How hard do I drive these HF drivers?

[Rich]

Hi there

 

I've just got some bi-amped top boxes with JBL 2446 compression drivers in them, and I'm not sure how hard to drive them. The specs say 150w program, does this mean 75w RMS? They sound great, and I've seen how much they cost so I'm scared of blowing them, what would be a sensible amount of power to give them?

 

Check out the specs hereJBL Specs

 

Also I've noticed from reading other posts that everybody seems to recomend using amps with power ratings double that of the speakers, I'm keen to follow this advice but concerned about damaging my speakers, will giving them peaks of double their rated power blow them?

 

Thanks for your help. Richard

[gazman]

yo dude, its gaz from uni.

just thought you should check this out. its the user manual for the SRX series, they all use the 1.5" version of ur 2" driver (they're pretty much identical). They're recommending around 150-300W for the HF driver from 1.2khz up, probs 24db/oct although it doesn't state.

The higher the crossover the more power the tweeter can run on but that doesn't mean u'll actually be putting all the power through the tweeter.

Eg. the eminence drivers are all 50w yet you can run them in a 2-way setup using passive crossover on amps up to 600w cos they cross at 5k.

I think the general idea is to use a similar gain (ie amp power) for the tweeter as mids/bass etc. Just minus the sensitivity. (those jbls produce 111db compared to ya average frontloader sub producing 95-100db). It's confusing and I don't understand it fully myself, but I know my mates martin system (3-way active) used to run a RA3001 on tops, thats 300w per tweeter an they were only 50w (albeit 12ohm). The idea is to have the headroom so ur not clipping the amp, using a low power amp because you don't want to put too much power through the tweeter and then having to drive it all the way to clip to get the level right defeats the object and cos its a tweeter will almost certainly cause damage.

If ur driving the tweeter in a passive setup the amp u pick is based on the LF drivers power generally, so if you remove the LF driver u don't actually want to necessarily lower the gain u were feeding the HF driver (ie. a lower powered amp), you just don't want to be inputting any more signal into the amp and clipping it. The HF amp should NEVER clip if pos. (its BAD!)

Don't know if this helps but check out the martin audio website and the old F2 system datasheet in archive downloads, they explain quite simply what to drive what with an that was back in the days of dodgy limiting!

my god, ive just done more typing than I have for my entire 4000word project so far this holiday. :)

[Rich]

Thanks Gaz, that pretty much answers all my queations.

 

See you around the Pav then mate!