JBL PB12 subwoofer, Class D amp, dead. - Page 27 - diyAudio
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Old 10th May 2006, 02:02 PM   #261
VMat is offline VMat  Brazil
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Hi guys,

Yes, I measured 6.2ohms, but that was with a (cheap, although good-branded) handheld meter. I wouldn't be surprised if it were off by 10 or 20% in this very low range (top of scale is 200ohms, I think).

Anyway, I have just purchased that #300-792 from PartsExpress. Can't wait to have it home and put it to work.

VMat
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Old 11th May 2006, 12:32 PM   #262
wattz is offline wattz  Canada
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Okay, I found a replacement driver which was 8ohm, 300W, and a 50 ounce, ported magnet. Some cheapo no-name brand called "Rock Sound" that I paid only $25 cdn for

Anyhow, I installed it and it worked fine for a little bit. Then it started doing the same thing as my original sub. What happens is pretty simple. The speaker volume drops to almost nothing at mostly lower volumes. At maximum volume it works for about 5-10 minutes after I push the front or back rim of the cone with my hand.

Like WTF could be causing that? Strangly enough this speaker works slightly better than the last. I'm pretty sure it's not the speaker but something to do with the amp. Perhaps pushing against the cone exerts physical resistance which changes the characteristics of the load. I dunno, it has to be the amp. Unless the it could be the driver impedance in combination with the amp (which has been previously repaired)

Anyone know what could be causing this? It's getting really tiresome going pushing the speaker in every 5-10 minutes
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Old 14th May 2006, 04:51 PM   #263
Abolish is offline Abolish  United States
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Been reading this entire thread for about 2 hours now and I'm amazed by all your efforts to fix this problem with this amp. I also commend pat for all that work, even though at the end of it all it was scrapped.

I have a PB10 and a week ago I noticed that it was not on. So I opened it up and saw that the 3AG fuse was blown. Went got a pack of new fuses. Put the new fuse in and as soon as I turned it on it blew. So I took it to a friend that is an audio equipment engineer for a local radio station. Checked it out and said that it was the S53AMI module.

Now i've read all your posts and most of the symptoms you guy's are getting are the Hummming and the poping but nothing about a blown fuse. My question is could a faulty module be the cause of the amp to keep blowing the fuse? Or could it be something else. Even worse is that I have two of these subs. One is still functional. I was thinking of taking the module of the good sub and trying it out on the busted amp to confirm that this is what is causing it to blow the fuse.

Let me know your thoughts.
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Old 15th May 2006, 05:07 AM   #264
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Hi,

They had a number of problems across all versions it seems, hard to say which of the many could be affecting you.

A faulty module should blow the fuse I'd think. Can't say with any degree of certainty that plugging in a working module won't destroy that working module so for that reason I'd advise against it.

Enjoy the one you have left while it lasts.
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Old 15th May 2006, 06:28 AM   #265
Abolish is offline Abolish  United States
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I figured you'd advise not to do it. I guess my next question is what plate amp would be suitable for the drive that comes in the PB10?
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Old 15th May 2006, 08:55 AM   #266
PM650 is offline PM650  United States
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I *think* this amp will work: http://www.apexjr.com/CVT200S.htm
I was considering buying one to replace a dead pb12 amp, at one point. You would have to enlarge the original amp cutout in order for it to fit, though. Haven't been able to find any other amps that are larger in both dimensions then the original other than the cerwin vega amp.
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Old 17th May 2006, 11:28 AM   #267
wattz is offline wattz  Canada
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BUMP
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Old 17th May 2006, 12:52 PM   #268
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wattz, what is your amp, same as the ones described in the thread ?

If yes, its most likely on its way out.
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Old 18th May 2006, 06:45 AM   #269
Abolish is offline Abolish  United States
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any other plate amp suggestions besides that Cerwin Vega?
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Old 18th May 2006, 06:46 AM   #270
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Check out Adire audio's stuff, pretty sure though have a few for sub use.
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