100v Celling speaker outputting lower volume than wall mounted ones

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jordan8thepie1

56 posts

Master Geek

#317445 15-Oct-2024 19:35

We have a 100v speaker system powered from an Australian Monitor AMIS 120 amplifier.

The system comprises of 4 Australian Monitor QF8C 15w speakers the tapping's are as follows: 1 tapped at 15w 2 tapped at 10w and 1 tapped at 5w. Using cat 6 cable. I know the cable is incorrect but management don't want to change it.

These are wall mounted in a sound craft enclosure.

I added another QF8C celling mounted speaker tapped at 15w into a false celling tile and the volume is quieter than the wall mounted one around the corner. in the same space. Wall mounted one overpowers it.

View of Wiring block on speaker

3 of the wall mounted speakers are in different rooms but are still louder.

What could be causing the Ceiling mounted speaker to be quieter than the other 4 wall mounted speakers which are the same model speaker?

Radiotron

179 posts

Master Geek

#3297844 15-Oct-2024 19:46

Look for flaky terminations to the block, and maybe find a multimeter and measure around the transformer windings, compared to a known good one. Wouldn't hurt to measure resistance of the speaker itself too.

jordan8thepie1

56 posts

Master Geek

#3297849 15-Oct-2024 20:00

I've checked all terminations from the amplifier to the block on the speaker and they are nice and tight and ok.

I tried removing the capacitor to see if that makes a difference but get even lower volume from the speaker.

Should i check the connections on the speaker side of the block?

I Will measure speaker with a multimeter tomorrow.

Radiotron

179 posts

Master Geek

#3297853 15-Oct-2024 20:06

Yes, if you can get a meter, have a good look around. Definitely check connections on speaker side of the block, the impedance of the speaker should only be a few ohms, so any added resistance will make a difference.

jordan8thepie1

56 posts

Master Geek

#3298006 16-Oct-2024 11:22

So I've tested the common and 100v wires with a Multimixer and got a reading of 0.758 ohms.

Checked all connections on the speaker side and they are ok

I removed the Capacitor and the black wire going from common to 5w tap on the 100v block and the volume has improved significantly.

The below image shows how I have wired up the speaker

Radiotron

179 posts

Master Geek

#3298193 16-Oct-2024 19:35

If it's now working as expected, all good. I had a quick dig and couldn't find a schematic of exactly how that animal is wired, so not much to add. Fingers crossed it behaves :)

jordan8thepie1

56 posts

Master Geek

#3299076 19-Oct-2024 15:30

I emailed the manufacturer and they supplied me with a pdf of the termination diagram for the QF8 model which was helpful. am now all sorted and speaker is working great.

Turns out the QF8C and QF8 model are the same speaker.