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I would like to enter the speaker measurement universe and have nothing other than a JBL 5860 mixer that is probably not going to add much to the effort. I have been looking at mic's and sound card processors but haven't made any decisions.
What would be a good entry level set of gear to measure speaker response?
"Entry level" can get you in trouble unless you just want to use it once or twice. You can start with an onboard soundcard, compatible mic, and freeware. If you're like most of us though, a little info just makes you more curious, and soon the limited capability/accuracy of entry level doesn't get it anymore. I went through several upgrades just trying to have enough to get by the task at hand, and wasted a lot of dough getting there. I'd have been many dollars and headaches ahead to jump in the deep end first.
The deep end doesn't have to hurt too bad though. Around $300 for hardware and the same or less for software should get you there. Another $150 for a WT2 to do TS specs if desired. Since my gear is a few years old and I know there is newer/better out there now, let those that have been in the market recently point the way.
Thanks guys, good info, so far. I was looking at the Behringer ECM8000. Do you think a calibration is necesary?
What are the advantages of the M-audio product? As for phantom power, can this be as easy as just providing a power source? I do have some stand-alone power supplies in the 24v.-30v. range.
I'll take Bfish's advice on not trying to bottom-feed this to fruition. I've learned the hard way about not having good tools. I will probably start with one of the freeware software products just to get my feet wet, though.
I would like the gear to be able to interface with a laptop, for convenience. What is the typical connectivity, USB?
There are some reports (from reliable sources) that WT2 may still be the preferred option;Quote:
Originally Posted by Altec Best
WT-3 testing of 2204, Fs higher in sealed box???
Which brings up another point. Test results are only as good as the gear, the setup procedure, and the interpretation of the results. It's a real treat that DIYers can now get the info they need, but bad info is worse than no info.
For example, TS specs can vary widely depending on the position and securing method (or not) of the driver. Indoor acoustic tests will have all sorts of false data unless the software has "windowing" ability to catch only the direct sound and shut off before any reflected sound arrives, and the user must set the appropriate parameters based on mic placement and distance to reflective surfaces. There's plenty of bad data posted online to prove it. Bottom line, read the book and follow the instructions.
I use an off-the shelf ECM-8000, but I preload the provided calibration file. There's certainly nothing wrong with calibration, every aspect of the hardware should be calibrated. You'll end up testing your testing system in order to trust it.Quote:
Originally Posted by westend9
Integral phantom power can't be beat, especially for laptop/portable use.
USB 2.0 or Firewire ports offer the needed bandwidth.
The specs of your external card determine the resolution of your test. Pay close attention to the duplexing ability (simultaneous input/output), many units say "full duplex", but when you read the fine print, they only duplex at low to medium bit rates.
I was wondering about the reliability of test results when doing "in room" setups. It would seem that any reflections (or absorbtions) are going to foster inaccuracies. Hell, I'll get my buddy that used to eat his lunch in the Bose anechoic chamber to help me set up something, lol (as long as we don't end up with something Bose-like).Quote:
Originally Posted by bfish
Great information, this is just the kind of things I need to know. Thanks!Quote:
Originally Posted by bfish
Are there any sound cards that are better at testing than just doing audio? Or, are the sound cards that have a good set of DAC's good at both? I'm looking for cross-purposing or lack of that, here.
There are (or at least used to be) externals made explicitly for testing, but waay more expensive. Consumer cards for music usually have little need for simultaneous input and output, you're usually either playing or recording, but not both at the same time. That's where the duplexing factor comes in for testing, you're sending a signal and listening for the real-time response at the same time.
The Edirol FA-66 I use was made for multi-channel recording, and the live monitor function allows 24/96 duplexing.
Speaking of real-time, latency is a term to learn and understand how it applies to your hardware;
http://en.wikipedia.org/wiki/Latency_(audio)
With that in mind, time-sensitive data loops on Windows platforms benefit from hardware using ASIO drivers in place of the std WDM.
One of the M-Audio USB cards will be just fine and dandy. Just be sure you get one with phantom power if your mic needs it. If it doesn't - I have one to sell you. ;)
What’s the likelihood that measurements might be contaminated by a mic preamp, like this one that is designed to “add warmth to condenser microphones” ?
BEHRINGER: MIC100
I’ve been trying to figure out what’s causing some mysterious 2 millisec / 70cm / 28 inch resonances in my measurements. I’m pretty sure they’re not from room reflections.
