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Macro Tech 600


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#1 AllanS

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Posted 28 March 2014 - 09:12 AM

Hi, looking to push JBL 16ohm compression drivers (50Watts or 30Watts) with a Macro Tech 600 not sure what the power ratings are for both channels driven @ 16ohms? Is the 600 safe, using speaker line fuses? Thanks for all your time!

Regards,
Allan

#2 joust

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Posted 28 March 2014 - 03:00 PM

Hello Allan,

The MA-600 pushes around 120W @16R (ohms), 220W @ 8R, 325W @ 4R, 400W @ 2R.
The MA is still powerful for the 50W driver, even at 16R. So, beware of clipping! Use the MA at half power, leaving the other half for headroom and excursions.
Personnaly, I don't like using fuses for cabs or drivers. If you have a limiter, perhaps use it! A compressor, if used well, can also reduce the likelihood of an overdriven driver. Note that the compressor will not halt or apply a brick wall to the sound as a limiter can do!

Hope this helps!

Alain

#3 AllanS

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Posted 29 March 2014 - 06:27 AM

Hi Alain, thanks for all your help! A limiter along with line fuses will be used, that should be enough to protect the drivers. Thank you and have a great day!

Regards,
Allan

#4 dakos

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Posted 30 March 2014 - 02:49 AM

Hello Allan,
The usage of a line fuse is not recommended for live shows, if it blows then the driver is out until you can replace the fuse. Why not use a lamp, which also give you a visual warning and functions as a compressor and in the end like the fuse, or a more sophisticated zener based protection circuits instead?

All the above solutions are more for a passively amplified speaker with an internal crossover, where the HF driver is less protected then the LF driver. When you biamp the speaker and have a limiter (RMS and Peak) I just don't see the logic in putting in additional components.

Did you have repeating problems frying those drivers?
Avi

#5 AllanS

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Posted 06 April 2014 - 08:39 AM

Hi Avi, thanks for the input! The system will be for studio(home) play back not live sound. I will be using active crossovers(behringer 2496 speaker management system) in a 5-way set up, so the limiter in the 2496 should be sufficant? I'm using an MA 2400 and two MA 1200's for the JBL 18",15" transducers with one of the 1200's on a 2482(2" compression driver) the manual suggests using line fuses on each transducer or driver. My concern is for the mid-hi and hi 1" compression drivers, thinking that the MA 600 is to powerful for the 50Watt(16ohm) and 30Watt(16ohm) drivers? Looking at using two DC300A amplifiers, but the inputs do not offer a balanced signal, can I use an adapter type cable for the signal coming from crossover(balanced XLR) to the DC300A's without significant impact on the signal keeping in mind the cable runs will be short, under 5 feet? Thanks for your time!

Allan

#6 dakos

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Posted 07 April 2014 - 03:58 AM

If you have only one type of limiter available, what you should do is select and amp that has about as much power as your drivers peak power spec or a bit less. If you don't clip the amp that would serve as our (sort of) peak limiter. You should configure your limiter as an RMS limiter taking into account the RMS spec of your driver and power compression.

Peak limiters are used to make sure amps don't clip (that's sort of the type of limiter your behringer has). Now, if you matched the amp to the speakers correctly, you should be fine but since you're using what's available then our amp selection is a bit limiting. The behringer limiters are peak limiters, not RMS and have limited configurability (only threshold and release). To be more exact here is a deteiled thread about the behavior of the limiters. We might fall into category 1 ("if your power amps are too big for the speakers") in the link so I have a few followup questions...

The power ratings you provided earlier, are they RMS? What speakers are you powering?
Avi

#7 AllanS

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Posted 07 April 2014 - 04:54 PM

Hi Avi, here is what I have one side, all transducers and drivers are JBL. One 18" transducer 2240(8ohm) 600Watts RMS driven by MA2400. Three 15" transducers(parallel) 2220(16ohm) 100Watts RMS each (3x100W, 300W total) driven by MA1200. One 2482 driver(16ohm) 120Watts RMS driven by MA1200. One 2461driver(16ohm) 50Watts RMS driven by (MA600?). One(may be two, parallel) 2420 driver(16ohm) 30Watts RMS driven by (MA 600?). I have not purchased the two MA 600's until I know how to protect the HF drivers. Interpreting from the link that you sent me to, a compressor can be used to limit RMS for the HF drivers or is there another way? Keeping cost in mind as I do not have an unlimited budget. Thank you very much for your time!
One more thing if you do not mind,the lamp option I do not know what it is or how to use it. As you may have noticed I am an amateur to all this and greatly appreciate all your help!

Allan

#8 dakos

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Posted 08 April 2014 - 11:36 PM

Dear Allan,
Looking at the link I posted thoroughly (page 3 to be exact), the limiter in the behringer is both Peak and 3dB below that setting it has an RMS limiter, therefore if we set the peak limiter so that the RMS limiter will have the correct value, we should be fine.

I would start by setting the limiter to half the wattage specs you posted or a bit less, that way your drivers will be protected and the SPL will not suffer much if at all. The behringer takes values relative to the +22dBu it has on it's output so you need to translate the values you want to that +22dBu and the amps input sensitivity.

Keep in mind I'm trying to do my best here but the data I'm relaying on is not in the manual but rather measurements made by other (professional) users.

I'm guessing you're building your own speakers? Can you upload a picture of what you have? Some of the drivers have overlapping frequency response, so what frequencies you have the crossover set for them?
Avi

#9 AllanS

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Posted 10 April 2014 - 06:47 PM

Hi Avi, I can not post pictures at this time as I am still trying to acquire JBL 4520 double transducer scoop bins, they are significant with respect to placement of all the other drivers and transducers, when I get  them I will post some pics. As far as crossover points they will be 100x500x2500x8000 give or take.

Allan

#10 dakos

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Posted 11 April 2014 - 12:41 AM

Except for the Behringer, this is sounds like a studio from the past, amps, drivers and all :)

Looking forward to those pics.

If you need more help configuring the rig (I suspect you will), let me know.
Avi