help appriciated designing correction filter for speakers
- Thread starter erikb1971
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Help Support GroupDIY Audio Forum:
These response curves are suspect especially at LF where the S/N is very poor.erikb1971 said:
Can you do an impedance curve? Use RMAA and this simple circuit. Sweep from 20Hz to 2kHz and check that neither the power amplifier or your soundcard input is overloading. Do this in a quiet room with the speaker on a cushion as the speaker will act as a sensitive microphone.
Or if you have a calibrated oscillator, you can just look carefully at the movement of the Passive Radiator and the A3 unit. The frequency you want is where the Passive Radiator moves the most and the A3 moves the least. It will be quite a distinct frequency.
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Erik,
Before you go the hi-tech route, try a 7.7mH air coil, with parallel 6.8 resistor, in series with the speaker. I calculated that on a 6 ohm speaker and 140 Hz and it should arrive at a 6db bass boost. There is a wealth of knowledge on series crossovers on the net and this coil idea is to compensate for the loss of bass due to the baffle width effect. ( Middle and treble is direct to your ears, bass goes everywhere). Its worth a read even if you don't go that route. I use series crossovers on my monitors and home hi-fi.
Use heavy gauge enamelled wire wound on a bit of broomhandle with sides! I would sooner put my sound through copper than silicon.
best
DaveP
Before you go the hi-tech route, try a 7.7mH air coil, with parallel 6.8 resistor, in series with the speaker. I calculated that on a 6 ohm speaker and 140 Hz and it should arrive at a 6db bass boost. There is a wealth of knowledge on series crossovers on the net and this coil idea is to compensate for the loss of bass due to the baffle width effect. ( Middle and treble is direct to your ears, bass goes everywhere). Its worth a read even if you don't go that route. I use series crossovers on my monitors and home hi-fi.
Use heavy gauge enamelled wire wound on a bit of broomhandle with sides! I would sooner put my sound through copper than silicon.
best
DaveP
OK. PRR's electronic filter is safe if your Passive Radiator is tuned to 34Hz. It's worth confirming with an Impedance Plot sometime. It only needs a 1k resistor and RMAA.erikb1971 said:
However, the Passive Radiator is not giving you any benefit. On your next iteration, if you use the same size box, try leaving it out; ie use a simple sealed box.
DaveP, have you worked out the size of that 7.7mH coil? It is huge. About 3 lbs of copper. And it doesn't give the LF filter protection that PRR's evil electronic filter gives. IMHO, it's essential for this tiny unit.