Is it necessary to have a mic preamp between a condenser mic (ECM8000) and a sound card (Echo Indigo I/O), or would a plain 48-volt phantom power supply be enough ?
http://img819.imageshack.us/img819/2...03millisec.png
http://img444.imageshack.us/img444/4...isecnormal.png
RE sampling rates and connectivity:
44/48kHz sampling rate is the minimum needed to sample 20kHz audio. Your hardware needs to support simultaneous in/out (duplex) at that rate at a minimum. Most cards advertise their maximum one-way sample rates, but you need to read the fine print to see what rate they'll duplex at, it's usually half of the maximum. If the duplex rate isn't specified, move on.
Sampling rate x bit depth x2 = the data stream (in bits per second) you need to be able to run from the card to your computer.
USB 2.0 offers 480 Mbit/s, a fortyfold increase over 12 Mbit/s for the original USB 1. 1394A (Firewire, ilink) ports support 400Mbits/s, making it comparable to USB 2.0. For desktop PCs, the low cost of a USB 2.0 or a 1394 PCI card (~ $40) makes it a no-brainer. If your laptop already has the port, pick an external card that can take advantage of it.
If you don't care to do the homework before buying your gear, you can join the guys that buy some crap, plug it in, run some tests, then splatter the web with their "scientific data", or at the least can't figure out why their results are unexplainable. Otherwise, read on...
Once you're setup with your gear...
...you should test it if you want any confidence in your measurements. Why go to the trouble of calibrating a mic if the rest of the system is unknown? Fortunately, there's a simple and freeware option for detailed souncard benchmarking called Rightmark audio analyser. I use it regularly, and it has exposed connection and settings flaws that I'd have overlooked many times;
Download. Audio Rightmark
Benchmark setup is stupid easy, just loop the soundcard output back to the input and run the level setting utility. Then click "run tests", and a few seconds later you get a detailed text/graphics report of your system performance.
For ASIO support you'll need to buy the Pro version. Well worth it if you're serious about accuracy (and your card is running ASIO).
An unintended extra function is the ability to insert nearly any audio device in the test loop so you can benchmark it too. ;)
For the mic pre, it depends on whether the "tube warmth" is mere marketing blather, or real. If it's real, the pre will add harmonics that will invalidate your measurements. To find out, download the benchmark software I linked above, and run the tests with your pre in the loop.Quote:
Originally Posted by sba2
Check the soundcard input level (dBu) spec to see if you need the preamp or not.
Your 28" 2nd impulse is a bit harder. Try moving the mic back. Does the impulse change accordingly?
That's pretty offensive.Quote:
Originally Posted by bfish
The M-Audio cards are fine for the hobbyist and can rival much more expensive equipment if used with care. The softwares mentioned here and elsewhere all contain calibration routines for the DAC/ADC loop. I include my mic preamp in that loop. I also use RightMark.
With a modest amount of modern equipment and some practice, good measurements are possible. Most of it comes down to measurement technique, not the equipment. Most hobbyist are not looking for laboratory results, they just want decent tools. Those tools can be had for about $300.
Buying a table saw does not mean you know how to use one. But it's a start. And your chances of getting straight, repeatable cuts is a lot greater than with a handsaw.
Then you shouldn't be offended.Quote:
Originally Posted by Panomaniac
Thought I'd elaborate to show the parameters that the free version of RMAA provides. Here's a sample of RMAA data from my card (integral preamp, included in the loop);Quote:
Originally Posted by bfish
I respectfully disagree. I think they want lab results at bargain prices and there's nothing wrong with that. It's actually doable if do your homework before you buy. That was my point. I learned this the hard way, going thru 3 different setups before I was satisfied.Quote:
Originally Posted by Panomaniac
Whether building speakers from scratch or upgrading and tweaking, DIYers are seeking to get that last bit of performance that simple economics preclude in most production systems. If that last bit of perfomance is shaving a 3dB peak at x frequency, you need the tools to reveal that detail accurately.
Well the equipment might be able to do lab quality results on the cheap, but learning to use it is another matter. Skills take time. And guidance is not unwelcome.
I completely agree, but learning to use it wasn't the OP's question.Quote:
Originally Posted by Panomaniac
That's why it's another matter. ;)
Bfish,
Thanks for all the good info.
