Quantifying Audio Upgrades

turbodog · 10-22-2010, 03:39 PM

So, lots of stuff already posted about upgrades of all sorts. Just for grins, I decided to see if some of this can be quantified. So, using my trusty Radio Shack SPL meter, I set forth to measure.

The RS SPL meter is only rated 50Hz to 10kHz, so I first set out to see just how bad it is beyond that range. I hooked up a pretty nice set of Sennheiser superaural headphones directly to the headphone jack on my Sony CD player/recorder (yes, people actually had those, back before every computer sold had CD burning capability). I sandwiched the SPL meter mic between the earmuffs, and tested. I found (assuming my CD player and headphones have reasonably flat response), that the meter sensitivity is only down a dB or 2 at 30 Hz. It is down 3dB at 10kHz, down an additional 3 dB at 14kHz, and down a total of 10dB at 20kHz.

OK, so next, I took the meter for a little ride. 70 MPH on I-635, eastbound, at Plano road exit (fairly new asphalt), I measured 90dB (C weighted). 40MPH on Spring Valley eastbound approaching Preston (noisy concrete) I measured 92dB.

Finally, I sat in a quiet garage, and measured the frequency response of the stock, base stereo.
Settings:
Ignition setting: ACC
Bass and treble =0
Volume = 17 (set to 90 dB SPL at 1kHz)
Meter chest high (gotta be able to read the display!)
Meter settings: C weight, fast response, "Max" (gives max reading obtained in the 'fast' sample period, about 1 sec)
Source: "Digital Recording" brand hearing test CD

I see now why I tend to leave the bass at "-2". The system is definitely tuned for, er, how should I say this.... a 'younger' perspective on music tonal balance. How's that for keeping it PC

More to come.... But not right away. Gotta prep my Typhoon for selling first.
If anyone in the DFW area wants to run this test on their (Bose, upgraded, etc) system, we can arrange that.

Also planning to use a mic and oscillioscope to find the max SPL without visible distortion.

kenchan · 10-22-2010, 04:37 PM

not only that the stock system is missing a lot of mid-band 350-650Hz range too.

the over all sound is like having your boom box set to "pop" or "rock" EQ.

turbodog · 10-22-2010, 07:18 PM

We are in complete agreement.
"tuned for, er, how should I say this.... a 'younger' perspective on music tonal balance" = "like having your boom box set to "pop" or "rock" EQ."

sonic370 · 10-24-2010, 08:15 PM

everyone has an opinion on this but the base will sound better with better speakers. you know which comes first HU or Speakers

turbodog · 10-25-2010, 10:37 AM

Yeah, it will be speakers for me. Updates will be posted after dynamat and after speakers.

I did, over the weekend, try various bass/treble adjustments to see if I could flatten the response any. -2 bass, -1 treble helped, but it still has a major dropout at 750 Hz.

10-22-2010, 03:39 PM	#1 (permalink)
turbodog Base Member Join Date: Sep 2010 Location: Dallas, TX Posts: 129 Drives: 370Z Rep Power: 15	Quantifying Audio Upgrades So, lots of stuff already posted about upgrades of all sorts. Just for grins, I decided to see if some of this can be quantified. So, using my trusty Radio Shack SPL meter, I set forth to measure. The RS SPL meter is only rated 50Hz to 10kHz, so I first set out to see just how bad it is beyond that range. I hooked up a pretty nice set of Sennheiser superaural headphones directly to the headphone jack on my Sony CD player/recorder (yes, people actually had those, back before every computer sold had CD burning capability). I sandwiched the SPL meter mic between the earmuffs, and tested. I found (assuming my CD player and headphones have reasonably flat response), that the meter sensitivity is only down a dB or 2 at 30 Hz. It is down 3dB at 10kHz, down an additional 3 dB at 14kHz, and down a total of 10dB at 20kHz. OK, so next, I took the meter for a little ride. 70 MPH on I-635, eastbound, at Plano road exit (fairly new asphalt), I measured 90dB (C weighted). 40MPH on Spring Valley eastbound approaching Preston (noisy concrete) I measured 92dB. Finally, I sat in a quiet garage, and measured the frequency response of the stock, base stereo. Settings: Ignition setting: ACC Bass and treble =0 Volume = 17 (set to 90 dB SPL at 1kHz) Meter chest high (gotta be able to read the display!) Meter settings: C weight, fast response, "Max" (gives max reading obtained in the 'fast' sample period, about 1 sec) Source: "Digital Recording" brand hearing test CD I see now why I tend to leave the bass at "-2". The system is definitely tuned for, er, how should I say this.... a 'younger' perspective on music tonal balance. How's that for keeping it PC More to come.... But not right away. Gotta prep my Typhoon for selling first. If anyone in the DFW area wants to run this test on their (Bose, upgraded, etc) system, we can arrange that. Also planning to use a mic and oscillioscope to find the max SPL without visible distortion. Last edited by turbodog; 10-22-2010 at 03:42 PM.

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10-22-2010, 04:37 PM	#2 (permalink)
kenchan A True Z Fanatic Join Date: Aug 2009 Location: N/A Posts: 76,801 Drives: N/A Rep Power: 141521	not only that the stock system is missing a lot of mid-band 350-650Hz range too. the over all sound is like having your boom box set to "pop" or "rock" EQ.

10-22-2010, 07:18 PM	#3 (permalink)
turbodog Base Member Join Date: Sep 2010 Location: Dallas, TX Posts: 129 Drives: 370Z Rep Power: 15	We are in complete agreement. "tuned for, er, how should I say this.... a 'younger' perspective on music tonal balance" = "like having your boom box set to "pop" or "rock" EQ."

10-24-2010, 08:15 PM	#4 (permalink)
sonic370 A True Z Fanatic Join Date: May 2010 Location: Orange Texas Posts: 1,574 Drives: 09 370Z Sports PGK Rep Power: 18	everyone has an opinion on this but the base will sound better with better speakers. you know which comes first HU or Speakers

10-25-2010, 10:37 AM	#5 (permalink)
turbodog Base Member Join Date: Sep 2010 Location: Dallas, TX Posts: 129 Drives: 370Z Rep Power: 15	Yeah, it will be speakers for me. Updates will be posted after dynamat and after speakers. I did, over the weekend, try various bass/treble adjustments to see if I could flatten the response any. -2 bass, -1 treble helped, but it still has a major dropout at 750 Hz.