JBL PB12 subwoofer, Class D amp, dead.

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V

VMat

Member
Joined 2006
It is part of the muting/delay turn on and high level inputs.
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Could they do anything uglier than that?

You might try to play with the on/off switch and you will see that it will start to run correctly...thats baaaaad.
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Damn JBL... If I only knew it before I spent my money... :headbash:

As a matter of fact, I did that once, and noticed the leds went green, and there were no pops. But after 10~15 seconds I started hearing a hiss that made me think I should better turn it off... :sad:

The Sami module is about to die. You will burn your sub very soon if you keep it that way...
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That's good to know, after all... at least I can stop buying parts for it and get something else that works. :(

btw, you have the oldest version
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I guess I do. Actually, I don't even have an on/off switch. I built an external one myself (I needed an extension cord anyway).

So, back to the plate amp - do you think those Daytons are good enough? They are all class AB (I'm considering http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-792 and http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-784 - the latter might even fit in the box). Any suggestion?

Thanks again!
 
V

VMat

Member
Joined 2006
Well, actually... my apologies for so many posts :ashamed:. But now that I really gave up fixing the lemon, I wonder if you can give me a tip :shy:.

These three amps caught my attention for the price and specs:

http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-792
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-802
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=300-784

I'm tempted by the second one (that I had not seen until last night), because it is smaller than the first but more powerful than the last one. I'd like to know from you if they are reliable (once beaten, twice shy :)), and if they sound good enough to watch action movies and listen to rock/jazz music. Not too loud - I live in an apartment.

In other words: do you have any reason *not* to buy one of these?

Thank you very much!
 
3

38628

Disabled Account
Joined 2004
at 89$, you not loose anything...

but it will not fit the opening into the enclosure...

you might just ditch out the amp section out of the JBL board and get a 41hz amp2 in bridged mode...

i dont know nor did play with any of these except the IR audamp design.

Pat
 
V

VMat

Member
Joined 2006
you might just ditch out the amp section out of the JBL board and get a 41hz amp2 in bridged mode...
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Geez! That's a nice kit! Come on, Pat, you're getting me more confused... :)

I'm afraid I can't find the time (and tools, etc.) to assemble it right now. But I'll definitely keep it in my wish list. Thanks for the tip!

If you don't have any cons for the #300-802, I think I'll get it.

but it will not fit the opening into the enclosure...
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I'll measure the box again. Maybe 6-1/2" will fit in the box. Or maybe I can arrange something to fix it outside the box. Wood and nails are easy to get around here (unlike electronic parts).

Thank you all,

VMat
 
3

38628

Disabled Account
Joined 2004
I was just meaning that you can actualy "cut" the JBL pcb in half to keep the preamp section and part of the power supply. There is even a line drawn on one side where to "cut"...so then you can put in any amp and keep the actual faceplate with input connectors.

the other one at 89$ is realy realy cheap, go for it...

just be sure to check the JBL sub itself, it can be damaged due to the way that the unit fail...you may also check for cross over compatibility, the impedance of this sub is unknown.... (mine tested 2 ohm...should be 4)

btw, mine was damaged...

Pat
 
V

VMat

Member
Joined 2006
Correction: driver resistance is 6.2ohms.

There are ~6-1/4" between the port and the internal wall. Almost what I need... :( Maybe I can still carve the wall to get the extra 1/4", but that might make the box very fragile.

I think it won't be too bad if I put it outside the box. It's in the back anyway, so I won't see it. :)
 
N

nillerviborg

Member
Joined 2006
Hello There!! - Im new on this thread, but here goes..:

The company developing the D module for Harman went down, so it is only possible to get a complete exchange module...

But on the other side, it is quite easy to distinguish between the Filter and the Amp section of the board, so you can strip the amp, mout a LC ZapPulse, Hypes UCD or something like that, and get a better unit than before...

Sincerely, Lars / Viborg
 
3

38628

Disabled Account
Joined 2004
Hows it going with this wicked amp ?

Working properly or still laying there on the shelf collecting dust ?
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I have trashed it all, ALL !!!

i needed space for other projects.

All that remains is a bit of experience with theses pieces of sh*t.

I always hated the sound of any subwoofer like that anyway, no worth it at all.

I can still answer questions related to it if someone ask :)

sincerely yours

Pat Allen, hardware and software designer.
 
W

wattz

Member
Joined 2005
Just reading the thread and VMat stated the driver impedance is 6.2 ohms. Can I use a normal 250W 8 ohm sub as a replacement? Or will that be bad for the amp? Please let me know. I think the coils on mine are messed up since I have to push the sub down to get it to work.
 
3

38628

Disabled Account
Joined 2004
since its a class D amp, and that there is a low pass filter at the output, you might want to do some calculations before...
the bandwidth of this amp is already poor ;)

let me check...

main filtering inductance is 220uh, 4.7uf and .33uf...what the...

forget it, i never saw the filter that much bad designed...i dont think it can hurt anything, the circuit can hurt itself anyway :eek:

the power output will be far less than before with a 8 ohm.

hth

Pat Allen
 

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