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Discussion Starter · #1 ·
I replaced the SC-816 headunit in my 2000 S70 with the Nakamichi MB75. I love the improved soundstage, but the MB75 has considerably less bass than the SC-816. The bass is there, it just does not have the "punch and presence" that was there with the SC-816.<P>I had four ideas why I get less bass from the MB-75:<BR>1. The SC-816 had some sort of lowdness compensation built in. The lowdness from the MB75 is too boomy to use.<BR>2. The amp with the MB75 (10W per channel) is too wimpy in the low end to power the speakers in the bass frequencies.<BR>3. The SC-816 more closely matched the impedence of the speakers (a corollary of #2?) <BR>4. The SC-816 has built in equalization to match the sound to the interior of the car. The MB-75 has a pretty flat frequency response.<P>Does anyone have an idea why the bass is diminished? And, more importantly, what can be done to correct it?<P>TIY
 

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The SC-816 (as all Volvo radios) has a built-in EQ to adapt the frequency response to the acoustics of the vehicle. On top of the EQ there is also a psychoacoustic loudness function that basically has more bass lift at low volumes and less bass lift as volume increases to be zero bass lift at maximum volume. The hearing also has this sound pressure dependent sensitivity in the lower frequencies.<P>Typically a car-adapted EQ curve has a bass lift in frequencies around 50-60 Hz, a cut at around 180-200 Hz to compensate for the transversal modes and then some various boosts and/or cuts to compensate for loudspeaker performance and location in the higher frequencies.<P>The output power of the SC-816 is 25 W per channel, rated at 10% THD. The speaker impedance is matched to the amplifier in the radio, not the other way around.<P>An aftermarket radio such as the MB-75 seldom has built-in EQ, although it is becoming more common now when more manufacturers are putting DSP in their head units. So to cure your problem you need to add an EQ and a more powerful amp to your radio to make your setup as adapted and powerful as the original Volvo radio.
 

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Thanks for the info, that was exactly what I was looking for!<P>Now, off to search for an amp and EQ. Do you have any recommendations?
 

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<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by waymod:<BR><B>Now, off to search for an amp and EQ. Do you have any recommendations? </B><HR></BLOCKQUOTE><P>Since I live in Sweden I have a limited possibility to check what's available at your local dealers. I suggest that you contact a dealer you trust and let them suggest a setup that matches your MB-75. I'm sure other list members can join in and suggest equipment, too.<P>If you can get a parametric EQ it is preferred over a graphic since you can more exactly match the EQ curve to the car acoustics with a parametric.
 
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