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programs for testing speaker response

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Posted on May 17, 2016 at 11:50:52
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 I realize that I need to measure the frequency response of my speakers to understand what is going on. But which program? I am aware of ARTA, REW, and TrueRTA. There are probably other programs out there. I have a laptop, measurement microphone and a Tascam USB interface. Which program would you recommend to someone who is not the most technically literate fellow out there? Ease of use would be helpful, although I am willing to put in the effort if the directions are clear.

 

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what is "going on" that you're trying to understand? (nt), posted on May 18, 2016 at 04:13:28
mhardy6647
Audiophile

Posts: 16015
Location: New England
Joined: October 12, 1999
Contributor
  Since: October 23, 2016
 nt
all the best,
mrh

 

RE: programs for testing speaker response, posted on May 18, 2016 at 04:37:10
Bill Fitzmaurice
Industry Professional

Posts: 5370
Location: New England
Joined: October 20, 2002
 I use HolmImpulse, which works very well. However, the instructions that come with it aren't the best, as they assume that you know what you're doing already. You'd have to find third party instructions that are better suited to a novice, which I'm sure are out there. From what I understand REW has very good documentation and support, though I've never used it myself.

 

RE: programs for testing speaker response, posted on May 18, 2016 at 04:53:35
lokie
Audiophile

Posts: 1989
Location: Georgia, USA
Joined: January 28, 2003
 I tried using REW and it left me feeling like a mental midget. I chose it because of the forum, but they weren't help much either.

Room and speaker measurements are so key to refining your speakers crossover. It's something I've been struggling with.

 

RE: what is "going on" that you're trying to understand? (nt), posted on May 18, 2016 at 09:08:29
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 I would like to do frequency response measurements.

 

RE: programs for testing speaker response, posted on May 18, 2016 at 10:52:36
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 F.

I have used REW and it works quite well, but there was a learning curve going from the old school way of making freq. resp. graphs using the warble oscillator test tracks on the Stereophile Test CD, test mic with a VU meter and graph paper.

Good news: You can generate a lot of data very quickly on your laptop with REW.
Bad news: You can generate a lot of data very quickly etc.

Interpreting all the data is still the difficult part. It took me awhile to understand why the measurements were quite different between REW and my old graph paper data. The reason is largely due to the tendency of the warble oscillator and VU meter to average out and smooth the response. You will need to select an averaging option with the graph REW creates, and 6 dB per octave is a good start as Atkinson usually uses this in his frequency response graphs in Stereophile (when this is specified). Using no smoothing will provide a graph that looks like a field of grass with too much micro information. Using a high order of smoothing, like 24 dB per octave, will make the results unrealistically smooth (read: too good to be true). What you want to look for is a signature, or the lay of the forest rather than overly focusing on particular trees in it. I have obtained similar results to Atkinson's measurements when measuring the same speakers he has tested in Stereophile

Make a paper copy of the REW instructions as you'll need it while your laptop is running REW. Also there's a good instructional video on Youtube about using REW. The Home Theater Shack website (where you can download REW for free) is mainly concerned with measuring room response which can be addressed with active EQ, and not so much with what the speakers themselves are doing without what the room is adding.

A bit of history: Richard C. Heyser invented Time Delay Spectrometry which he used to test speakers in Audio magazine back in the day. The first TDS unit cost $30,000 to cobble together out of various computer and pieces of scientific equipment. Nowadays a functional facsimile program is a free download, but we're still scratching our heads about the data! Heyser saw similarities among the discrepancy between what we hear and the measurements we obtain, and similar discrepancies between measurement data in Quantum mechanics.

Good Luck!

Paul

 

RE: programs for testing speaker response, posted on May 18, 2016 at 22:29:52
amandarae
Audiophile

Posts: 2591
Location: So.Cal
Joined: November 30, 2004
 I use REW, and I am trying hard to teach myself what I can get from it especially on trying different crossover combination. But I also use UMIK-1 and miniDSP, so you have to invest some dough. Yes, it will take a lot of time and a lot of staring at the graphs but once you grasp the basics of it, it is not that hard to interpret.

Go to mini DSP tutorial website for some tips using REW in Acoustic Measurement, Loudspeaker Measurement, etc. examples. Also, look for topics like "2 way crossover design" etc. on the net.

Link Below

 

Often people are shooting over the target, posted on May 19, 2016 at 23:22:38
pix
Audiophile

Posts: 411
Location: sweden
Joined: March 18, 2006

Some people really need ARTA and such complex sofwares. But for most of us, a a simple mobile-app. (like Audio Control from Mobile Tools) are good enough.
Itīs, free have RTA-, FFT- and SPL-feature. And als a signal generator with white- and pink-noice through the headphone plug.
After all, most acoustic measurements in home environment are quite rough anyway.

 

RE: what is "going on" that you're trying to understand? (nt), posted on May 20, 2016 at 12:46:24
Inmate51
 So, you're not interested in ETF or dispersion? Just FR?

