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Ignorance is Bliss
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Discussion Starter #1
I was reading the guide on "Setting up a PC based loudspeaker measurement system" and wanted to attempt the "unreliable" ratshack spl meter method of tuning my system before going out and getting all this hardware. $$$

With this said, can anyone link me in the direction where i can get test tones, or test cd's to be able to use my spl meter properly? In home audio i use an AVIA DVD which displays the frequency being played on the TV and i can see where my peaks in the system are using the SPL meter, but how will that work for car audio?

A little mock up guide or a link to a guide would be great also.

Thanks.

I believe in my ears and like to tune my system by ear, but a few measurenments would be great.
 

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I'm sure there are much better CDs than what I'm about to suggest, but Bass Mechanic has a disc that I used to play with, mostly for base but it also has full sweeps on it and pink noise. I don't think the radio shack equipment responds fast enough to be useable though. You'd either need faster responding equipment and/or the ability to select your frequency. On the Bass Mechanic CD you can select one Hz at a time from 10-100Hz. Beyond that you'd have to use the sweeps and pink noise.
 

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Ignorance is Bliss
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Discussion Starter #4
Airforceyooper said:
I'm sure there are much better CDs than what I'm about to suggest, but Bass Mechanic has a disc that I used to play with, mostly for base but it also has full sweeps on it and pink noise. I don't think the radio shack equipment responds fast enough to be useable though. You'd either need faster responding equipment and/or the ability to select your frequency. On the Bass Mechanic CD you can select one Hz at a time from 10-100Hz. Beyond that you'd have to use the sweeps and pink noise.

what do you mean by pink noise and what can it tell you?


well, even if the equipment is slow, i believe it should be able to give you a before and after comparison on the changes you made. I'm not quite ready to drop a few hundred on laptop software, soundcards, preamps, and mics yet.

MIAaron: that looks great, thanks.
 

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what's wrong with using PC measurements? you can use a cheap behringer microphone and use free software.

if you know how your songs should sound like under hi-fi speakers, and you know how to recognize the frequency range, then it should be pretty easy. ears can still do a lot of measurements better than instruments, and are essential to getting the mid frequencies right.
 

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Ignorance is Bliss
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Discussion Starter #6
cotdt said:
what's wrong with using PC measurements? you can use a cheap behringer microphone and use free software.

if you know how your songs should sound like under hi-fi speakers, and you know how to recognize the frequency range, then it should be pretty easy. ears can still do a lot of measurements better than instruments, and are essential to getting the mid frequencies right.

which free software are you talkign about. and how much would the microphone be?

i already have a laptop and an usb audigy2zs
 

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In my less than technical verbiage, pink noise is all frequencies played at the same level. If you're using an RTA or equivilant, it will tell you where your peaks and valleys are in your frequency response.
 

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Ignorance is Bliss
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Discussion Starter #8
Airforceyooper said:
In my less than technical verbiage, pink noise is all frequencies played at the same level. If you're using an RTA or equivilant, it will tell you where your peaks and valleys are in your frequency response.

RTA = real time analyzer?
 

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Discussion Starter #10
so what do you mean by "using an RTA or equivilant" is that the same as using an spl meter?
 

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af22 said:
so what do you mean by "using an RTA or equivilant" is that the same as using an spl meter?
With an RTA you get SPL for each frequency at the same time, on the same graph. With a SPL meter you have to check each frequency separately.
 

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Well, the fact that you have a laptop already cuts the cost of putting together an RTA.

Cheap Software:
http://www.trueaudio.com/rta_abt1.htm

Cheap Mic, preamp, mixer:
http://www.trueaudio.com/rta_faq1.htm

Maybe you don't want to spend $200 on test equipment but, that is cheap compared to an all-in-one RTA unit....$1200 +

http://www.woofersetc.com/index.cfm?fuseaction=product.display&Product_ID=1271
http://www.partsexpress.com/pe/pshowdetl.cfm?&PartNumber=390-805&DID=7&raid=50&rak=390-805

Software is the way to go!

However, if you want to use the Radio Shack meter, you will need a 1/3 octave disc.
http://www.davidnavone.com/detail.asp?PRODUCT_ID=A2521

Also, there are some corrections to add to the chart from the Radio Shack meter:
http://www.hometheaterforum.com/htforum/showthread.php?s=&postid=231211#post231211
 

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A behringer ecm8000 mic can be had for $40. A mic pre-amp can be had for $50. All you would need is a few cables, and maybe a stand which can be done for under $50.

Software... speakerworkshop is free and there is a very good manual that you can download for it. You can also find alot of trial software that will do simple MLS based measurements.
 
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By far, the cheapest way possible to tune your system is...to borrow your friends PC measurement system ;) .
If they don't have one, then you need new friends....with jobs:rolleyes:

Cheers,

AJ :D
 

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Discussion Starter #16
npdang said:
A behringer ecm8000 mic can be had for $40. A mic pre-amp can be had for $50. All you would need is a few cables, and maybe a stand which can be done for under $50.

Software... speakerworkshop is free and there is a very good manual that you can download for it. You can also find alot of trial software that will do simple MLS based measurements.
after that, wouldn't i need some "test cds" to play the desired test tones. let me go read the DIY guide again....??
 

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Ignorance is Bliss
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Discussion Starter #17
af22 said:
after that, wouldn't i need some "test cds" to play the desired test tones. let me go read the DIY guide again....??
"Generally speaking, a RTA is more convenient because all you need to do is burn a “pink noise test cd”, and play that on your headunit. Then you turn on your mic, and you are given a 1/3 octave frequency response graph to look at. It’s as simple as that.

A MLS based system can give you a FAR greater amount of information and flexibility (especially time domain info and not just frequency response), but it will require you to connect your soundcard’s line output to the input of your audio system before any crossovers, eq, or processing is used. The way it works is that the software generates the test signal, sends it out through your soundcard, and into your stereo. "

Answered my own question.
 
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