burnedfingers said:
The contact surface area of 2 LM3886's is larger than that of on LM4780. If you keep the rail voltage less than or equal to 24V you shouldn't have a problem in this regard.
If you want, you can always dissemble the chip from the heat sink and send it back here and I'll take a look at it.
Hi,
a shelving bass response that is 3db down compared to the midband will sound as though someone has turned the bass way down.
Even -1db shelf is easily detectable within the passband of music. It's so easy for the ears to compare the various signal levels and frequencies that are present simultaneously.
Some commentators claim that errors as low as -0.1db are detectable, I would not try to substantiate that.
Where I'm coming to is that a frequency response that is just 90% of voltage in the bass band compared to full voltage in the mid and treble will sound quite bass light.
Your measuring system must be able to give results better than 2 or 3% to see that 90% reduction with some confidence.
Good technique and careful calibration will get you into the right ball park. You must be able to guarantee that you are using the same input signal when measuring the output signal AT VARIOUS frequencies.
Don't worry about reactive loads at the moment. Concentrate on 4ohm, 8ohm, & 100ohm and 20Hz, 100Hz, 1kHz, 10kHz at output levels of 1Vac and 10Vac
Are you able to confirm the impedance of that 15inch driver? Have you got a 4 to 8ohm speaker?
a shelving bass response that is 3db down compared to the midband will sound as though someone has turned the bass way down.
Even -1db shelf is easily detectable within the passband of music. It's so easy for the ears to compare the various signal levels and frequencies that are present simultaneously.
Some commentators claim that errors as low as -0.1db are detectable, I would not try to substantiate that.
Where I'm coming to is that a frequency response that is just 90% of voltage in the bass band compared to full voltage in the mid and treble will sound quite bass light.
Your measuring system must be able to give results better than 2 or 3% to see that 90% reduction with some confidence.
Good technique and careful calibration will get you into the right ball park. You must be able to guarantee that you are using the same input signal when measuring the output signal AT VARIOUS frequencies.
Don't worry about reactive loads at the moment. Concentrate on 4ohm, 8ohm, & 100ohm and 20Hz, 100Hz, 1kHz, 10kHz at output levels of 1Vac and 10Vac
Are you able to confirm the impedance of that 15inch driver? Have you got a 4 to 8ohm speaker?
I will try to get a warble generator plot to show up.
This should provide the necessary proof there isn't anything wrong with the speakers.
Plot using a calibrated flat microphone, warble generator and HP plotter. I went over it several times because the pen is getting hard to read. As you can see there is a 1db boost in the lower region. The speakers graph very good and sound even better.
This should provide the necessary proof there isn't anything wrong with the speakers.
Plot using a calibrated flat microphone, warble generator and HP plotter. I went over it several times because the pen is getting hard to read. As you can see there is a 1db boost in the lower region. The speakers graph very good and sound even better.
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