Beginner's test equip for speaker design. Advice?

[OzMikeH]

I want to measure frequency response. Phase changes through the crossover region would be helpful as well. (for both driver positon and filter design)

Can anyone direct me to any helpful homebrew loudspeaker measurement website? I was using a borrowed ancient Low distortion oscillator and an SPL meter. It's too time consuming and sitting there measuring tones for hours isn't worth the domestic political fallout

First I need to find a reasonably flat microphone, Any suggestions there?
I don't mind using 2 or more different microphones to cover the whole range. I want to correct the bass response in the room and my hearing is still very sensitive past 19kHz. My external sound card can record OR play at 24 bit 96kHz, it can do both at 48kHz.

This leads me to the software. I use PCs, particularly old hand-me-downs. I don't want to spend a lot of money on some software I'm only going to use a few times. Freeware or crippleware is even better so I can start to figure out what I really need before spending anything.

[noodle_snacks]

Speaker Workshop
Behringer ECM8000
Behringer UB802 (or similar, you just need mic preamps).
Claudio cable jigs.
Use room eq wizard for room measurements etc.
The software is free, and the measurement equipment is cheap (Everything under $250)

[SY]

And don't forget a copy of Joe d'Appolito's book on loudspeaker testing. Otherwise, you will efficiently gather a lot of incorrect and misleading data.

[noodle_snacks]

Agreed, The speaker workshop manual will tell you how to gather the data. But data is useless without being able to accurately interpret it.

[Dave Bullet]

2nd noodle_snacks recommendation.

You don't have to buy a UB802 from behringer. all you need is a mic-preamp with a +48v phantom supply to power the ECM8000 mic (although the UB802 is fine too... just in case you can lay your hands on an alternative cheaper mic pre-amp).

SpeakerWorkshop is good but takes a bit to learn. Grab Jay Butterman's SW manual to help the learning curve.

Also download a generic ECM8000 mic calibration file to use, since the ECM8000 isn't flat (most have a rise above 10KHz). The generic one I use brings the top end down to match others measured results.

Cheers,
David.

[y8s]

definitely speaker workshop.
here's the super manual:
http://www.audiodiycentral.com/resou...anual/SWM2.zip

The M-Audio Audio Buddy is a really simple preamp. I tried the Behringer Shark DSP110 and I can never tell what the settings are. I loaned it to my work and got an Audio Buddy and it's ready to go.
http://www.m-audio.com/products/en_u...uddy-main.html

Also if you don't have a decent sound card (you probably do though), you can pick up an M-Audio transit USB interface. Simple to use and works great.
http://www.m-audio.com/products/en_us/Transit-main.html

I like to shop at 8thstreet.com because they have decent prices and usually everything in stock. They carry all of the above stuff and the ECM8000 mic as well.

I also like to use the Wallin Jig 2 to connect the driver to the computer. It's a little more involved than the claudio negro stuff but it works well. My personal upgrade was tape on the sides to label the connectors with detailed descriptions of what to connect to.
http://mysite.verizon.net/tammie_eri...jig2/jig2.html

Matt

[Dave Bullet]

Make sure if you go the Wallin Jig way - you buy toggle switches with a low contact resistance.

The stuff Dick Smith sells (well in NZ anyway) is hopeless. The switches vary between 4 and 80 ohms when switched!

Hence why I labotomised my Wallin jig and turned it into a Claudio jig using the binding posts to hardwire the modes.

Cheers,
David.

[OzMikeH]

Thanks everyone for the information.
I've ordered the Loudspeaker Measurement book from Amazon.
Downloading the software as I type.

My sound card is an Edirol UA-1EX. I chose it over the M-audio transit because it has better connectors on it and was slightly cheaper. I can knock up a separate 5v power supply for it with a bastardized USB extension lead to keep things nice and quiet.

Buy a Preamp? This is DIY Audio!
Throwing together a 48V phantom power injector should be easy, I'd rather capacitor couple the mic straight into the sound card than have an extra preamp. Or am I better off with a separate preamp and running line level into the sound card? I'll probably be able to answer this myself in a few days.

Time to look for the microphone next. Rising from 10kHz you say, that's a worry. 10k is my current crossover frequency, I may even move it higher to about 13k depending on how my main drivers perform. That's where I need the accuracy. Are there any other mics I should be considering?

Thanks again people.

[Dave Bullet]

Rather than paying for an expensive flat mic, it is cheaper to get a Behringer ECM8000 then pay Kim Gardin (?) apprxo $40 to get it calibrated. He'll (?) send you a calibration file when loaded into SpeakerWorkshop will give you a flat response curve.

I don't have Kim's details handy nor whether he still offers that service.

Cheers,
DAvid.

[gtforme00]

On Eric's site are also instructions for a preamp. http://mysite.verizon.net/tammie_eri...2/preamp2.html I built this preamp for a panasonic electret mic in a piece of grey water closet supply line (presses in perfectly) and it works great for me! He even provides an image for a single sided board for you to etch your own board.

Regards,
David