Testing gear, where to start?

[prickears]

Hi all,

I'm looking into setting up audio testing gear, I know virtually nothing WRT, up-to-date software, which setup yields accurate results, ease of use, pros & cons of various gear and the like. I would like to use my pc as a tool for this. I would like to test individual drivers response, as well as, complete systems. I guess, to figure XOs with superior accuracy than my current and primative methods.

I figure the best people to ask, would be the ones who use this type of gear the most, DIYers!

Any advice/suggestions/info will be greatly appreciated.

Thanx in advance,

Mick.

[Pano]

Well... my advice would be:

1. WT3 woofer tester from Parts Express. Or similar. This way you can really measure the electrical parameters of your drivers.
2. HOLMImpulse software. Free measurement software that is very good.
3. A USB or firewire soundcard with built in mic preamp. M-Audio make several good ones. Can be found used at good prices
4. Behringer ECM8000 microphone. Get a calibrated version if you want.
5. A VOM. Try to find one that has low voltage AC ranges - many don't.

With this setup you can do a lot of good measuring. And there is more great freeware out there to use, such as:

• ARTA - for measurements
• EDGE - for baffle simulation
• FRD softwares for box calculation, crossover design, etc.

[prickears]

Thanx heaps for that info, makes a great starting point for where to look and what to look for. As I said, I know plenty of nothing in this regard, you've been a great help!

Thanx kindly,

Mick.

[wintermute]

Hi Mick,

I use speakerworkshop and a Walin Jig II for doing my T/S parameter measurements. Though Speakerworkshop does have a pretty steep learning curve, unless you get the very good tutorial and manuals on Claudio Negro's site http://www.claudionegro.com./ go to the downloads section. There is Claudio's tutorial, and also Jay Buttermans manual.

It does require proper calibration, and also fiddling with sound card levels settings before getting good results, but once set up works very well (getting to this point is the hard part!).

I've had less success with doing acoustic measurements with Speaker Workshop, and I'm going to give holmeimpulse a try myself.

I have an Eric walin preamp II for mic preamp and a panasonic mic with linkwitz mod for the microphone. I originally made the preamp on verro board, but had a few issues and when Vikash very kindly donated a pc board when I helped him with debugging I made it on that and haven't looked back. As I said though I have had problems with SW doing acoustic measurements (as have others) so Holmeimpulse looks like the way to go there.

Note that getting the panasoic wm60a mic capsules can be a real pain in Aus and modding them is also a bit of an art! so buying a premade measuring mike and a card with bit in mic preamp as panomaniac suggests could save a lot of frustration!

I have an audigy II ZS soundcard, I bought it specifically for using with speaker workshop. A decent sound card is an absolute must!! My results improved dramatically when I got it!

Tony.

[prickears]

G'day Tony,

Thanx for that advice mate, HOLMImpulse seems to be where its at. Also a good quality calibrated mic, I will look into M-Audio sound cards, Thanx for the heads up with the pros and cons there too, The less headaches the better! I'm sure you know what I mean! If I get up-to-date gear now, it may last me a bit longer, and cause less headaches.

I do have a SPL meter with an output, Does this qualify as a calibrated mic? It maybe a dumb question, but I am a dum kopf, WRT this kinda stuff!

Thanx again Tony,

Mick.

[John Sheerin]

If you don't know that it's calibrated, probably not. The point of getting a calibrated mic is to correct the frequency response. The calibration tells you what the response of the mic is (assuming it's not flat). You put that curve into your frequency response measurement software. The software then corrects all measurements so it's as if the mic were perfectly flat to begin with.

There's another aspect to mic calibration - sensitivity. This is typically a value of mV output from the mic per pascal of pressure at 1kHz. This can be nice, but it's not really that important for what diyers do. It can also change based on environmental conditions for certain types of mics. We typically measure all the drivers for a speaker and note the relative sensitivity differences between them which can then be accounted for in the crossover.

[prickears]

Thanx John,

The spl meter is calibrated, According to specs, and 'rolls off dramaticly above 10 khz', Although I found the roll off starts around 8 khz. This is a fair way above any xo point i'm likely to use. Is this likey to do until I can get something better?

Thanx, Mick.

[wintermute]

Hi Mick, not sure if you are into electronics as well as speakers, but if you do decide you would like to go down the DIY preamp/mic route (even after my comments) then Vikash seems to still have pcb's available for the mic preamp that I'm using. It is a really nice preamp, and you should hopefully be able to buy all the parts required from rs components Vikash also has wm61a mic capsules available (I'm using wm60AY which are flatter in freq response from memory, but no longer available). Vikash has a mike calibration file available for download which while it won't be a perfect match for any particular mic will be a good approximation to give reasonably good results.

I was probably put off somewhat by the steep learning curve (and possibly bugs) with speaker workshop... some of my pain can be seen in this thread! using the same mic and preamp, I might have a completely different experience with holmimpulse! I'll let you know

Tony.

[John Sheerin]

Sure, it could work. I started out measuring frequency response using a RS SPL meter I already had hooked to my computer.

[speedie]

Hello all
Seems like we were on a similar thought line as I posted for information only moments after prickears on the same subject
I will give some thought to getting woofer tester to complement my bass box program
I have seen that the sound meter from radio shack gets used quite a lot
I down loaded Holm impulse but it would appear that there is substantial learning to be done just to use this (free, thank you Mr. Holm) program.
Do you all use laptop computers for your measurements as mine is a tower type and I see possible usage problems(moving around) from system to system
There has been indication of equipment for measurements but little explanation of what to do for the process involved with obtaining results!
Thanks again
Cheers Speedie
Ps it just seems to grow and grow for the list of equipment needed to really fully expand this diy thing
Most of us start out doing it to save on speaker costs which inevitably get consumed in equipment costs?