Lepy Amp - Subwoofer Wiring

[bill0r]

Hi,

 

Can someone share how to wire the Subwoofer into the Lepy LP-168HA amplifier? I have connected both speakers and the amp, but I can't seem to be able to get the sub working.  I have wired according to the manual here: https://www.parts-express.com/pedocs/manuals/310-308--lp-168ha-manual.pdf

 

Thanks!

[DDH]

If you've followed the diagram you should be fine.  You have two possible +ve terminals and two possible -ve terminals for the subwoofer.  So provided you have one wire from the subwoofer to one of the bottom right terminals and the other to the bottom left things should be fine.  Speakers should be connected according to polarity (ie negative to negative) but even if you've got that wrong it will not stop it working.

 

The most likely candidate is the crossover point.  The subwoofer will only have an output when low frequency sound is being amplified.  This amp has an adjustment to set the point when the sound will 'move' from the standard speakers (L / R) to the subwoofer.  Try adjusting that.  Also, check what you are inputting as a sound source.  If pinball sounds are not activating the subwoofer, try some music, preferably very bass heavy stuff.

[bill0r]

Thanks DDH! I gave it a try and the sub does kick in now. However, I have to keep the sub volume really low (around 5%) so that it does not sound distorted. Also the speakers sound low even with the master volume knob turned all the way up.

Here's a pic of how I wired the speakers and sub:

http://imgur.com/bSE8Ifm

[AndersE]

Excuse me, but according to your picture and the manual you have connected the sub wrong. It shows that you should connect both - together to one - of the sub, and

both + together to the + side of sub.

 

The distortion at higher levels is probably because the sub gets all frequencies becuse the other + pole is not connected.

 

I know how to bridge an amp but this looks weird. How is the amp constructed to separate the crossover from the outputs of the normal speakers when connected like this?

IS it an actual bridging or are there 3 real amplifiers in it? Then why 4 speaker connections?

 

There are so many wrongs and weirdnesses with the looks of the manual and the amp that i am very sceptical to it.

 

Actually i think the cheapest computer 2.1 set would sound and work better.

 

Update: I found an youtube review of it. 1% distorsion at 7W, 11W on the sub (17w and it's almost a squarewave output).

Crossover does nothing on the test.

[DDH]

Hmm, interesting what AndersE has to say.  I was reading that diagram as being able to hook up two subwoofer speakers (L and R).  I was presuming, being a cheap amp, that is was using some really basic passive crossover circuit and getting separate subwoofer outputs after the amplification stage.  It would be weird to have to join terminals external to the amplifier.  On a second read the diagram and description is certainly ambiguous.

 

You could try joining the subwoofer outputs, worst that could happen is damage to the amp (in my opinion, possible but unlikely - but its your amp)

 

Do you know that your input signal is clean?  ie you aren't simply amplifying a crappy input?  Where is you input signal coming from, ie PC out, TV out, line or headphone connections?  From your picture you are using the line in, so make sure that your signal comes from a line out.  If you are using a headphone out for signal you should be using the aux in on the front panel according to the manual.