I narrowed the problem down to an interaction between HOLMimpulse and my sound card, an Echo Indigo I/O. Only when a soundcard calibration is used does the caca at 2 msec appear on the IR plot. I don?t know why though?there was no problem when I tried REW (room eq wizard) using a soundcard cal.
Originally I was so focused on the FR plots that I neglected IR ones. I really wish I had magnified and examined the IRs much earlier, before making a multitude of measurements. Now I?ll have to re-measure everything. I tried erasing the soundcard calibrations from my data files, as well as un-checking the calibration box in HOLM, but had no luck. Once the soundcard file is enabled, it seems to become an integral part of the measurements.
Next on the agenda is running some tests using RMAA (thanks again, bfish).
********************
today--
HOLM, measurement of the speaker -- caca at 2 msec still there.
HOLM, measurement of something different (JBL) -- caca at 2 msec still there.
Abandoned HOLM
Installed REW (room eq wizard) & made soundcard calibration.
REW, measurement of the speaker -- caca at 2msec not there
http://img185.imageshack.us/img185/5976/rewb.png
HOLM, restarted, cleared everything, & reset default settings
HOLM, measurement of the speaker, without soundcard calibration -- caca at 2 msec not there
http://img155.imageshack.us/img155/1361/holmwo.png
HOLM, made soundcard calibration
http://img710.imageshack.us/img710/3449/loop.png
HOLM, re-measurement of the speaker with soundcard cal -- caca at 2 msec back again.
http://img294.imageshack.us/img294/1223/holmwith.png
*********************
Echo Indigo I/O soundcard: CardBus-format soundcard for PCs and Macs with two-channel analog inputs and outputs on stereo 1/8" connectors, 128x-oversampling A/D and D/A converters, 24-bit data resolution maintained throughout signal path, onboard 24-bit Motorola DSP for mixing and monitoring, and headphone amp with volume control. Sample rates supported: 32kHz, 44.1kHz, 48kHz, 88.2kHz, 96kHz. Supports full-duplex two-channel in, two-channel out operation. CardBus slot required. Analog input: Frequency response: 10Hz-20kHz, ?0.5dB. Dynamic range: >109dB (A-weighted). THD+noise, 1kHz sinewave at -3dBFS: <0.0014% (A-weighted). Crosstalk, 1kHz sinewave at -3dBFS: <0.0005% (A-weighted). Nominal input level: -10dBV (316mV). Maximum input level: +7.2dBu (1.775V). Input impedance: 10k ohms. Analog output: Frequency response: 10Hz-20kHz, ?0.5dB. Dynamic range: >109dB (A-weighted). THD+noise, 1kHz sinewave at -3dBFS: <0.0013% (A-weighted). Nominal output level: -10dBV (316mV). Maximum output level: +6.3dBu (1.6V).
Glad you found the problem. Unfortunatly I have no experience with HOLM, so I can't help figure out how to fix it.
I noticed your card has stereo mini connectors, which brings back some nightmares I had long ago with an SB Extigy with stereo jacks. The common-to-both-channels neutral pin wasn't grounded, nor was the output neutral common to the input neutral. The details of the problems that caused were too many problems ago for me to remember, all I remember was it was unusable for some testing purposes, so I gave it to a friend's kid to play MP3s through. Might not be a problem with yours, but if it keeps anyone from using an Extigy for measurements, the time it took to type was worth it. (FWIW, the clue that led me to the solution was an unexplainably high degree of stereo crosstalk noted by RMAA).
Another past problem I've had that may only be good for general info...
...Any audio apps on your PC may interfere with your measurement app. Some media players can be very controlling when it comes to your sound card settings. Any add-ins you might have like DFX etc might run on anything sent to your card. Took me several hours to figure out a reverb module I had as an audio addin was causing the crap readings I got. I thought that would only run when I told it to, but that wasn't the case. Had to uninstall it.
While my current setup was close to plug-n-test, I've never had a 100% plug-n-test experience. Oh, sure I could run sweeps, but they weren't right until I fixed whatever it took to get all my cal routines and benchmarking to satisfaction.
If you have a soundcard with ASIO drivers, that can go a long way toward solving those types of problems.
If your soundcard does not feature ASIO then you can add it with the following freeware.
ASIO4ALL - Universal ASIO Driver
Google ASIO4ALL to get more information. I intend to try it at a later date so this post is not a personal recommendation but just information that might save a DIYer from an upgrade. Your risk of course. :coffeedrinker:
Regards, Marshall.
