Whoops? Plus is Plus, right?

[Stub Mandrel]

TL:DR - I fixed up some speakers.

I have two cheap Thomann Fun Generation powered 15s and a pair of Passive 12s as extensions.

I've realised that a powered 15 and a powered 12 would give me more flexibility (you can work out the combos, but being able to use 2x12s as monitors while still being able to run a 12 and a 15 each side as a small PA appeals). Using a Powered 15 and a passive 12 as monitors was clumsy, the 15 is noticeably more bulky.

 

Luckily the rear panels have identical dimensions, so it's simply a case of swapping them over and switching the spade connections to the 12 and hard-wiring the 15.

ON opening up a powered 15, I noticed that the board doesn't have the built-in crossover, instead using a separate crossover like the 12, connected from the L (low) terminals. I noticed that as expected there was a red wire from + on the speaker and a black from -, but they were connected to L- and L+ instead. I was going to reverse them... until I noticed the wires to the speakon connector from the power amp were also reversed...

I did a phase check against (correctly wired) extension speakers and lo and behold, it appears the power amp board is incorrectly marked.

Incidentally, despite the 15 being rated at 115db and 70-18,000 Hz and the 12 114dB and 80-18,000Hz, the spate of A/B testing that this exercise brought on showed that the 15s have vastly more bottom end to my ears.

[itu]

2 hours ago, Stub Mandrel said:

Incidentally, despite the 15 being rated at 115db and 70-18,000 Hz and the 12 114dB and 80-18,000Hz...

Every dB and Hz means a lot in the low end. Those quoted frequency bands should also include the limits: ±3, or ±6, or maybe ±10 dB? If they are measured with different limits, you cannot compare the results.

[Stub Mandrel]

1 hour ago, itu said:

Every dB and Hz means a lot in the low end. Those quoted frequency bands should also include the limits: ±3, or ±6, or maybe ±10 dB? If they are measured with different limits, you cannot compare the results.

 

Thomann's specs are more honest than most (they even state the '600W cabs' are 15W RMS).  That said, I suspect the perfomance figures are largely 'theoretical'.

[Woodinblack]

1 hour ago, itu said:

Every dB and Hz means a lot in the low end. Those quoted frequency bands should also include the limits: ±3, or ±6, or maybe ±10 dB? If they are measured with different limits, you cannot compare the results.

 

they are both -3dB