Percy

Hi guys!

Just had a chance to measure out the response in the GS. To say that it's ragged is an understatement. Here's what I'm using...

Stock head unit (Pioneer/Premium)
Settings +7 bass, +7 Mid, +5 treble
Dynaudio MD100 tweeters for the pillars
Dynaudio MW160's for the fronts and rears
Velodyne (passively run) DF12sc.

Measuring equipment...
Bruel & Kjaer 2206 Sound Level Meter with 1/2 inch microphone (4148) cartridge. Measures from 6hz to 20khz. Using A weighted settings, microphone and sound meter calibrated with 4230 Bruel & Kjaer calibration device.

I recorded some test signals from a function generator (sine wave of course) onto a cd, 1/3rd octave, pure test tones. This was done since it gives more accuracy than a pink noise generator with a 1/3rd octave spectrum analyzer. (More on that in a moment)

The peaks are awful. There's almost a 20dBA difference between 630hz and 1khz. So, if you're tuning out, make sure to knock down the 630. Also, 250hz and 8khz are some of the nastier peaks. By the time it gets down to the 16khz region, it's almost 30db lower than the 630hz. (Ideally they're supposed to be equal).

I'll have to scan in the graph. Anyone interested can PM me.

If it's this bad with the Dyn speakers, imagine what it would be with the stock sub and paper speakers. I might have to include this in the revised version of THE BOOK (as Ron430 so affectionately calls it)

As for the RTA and pink noise, most meters won't have the response time to capture everything. Even with the meter on "accumulate" or "hold", it still isn't an accurate representation of the REAL things that are going on. Dynaudio uses a frequency sweep with B&K equipment, and that's the most accurate way of measuring since the speaker (and generator) are only using a single tone at one time for a certain duration, and to make sure that the microphone is really responding. Pink noise is nice, but it's not the most accurate. (it's good for the quick stuff though.)

Percy

RON430

Percy, please figure out how to scan in the graph. I am not sure I will understand all of it, but I would like to see it. I have not put the dyn 180 sub in yet but I obviously have the dyns in the front doors and the ADS's in the rear doors. I am very sensitive to the need to change the head unit equalization for varying material but I am most commonly set on Bass +6, mid +7, and treble +6. By the way, I assume this is with the Deflex and Vel running free air but anything else unusual on sound deadening?

Also, could you swing by Eric G's thread on dyn installation. He asked about getting THE BOOK and I recommended he PM you, I've forgotten all the pertinent info. Really need to figure out how to get a continuous sticky at the top with THE BOOK acquisition info.

amlin423

Hi Percy,
I'd be very interested in seeing the graph also. Are your Dyns powered by your Macs? If so, I'm assuming your MENs (EQ) are in there too right?
Thanks
Andrew

LexusRules

would a new amp fix taht dude? is there any way to fix it other than like a 3000 band equalizier?

haha hope it gets tuned bettter!

Percy

Ron,

This is with the Deflex and Vel running free air, passive. Stock head unit and stock amp. Haven't had the chance to install the good stuff yet...too busy helping out the college students in science and physics.

I'll try to scan in the graph...I knew the frequency response was bad (just by ear) but didn't know it was THAT bad!

Percy

Percy

Andrew,

This is the STOCK system with the STOCK amp and Dyn/Vel speakers. If it was the "supercarrier" system then the FR would be worlds better. (and all the other good stuff.)

Percy

Percy

Hi Sasha!

This is the STOCK amp and STOCK head unit with Dyn/Vel speakers. Obviously Lexus tuned it out for the DEAF and the graph would be MUCH more severe if the stock speakers were also in place. Most people as they get older will get "notched" hearing (midrange sensitivity goes WAY down) and from the looks of it, Lexus tried to compensate. I wouldn't be surprised to see an older guy with at least 10db(A) loss in the 630-1khz region. They also tried to crank up the 8k region since most older people will lose the high frequencies also.

You wouldn't need a 3000 band eq...that's way overkill and you'd go nuts trying to tune it out. As ragged as it is, all you really need to do is to get a 6 band (you read right) PARAMETRIC (not graphic) eq in there and mess around with the xover and level settings.

I should really get a graph for the ML equipped system. That would be interesting...

Percy

Ira Senoff

Dumb questions - what are the crossover points and slopes? Did you play with phasing at all? Stock speaker locations or kicks? Little changes in this area could make big changes in freq response.

Also, as an avid IASCA competitor, I care very little of what the freq curve/resposne looks like to a mic, I care how it sounds to my ear.

Rather than the peak in response being attributed to tuning of the stock system, is it possible that you could be experiencing some anamoly between the stock amplifier and the Dyn X-overs/impedence problems...........

As my GS is finally getting done for competition purposes starting next week (I waffled between my Expedition, my GS, and even buying a '69 Camaro w/ a LS6 & 5.88 gears for a while as the platform for the system), I will keep you all posted.

Percy

Ira,

SInce this was the STOCK system, this is pretty much an unknown. I have the tweets crossed over at 3khz, 18db/oct. STOCK speaker locations (I'm not a kick pod fan).

