BillFitzmaurice.info

So I was so happy with my Lepai 2020 (http://www.parts-express.com/pe/showdet ... er=310-300) to power my J10 (Beta 10, Flat 6 Piezo array) that I ordered another one from PE to power my new J15 (2515, Melded 20 Piezo array) for an easy backyard party rig.

I initially hooked up the new Lepai to a pretty inefficient 3 way box (the Golden Boys from the PE projects) that I made a while ago (before I discovered this site) to give me something to listen to while rigging up a cable for the J15. The Lepai worked great.

Then I hooked it up to the J15 and things got weird. The amp started cycling off at very moderate volume. Hooked it back up to the Golden Boy at the same ipod and amp settings and everything worked fine. Back to the J15, and same cycling problem.

I'm not putting it past the amp to be defective (which it probably is)- the first one I got for the J10 had to be exchanged. I'm more curious as to why the J15 would cause the amp to trip, while it works just fine with the other box at the same settings. I'm 100% sure that everything is wired fine inside the J15. My understanding is that the amp is presenting the same voltage to both the J15, and the Golden Boy- but the J15 is the voltage more efficiently, and is therefore, much louder at that voltage. Both cabs are supposed to have an 8 ohm impedance, so I can't imagine that the J15 is pulling more amperage.

Of course, my understanding could be wrong. Anyone have any thoughts?

Thanks for grinding through my long post.

-Nathan

do you wired the resistor on the piezo array????

I built the crossover as per the plans. I should have also mentioned that I wired in a switch (upstream of the crossover) to turn off the tweeters for use as a bass cab. The Lepai cycling off happens with piezo switch in the on and off position.

I know the problem is probably a bad amp; but I can't get it through my head why the amp wouldn't like the J15. Or, at least why it likes the crappy Golden Boy more than the Jack. I know I like the J15 better! It's actually the best speaker box I've ever heard.

aaahhh!! the crossover switch just interrupts the + cable of the tweeter array?? and to be 100% sure it interrupts before the xover??? try the cab with just the speaker wired ,if it still doing it, then theres something really wrong

Hmm, it sound like you built the crossover per plans, but didnt add the 4ohm resistor in series with the piezoes so the amp is self-oscillating at the higher frequencies, which it doesnt like.. However, you say you added a switch? Before or after the crossover?

It has to be the wiring or something else wrong in the cab, not the amp.

Gregory East wrote:It has to be the wiring or something else wrong in the cab, not the amp.

+1. Check your crossover.

Well, I guess someone should point me straight to the BF knuckle head club. By "sure I wired 100% correct", I must have meant about 95% correct. I looked through the port (they are pretty big in the J15) and saw that I put the capacitor on the wrong side of the inductor of the low pass filter. I was (I think) essentially shorting the amplifier output to ground, causing the amp to try its hardest to keep me from killing it.

It's worked fine when being pushed by my big old Carver amp, but I'm sure that the amp wasn't happy either. Just more resilient than the cheap Chinese Lepai. I'm really surprised that I set up the crossover wrong. I've typically been pretty good in the past about following electrical diagrams; but I guess there's nothing like a good kick in the ass to make sure I'm more careful next time.

Thanks guys for all the help.

-Nathan

Let us know the end results.

Moved the capacitor to where it's supposed to go. Everything it working well now. Thanks for the help, guys.

But how does it sound?

It sounds great. I'm now annoying the two guitarists who usually each have their 2x12 cabs pointing right at my face in rehearsal. Huge sound for bass guitar. I still need to remember to bring my volt meter to rehearsal to see how much I'm actually throwing at it.

I've only turned on the melded array and played music through it using the Lepai in the back yard. The 5 watts or so that the Lepai puts out is way more than enough for backyard or tailgate duty. Huge lows compared to anything else that I would try to use in its place (I'm no professional!). It's a bit big for easy tailgate transport, though. The J10 handles mobile tasks better.

I haven't been bothered to drag out the heavy Carver amp to see what that would do with the J15. I'm sure the neighbors are more than happy with that decision too.

The Lepai 2020 is an excellent little amp to power the Jack series. Cheap, light, and can be run off of a SLA battery all make for one heck of a potent rig. Just make sure that you unintentionally try to kill it like I did.