Love for the old passive C300's

[CyberHippy]

I have a pair of the original C300 speakers that I doubt I'll ever let go of - they were some of the most over-engineered affordable speakers ever built!

Yeah, their RMS is 300, music is 500, but peak at 750 means 100's of shows that I threw kick drum at these bad-boys at without a whimper.

I worked for a while at a club that had a pair of the SRM450's, same form-factor. One of the drivers died (beer) so I pulled it out and replaced it with one from my C300 while waiting for Loud to send a replacement - the magnet on the C300 is almost twice the size of the 450! No wonder they sound so much better… headroom is our friend don't ya know.

Anyway, saw this forum and felt like dropping this little thought here… anyone else sporting older versions of Mackie speakers they love?

[Greg C.]

If the SRM450s were the newer Chinese versions & your C300s were the RCF/Italian version, that would explain the difference in the woofer. The newer Chinese ones use a cheaper driver with a smaller motor. Mackie claims similar or same specs though with either one...

[CyberHippy]

That is likely the case, and they're full of it… impedance is the same, but that much difference in magnet size is not going to give the same response to wattage.

[Greg C.]

That is likely the case, and they're full of it… impedance is the same, but that much difference in magnet size is not going to give the same response to wattage.

Not necessarily. Mackie switched to neodymium magnets which are fraction of the size of ferrite based magnets and have the same or better Gauss field strength for a given speaker motor of similar performance. As an example, here are two RCF high performance 18" drivers. They're basically the same driver, but one uses a neo magnet and the other uses  ferrite:

http://www.rcf.it/en_US/products/precision-transducers/low-frequency-transducers/lf18x451

http://www.rcf.it/en_US/products/precision-transducers/neodymium-low-frequency-transducers/lf18n451

Note the difference in magnet/motor size. Yet the neo version is a half a dB more sensitive while being 10 lb. lighter with the relatively small magnet. But the average power handling with the same voice coil on the neo version drops a bit since the smaller motor means less surface area to dissipate heat.

[RoadRanger]

Also Neo is a bit more sensitive to being demagnetized by heat than Ceramic/Ferrite.

[Greg C.]

Also Neo is a bit more sensitive to being demagnetized by heat than Ceramic/Ferrite.

True. But there was a paper published recently that clearly demonstrated that the amount of heat generated by loudspeaker usage was far below the threshold to cause that issue.

[RoadRanger]

They've pretty much solved the Neo demagnetization issue with newer alloys. It was a definite problem with some of the first Neo speakers .

[CyberHippy]

The magnets in the SRM450 were ceramic, that change may have happened with more recent versions.

(I used to work at a speaker repair shop, so I have a clue about the differences between AlNiCo, ceramic & neodymium)

[Greg C.]

I know they use them for sure in the v2 model. Can't say for sure with the generation right before that.

[CyberHippy]

They were v1 and the magnet was heavy, but not nearly as heavy as the old c300's