 

RE: programs for testing speaker response, posted on May 21, 2016 at 10:59:31
John Sheerin
Audiophile

Posts: 524
Location: PA
Joined: July 28, 2003
 Hi Paul,
Fyi, smoothing usually works the opposite of what you've said. It's specified in fractions of an octave - 1/6 octave, 1/24 octave, etc. and 1/6 is more smoothing than 1/24. 1/6 octave smoothing is a good place to start. Less smoothing, like 1/24 octave can be useful if you're measuring outdoors far from reflections and actually want to see the finer detail of the system you're working on.

To the OP, I've used Speaker Workshop quite a bit over the years (it's quite old). It also can measure impedance and do crossover design. It's harder to pick up than current programs - it has a few bugs and you need to know a bit more to use it. But it can be very powerful. I'd also recommend that if you're trying to design a system from scratch, you go to the trouble of getting good outdoor measurements in order to design the system, then do fine tuning in your room. I find I get much better results that way.

 

RE: programs for testing speaker response, posted on May 21, 2016 at 14:45:54
Paul Eizik
Audiophile

Posts: 2120
Joined: September 15, 2001
 Hi John

With REW an initial un-smoothed measurement will provide a useless "too much grass" type of graph. A 6 dB smoothed graph will make the same measurement look similar to the frequency response graphs in Stereophile, though the scaling is different. At 24 dB smoothing with REW most of the detail is lost. Perhaps things are different with Speaker Workshop, which I've never used. Maybe it's a difference in nomenclature between the two systems.

As to doing measurements outdoors, that's "nice work if you can get it" as the song says. I live on a gentrifying block with at least two or three new or rehab house projects going on at any time, I'm a block away from a train line which is also next to the elevated train line, which is all under a glide path for O Hare airport. The presidential helicopter frequently flies over my house.

Don Keele observed that one of the weaknesses with these time delay sampling techniques was the one-size-fits-all sampling rate, and he suggested that the sampling rate should be longer at the lower frequency end, and higher at the high frequency end. REW uses the same same rate as far as I recall, perhaps some of the more sophisticated (non-free) programs use a sampling rate adjusted to the frequency. Keel's AES paper Time-Frequency Display of Electro-Acoustic Data Using Cycle-Octave Wavelet Transforms is a good read. He comes to a similar conclusion that Heyser did in that time-frequency displays suffer from quantum-like uncertainty because you can't get arbitrarily precise in one domain without getting less precise in the other.

I miss your JHS website!

Paul

 

RE: Often people are shooting over the target, posted on May 22, 2016 at 08:07:36
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 I agree with you. I just want a basic setup for measuring frequency response in my room. The app from Audio Control looks like just what I have been looking for, but the cost of the USB microphone that Audio Control offers to work with it is a little steep. ($229) I will keep this in mind. Parts Express sells a Dayton Audio USB microphone that works with REW for $80, but the "getting started with REW" manual that I found on The Home Theater Shack website is 116 pages long! Yeesh! I am still looking, and will report back on what I decided to do.

 

Best things in life are often free ;o), posted on May 22, 2016 at 23:37:53
pix
Audiophile

Posts: 411
Location: sweden
Joined: March 18, 2006
 Well, I use the cellphone microphone (not a computer) which I have level-calibrated using a friends pro-setup-mesuring system. But this is not needed for just seeing the curves.

And for the generator function I used a broken phone headset for the cellphone-plugg, a 5 meter shielded cable (twisted pair will do) and a RCA plugg (use two in parallell if you donīt have a stereo/mono-switch at the amp).
You could solder an external microphone to that phoneplugg to, but the cellphone mic will do the jobb.

The Audio Control has a free version of the app (without the phase mesturing feature) wich works fine.
The Picture in my previous post is the measure of my 200Hz Tricstrax horns by the way.

 

RE: Best things in life are often free ;o), posted on May 23, 2016 at 18:11:50
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 Oooooooh! You are a very clever person. I just downloaded the app onto my I-phone and in just a few minutes I had a graph using the pink noise track from the Stereophile test CD. 1/3 octave is plenty for what I want to do. Next step is to download it to my wife's I-pad so I can use the headphone out jack to an RCA cable. Thanks for pointing out this program!

 

RE: what is "going on" that you're trying to understand? (nt), posted on May 24, 2016 at 19:01:23
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 I am interested, but would consider it a good start if I can see what my speakers are generally doing in my room. Once I can figure out how to get basic FR measurements, then maybe I can expand to other measurements.

 

RE: programs for testing speaker response, posted on May 24, 2016 at 19:06:59
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 The speakers are built. They are 2 way with an active crossover. I would like to make some basic measurements to refine the crossover. I live in an apartment. Outside measurements would take a little more planning than for someone with a backyard.

