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-   -   measure speaker T/S parameter, what do I need? (http://www.diyaudio.com/forums/equipment-tools/191164-measure-speaker-t-s-parameter-what-do-i-need.html)

gychang 19th June 2011 08:04 PM

measure speaker T/S parameter, what do I need?
 
1. what equipment do I need to measure T/S?, been building fullranger cabinets but seems published specs are freq overblown?

what is a minimum equipment I would need? (lower cost will be good).

2. what kind of SPL meter do I need to get the the speaker frequency/SPL graph produced?, some sort of mic-software combo?

thanks,

zakman35 19th June 2011 09:29 PM

Most people use a Behringer ECM8000 mic and an external sound card with phantom power (sorry i don't remember the brand of it).

Alternative, I choose to use the cheapest possible solution since i do this just for fun.

So this is my setup.
  1. Laptop pc.
  2. Usb external soundcard, from ebay for approximately 15 $.
  3. Limp software for T/S measurements. (part of ARTA software package) free. http://www.fesb.hr/~mateljan/arta/
  4. A power amplifier. (although there is an option to measure without, i found this method more stable).
  5. A few cables, alligator clips etc.
  6. Patience.
I suggest you read carefully the manual of Limp before you start.

Now, If you like to make frequency response measurements as well, you will need the following.
  1. Self powered mic (uses one AA battery) with a 3.5 mm connector (i had this in stock).
  2. HOLMImpulse for frequency response measurements Free.HOLM Acoustics
  3. Alternative you can use "ARTA" but i found Holmipulse more user friendly.
  4. Mic stand. (i use my camera stand).
Have fun.

ByronInPortland 19th June 2011 11:31 PM

more suggestions
 
1 Attachment(s)
I've been tweaking/troubleshooting my setup for a few months now. Here is what I've settled on and what didn't work.
  • A PC running Speakerworkshop, available for free here: Speaker Workshop I'm sticking with SW because I invested so much pain & suffering into learning it, I'm afraid to switch to something else. If I were to do it all over again, I don't know that I would use SW.
  • A Behringer UCA222, which is essentially an external sound card which connects to the comp's USB port. I settled on this after failing to get SW to work with my on-board sound card, and with a Rocketfish card. SW requires 2 channel recording to use all of it's capabilities. Your comp's soundcard may be good enough to get started with SW or whatever software you choose. The Behringer is also nice because it uses RCA jacks for input and output which lets me use good quality cables. And the long USB cable lets me keep the signal-carrying wires short, yet position the computer further from the driver under test. If I were to do it again I would save a little money with the Behringer UCA202. BEHRINGER: UCA202
  • A power amp stable into at least 4 ohms. Theoretically, you only need 1 watt for frequency-response measurements, and a fraction of a watt (I use ~0.3VAC for 8 ohm drivers) for impedance curves. It's good to have a few extra watts.
  • A Wallin Jig, which is not available for purchase. Instructions for building one are here: Eric Wallin's Internet Homepage It's not necessary, but is convenient, especially if you want to calibrate your sound card in SW.
  • A little jig to hold drivers steady is nice, but not necessary.
  • If you want to do frequency-response measurements, add to this a microphone like the Behringer ECM8000, or the Dayton EMM-6. At least 2 people on this forum are using the ART Phantom I phantom microphone power supply.
  • Some way to add mass to the driver being tested, and a scale accurate to about 0.1g to measure said mass. Most people use some kind of reusable adhesive putty like this: Elmer's Tacky Adhesive can be Removed and Re-Used | Sticky Tack I've found at putty does not stick well to paper cones, and loses its stickiness after a few uses, so I've moved to small (~15g) magnets. Put them on opposite sides of the driver's cone, symmetrically around the dust cap. Also, I just weighed the magnets once and wrote their mass on them - very convenient.
  • Be aware that Parts Express is selling this little gadget: Dayton Audio WT3P WT3 Bundled with Precision Scale but I don't know anyone who's used it.
Enjoy!
-Byron

gychang 20th June 2011 12:27 AM

Quote:

Originally Posted by zakman35 (Post 2611950)

So this is my setup.
  1. Laptop pc.
  2. Usb external soundcard, from ebay for approximately 15 $.
  3. Limp software for T/S measurements. (part of ARTA software package) free. http://www.fesb.hr/~mateljan/arta/
  4. A power amplifier. (although there is an option to measure without, i found this method more stable).
  5. A few cables, alligator clips etc.
  6. Patience.
I suggest you read carefully the manual of Limp before you start.