I didn't have good luck with ASIO4All. I mean it worked OK, but did not seem to be "exclusive" the way a real ASIO driver is. Windows volume and mixer still seemed to be in effect, and those were 2 of the things I especially did not want!
Any good experiences with it are welcome. I like the ASIO drivers because nothing else can address the soundcard when you are using them. Maybe my ASIO4ALL isn't working right.
Just for posterity, I want lab results at bargain prices. Thanks, bfish.Quote:
Originally Posted by bfish
You ain't akidding, there.Quote:
Originally Posted by Panomaniac
Thanks, Marshall, I'll do a little research on that.Quote:
Originally Posted by mah
I guess measurement is going to be more than slinging a mic and stand in front of a driver and hitting the "enter" key. That's OK, I was a Windows 95 baby and am used to the software pitfalls. I've been looking around at some different gear and the M-audio Fast Track is going to be hard to better. It has the necessary phantom power, the correct interfaces, and seems to be priced right. I believe the Behringer ECM8000 electret condenser mic is also on the list. I happen to have three scrounged desktop boxes and might just make one of them a measurement only system. I'll have to mess around to see if the motherboards support a newer Windows OS.
Keep the good stuff coming guys, I've already learned a bunch and look forward to more.
If you want the lab results at bargain prices, get a calibrated mic. That's something that is hard to do yourself.
Another remembered passage from the "Book of Hard Knocks";
Most PCI cards and onboard laptop cards operate on the consumer 0.7V = 0dBv standard, but all the software I've used operates on the pro 1.0V = 0dBv standard. Sometimes you can tweak the levels to work OK, sometimes not. The external cards I've investigated all use the pro std, so no problem.
Looks like I have some (a lot of) issues to sort out with the software, my soundcard, and its drivers. When I figure it all out, I?ll add it to ?The Book of Hard Knocks"
It turns out that all of my HOLM FR plots were contaminated (at 2 msec) by a very poor soundcard calibration file, which turned out to be not really a calibration at all, but a feedback loop between the ?line in? and the ?output?.
The problem went unnoticed for a while because I didn?t closely examine the IR plots, and didn?t even know what a proper calibration plot was supposed to look like.
The HOLM software has no documentation to help with such calibrations? hell, it even told me that I had made ?valid? cal measurements.
I only discovered the feedback issue by reading about it in the REW manual.
Disabling ?record monitoring? usually gets rid of the problem, but, I haven?t yet been able to access this function, either through the card directly, or via its latest ASIO driver, or via ASIO4all, or via Windows (XP).
I bought my card years ago simply to get high quality sound from my laptop, as well as to occasionally transfer something from vinyl (my laptop?s input is only mono mic). Recently I had recalled seeing the card on ARTA?s list, so I didn?t think twice when I began measuring. At the moment I would give the Echo card a ?no go? for acoustic measurements.
By removing the Echo card and using my laptop?s piddly internal SigmaTel card with MME 16bit/41k , I was able to get a proper cal file, but I?m not yet confident of that whole scenario. The latency with the SigmaTel was pretty high, too
I?ll probably have to get a usb card.
*******************
RightMark is pretty cool ! Right away I discovered some bad cables and tossed them. Too bad the ASIO version cost US 110 !
Man, that's too bad. But we all go thru stuff like that. It takes a while to get it all running right.
I always check the loop measurement when I calibrate. I.E. , after all is set up and calibrated just run a measurement of the loop to see if there are any artifacts. The FR and impulse should be close to perfect. If they aren't, you've got problems.
Quote:
At the moment I would give the Echo card a “no go” for acoustic measurements.
The ECHO soundcard was not the problem.
HOLM and REW were also not the problem.
I’ve narrowed it down to my Fujitsu laptop (XP). Actually, I have two identical Fujitsu laptops with Echo soundcards. Both setups could not produce a proper soundcard calibration measurement in either HOLM or REW. Analyzing the two setups with RightMark, I discovered “very poor” FR and IMD--
http://img819.imageshack.us/img819/1...cardsonfuj.png
I then tried the two ECHO soundcards in an old Dell laptop (XP). Voila ! Normal soundcard readings--
http://img198.imageshack.us/img198/4...ardsindell.png
And…. I was able to make proper soundcard calibrations in both HOLM and REW--
http://img580.imageshack.us/img580/8048/holm48cal.png
http://img94.imageshack.us/img94/2878/rew48cal.png
****************
I don’t know whether it’s a software or hardware issue in the Fujitsu, but the troubleshooting ends here. I’ll use the Dell & ECHO card.