Granted, most good sounding systems are tuned by ear. This little experiement was done to see HOW BAD Lexus actually tuned out their Premium system. Generally the way I do it is to get the RTA as good as possible and then set it by ear. Saves time and it saves ear fatigue. With exceptions on this board, the general concensus is that most "older" people will only drive a Lexus. (no offense to the "senior" members of the board), thus the high midrange peaks and severe notches.

IME, impedance changes usually occurs at the xover point and then eases down from there, or at the drivers lower/upper limit point. I would find it very difficult to believe that, in the middle of the midwoofers operating range (a nice 630hz) that there would be a nearly 20 dBA difference from 630 to 1khz. The tweeter doesn't even come into the picture until about 3khz. Only thing that would make sense....Lexus idea of "tuning" within the amp/head unit and electronics.

Percy

engin_ear

iTrader: (1)

Percy:

Q1: Where exactly in the car did you place the B&K microphone? Driver head position? Front and center? This is critical, as the measured response will vary across the entire interior space of the car (I'm sure you're already aware of this.). Please let us know, if only for reference purposes, thanks.

Q2: Why is is that many seem to be running head unit tone controls all at +5 to +7? Is this to get a hotter signal at a lower volume control setting? Why aren't the tone controls set more around the 0 position, with the volume set a bit higher? Is there something non-linear going on, or maybe the response is harder to flatten out if you don't do this, in the case of the Pioneer head unit?

It would be interesting to see the same measurements on the GS Nakamichi system. After living with it for 2 years, and also hearing it with the Dyn's, I don't think it would measure out as poorly. I know that the Nak head unit output is fairly flat from measuring it with a scope and a test CD, it only varies a couple of dB in the midrange area. That's not to say what Lexus may have done as far as tuning in the amp, that I didn't measure...I'm also to the point where I can't go back and measure the stock stuff as well, my Nak amp has been yanked to the point of difficult return.

It would be also interesting to know whether the response raggedness you've measured is more due to head unit, amp, electronics mismatch, or interior acoustics. (My money would be on the latter.)

Jerry

Percy

[QUOTE]Originally posted by engin_ear
[B]Percy:

Q1: Where exactly in the car did you place the B&K microphone? Driver head position?

***Driver head position. Mic is right where the head would be.***

Front and center? This is critical, as the measured response will vary across the entire interior space of the car (I'm sure you're already aware of this.). Please let us know, if only for reference purposes, thanks.

Q2: Why is is that many seem to be running head unit tone controls all at +5 to +7? Is this to get a hotter signal at a lower volume control setting?


***They were set by ear to what sounded as good as possible for the stock system. If I went +7 on the treble, then it got too hot at the lower listening levels as well as the higher ones. If they were set at the zero position, then it really sounded bad. ***


Why aren't the tone controls set more around the 0 position, with the volume set a bit higher? Is there something non-linear going on, or maybe the response is harder to flatten out if you don't do this, in the case of the Pioneer head unit?

It would be interesting to see the same measurements on the GS Nakamichi system. After living with it for 2 years, and also hearing it with the Dyn's, I don't think it would measure out as poorly. I know that the Nak head unit output is fairly flat from measuring it with a scope and a test CD, it only varies a couple of dB in the midrange area. That's not to say what Lexus may have done as far as tuning in the amp, that I didn't measure...I'm also to the point where I can't go back and measure the stock stuff as well, my Nak amp has been yanked to the point of difficult return.

It would be also interesting to know whether the response raggedness you've measured is more due to head unit, amp, electronics mismatch, or interior acoustics. (My money would be on the latter.)

***I can usually "fudge" the settings on an aftermarket system to compensate for most of the interior acoustics, especially speaker mounting (area behind speaker) location. In the GS, it seems as if the interior acoustics aren't THAT bad, but rather it's the way the factory tuned out the electronics. I'll have more info as I'm going to try to get a ML system to test out. That should negate any interior acoustics (it's the same interior). I'm just wondering what they (Lexus) were thinking of when they dropped in the system.***

Percy

RON430

engin_ear - I understand your comments about the head unit equalizer positions. Maybe Percy can answer more technically but all I can say is that the dyns really came alive at settings over +5 that just did not happen with volume alone. With the dyns it is very noticeable when you get to +5 with any of the settings and you can definitely hear it. If I tend to play with anything, it is the bass settings. The dyn drivers in the front doors have really increased bass response but I am not sure if there is something else going on and Percy's response chart might show that. I also used the Deflex panels with CAE sound deadening in the doors (front and rear) and have the ADS's in the rear doors wired opposite phase as Percy recommended trying.

sirsomo

The GS stock system always did sound kind of high in the mid-high range to me, I just assumed that it was because my previous car was all aftermarket and that was how factory systems sounded? Anyway, I would like to see the graph also Percy.

Percy

Ron,

I just sent you a copy of the graph. Let me know what you think. Use the far left margin where it starts off from 0 to 50 dB. Add 40 to this number and you'll have the readings that I measured. 60dBA for 1khz, 79dBA for 800 hz, 78dBA for 630 hz. Scarry!

Sirsomo,

What's your email address? I'll send you a copy.

Percy

RON430

This is a test but if I am lucky I have attached Percy's file.

Ron