Now, If you like to make frequency response measurements as well, you will need the following.
  1. Self powered mic (uses one AA battery) with a 3.5 mm connector (i had this in stock).
  2. HOLMImpulse for frequency response measurements Free.HOLM Acoustics
  3. Alternative you can use "ARTA" but i found Holmipulse more user friendly.
  4. Mic stand. (i use my camera stand).
Have fun.

this is great, it also is just a hobby for me, will look into all this, any particular powered mic?

gychang 20th June 2011 12:34 AM

Quote:

Originally Posted by ByronInLawrence (Post 2612050)
I've been tweaking/troubleshooting my setup for a few months now. Here is what I've settled on and what didn't work.
  • A PC running Speakerworkshop, available for free here: Speaker Workshop I'm sticking with SW because I invested so much pain & suffering into learning it, I'm afraid to switch to something else. If I were to do it all over again, I don't know that I would use SW.
  • A Behringer UCA222, which is essentially an external sound card which connects to the comp's USB port. I settled on this after failing to get SW to work with my on-board sound card, and with a Rocketfish card. SW requires 2 channel recording to use all of it's capabilities. Your comp's soundcard may be good enough to get started with SW or whatever software you choose. The Behringer is also nice because it uses RCA jacks for input and output which lets me use good quality cables. And the long USB cable lets me keep the signal-carrying wires short, yet position the computer further from the driver under test. If I were to do it again I would save a little money with the Behringer UCA202. BEHRINGER: UCA202
  • A power amp stable into at least 4 ohms. Theoretically, you only need 1 watt for frequency-response measurements, and a fraction of a watt (I use ~0.3VAC for 8 ohm drivers) for impedance curves. It's good to have a few extra watts.
  • A Wallin Jig, which is not available for purchase. Instructions for building one are here: Eric Wallin's Internet Homepage It's not necessary, but is convenient, especially if you want to calibrate your sound card in SW.
  • A little jig to hold drivers steady is nice, but not necessary.
  • If you want to do frequency-response measurements, add to this a microphone like the Behringer ECM8000, or the Dayton EMM-6. At least 2 people on this forum are using the ART Phantom I phantom microphone power supply.
  • Some way to add mass to the driver being tested, and a scale accurate to about 0.1g to measure said mass. Most people use some kind of reusable adhesive putty like this: Elmer's Tacky Adhesive can be Removed and Re-Used | Sticky Tack I've found at putty does not stick well to paper cones, and loses its stickiness after a few uses, so I've moved to small (~15g) magnets. Put them on opposite sides of the driver's cone, symmetrically around the dust cap. Also, I just weighed the magnets once and wrote their mass on them - very convenient.
  • Be aware that Parts Express is selling this little gadget: Dayton Audio WT3P WT3 Bundled with Precision Scale but I don't know anyone who's used it.
Enjoy!
-Byron

thanks for a detailed information, I will have to digest this in detail...

wintermute 20th June 2011 03:39 AM

Speaker Workshop with Claudio's cable jig is probably the cheapest entry into T/S measurements assuming you have a half decent sound card. as mentioned, if you have a laptop you will need a good usb sound card. Check out Claudio's web page here Claudio Negro's home page, how to project and test a loudspeaker using Speaker Workshop

For impedance measurements (for calculating T/S params) most modern motherboards on board sound should be sufficient, so if you have a modern computer (as opposed to a laptop) you probably only need to buy some cable and resistors to be on your way :)

Tony.

zakman35 20th June 2011 06:05 AM

Quote:

any particular powered mic?
No, I just use a self powered mic.

As ByronInLawrence said, you also need “Some way to add mass to the driver being tested”. Instead of magnets and a scale, I use coins and bluetak. You can find the exact weight of coins from google, no need to measure them yourself. If I want extra weight, I stack two or more coins together with bluetak in order to achieve the target weight. Then stick them all together to the driver with bluetak again. Works for me.

zakman35 20th June 2011 06:49 AM

You can also built yourself a high quality mic on the cheap.
Build Your Own Microphone for Testing your Speakers

alexf 20th June 2011 08:31 PM

After reading a few web pages about using WM-61A as a test microphone I decided to try it.
I have Sony MDR-V6 headphones that are supposed to have a "flat" response from 5 Hz to 30K.
So I plugged them into the output of my sound card (Audiotrak Prodigy HD2) and put the mic close to the center of the speaker. The response is anything but flat: severe loss at both low and high ends. Any ideas?

gychang 20th June 2011 09:23 PM

Quote:

Originally Posted by ByronInLawrence (Post 2612050)
[*]Be aware that Parts Express is selling this little gadget: Dayton Audio WT3P WT3 Bundled with Precision Scale but I don't know anyone who's used it.[/LIST]Enjoy!
-Byron

seems this product review is very favorable, wonder if anyone on the fullrange is using this... Quick t/s parameters.


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