sorry that this isn't specifically dealing with dj's problem/s but it's all very familiar to me and i have some related questions.
i was given a sentrek sda-232 amp by my brother in law (i think my sister wont allow him to have it in his car anymore.... ahh married life!) and it claims to produce 320 watts when it's in bridged mono for a sub, or (i think) 80watts per channel in stereo.
i've run it in the house with a pair of 12v batteries paralleled and they lasted for quite a while running it pretty heavily. when i first pulled out of the garage after leaving it there for a year or two, there was no fuse in the fuse slot. i tried a 10A and it ate it in about 5 seconds. it's now got a 15A in it and it's ok but i have the level adjust screw at lowest.
anyway... a sticker on its base states that it has a PWM (pulse width modulated?) mosfet power supply. is that just marketing speak for a plain old switchmode supply? i would like to get a toriod instead and use it maybe as a sub-wooer amplifier.
if i were to try to measure the voltage that the supply steps up to, do i measure it when it's idle, i.e powered but no signal or even no speaker load? or should i measure it when it's amplifying a sine wave or something? are there any particular components within switchmode supplies that will tell you what their output voltage is, like any regulators or whatever? i don't know much about them other than they seem to be an array of capacitors and coils to look at.
oh well, i guess if i continue to use it i can easily use the batteries but they are so heavy and awkward!
thanks for any suggestions.
i was given a sentrek sda-232 amp by my brother in law (i think my sister wont allow him to have it in his car anymore.... ahh married life!) and it claims to produce 320 watts when it's in bridged mono for a sub, or (i think) 80watts per channel in stereo.
i've run it in the house with a pair of 12v batteries paralleled and they lasted for quite a while running it pretty heavily. when i first pulled out of the garage after leaving it there for a year or two, there was no fuse in the fuse slot. i tried a 10A and it ate it in about 5 seconds. it's now got a 15A in it and it's ok but i have the level adjust screw at lowest.
anyway... a sticker on its base states that it has a PWM (pulse width modulated?) mosfet power supply. is that just marketing speak for a plain old switchmode supply? i would like to get a toriod instead and use it maybe as a sub-wooer amplifier.
if i were to try to measure the voltage that the supply steps up to, do i measure it when it's idle, i.e powered but no signal or even no speaker load? or should i measure it when it's amplifying a sine wave or something? are there any particular components within switchmode supplies that will tell you what their output voltage is, like any regulators or whatever? i don't know much about them other than they seem to be an array of capacitors and coils to look at.
oh well, i guess if i continue to use it i can easily use the batteries but they are so heavy and awkward!
thanks for any suggestions.
What you really need to do...
I've done all of this and more. I built a home theater subwoofer from an old Kenwood car amplifier (before plate amps were widely available). I simply clipped the rectifier diodes out (TO-220 style 3 pin) connected the output of my +/- 35V power supply to the center pins, positive and negative, respectively, and grounded to the traces between the filter caps. It's that easy. I wouldn't waste time, as Beanz said, trying to run your amplifier from 12V input - after the power supply, it's all the same audio circuitry you'd find in a home amp (some better, far better than others of course!)
As far as car audio in general goes - I'm 1st Class MECP Certified which basically means nothing since I've been building car amps and their power supplies long before I got that piece of paper. I'm also weakly A.S. degreed in Electronic Repair, but that doesn't stop me from continuing the learning process and designing custom equipment for engineering collegues.
Please don't group all car amplifiers together. There are "Hi End" amplifier companies that lie about their RMS specs, too. Kenwood and Pioneer come to mind. The California Boom Amplifiers are from the same line as 95% of the rest of flea market amplfiers made in China. They're all the same with a slightly different layout and heatsink design/color. I could repair them with my eyes shut - no schematic necessary! Probably use either TIP35/36C or D718, B688 outputs - or their TO-3P brethren and TO-126 sized sink-less driver transistors (current starved, of course!). Power supply uses 6 IRFZ44s or Z34s per 200W with a 2" diameter toroid running from a TL494 PWM IC and a LM339 comparator for protection circuits. I'll quit now, but this is from memory - having repaired hundreds and hundreds of these things...