I need to get my life back….I’m not going to be victimized by this!
*****************
A few observations on the free software I’m using:
HOLM detects & provides a choice of interfaces (ASIO, MME, DIRECT),
REW does not (I didn’t see any interface options, and was not sure which was used).
HOLM will sample to 96khz and above,
REW only to 48khz
HOLM plots a max of three measurements,
REW plots more… It also has waterfalls, spectograms, and other cool stuff.
********************
Good advice!Quote:
Originally Posted by Panomaniac
Since an excerpt from my post above seemed to strike a couple of nerves here, I thought it only fair to revisit it. I concluded that the "offensive" portion was taken out of context, and when standing alone might be offensive to some, but when considered in context was really what I meant;Quote:
Originally Posted by bfish
This is a standard that I hold myself to as well. When I first bought some gear and ran some tests, I thought they were great. Later I found (by benchmarking and other self-checks) that they weren't. More gear, software, and fixing later, again I thought I was in good shape. Wrong. Now, I think all is good again, but considering everything, I'm very glad I didn't post my incorrect data.Quote:
Originally Posted by bfish
Posting/not posting your data is really irrelavent though. My goal in that post was to inspire others to do some self-checking so they would end up with better results. Merely saying offhand you should self-test is likely ignored. The shock factor of my "offensive" quote, not so much.
So, if my being a little coarse results in even one DIYer having second thoughts that prompt repairs and better results, so be it. The post stands as written. :)
Yeah, I remember critiquing someone's measurements and how to self check with proven math, which he did up to a point, but still didn't get it right (mostly from following published instructions and others well intentioned help IMO); so this went on for several iterations without his measurements lining up close enough to the math until finally he and others claimed I was just 'jerking his chain' and that they were 'good enough' for box design. I agreed, but argued that until one can do repetitive accurate tests where using proven math makes it easy to confirm, then how can one be certain of other measurements where there's no easy way to check them? To his credit though, he kept at it and eventually he was able to find/correct all the errors in set-up, etc. to get ideal math accuracy to within a tiny fraction.
GM
I guess I need to "de-bunk" that [802/511] measurement?LOLQuote:
Originally Posted by Earl K
As you might recall, I had discovered an anomaly in the impulse response that effects the resolution of the FR.
And not reported ?till now? While trying to solve that problem I found another. The mic?s phantom power supply / preamp (a Behringer tube mic100) was creating a significant amount of distortion. At least that?s what the audio analyser program indicated when I expanded a test beyond just the soundcard and included the cables, connectors, and finally the mic preamp itself into the in-out measuring loop.
After a lot of investigation I still don?t know the cause of the original problem, but a new soundcard installed on a different computer seems to work okay, so I?ll use that setup. For the distortion problem I replaced the Behringer with a Rolls MP13 mic preamp, which also seems to work okay. The analyser results are similar to those posted by bfish.
Soon as I find time I?ll re-measure and post here.
Hi sba2 ,
Admitting ( once you found out ) that your measurements were contaminated by some glitch was absolutely the right thing to do . We all benefit by your honesty .
Anyways, I'd love to see some new plots of your 802s on ( your finless ) 511s .
- You represent one of only a couple known users with this unique combo ( & the only one I know with the ability to provide some measurements ).
- Any chance that you could do up a set polars in maybe 7.5 deg increments out to > 45 deg of axis / plotted by REW ?
<> cheers Earl K
Yup, BTDT. Tha's why my current card has integral mic pre & phantom.Quote:
Originally Posted by sba2
It does seem a bit tedious to test your test gear, but you'll never know it's right till you do. Sounds like you're well on the way to getting things whipped into shape.
FWIW, you can insert nearly anything in the test loop, though you'll be ahead to check one device at a time instead of the whole chain. For example, your test amp (or any amp FTM). I use a 1kHz sine to set up voltage levels. Say you ran 1V to amp input (or 0.7V if appropriate), and had the amp output loaded down with the appropriate power resistor to match the output tap. Run the amp gain up a bit to the output level you might use (I use 2.83V for 1M sweeps) and then add series R (variable's real handy there) to further load the output test point back to unity (1V). Hook that point to your card's line in, and the testware never knows it's there (unless the amp has problems). With RMAA you can retire a benchful of "old school" test gear and print out a detailed performance analysis in less time than it takes to hook it up.
