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      01-21-2010, 10:20 AM   #1
VP Electricity
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Professional HU speaker-level outputs

More testing. (Wish I had pics... might have some tomorrow).

With a 1K sine wave CD (0dB) in the Professional HU CD, I tested the following:

52 volume clicks as revealed in diagnostic mode of the HU.

The oscilloscope shows the set of clipping at 45 out of 52. At this point the HU was delivering 4.5VAC.

At 48, the clipping was more pronounced, and the HU was delivering 5.5VAC.

At 52, the HU was generating 9VAC, and clipping was pretty apparent on the oscilloscope.

What does this mean to you? It means that when setting your amp gains in an aftermarket system in a 1-series with Professional Radio, no OE amp, you should put the HU into diagnostic mode and set the system with the volume no higher than 45 for best results.

It also means that the HU is putting out a ton more voltage with the last few clicks of the volume knob, and that no system is gonna do well at both ends of the volume knob, and that's OK.

BTW, I went ahead and gained the amps down a bit and railed the HU with Led Zeppelin, track one. Didn't sound heinous...
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      01-21-2010, 10:26 AM   #2
mineo77
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2010 135i coupe  [7.56]
sounds f'n perfect to me...except the gong wakes up my neighbors!!
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      01-21-2010, 03:25 PM   #3
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Quote:
Originally Posted by VP Electricity View Post
More testing. (Wish I had pics... might have some tomorrow).

With a 1K sine wave CD (0dB) in the Professional HU CD, I tested the following:

52 volume clicks as revealed in diagnostic mode of the HU.

The oscilloscope shows the set of clipping at 45 out of 52. At this point the HU was delivering 4.5VAC.

At 48, the clipping was more pronounced, and the HU was delivering 5.5VAC.

At 52, the HU was generating 9VAC, and clipping was pretty apparent on the oscilloscope.

What does this mean to you? It means that when setting your amp gains in an aftermarket system in a 1-series with Professional Radio, no OE amp, you should put the HU into diagnostic mode and set the system with the volume no higher than 45 for best results.

It also means that the HU is putting out a ton more voltage with the last few clicks of the volume knob, and that no system is gonna do well at both ends of the volume knob, and that's OK.

BTW, I went ahead and gained the amps down a bit and railed the HU with Led Zeppelin, track one. Didn't sound heinous...
That could be a defect instead of a "feature"... in the 328i loaner that I've been driving since Monday I did an "audio-visual" test with some Booka Shade dance music.

At pretty much half volume, with bass maxed out at 10 and treble at 7, all front speakers started to shriek like something was going to explode, all of a sudden. So the audio test failed, and I almost hit the car beside me with the ruckus, so the visual test failed as well...
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      01-21-2010, 03:37 PM   #4
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I should have made clearer... this was mineo's car with two 80x2 amps, a 360.1, and Morels and a 10" sub... I'm sure it would have sounded heinous with stock speaks on deck power, ESPECIALLY with the bass at +10
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