I have 2 th-15a and went i put them to sound together trere is a big humming sound. i dont have a mixer and if i need one witch one should be

i) I assume the fuse you mentioned was in the mains plug - did you also check the fuse in the TH15A mains input socket? This is accessed by pulling out the tab in the bottom section of the socket (below the centre pin). This is a 3.15Amp antisurge fuse, 20mm type.

ii) If this fuse has blown, then replace it & all may be well ...... but if it blows again, then move to step iii).

iii) With mains disconnected, remove rear panel (outer screws) & check the power supply PCB for damaged components, especially R111 & R112 (100ohms). If the latter are burnt or open circuited, then the amplifier module may have blown.

regards, Dave

Don't even go there. In my experience these are just not reliable speakers, we have had and heard of so many issues with them we sold our working ones. If one has gone sell the other working one with the dead one as spares and repairs and buy something from QSC, EV, JBL or Yamaha or even Wharfedale Pro.

As Tom Jones sang 'It's not unusual....' The amp has probably gone and you need to get it fixed. These are not the most reliable and I would suggest getting something better from another manufacturer if you can afford it, perhaps a local shop would do you a trade in if they can fix it?

Could be the crossover has died or the main speaker winding has failed. Open her up and connect on side of the main speaker direct to a 9v battery and then wipe the other wire over the other terminal. If you get a crackling from the speaker then it's likely the crossover, if there is no response at all from the speaker then it is dead and possibly the crossover too.

Remove 115V jumper in the Power Supply Unit at secondary side in order to operate Mackie TH-15A Speaker on 230V. Download Schematic Diagram from the below website:
https://elektrotanya.com/mackie_thump_th-15a_sch.pdf/download.html#dl https://elektrotanya.com/mackie_thump_th-15a_sch.pdf/download.html#dl

One of the power supply voltages is bad... either a short or the regulator is blown. Follow my instructions for a previous poster:

http://www.fixya.com/support/t10013559-mackie_1604_vlz

You failed to give us the most important information... what brand and model of the mixer? Youwill use balanced interconnect lines to a balanced MAIN output jack, assuming it exists...

Make sure you are using BALANCED audio line to the speaker AND your mixer is powered from the SAME receptacle as this speaker. One MAY have to run an extension cord back to the mixer and othe equipment, but this must be done to reduce noise and also for equipment safety. Multiple recepatacles in a building have grounding issues that can generate noise or worse damage equipment due to ground loops. If you DJ mixer does NOT have balanced outputs, use DI boxes so you can use balanced lines to your speakers. Your cables will either be XLR or 1/4 inch TRS types, not just TS type.

Make sure you are using BALANCED line to this... XLR connections boyh ends. Make sure ALL interconnected devices are powered from the same receptacle or power conditioner. Test your cables... they do go bad. This unit REQUIRES line level input. Do NOT expect a mic to drive it directely. Make sure your mixer uses the XLR outputs and is powered from the same receptacle, even if you have to run an extension cord to it. This is a bi-amped speaker so there are independent amps for high and lows. With nothing out and known good in there is very little electronics before the signal is split to the separate amps. At line level, your volume control should probably be about 2 o'clock with the EQ's straight up flat.

The internal amp is in need of repair. Are there any other symptoms or signs?