My first amp: constant white noise problem - Page 2

AndrewT · 10th March 2008, 05:47 PM

sounds like there is a resistor missing at the input.
I wonder if there is anything else missing?

simsim · 10th March 2008, 06:02 PM

Well, knowledge on my part is missing of course :-) , but apart from that there's only 4 components in the whole 1558q amp not counting the chip. There is no resistor in the datasheet circuit for the BLT. I'm pretty happy with it now, it was my first project. Only thing I notice is that the speakers in the schematic says 4 ohm and mine are 8.

I also finished my lm1875 amp and I'm looking for a nice box to put it in.
Thanks again.

AndrewT · 10th March 2008, 07:04 PM

Quote:

Originally posted by simsim
there's only 4 components in the whole 1558q amp not counting the chip. There is no resistor in the datasheet circuit for the BLT.

then some components are certainly missing.

simsim · 10th March 2008, 07:49 PM

I realise now when I look at the picture that I always assumed the resistors drawn inside the chip were illustrations of its internal workings, not external components to be added. It's very unclear if that's what they mean.

This is the circuit I built:

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10th March 2008, 05:47 PM	#11
AndrewT diyAudio Member Join Date: Jul 2004 Location: Scottish Borders	sounds like there is a resistor missing at the input. I wonder if there is anything else missing?

10th March 2008, 06:02 PM	#12
simsim diyAudio Member Join Date: Mar 2008	Well, knowledge on my part is missing of course :-) , but apart from that there's only 4 components in the whole 1558q amp not counting the chip. There is no resistor in the datasheet circuit for the BLT. I'm pretty happy with it now, it was my first project. Only thing I notice is that the speakers in the schematic says 4 ohm and mine are 8. I also finished my lm1875 amp and I'm looking for a nice box to put it in. Thanks again.

10th March 2008, 07:49 PM	#14
simsim diyAudio Member Join Date: Mar 2008	I realise now when I look at the picture that I always assumed the resistors drawn inside the chip were illustrations of its internal workings, not external components to be added. It's very unclear if that's what they mean. This is the circuit I built: