Oh dear! You are going to find this tricky then.right let me explain for you guys my knowedge on electronics!!
I understand lpf, hpf etc for sound but talking about ICs and different switches on them etc i dont have a clue.
I am wanting to use a microphone to read the bass tone yes. What would i start to buy other than the mic??
Very true BB. I was also going to suggest using the power amp readings too- measure the SPL power at certain power output levels with a tone then calibrate a picaxe to read the power going into the amp. That might be defeating the purpose I guess.@ andrew qld.
I'd guess that the objective is to measure the efficiency of the speakers so you would be eliminating the very thing that is being tested.
Otherwise it would be even simpler, you know the power amp rating!
Designing an accurate SPL meter isn't a simple exercise. And considering all the fooling around you'll have to do to select the proper components, design, test, redesign, tweak, test, and calibrate, probably not cheap, either. It's unlikely that you'll find anyone to design this for you as a freebie project, since it would entail a significant out-of-pocket outlay on the designer's part.i was looking at the LM3915 chip to drive a diplay. However, i think you can all agree im doomed and need someone to design me a circuit lol!!
I just dont understand how youd go from a signal in to a mic, into a filter, then into a display driver and then a display for your dB level!!!!
I just peeked at the data sheet. Yes, it's spec'd down to 20 Hz.Another idea would be something like an AD8307 which is a logarithmic amplifier designed for RF work. You feed RF into it and it gives you an output in dBm. It MAY work at low AF frequencies.
It depends how it's coupled. You can actually use it at DC, but you have to be VERY careful about your input matching and filtering, otherwise it gets wonky (experience here). Also, I've used it even past the 900mhz "top end" so to speak with careful matching. The response drops off like a rock off a blimp above, say, 6 or 7 hundred mhz, but if you're not looking for anyhitng super accurate, and just want to see some relativity, it'll work. The whole lineup is fantastic.I just peeked at the data sheet. Yes, it's spec'd down to 20 Hz.
That's a real honey of a part, Andrew. 90 dB of dynamic range from audio to 500 MHz is nothing to sneeze at. $10.18 (in PDIP) or $7.42 (in SOIC) from DigiKey, qty 1, in stock.
Many thanks for the tip!