Mackie SRM 450 replace Amp

[scott2000]

Crossovers shift frequency so much at the crossover point , typically one by minus 90 degrees, the other by plus 90 degrees, that at crossover point thay are 180 degrees from each other ... perfect out of phase, which produces a severe notch at that frequency.
So the practical solution is to invert phase from one of the drivers, and inverting HF is safest option.
I was chiming in to suggest exactly that.

Thanks for chiming in JMF! Yeah I had noticed this HF phase being flipped before in the SRM schematics. I think I had brought this up in some other thread in the past. I guess checking the phase of the tweeter would be in order at the end of the day with this marriage... I was actually referring to the fact that the passive 300z crossover has the low and high freq drivers reversed at the connector itself so, plugging the SRM directly as is to it will not give much sound at all... I'm guessing the crossover frequency only.....

I live in Argentina where every commercial product is available, Mackie, JBL,you-name-it but because of distance freight is horribly expensive and Customs Tariff is high .... plus going through all the bureaucracy and red tape.
The end result is that commercial products come in (same paperwork to bring 1 or 1000) but **spare parts** do not,

Interesting.... Yes the spares for these are getting more of a challenge to source. I had to use a CoolAudio VCA in one of the amps in the past and, am on the hunt for some of the fets next. The second hand market and the counterfeit stories of any available new ones makes things more challenging. It would be nice to have the experience to know where widely available substitutes could be used but,  without this knowledge, things take the back seat to other projects unfortunately .

2 precautions:
1) don´t drive them with more than, say, 250W or 300W (tops) per cabinet.
Original Mackie built in preprocessor has tons of limiters, variable high pass filters, voice coil current sensors (predict voice coil temperature) , etc; NONE of that is present in the oldschool cruder approach.
IF the power amp has an anti-clipping limiter, by all means activate it.
2) since passive crossover has NO protection at all, PLEASE add a car type lightbulb in series with driver.
A 12V 15W one will protect most common drivers, any size.
In the specific case of SRM450 they have a stronger 44mm voice coil which stands more power (not 150W by any means) so you can use a larger lightbulb, a truck type 24V 30W to 45W should do.
Unprotected drivers will die on the first high pitched microphone squeal.

Great! Thanks!

Here it´s very common to see, at small Rock Festivals (say a neighbourhood one played in the street or a Club by non Pros) some small PA company with, say, 10 to 20 such speakers, mixed brands and models, a veritable salad, bought dead for cheap and recycled.

Let me tell you that 10/20 recycled ones beat the dust off 2 or 4 "original" ones any day of the week 

Sounds like a fun place! Mmmm... I do like  Salad... So much for them being light....Haha