2 x Jack 112 Lite

[Charles Jenkinson]

This is what I think the phase tester circuit looks like.

[AntonZ]

I think you should be good with that wiring.

[Charles Jenkinson]

Well, once again I'm in a bit of a pickle with this phase testing. I've tested all my piezos. I reckoned on initial testing that 14 were out of phase and 24 were in phase (total 38). But I've just tested a sample of 3 of the out of phase ones and reckon 2 of those are now in phase and one is still out of phase. Bottom line, I have difficulty saying what is louder and quieter when I flick the phase swapping switch over. Worse still, if I swap ears round, one ear 'measures' the sound difference one way and the other ear measures it the other way, for the same piezo, without moving anything other than the switch! If I use both ears head-on, i.e. don't rotate any individual ear to the sound, it's almost impossible to distinguish any difference, to me, though there sometimes appears to be a 'pitch' change rather than an intensity change or it seems to alternate which tweeter the sound is coming from when the phase on just one changes. The wiring is correct mind you. I'm using white noise with the 'HF Generator' (from http://www.hfaudio.ca) available on line. I don't like to feel I'm getting anal about this, but my hearing isn't that bad, and I'm not getting anywhere fast, so it might be time to just pot-luck it and ignore the results of the 'test' - which is what bothers me more than anything, that this is turning out to be subjective rather than objective. I could always come into the shed every day for the next fortnight listening to 'in phase' and 'out of phase' piezos, refining which box they should or shouldn't be in. The good news is, I took another broken one (in the plastic horn surround) apart and the element came out no probs. It was a bloody loud one too! On that sample of one, I'm wondering if the glued ones are more damped than the unglued ones, and therefore quieter.

[Bill Fitzmaurice]

what bothers me more than anything, that this is turning out to be subjective rather than objective.

Probably. I doubt the numbers that you gave for how many were bad. A switching circuit is not required. Designate one tweeter as the control, it stays plugged into the sound source. A second set of leads are attached to it. The tweeter being tested is placed right next to the first, the second set of leads attached to it. if the volume goes up it's correct, if it goes down try it the other way. It's best not to rely on your ears as testing devices, they are neither accurate nor reliable. A sound meter should be part of your kit.

[Charles Jenkinson]

It's best not to rely on your ears as testing devices, they are neither accurate nor reliable. A sound meter should be part of your kit.

Thanks Bill. This is the nub of it. I'd been assuming folks just used their ears. So when you test phase, do you use an SPL meter?

[Bill Fitzmaurice]

So when you test phase, do you use an SPL meter?

I do.

[Jools4001]

Oops...appear to have replied to what I thought was the last post in the thread only to find the thread went on for several more pages....just ignore me, I'll go way now

[Chris_Allen]

Oops...appear to have replied to what I thought was the last post in the thread only to find the thread went on for several more pages....just ignore me, I'll go way now

Been there, done that.

[Charles Jenkinson]

...only to find the thread went on for several more pages....

...ain't that life.

Do share, please.

[Charles Jenkinson]

How's this for lining the back of the jacks? It's 15mm thick at the bottom of the troughs, and 45 thick overall. It popped up on Amazon as a bargain when i was searching for an spl meter.

[biggerrigger]

I hope it's ok Charles, I just used the same product to line all 4 of my DR250's. Seemed to my ears to do the job quite well.

[Charles Jenkinson]

Noise maker and noise meter.

Finally phase testing.

[Bill Fitzmaurice]

Noise maker and noise meter.
Finally phase testing.

Place the mic about three feet from the tweeters, otherwise you might be reading mainly one or the other.

[88h88]

Sup kid?

[Charles Jenkinson]

A query on array construction:

Will the ABS cement adequately glue or fix (painted) birch dowel in for the diffuser rod on the arrays?

....5/8" OD rigid PVC pipe is proving elusive. Aluminium tube is pretty available also, in 5/8" OD, thin wall.

Cheers,

Charles