Test-source recommendations?

[taudo]

How about some recommendations for CD's that are good sources of 1) test tones, frequency sweeps, etc and/or 2) music that lends itself to tweaking enclosure response?

Also, any recommendations on test equipment that will allow plotting frequency response curves is appreciated.

Thanks!

taudo

[cclark65]

I was thinking about making a cd on a computer with a bunch of test tones and sweeps on it. If I get it done, I will gladly post it for download somewhere.

[MikeInNH]

Crown produced a CD several years ago that was meant to show off the characteristics of their new Microphone. The CD cost $5 from Crown. It is a EXCELLENT CD for testing out speakers (in fact your whole system). You better have a good amp and speakers to play the Fireworks section. But if you system lives through it, it's awsome.

[taudo]

A couple of great recommendations. Thanks guys!!

taudo

[taudo]

PLEASE CHECK THIS OUT

In looking for test CD's I came across one developed by Alan Parsons (who engineered The Dark Side of the Moon LP and is the same guy from the Alan Parson's Project) and produced by Cliff Engineering. It has a test CD with a simple frequency analyzer built right into the jewel case for $80.00

Now, I'm not expecting miracles, but if this thing works _at all_ it could be a real boon to non-test-equipment-owning mopes like me. I have one coming and will post a report here when I get to test it out. In the meantime, you can check it out at the following link:

http://www.barryrudolph.com/newtoys/toys/parsons.html

It is sold through MusiciansFriend.com

http://www.musiciansfriend.com/srs7/...se_pid/941270/

Looks cool!

taudo

[taudo]

It seems to me that audio real time analyzers like the Phonic PAA2 and/or the Sampson D1500 would be reasonably inexpensive (~$400) ways to get an idea of a speaker system's acoustic output curve. Has anyone had experience with either of these instruments? Is there a better method available?

Thanks!

taudo

[cclark65]

I have downloaded spectrum analyser software in the past and used it. Don't know how accurate, but I was using a mic that was calibrated for my yamaha spectrum analyser. I suppose it also depends on the sound card, but most of them should be able to do it easily.

[joyspring]

Taudo,

The Mix (Magazine) Reference disk is a fairly comprehensive test CD; for test signals on the economical side, it really can't be beat.

For measurements, however, I do recommend one of the PC audio measurement systems -- there are now quite a few and some even support 24-bit, 96kHz+ dynamic range and frequency response. This is a must to make meaningful measurements at 100dB+ below 1V and second/third harmonic distortion as well. Many can also extract Thiele-Small values from loudspeaker components as well.

Praxis by Liberty Instruments and CLIO are just a couple examples that I can readily recall.

For acoustic (speaker) measurements, it is imperative that the measurement system is gated to simulate an anechoic (reflection-free) environment; even then, the lower measurable frequency limit is determined by the wavelength vs. the nearest boundary.

Generally speaking, gated measurements are usually good down to ~200Hz. These are combined with extremely close-miked measurements (to swamp out reflections) below 200Hz to obtain a combined response plot.

RTAs are good for measuring environments (speaker + room) but cannot deliver accurate speaker-only measurements. Same goes for any test CD + SPL meter combination.

In any event, sub-$1000 PC measurement systems now replace what used to require $10K+ worth of instruments I highly recommend them.

BobR

[taudo]

BobR,

Thanks very much for this info/recommendation!! I'm going to investigate these.

A question: How do such systems compensate for the differences between mics? I have always assumed (remember, I've never owned any test equipment) that the only way these things can work is with a "known" mic. True?

taudo

[joyspring]

Taudo,

Audio measurement systems require a calibrated measurement microphone.

Some vendors (i.e. - Liberty Instruments) also offer microphones with calibration data for their software. This is the best option if offered, IMHO.

BobR