 

RE: programs for testing speaker response, posted on May 24, 2016 at 19:14:37
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 I feel your pain. Spent Saturday morning trying to get REW to work, until I realized that my microphone amplifier/USB interface doesn't work with Windows 10! Time for Plan B. I downloaded a program called Mobile Tools to my iphone, and in a few minutes, using the microphone in the phone, I had a 1/3 octave FR measurement. Next step is to see if I can use my Dayton Audio measurement mike plugged into the phone or into an ipad.

 

RE: programs for testing speaker response, posted on May 24, 2016 at 19:21:05
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 Thanks for your response. I have never claimed to know what I was doing with anything. ;) However, I will keep working the problem and report back with any progress.

 

FuzzMeasure, posted on May 24, 2016 at 19:41:56
Chip647
Audiophile

Posts: 2649
Location: The South
Joined: December 24, 2012
 Basic functionality (demo) is free. Awesome Tool.

 

RE: programs for testing speaker response, posted on May 24, 2016 at 22:06:26
John Sheerin
Audiophile

Posts: 524
Location: PA
Joined: July 28, 2003
 If your speakers are built, then you've fixed a couple of the variables - what the drivers are, the raw response they'll have, and their physical location relative to each other. The remaining work is to design filters that make the drivers work together in the best way possible. This is typically what determines a lot of how good a speaker will be. If you use the best components in the world but design bad filters for the drivers, it will still sound like crap.

I'm not saying you have to measure outside, but I've found it much easier to get good results if I design the filters for the drivers in an environment where I don't see the effect of the room and then tweak the response of the total system in the room without having to worry about whether I've got the crossover right or not.

Parking lots are usually my go-to places, like school parking lots on the weekend. I'll do a ground plane measurement where you place the mic on the ground to eliminate reflections up to a fairly high frequency. I typically use a laptop and a UPS to power my measurement system and amp. If you get a decent sized one it will go for a couple of hours. You definitely want to have your process down cold before you go do that though. You also want to be aware of what the noise floor is - take a measurement without any of the drivers playing and compare it to what you get when you measure the drivers.

 

RE: programs for testing speaker response, posted on May 25, 2016 at 09:49:41
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 This makes sense to me. I can access the roof of our building, and we live in a relatively quiet neighborhood. The speakers are in 2 boxes, woofer and fullrange, so shouldn't be too hard to haul them up and back. Thank you for weighing in. We have some very knowledgeable folks on this board (you being one of them) and I always appreciate their willingness to share and teach.

 

RE: FuzzMeasure, posted on May 25, 2016 at 12:14:13
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 Interesting! I will download the demo to my wife's ipad (if I can pry it out of her hands) to try it out. Thanks for pointing this out.

 

RE: programs for testing speaker response, posted on May 25, 2016 at 19:23:43
John Sheerin
Audiophile

Posts: 524
Location: PA
Joined: July 28, 2003
 Happy to help.

The roof is a bit different situation, but potentially better. What I would try is positioning your speaker at the corner of the roof pointing away from the building and put the mic on a boom of some sort out into the air. If there's nothing flat behind the speaker, you should mostly eliminate reflections that way. You would get a reflection from the ground, but if you're high enough up, you could gate that out and get good LF resolution.

 

RE: programs for testing speaker response, posted on May 26, 2016 at 10:11:20
Inmate51
 THIS is ONE of the reasons why audiophile-land hasn't changed in 45 years. I feel like I'm reading an article from 1972!!

 

RE: programs for testing speaker response, posted on May 26, 2016 at 11:14:23
John Sheerin
Audiophile

Posts: 524
Location: PA
Joined: July 28, 2003
 I'm not exactly sure what you mean, but if you're saying that people not measuring the speakers they're building is like being back in the 70's, I suppose I'd agree although I'd say it's like any time before ~2000. Of course the difference now is that it's fairly straight forward to get a good measurement program, a decent mic and sound card, and start learning how to incorporate measurements into building speakers if one is inclined to put in the effort.

 

RE: programs for testing speaker response, posted on June 26, 2016 at 15:56:41
floydandrews
Audiophile

Posts: 318
Location: Port Townsend, WA
Joined: December 29, 2003
 I wanted to let everyone know what I ended up with for speaker testing. This rig works for my purposes, but may not be powerful enough for others. I bought a Dayton Audio iMM-6 calibrated microphone from Parts Express. Currently listed for $16.25 each. It plugs into an i-pad or i-phone.I downloaded a program called "Audio Tools" from the Apple app store for $9.95. I downloaded the individual calibration file for the microphone. So far I have only used the RTA, which measures octave or 1/3 octave segments and has adjustable decay times. Using the pink noise track from a Stereophile test CD, I have been looking at my speaker response at different distances from the speakers. 1/3 octave may not be fine enough for some, but works for me. I will be trying the built in pink noise generator and the FFT measuring tool in the near future. The Audio Tools app has a number of different programs related to audio measurement, some of which are available by in-app purchase. Highly recommended, especially for the price.

 

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