I've done all of this and more. I built a home theater subwoofer from an old Kenwood car amplifier (before plate amps were widely available). I simply clipped the rectifier diodes out (TO-220 style 3 pin) connected the output of my +/- 35V power supply to the center pins, positive and negative, respectively, and grounded to the traces between the filter caps. It's that easy. I wouldn't waste time, as Beanz said, trying to run your amplifier from 12V input - after the power supply, it's all the same audio circuitry you'd find in a home amp (some better, far better than others of course!)
As far as car audio in general goes - I'm 1st Class MECP Certified which basically means nothing since I've been building car amps and their power supplies long before I got that piece of paper. I'm also weakly A.S. degreed in Electronic Repair, but that doesn't stop me from continuing the learning process and designing custom equipment for engineering collegues.
Please don't group all car amplifiers together. There are "Hi End" amplifier companies that lie about their RMS specs, too. Kenwood and Pioneer come to mind. The California Boom Amplifiers are from the same line as 95% of the rest of flea market amplfiers made in China. They're all the same with a slightly different layout and heatsink design/color. I could repair them with my eyes shut - no schematic necessary! Probably use either TIP35/36C or D718, B688 outputs - or their TO-3P brethren and TO-126 sized sink-less driver transistors (current starved, of course!). Power supply uses 6 IRFZ44s or Z34s per 200W with a 2" diameter toroid running from a TL494 PWM IC and a LM339 comparator for protection circuits. I'll quit now, but this is from memory - having repaired hundreds and hundreds of these things...
wow thats pretty impressive right there Envision.
I just did a comparsion of chips in a few amps that we had laying around. One was fine, one needed 3 of 6 power supply mosfets (K2312) and the other needed a new gain potentiometer.
All 3 amps used TIP35C/36C outputs..
Hifonics Centurion 100x2@4 or 320x1@4
4 pairs tip35/36, and (6) IRFZ44 803F
Hifonics Atlantis 175X2@4 or 600x1@4
6 pairs tip35c/36c and (10) IRFz44 803C
JBL 80.4 40x4@4 or 160X2@4
4 pairs tip35c/36c and 6 K2312
I was sort of wondering if there was any easy modification possible to mprove the power ratings of any of these amps? IE are there any obvious bottel necks that can be beefed up to go to a lower impedance or anything? becasue for example the JBL gets 80 watts per pair, it seems the atlantis is over rated when bridged, or it is geting 100w per pair? (outputs )
I just did a comparsion of chips in a few amps that we had laying around. One was fine, one needed 3 of 6 power supply mosfets (K2312) and the other needed a new gain potentiometer.
All 3 amps used TIP35C/36C outputs..
Hifonics Centurion 100x2@4 or 320x1@4
4 pairs tip35/36, and (6) IRFZ44 803F
Hifonics Atlantis 175X2@4 or 600x1@4
6 pairs tip35c/36c and (10) IRFz44 803C
JBL 80.4 40x4@4 or 160X2@4
4 pairs tip35c/36c and 6 K2312
I was sort of wondering if there was any easy modification possible to mprove the power ratings of any of these amps? IE are there any obvious bottel necks that can be beefed up to go to a lower impedance or anything? becasue for example the JBL gets 80 watts per pair, it seems the atlantis is over rated when bridged, or it is geting 100w per pair? (outputs )
you cant. the way this bridging works is you take a pair of channels with the same power supply and give one of them a signal 180 degrees out of phase (inverted) . then your output is the sum of the volatage swing of each channel. EX if each channel went +-10 volts, and you hooked them up end to end with one inverted you would get +-20 volts now, and if the amplifier was beefy enough and could provide the current, you would get 4 times the power out of it.
Since you have a 4 chanel amp with one +- power supply, you end up with 2 bridged modules that are the same volate swing. you cant tie them end to end or anything as they share a power supply.
and btw, your amp has 6 IRFz44's?? that is the same amont as the 2 ~360 total bridged watt amps I listed. (te jbl and the centurion) so I bet you would be okay with a 30 amp power supply. I think the suggestion of directly powring the +- rails like Envision suggested is best bet tho.
Since you have a 4 chanel amp with one +- power supply, you end up with 2 bridged modules that are the same volate swing. you cant tie them end to end or anything as they share a power supply.
and btw, your amp has 6 IRFz44's?? that is the same amont as the 2 ~360 total bridged watt amps I listed. (te jbl and the centurion) so I bet you would be okay with a 30 amp power supply. I think the suggestion of directly powring the +- rails like Envision suggested is best bet tho.
