New Posts. Members Profile. Post Reply. Hi guys, I have a load of LEM active cabs all with the same amp units and also the same faults. All of the units power up.
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Discussion in ' Amp Tech Center ' started by stax , Jun 16, Telecaster Guitar Forum. Converting active speaker into passive wiring help needed. Jun 16, 1. Posts: 1, I need some info on wiring up the speakers mainly regarding the crossover between the 1" compression driver and the 12" woofer, I've done loads of guitar speaker jobs but not this sort of thing so any help would be most appreciated.
Thanks in advance. Jun 16, 2. Posts: 6, I have a behringer b pa spkr with horn theat powers up but immediately goes to red clipping light no sound. Jun 16, 3. Posts: 5, If you cannot repair it You could replace the whole power amp section.
If it does not have a separate crossover, you are going to have to wire one some how or another. There is probably a crossover that fits that model speaker as most are sold in both powered and non powered versions.
It will be pricey. As a last ditch, you could not wire to the tweeter and just run direct to the large speaker and run it full range. Jun 16, 4. I found the spec for it and it has a passive crossover but just heard from the tec who is looking at it that it can't be used if I go passive, maybe it is on the main board or something rather than a separate module.
He did fix the first one of the two I took in a year ago but said there were certain parts on these that are now unavailable, it was him that suggested a passive option if the worst came to the worst and he has converted this same model before but I thought I'd have a go, perhaps I'll let him do it, the last time I looked in a passive pa cab it just had a big white resistor hanging off the tweeter but I can see it is a bit more involved.
Jun 16, 5. Posts: 2, As someone who has built many high power passive crossovers, I would recommend you get an active crossover to go with your external power amp. A small miscalculation in the design or execution and you could very easily have a blown HF driver or worse.
Also, passive crossovers are "lossy"devices, you will have an insertion loss of 3dB or so with a passive crossover. That is a lot of power to throw away. If you have specs for the guts in your LEMs, let me know and I can scratch out a passive design for you if you like. Jun 17, 6. This is all I can find on the tech specs. Jun 17, 7. Jun 17, 8. Posts: 7, It indicates a WRMS crossover at 2. How about this one? Edit: Plus it has selectable impedance, either 4 or 8 ohms. Last edited: Jun 17, Jun 17, 9.
Anyway if I could get something like the one in the link that would be perfect or if there is a simpler way of doing it I'll wire up my own. The LEM stuff was quite well thought of and the cabinets are great quality so I'm assuming the speakers are also, it seems a shame to dump them if I can sort them out. Apparently LEM were bought out by someone who soon after shut them down leaving all the people who had the gear in trouble if the dsp unit failed as there are no spares for them.
Jun 17, Posts: 3, I'm goona use that one You should find someone that can run an impedance curve on your drivers. If you design a passive crossover for 8 ohms on the HF you will at least be be safe. If the actual impedance is lower 4 ohms the hi pass part of the filter will have it's 3 dB point an octave or so higher, it would leave a bit is a hole between hz and hz.
Also, odds are that the HF has a much higher sensitivity, and thus would probably require an L-pad or resistive network to lower it's output. Thanks everyone but this is getting a bit too technical for me, I was expecting a resistor, inductor and cap or two. I'm not getting why if I turn them into passive pa cabs run from a separate power amp like I've used most of my life I need an active crossover which presumably would need dc voltage sent to each side instead of just a speaker lead.
Should be written on the cabinet, if not then measure the static resistance of the woofer with a multimeter. Yea of course that make sense, thanks. The active hf amp is rated at watts, so the tweeter is probably robust enough to handle a simple crossover. Or, you could find one with a lover crossover point, say 2khz, which would put less stress on the tweeter. Jun 18, Oh crap, you are right. My bad. I meant to say Maybe , or 3K. Thanks Paratus. You must log in or sign up to reply here.
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Converting active speaker into passive wiring help needed.