true power and measurable will be almost 70-75 W at 8 ohms resistive load before cliping ( with 42+42 rails )
continius though is another thing .... heatsink is marginal for this kind of power and there is no thermal control .... so for once more if the amplifier is a cfp that will mean power goes directly to the emmiter of the output transitors you might get away with it but i think not full power condiniously ...i would say something like 50-60% of the power will be ok
if its a efp that means power goes to the collectors of the output transistors amplifier will overheat and shelf destroy if used for more than 50% of the power and or more than one hour ..
calculate that this will get worst if room temperature is above 25 degrees ..
tick tock
continius though is another thing .... heatsink is marginal for this kind of power and there is no thermal control .... so for once more if the amplifier is a cfp that will mean power goes directly to the emmiter of the output transitors you might get away with it but i think not full power condiniously ...i would say something like 50-60% of the power will be ok
if its a efp that means power goes to the collectors of the output transistors amplifier will overheat and shelf destroy if used for more than 50% of the power and or more than one hour ..
calculate that this will get worst if room temperature is above 25 degrees ..
tick tock
Is there any way to beef up the heat-sink, so that we can run the amp at high volumes for a sustained period of time.
How about buying an exact pair of heatsinks, and bolting it at the back of the existing heatsink?
Also, what is the name of the white paste that is used as a paste between the transistors & heatsink (I think for uniform absorption of heat).
I was thinking about buying another heatsink which has same distance between the adjacent fins, and apply that white paste on one side of the fins & bolt the two heatsink together so that the fins remain attached to each other.
Heatsink 1
|
|-----
| -----|
|----- | <-- Heatsink 2
| -----|
I was thinking about buying another heatsink which has same distance between the adjacent fins, and apply that white paste on one side of the fins & bolt the two heatsink together so that the fins remain attached to each other.
Heatsink 1
|
|-----
| -----|
|----- | <-- Heatsink 2
| -----|
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Use a fan on the heatsink if you want the amp to run for extended periods of time. A fan extends the dissipation significantly. If you bolt another sink on the back in reverse, you're effectively destroying the heat dissipating ability of the sink by covering up the fins. The power capability of the amp will go down, not up.
^^It's not possible to easily find extrusions over 8" in India, so that's as wide as it gets. Plus, there's no space on the back panel anyway. There are other sections available, but most of them are not really flatbacks so finding something to squeeze in will be tough.
Plus, RS has a 300mm minimum length in India, they don't cut to reasonable lengths. Given the fact that a good heatsink will end up costing him 25% of what the amp did, he would be better served with a PC fan or two, and a gentle hand on the volume control, IMHO.
Plus, RS has a 300mm minimum length in India, they don't cut to reasonable lengths. Given the fact that a good heatsink will end up costing him 25% of what the amp did, he would be better served with a PC fan or two, and a gentle hand on the volume control, IMHO.
@ sangram, can you tell me any specific shops in Chandni Chowk where i can get these PC fans, so that I can run them at the back of the amp?
Also I need a 12volt adopter to run from mains. Can I get these as a complete kit? I mean just plug in mains, and fans starts to work.
First Rishi, you've to understand the feedback of everybody in this thread - that the amp specifications will not be consistent with its actual performance.
Hence the advice to watch the volume control, use only high-impedance loads, and so on. Everything else you are doing is band-aid, because the amp is not correctly implemented.
There are two kinds of fans available in CC. One is the 220V models, starting at about 180mm. They are very loud and noisy, and should be available at general electric store. The other are 12V models, available at every computer store. M D computers is a decent place to look, a set of 4 Coolermaster entry-level fans should be around 400-500. The ones available individually will be more expensive and probably not as good.
Strap them to the back using cable ties and connect them to a 12V adapter or connect them all in series and power them off the +42V supply inside the amplifier. They will work fine a few volts down, no worries. You can be slightly creative with how you power them, but they need DC - not AC.
Even with all the fans, you will have to watch the volume control and speaker impedance. It does not guarantee safety, just makes it a bit safer.
Hence the advice to watch the volume control, use only high-impedance loads, and so on. Everything else you are doing is band-aid, because the amp is not correctly implemented.
There are two kinds of fans available in CC. One is the 220V models, starting at about 180mm. They are very loud and noisy, and should be available at general electric store. The other are 12V models, available at every computer store. M D computers is a decent place to look, a set of 4 Coolermaster entry-level fans should be around 400-500. The ones available individually will be more expensive and probably not as good.
Strap them to the back using cable ties and connect them to a 12V adapter or connect them all in series and power them off the +42V supply inside the amplifier. They will work fine a few volts down, no worries. You can be slightly creative with how you power them, but they need DC - not AC.
Even with all the fans, you will have to watch the volume control and speaker impedance. It does not guarantee safety, just makes it a bit safer.
@sangram
ok understood. So now i need to DIY a fan set.
I have got a rough idea of strapping a pair of them at the back of those fins, and run them on series on a 24 volt supply. What will be the ampere rating of the AC/DC adopter?
Anyway the main point is taken, i.e. no matter what ever DIY i do, i should never take the volume past 50%.
Got that!
If they are not very visible, you can just glue them to the back of the sinks so they blow fresh air at the fins, I used to use normal cold white wood glue.
Most 80mm fans draw about 100 to 110mA. It is normaly advisable to not run them a ttheir top voltage, as this causes alot of fan noise.
Most 80mm fans draw about 100 to 110mA. It is normaly advisable to not run them a ttheir top voltage, as this causes alot of fan noise.
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@ sangram --> Contacted MD Computers, a pair of CoolerMaster PC fans will cost Rs. 150 X 2 = Rs.300. Local fans cost Rs.40
Also AC/DC adapters for fans are available, Rs 50 each.
Going tomorrow to buy the kit @ Rs. 400 @ will use instant glue like FeviWick to paste them with the fins.
If i missed something kindly inform.
And thanks to all the members for diyAudio for providing the enormous support to me.
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