Re: What you really need to do...
Even the "IND PROTECT" led comes on.
Now, it's 4 channel, and it uses one set D718's and B688's for each channel. It only appears to be one channel thats gone however, since one D718 and one B688 gets hot when i connect the power to it (with the remote already connected). Also, these chips also have no resistance between them while the other 6 do...
Any idea what the problem is? I have 2 non working amps, so I can use spares from one, andmake one good one out of the 2.
EnvisionAudio: I have one of these amps... but it's broken. I power it with the + and -. When I connect the remote line the amp shorts the + and - out, and the power wires get really hot.EnvisionAudio said:
Even the "IND PROTECT" led comes on.Now, it's 4 channel, and it uses one set D718's and B688's for each channel. It only appears to be one channel thats gone however, since one D718 and one B688 gets hot when i connect the power to it (with the remote already connected). Also, these chips also have no resistance between them while the other 6 do...
Any idea what the problem is? I have 2 non working amps, so I can use spares from one, andmake one good one out of the 2.
There is no way for that amplifier to give you 800 watts unless its 130% efficient! is that even possible!
I have only seen the first post but most car amplifiers are at best 60% efficient so an amplifier two white 25 amper fuse can only make 600 watts maximum power, for a few seconds, it would be more realistic to say it around 300 watts,
Forget about a power supply, get a big battery and a charger.
I used a car amplifier in a home audio setup when i was a student, oh and there is nothing wrong with mass market amplifiers there just not normal, nothing wrong with that at all.
The only thing i have found is getting parts is hard, SB688 are not something i can find in my town.
I have only seen the first post but most car amplifiers are at best 60% efficient so an amplifier two white 25 amper fuse can only make 600 watts maximum power, for a few seconds, it would be more realistic to say it around 300 watts,
Forget about a power supply, get a big battery and a charger.
I used a car amplifier in a home audio setup when i was a student, oh and there is nothing wrong with mass market amplifiers there just not normal, nothing wrong with that at all.
The only thing i have found is getting parts is hard, SB688 are not something i can find in my town.
Forget the critics. This is a fine amp if used well below rated power. Just because it says it will do it doesn't mean you have to turn it up that loud.
The power that this amp takes will not be evenly distributed. It will depend on the audio vs time. The current will be taken from the battery in spikes and not continuous. So if your charger will put out the RMS or average current the amp needs, the battery...lead acid car battery, will handle the current spikes, as long as the charger puts the RMS current back into the battery. This is what car batteries do... how much current do you think is sucked through the starter motor on a car??? but only for a short time. A capacitor will help with these spikes, but probably is not needed for this.
With the battery charger in parallel with the battery terminals, the charger must produce the RMS current used by the amp, and this way won't discharge your battery.
ps: your charger better be of some size.
If the amp outputs 200W (more reasonable) from all ch., at 50%, then 400W from 12V is 33A. need at least this much from charger to run continuously at full power.
If you hook this up right, then it should work.
The power that this amp takes will not be evenly distributed. It will depend on the audio vs time. The current will be taken from the battery in spikes and not continuous. So if your charger will put out the RMS or average current the amp needs, the battery...lead acid car battery, will handle the current spikes, as long as the charger puts the RMS current back into the battery. This is what car batteries do... how much current do you think is sucked through the starter motor on a car??? but only for a short time. A capacitor will help with these spikes, but probably is not needed for this.
With the battery charger in parallel with the battery terminals, the charger must produce the RMS current used by the amp, and this way won't discharge your battery.
ps: your charger better be of some size.
If the amp outputs 200W (more reasonable) from all ch., at 50%, then 400W from 12V is 33A. need at least this much from charger to run continuously at full power.
If you hook this up right, then it should work.
Ok, I managed to fix my amp tonight... I simply ripped out the offending D718 and B688 from the amp, and I now have it working again! With 3 instead of 4 channels, however.
Anyway, I am now powering this amp in the house... It works great with a car battery. My charger is a little weak, so I'm gonna look out for a better one.
Finally, I can now power my centre and sub, so I now have a 5.1 set up!
Anyway, I am now powering this amp in the house... It works great with a car battery. My charger is a little weak, so I'm gonna look out for a better one.
Finally, I can now power my centre and sub, so I now have a 5.1 set up!
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.