Just to ask ?
He I have been watching this thread for a while and I am wondering is there any chance to make this amplifier to work in full range (20hz-20kHz) is this classd module enough fast to amplify frequencies above 200Hz. Can I just rearange the input stage (preamp) etc. . .
If enyone knows please post your oppinion .
He I have been watching this thread for a while and I am wondering is there any chance to make this amplifier to work in full range (20hz-20kHz) is this classd module enough fast to amplify frequencies above 200Hz. Can I just rearange the input stage (preamp) etc. . .
If enyone knows please post your oppinion .
Thanks Pat
Hello
Pat I understand what you are saying. The plate amp solution is most likely what I will do. I am interested in the Hypex solution but I understand it is not availible yet. Also not found anything that will slde in where the old amp was. I am still looking however. And Thanks
qwerty
Hello
Pat I understand what you are saying. The plate amp solution is most likely what I will do. I am interested in the Hypex solution but I understand it is not availible yet. Also not found anything that will slde in where the old amp was. I am still looking however. And Thanks
qwerty
Hi, this amp is a minimalistic option, the mosfet used and the way they are powered simply dont permit the free oscillating to be increased, to gain bandwidth. Even at 200hz, i find it ridiculous, it is way too marginal to be souped for anything. All effort should be put on reliability problem and protections.
cheers.
Hey there!
I too have a dead JBL sub - with a version 6 AMI amp. I found a small transformer or inductor (not the toroid) melted. I found several resistors (various values) of about 1/2 Watt that looked like they had been mighty warm too.
Anybody have any luck repairing this version? Looks like I might use it for a frisbee. Amps i can get, I just thought it would be fun to do the repair.
I too have a dead JBL sub - with a version 6 AMI amp. I found a small transformer or inductor (not the toroid) melted. I found several resistors (various values) of about 1/2 Watt that looked like they had been mighty warm too.
Anybody have any luck repairing this version? Looks like I might use it for a frisbee. Amps i can get, I just thought it would be fun to do the repair.
Has anyone looked at using National's LM4651 Class D module to build a replacement board?
Thanks!
http://www.national.com/ds/LM/LM4651.pdf
Thanks!
http://www.national.com/ds/LM/LM4651.pdf
i too have had my JBL PB12 for about 4 years and have thoroughly enjoyed it during that time. now i'm experiencing what appears to be a very common problem with the unit (front LED's flicker between red and green as if it's not sure that it's actually getting a signal or not and it just sounds terrible). has JBL refined the design of the boards in the E250P? is it possible to purchase the entire input/power/amp module from the E250P and just swap it out with the bad unit? any help that you can offer would be greatly appreciated.
Pat/classd,
I have a PB-10 that pops really loud at ~15Hz when turned on. I have replaced C1 and C2, and swapped R42/D10 (although they worked where they were for 4 years). No luck.
I'm still planning to replace L1 and maybe Q1. If that doesn't work either, do you think it's worth to put the S53AMI apart?
I have a couple of multimeters, but no scope... and it seems that plate amps are hard to find in South America. Maybe I should build a class AB instead (that is something within my reach). What do you think?
There is no signal of blown caps or burnt transistors. The problem appeared gradually - at first, I could turn the thing off, wait for a while and turn it on again, then it would work. Now it happens every time I turn it on.
Your opinions will be greatly appreciated.
Thanks,
VMat
I have a PB-10 that pops really loud at ~15Hz when turned on. I have replaced C1 and C2, and swapped R42/D10 (although they worked where they were for 4 years). No luck.
I'm still planning to replace L1 and maybe Q1. If that doesn't work either, do you think it's worth to put the S53AMI apart?
I have a couple of multimeters, but no scope... and it seems that plate amps are hard to find in South America. Maybe I should build a class AB instead (that is something within my reach). What do you think?
There is no signal of blown caps or burnt transistors. The problem appeared gradually - at first, I could turn the thing off, wait for a while and turn it on again, then it would work. Now it happens every time I turn it on.
Your opinions will be greatly appreciated.
Thanks,
VMat
Does it pop/thump at turn on, and then play, or does it just HUMMM at say, 60 or 120Hz. (I doubt you could hear 15Hz).
If it's the first one, maybe there's a sticking relay with the soft start circuitry or something, which is fixable enough. If it's the later, it likely is the AMI module.
Trying to repair those junkers has proven to be an exercise in futility for all who've tried, AMI included.
If it's the first one, maybe there's a sticking relay with the soft start circuitry or something, which is fixable enough. If it's the later, it likely is the AMI module.
Trying to repair those junkers has proven to be an exercise in futility for all who've tried, AMI included.
Sorry, I should have explained it better.
It pops like if it was turning on. The pops repeat at ~15 times per second - that's what I meant by 15Hz.
After this started happening, I never let it on for more than a few seconds to know what happens next (because something tells me there will be some smoke in the air if I do...).
I have recorded the noise, check it out if you'd like.
Thanks,
Vini
It pops like if it was turning on. The pops repeat at ~15 times per second - that's what I meant by 15Hz.
After this started happening, I never let it on for more than a few seconds to know what happens next (because something tells me there will be some smoke in the air if I do...).
I have recorded the noise, check it out if you'd like.
Thanks,
Vini
Well, just replaced Q1 and... it PLAYS!! Played for a couple of minutes.
Then I shut it off, reconnected the leds, placed the board back into the box. Loaded The Matrix, chapter 29, turned the sub on again and... "pop-pop-pop-pop-pop...". Damn!
I wish I had a scope. Any idea for the next target? Maybe the preamp capacitors? Or the op-amps?
Side question: someone has suggested a plate amp - partsexpress' #390-792. I think it won't fit this box (there's about 6" between the side wall and the port), has anybody actually replaced the shabby JBL's class D with a plate amp in a PB-10? Please let me know if you have (and which model/brand you used).
Thanks a lot,
Vini
Then I shut it off, reconnected the leds, placed the board back into the box. Loaded The Matrix, chapter 29, turned the sub on again and... "pop-pop-pop-pop-pop...". Damn!
I wish I had a scope. Any idea for the next target? Maybe the preamp capacitors? Or the op-amps?
Side question: someone has suggested a plate amp - partsexpress' #390-792. I think it won't fit this box (there's about 6" between the side wall and the port), has anybody actually replaced the shabby JBL's class D with a plate amp in a PB-10? Please let me know if you have (and which model/brand you used).
Thanks a lot,
Vini
Hi, i did play too much with these...
suggestions: when the amp is making pop pop pop, its when it cant start to self oscillate correctly, because of the wrong design.
You might try to play with the on/off switch and you will see that it will start to run correctly...thats baaaaad.
The Sami module is about to die. You will burn your sub very soon if you keep it that way...
Pat
suggestions: when the amp is making pop pop pop, its when it cant start to self oscillate correctly, because of the wrong design.
You might try to play with the on/off switch and you will see that it will start to run correctly...thats baaaaad.
The Sami module is about to die. You will burn your sub very soon if you keep it that way...
Pat