Ok, great.
It's actually very ironic, the airport people here went to a strike as of today morning, and then they closed the airports down anyway...
hi,
I have the LM3915 built on a project board.
Using the same components as the original circuit except for the PNP transistor I have a BC214.
The offset at pin #5 is only +0.29V, so only the first 2 LED's are lit with no audio signal input.
By using a 5K pot on pin #4, connected between pin #7 and 0V, with the wiper of the pot to pin #4, I can back off the +0.29V on pin #5, so that no LED's are lit.
When I connect a signal generator to the input of the 100nF I see that the 1st LED lights when the input signal is 0.5Vppk and the 10th LED lights when the input is 8Vppk.
As I said previously we need to add a pre amp for the MP3 input.
You will have to find a way to measure the output signal voltage of the MP3 so that I can post a preamp circuit, use a scope if possible.
Regarding the 1V signal you have on pin #5, its possible the transistor is damaged when you had it reverse connected, try another pnp.
I'll wait for the MP3 tests...