I'm looking for opinions on a somewhat odd pairing of variables.
From what i've read since i got hooked on NatSemi's line of amp chips, the LM1875 and the LM3886 sound a certain way at certain voltages and/or at certain gain settings.
I'm set on making a pa-150-like amp for the mid-bass driver for an active 2-way (3xLM3886, paralleled). This one's gonna be "fueled" with about +-30V, although i'm not entirely decided on the gain i'll use (20 or less - 16-18).
Each of the tweeters will be powered by an LM1875. I *might* power these with less than the +-30V for the mid-basses (possibly by regulation), and i'm pretty much set on lowering the gain on these (ZeroOne on the Gainclone forum seems to have experienced improvements on the high-end of the frequency spectrum this way).
Anyone else have confirming / conflicting opinions or advice???
From what i've read since i got hooked on NatSemi's line of amp chips, the LM1875 and the LM3886 sound a certain way at certain voltages and/or at certain gain settings.
I'm set on making a pa-150-like amp for the mid-bass driver for an active 2-way (3xLM3886, paralleled). This one's gonna be "fueled" with about +-30V, although i'm not entirely decided on the gain i'll use (20 or less - 16-18).
Each of the tweeters will be powered by an LM1875. I *might* power these with less than the +-30V for the mid-basses (possibly by regulation), and i'm pretty much set on lowering the gain on these (ZeroOne on the Gainclone forum seems to have experienced improvements on the high-end of the frequency spectrum this way).
Anyone else have confirming / conflicting opinions or advice???
Hi,
compare the actual sensitivity of the treble and mid/bass drivers in their finished cabinet. Use this info to determine if you need a different voltage drive from the treble amp and mid/bass amp.
eg. treble 92db/2.8V & bass/mid 86db/2.8V the bass/mid needs double the voltage (-6db relative sensitivity) to give equivalent output.
I would try for equal gain in all amps and use attenuators to adjust volume into each channel. Many crossovers arrange for active/passive attenuation on their outputs.
When you reduce the gain across a chipamp (or opamp) you increase the risk of instability. Take care to follow the manufacturer's or experienced builder's advice if you go for unusually low gain through your chipamps.
compare the actual sensitivity of the treble and mid/bass drivers in their finished cabinet. Use this info to determine if you need a different voltage drive from the treble amp and mid/bass amp.
eg. treble 92db/2.8V & bass/mid 86db/2.8V the bass/mid needs double the voltage (-6db relative sensitivity) to give equivalent output.
I would try for equal gain in all amps and use attenuators to adjust volume into each channel. Many crossovers arrange for active/passive attenuation on their outputs.
When you reduce the gain across a chipamp (or opamp) you increase the risk of instability. Take care to follow the manufacturer's or experienced builder's advice if you go for unusually low gain through your chipamps.
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