C6 Bose Frequency Response Measurements
11-01-2008, 09:52 PM
#1
Intermediate
Thread Starter
C6 Bose Frequency Response Measurements
I went from a C5 Z06 with Bose to a C6 Z06 with Bose (and Nav) this summer. From reading this forum I expected the new Z to sound as bad as the old one but I was wrong. The C6 is noticeably better but still not very good. So I thought about swapping out the mids/tweeters like I did on the C5. It helped on the C5, not a lot but noticeably. Reading the forum I found some people thought it helped a little and other thought it made the mid base hole worse. So, I decided to take some measurements and see what they told me.
Before I get to that: I fully agree with those of you that say for really good sound you need to start from scratch in our cars. I'm looking to make it better not great. I have an excellent home system that has me spoiled. I won't get that in any car so I'm not interested in trying. I didn't buy Z for the stereo but as this is my daily driver I do listen to it.
To take these measurements used a Denon Audio technical CD with single frequencies and a radio shack sound pressure meter propped up on the shift ****. Not the most scientific or accurate but useful.
The CD has tones at 40, 100, 315, 1001, 3149, 6301, and 9999 Hz. The CD goes higher but our cars and my hearing does not, at least not at anywhere near the same volume as the lower frequencies. If I crank up the volume I can get a reading at 15999 Hz but my 51 year old ears don't hear it.
If I use 315 HZ as a zero point I get the following results
40 Hz +35 dB
100 Hz +23 dB
315 Hz 0 dB
1001 Hz +1 dB
3149 Hz -6 dB
6301 Hz +1 dB
9999 Hz -6 dB
I then took more measurements with the tone controls individually full up and full down. To see what frequencies they change.
The BASS control is +3db and -7dB at 100 Hz.
The Mid Control is +2db and -1dB at 315 Hz and +9 dB and -6dB at 1001 Hz
The Treble control is +4 dB and -0dB at 3149 Hz +6 dB and -2dB at 6301 Hz.
I should note that the higher frequencies were very touchy to the position of the mike, my hands and the pad I was writing on. I tried to be consistent but I doubt its perfect.
What does all this mean relative to replacing the mids and tweeters in a C6. I think it means the sound will improve if the new speakers are more efficient than the Bose speakers and will quite likely sound worse if they are less efficient. I have not seen any efficiency ratings for the Bose speakers but ratings are available on the aftermarket replacement speakers. If anyone is doing a swap I would be interested if you replaced one speaker and then measured or just listened the new one vs. the Bose on the other channel to see which one is louder.
I fear the Bose speakers are quite efficient. For one, efficiency is not a sign of quality or high cost. There are many tradeoffs in speaker and system design and in our cars the more efficient the speakers are the louder the system will be with smaller (i.e. cheaper) amps.
You may be reading the above and saying wait a minute, my car does not have that much BASS, this guy is nuts. I don't think I’m nuts, here is why. One of the songs I have used for years to check out speakers is Elton John, Candle in the Wind from his Live in Australia album (hey I'm old). This song has loads of very low frequency sound in the 2ed and 3th verse. Many decent home speakers miss this sound entirely but I heard it very clearly in the Vette, I was shocked. The measurements above confirm what I heard. But why do many people say No Highs, No Lows much be BOSE?
(The following is my opinion, I have no real data or hard information, just years of listening to different systems including BOSE and an EE degree to develop this theory)
Bose uses an equalized amp. This equalization changes with the volume level, it boosts very low frequencies at low and moderate volumes but when the sounds gets loud is reduces the low frequency volume to not overdrive the amp or the speakers. Not a bad way to make systems that sound pretty good on a test drive but not really high quality. They should have boosted the highs a bit, it’s much easier to boost highs than lows but it would have required another equalizer and amp that would have added cost. Also, given that our cars are not very quiet when driven my guess is this improvement was not deemed worth it.
I found all of this interesting and I am sharing it hoping some of you will also although the only useful conclusion I can draw is our systems should sound better with the treble turned up. Now there is a cheap mod for you!
Before I get to that: I fully agree with those of you that say for really good sound you need to start from scratch in our cars. I'm looking to make it better not great. I have an excellent home system that has me spoiled. I won't get that in any car so I'm not interested in trying. I didn't buy Z for the stereo but as this is my daily driver I do listen to it.
To take these measurements used a Denon Audio technical CD with single frequencies and a radio shack sound pressure meter propped up on the shift ****. Not the most scientific or accurate but useful.
The CD has tones at 40, 100, 315, 1001, 3149, 6301, and 9999 Hz. The CD goes higher but our cars and my hearing does not, at least not at anywhere near the same volume as the lower frequencies. If I crank up the volume I can get a reading at 15999 Hz but my 51 year old ears don't hear it.
If I use 315 HZ as a zero point I get the following results
40 Hz +35 dB
100 Hz +23 dB
315 Hz 0 dB
1001 Hz +1 dB
3149 Hz -6 dB
6301 Hz +1 dB
9999 Hz -6 dB
I then took more measurements with the tone controls individually full up and full down. To see what frequencies they change.
The BASS control is +3db and -7dB at 100 Hz.
The Mid Control is +2db and -1dB at 315 Hz and +9 dB and -6dB at 1001 Hz
The Treble control is +4 dB and -0dB at 3149 Hz +6 dB and -2dB at 6301 Hz.
I should note that the higher frequencies were very touchy to the position of the mike, my hands and the pad I was writing on. I tried to be consistent but I doubt its perfect.
What does all this mean relative to replacing the mids and tweeters in a C6. I think it means the sound will improve if the new speakers are more efficient than the Bose speakers and will quite likely sound worse if they are less efficient. I have not seen any efficiency ratings for the Bose speakers but ratings are available on the aftermarket replacement speakers. If anyone is doing a swap I would be interested if you replaced one speaker and then measured or just listened the new one vs. the Bose on the other channel to see which one is louder.
I fear the Bose speakers are quite efficient. For one, efficiency is not a sign of quality or high cost. There are many tradeoffs in speaker and system design and in our cars the more efficient the speakers are the louder the system will be with smaller (i.e. cheaper) amps.
You may be reading the above and saying wait a minute, my car does not have that much BASS, this guy is nuts. I don't think I’m nuts, here is why. One of the songs I have used for years to check out speakers is Elton John, Candle in the Wind from his Live in Australia album (hey I'm old). This song has loads of very low frequency sound in the 2ed and 3th verse. Many decent home speakers miss this sound entirely but I heard it very clearly in the Vette, I was shocked. The measurements above confirm what I heard. But why do many people say No Highs, No Lows much be BOSE?
(The following is my opinion, I have no real data or hard information, just years of listening to different systems including BOSE and an EE degree to develop this theory)
Bose uses an equalized amp. This equalization changes with the volume level, it boosts very low frequencies at low and moderate volumes but when the sounds gets loud is reduces the low frequency volume to not overdrive the amp or the speakers. Not a bad way to make systems that sound pretty good on a test drive but not really high quality. They should have boosted the highs a bit, it’s much easier to boost highs than lows but it would have required another equalizer and amp that would have added cost. Also, given that our cars are not very quiet when driven my guess is this improvement was not deemed worth it.
I found all of this interesting and I am sharing it hoping some of you will also although the only useful conclusion I can draw is our systems should sound better with the treble turned up. Now there is a cheap mod for you!
11-01-2008, 10:15 PM
#2
Team Owner
Mah, show me a distortion graph. Even the best RTA can't show you how a system sounds, just how much noise exists at certain frequencies when the stereo is playing.
