Hi,
sorry my english isn´t that good, it´s not my first language. For me, Restistance and Impedance is quiet the same, I know now it´s not. Thanks. So the 16 Ohm is right. I need this 16 Ohm because I build a miniamp to use the Sansa Clip with my normal amp, so that it is not needed to turn the volume control very high.
Thanks again and
Greetings Gambler
It sounds like you have a fun project going with your miniamp. Depending on your amp design, you should probably set your miniamp input impedance slightly higher than 16 ohm (maybe around 20-32 ohm). If you load it at 16 ohm you may get distortion due to the Clip’s amp running at maximum load constantly. This assumes you are building a transistor or transformer-coupled amp. If you are building an op-amp based amp, you’ll probably have to go much higher on the input impedance to avoid overloading the input. It looks like it may take some experimenting to get the results you want - sounds like fun!
Hi,
it´s an op based amp (op 2134) like the Cmoy one. But I use a usb-wallpower thing ( I don´t know the right name in english) for both, charging the Sansa and drive the miniamp. Therefor the miniamp has a twin-USB-socket and a DC/DC changer “SIM1-0505” (don´t know the right english name). At the miniamp input is a 100 Ohm resistor and a 100 pF capacity to GND. To configer properly the C the Impedance was needed, because if the C is to high, the frequence range would go down. The resistor and the Capacity are good for defending against noise. Yeah, I like the miniamp, it works and sounds great, and I need to turn the volume control at the amp only a very little and the volume control at the Sansa just normal. The miniamp give about +66 dB.
Regards Gambler
Message Edited by Gambler on 09-02-2009 10:53 AM
Message Edited by Gambler on 09-02-2009 10:58 AM