You're gonna win, I just know it. :)
Hi Earl,
It would be a pleasure to do polars and plot them in REW. I'm swamped with stuff for the next month or so, but I'll eventually find the time to make some measurements.
*********
Hi bfish,
Thanks for the additional info and the encouragement.
After fixing some seemingly insurmountable problems with my soundcard and computer, I was finally able to get some decent measurements of an 802-8g on a 511b horn.
I don?t remember which details I?ve already posted, so once again?
The 802 was re-magnetized at GPA, and received a new 34647 diaphragm. The bug screen was removed, too. The 511 horn, in addition to being finless, is damped with self-adhesive roof flashing.
I made the latest measurements using both Holm and REW. With REW, 1/24 smoothing was about as high in detail as I could tolerate on the crowded plots?.so all of the REW and Holm plots that are posted here have 1/24 smoothing. I don?t have an SPL meter, so the SPL is only relative within a particular plot. The measurement distance was four feet.
I was also curious about seeing the 802 / 511 combo being run through a crossover. For that I used a Zilchlab designed model 19 network, and installed an 8 ohm dummy load at the crossover?s LF output. Before making the measurements, I used REW?s pink-noise generator and RTA screen to adjust the two Lpads for the flattest response. The Lpad closest to the driver was set at maximum, and the other Lpad, which controls the FR slope, was set at minimum. I noticed that the tradeoff here is with efficiency? in pursuing a flat FR, the output went down..
* * * * * * * * * * * * * * * * *
Plot showing a corrected trace (top) and the earlier contaminated traces (below) --
http://img801.imageshack.us/img801/3...contami.th.png
* * * * * * * * * * * * * * * * *
Plots created in both Holm and REW in order to cross-check the measurement systems --
http://img198.imageshack.us/img198/3...040holm.th.png
http://img512.imageshack.us/img512/7...2040rew.th.png
* * * * * * * * * * * * * * * * *
Plot of the 802/511, 0 to 90 deg --
http://img811.imageshack.us/img811/3415/80290.th.png
* * * * * * * * * * * * * * * * *
A less crowded plot , 0 to 40 deg --
http://img301.imageshack.us/img301/4374/80240.th.png
* * * * * * * * * * * * * * * * *
Same as above, with the traces separated --
http://img264.imageshack.us/img264/9...parated.th.png
* * * * * * * * * * * * * * * * *
* * * * * * * * * * * * * * * * *
Plot of the 802/511 connected to the network, 0 to 90 deg --
http://img638.imageshack.us/img638/56/802net90.th.png
* * * * * * * * * * * * * * * * *
A less crowded plot, 0 to 40 deg --
http://img220.imageshack.us/img220/4072/802net40.th.png
* * * * * * * * * * * * * * * * *
Same as above with the traces separated --
http://img832.imageshack.us/img832/8...parated.th.png
* * * * * * * * * * * * * * * * *
The crossover --
http://img547.imageshack.us/img547/8...model19.th.jpg
http://img547.imageshack.us/img547/8...labmodel19.jpg
http://img198.imageshack.us/img198/3...202040holm.png
http://img512.imageshack.us/img512/7606/80202040rew.png
http://img301.imageshack.us/img301/4374/80240.png
http://img264.imageshack.us/img264/9...0separated.png
http://img801.imageshack.us/img801/3...onwcontami.png
http://img811.imageshack.us/img811/3415/80290.png
http://img220.imageshack.us/img220/4072/802net40.png
http://img638.imageshack.us/img638/56/802net90.png
http://img832.imageshack.us/img832/8...0separated.png
WOW, Great Stuff sba2 !!!
Thank You, for providing such a comprehensive look at this horn/driver combo .
It's wonderful to have this as a resource :2thumbsup: ( hopefully you won't mind if I download your pics ? )
<> cheers EarlK
btw; what was your measuring distance ?
Very cool stuff, I have 802's and am considering different horns so it is very relevant. Thanks for posting those results.
Getting closer to compiling what I think is going to get me started, first iteration will be a Behringer Electret mic and stand, a breakout box that will handle the mic phantom power and the usb interface, probably the M-audio product. Since I do most of my computer stuff on a laptop, I'm thinking a stand-alone PC just for measurement might be a good thing, I have a few. Choice for the PC might hinge on the sound card. What's a good soundcard for this kind of application?