# Help with New KG5150 Amp



## CMT8T (Jan 29, 2011)

Hello-
I have thoroughly enjoyed this forum so far.

I bought a replacement amp (KG5150) for my JBL-Bass20 powered subwoofer that I purchased back in 1998.
It was only after my amp arrived that I though to check the ohm rating on the speakers (I know).
They happen to be 6 Ohm speakers and the amp can operate in 4 to 8 Ohm impedence. I know that I wouldn't want to wire these in parallel, but can I wire them in series at 12ohm with out damage to my amp?

At least until I need some new woofers... that is.

Thanks to all.


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## legacyman (Jan 25, 2011)

you can wire your speakers in paralell to get 12ohms, and it won't hurt the amp, but you will lose half of the power of your amp. The lower the ohm rating of your speakers the more current drive from your amplifier. you just want to make sure you do not exceed the lowest ohm rating on your amp. I hope this was a little help for you:


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## CMT8T (Jan 29, 2011)

Thanks for the reply. 

I am guessing that since it is 150w at 8ohm and 200w at 4 ohm the out put would be somewhere between 75 and 100w.
That would be fine I guess until I need to pick up some new drivers.


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## vann_d (Apr 7, 2009)

Try them in parallel. If it's too much load the amp will go in to protection but you won't hurt anything. My guess is that they will work fine. Then no need to spend $$


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## Anthony (Oct 5, 2006)

No, if you wire them in parallel you will get 3 Ohms Rp=R1R2/(R1+R2) Since they are both 6 Ohms, Rp=3 Ohms and that's below the load capacity of you amp. Trust me, I blew a 6 Ohm amp with a 4 Ohm speaker. It worked for years and then one day gave up the ghost. Too much current and heat eventually burned out a transistor.

You were right on series being 12 Ohms. You can wire them up like that and not hurt the amp. The extra load lowers the current demand, although it does halve the power to each speaker.

Best of luck.


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## gattech (Mar 9, 2011)

CMT8T said:


> Hello-
> I have thoroughly enjoyed this forum so far.
> 
> I bought a replacement amp (KG5150) for my JBL-Bass20 powered subwoofer that I purchased back in 1998.
> ...


Hi CMT8T!

I have a Acoustic Research S115PS powered subwoofer that uses that same amplifier. It was made by Keiga but AR branded. Last summer it was burned by a power surge caused by a nearby lightning strike. The aftermath was 3 of the 4 final transistors shorted, 7 small signal trasistors shorted/burned, two power supply capacitors/filters exploded, etc. The woofer driver didn't suffer any damage.

Repair is out of question, but amplifier replacement looks like a good option.

Could you tell me were did you purchase your Keiga KG5150 subwoofer amplifier?

Thanks!


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## fusseli (May 1, 2007)

vann_d said:


> Try them in parallel. If it's too much load the amp will go in to protection but you won't hurt anything. My guess is that they will work fine. Then no need to spend $$


^ I agree, try it. It will be obvious if the amp runs hotter than it used to with a load above four ohms. Stuff has to run _hot_ for anything to burn up, chances are it will be fine.



gattech said:


> Could you tell me were did you purchase your Keiga KG5150 subwoofer amplifier?


I'm guessing Madisound?


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## gattech (Mar 9, 2011)

fusseli said:


> ^ I'm guessing Madisound?


You are right! They sell it for $169 plus s/h, but I'm hoping to get a better deal on it since Parts Express have a comparable unit for $139 and even less than a hundred last month on sale.

The KG-5150 produces less power than the Dayton SA-240. The Dayton have a more rugged and sturdier construction, better quality components, etc.

But the Keiga KG-5150 is direct fit for the amp that came factory installed in the Acoustic Research S115PS amplified subwoofer. Keiga made it for AR. So it just a thing of 5 minutes to return to life again the S115PS. Remove 10 screws, lift the old amp from the sub enclosure, disconnect the two wires from the woofer and do that again backwards with the new KG-5150 amp. 5 Minutes!!! :sn:


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