Originally Posted by Giraffe
Will the battery test not damage the CDT?
No, but proceed at your own risk.
I have used this test on probably 50 different speakers. Many of them were sound reinforcement and had either compressor horns and/or traditional piezo electric tweeters. Never seen any damage from this momentary pulse test. Here is why:
Let's say an amp delivers a maximum of 350W (W) to the Ref 3.1 which provides an average 6 ohm load resistive load (R). The power formula (P = I^2 * R) where (I) is the current flowing through the circuit. First we solve for the current flow:
350 = I^2 * 6
7.6A = I = current
Now we use ohms law to figure out what voltages the speaker will see at 350W. Ohm's laws for this is V = I * R:
V = 7.6A * 6R
V = 46 = voltage
This is considerably less than either the 1.5V or 9V battery. Also, the batteries will put out orders of magnitude less current than an amplifier. The max for an AA is at 3A and a 9V is 1.2A for lithium cells. Therefore, the power is very low and it would seem impossible/improbable that this could damage the CDT (which is a piezo transducer) or any other speaker.
Also consider that all common transducers react to change, not steady state. Since a battery is DC, it only reacts to that change from 0V to either 1.5V or 9V. Don't leave the battery connected, however, just touch it momentarily to the speaker terminals to see which direction your drivers move.
I'll try it later, but again, proceed at your own risk, or not at all if you're uncomfortable with this. Suggest you do the phase test first (see my recommendation on the Stereophile Test CD 2), and if everything sound fine, it probably is.
I used this procedure when I was in a rock band and had to quickly test tens of speakers for proper phase very quickly. And also less frequently on my DIY speakers to make sure I hooked everything up correctly
The reason you need to disconnect your speaker cables is because most amplifiers have very low resistance (R) values. Therefore, all the momentary energy from the battery would effectively be shorted out.