LM3875/LM3876 load question. - Page 2

JoeBob · 16th December 2001, 10:59 PM

Well, I've found a solution to my problem, I'll just bi-amp and use two LM3886's per channel, still powering 4ohms but gives me more power. Everyone's been telling me to bi-amp anyways...

AudioFreak · 16th December 2001, 11:12 PM

Quote:

Originally posted by downhere
Peltiers are just good at lowering chip temperatures, e.g removing heat, but they do not do much in reducing overall heat production. I think a previous thread had something about it... overclocking circles also have alot of info on the subject

Yes i know so you then stick a massive heatsink (maybe with a fan) on the other side of the peltier or better yet a water cooling rig ..... oh the price we pay for this hobby of ours.

JoeBob · 17th December 2001, 12:25 AM

But with peltiers they also produce heat of their own. And you need one rated higher then the wattage of heat you intend to move. They're rather inefficient.

You'd only use a peltier to cool something below ambient. Because whatever you'd use to cool the peltier would cool whatever you want to cool, down to pretty near ambient anyways. Even in CPU overclocking peltiers don't have many uses. Try dissipating 300w+ of heat from from a computer...

AudioFreak · 17th December 2001, 12:30 AM

Yes i understand that ... but they do have their uses ... and below ambient is nice but then humidity becomes a problem ... its just a matter of which compromise you prefer.

downhere · 17th December 2001, 03:32 AM

Yeah peltiers are just used for overclocking, it may improve the sound I guess, by producing a steady temperature, but peltiers introduce their own problems. E.g condensation, you have to insulate practically everything around the peltier, high heat on one side of the peltier, and watercooling the peltier, which is a huge problem by itself.

JoeBob · 17th December 2001, 03:55 AM

A peltier wouldn't exactly produce a steady temperature. A rise in heat output of the device being cooled would result in a rise in heat being transfered from the cold side to the hot side of the peltier, therefore also increasing the amount of total heat having to be dissapated. While I may seem to be putting peltiers in a bad light, they do have their uses and are excessively usefull in some applications. They do for one work rather well if you ever intend to build a DIY mini-fridge

.

paulb · 17th December 2001, 04:50 AM

Quote:

Originally posted by JoeBob
Well, I've found a solution to my problem, I'll just bi-amp and use two LM3886's per channel, still powering 4ohms but gives me more power. Everyone's been telling me to bi-amp anyways...

Excellent solution. If you're not already aware of it, this site has much info on biamping and projects for LM3886 amps and active crossovers:
www.sound.au.com
If you already have 4-ohm speakers, fine, but if you haven't got them yet check the 3886 specs carefully. Depending on your supply voltage and heat sinks, you might actually get more power into an 8-ohm load.

JoeBob · 17th December 2001, 05:04 AM

Ya, I'm aware of it's output into 4 and 8 ohm speakers. But I already have my speakers built, it was my previous project, now the amp comes secound.

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16th December 2001, 10:59 PM	#11
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	Well, I've found a solution to my problem, I'll just bi-amp and use two LM3886's per channel, still powering 4ohms but gives me more power. Everyone's been telling me to bi-amp anyways...

17th December 2001, 12:25 AM	#13
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	But with peltiers they also produce heat of their own. And you need one rated higher then the wattage of heat you intend to move. They're rather inefficient. You'd only use a peltier to cool something below ambient. Because whatever you'd use to cool the peltier would cool whatever you want to cool, down to pretty near ambient anyways. Even in CPU overclocking peltiers don't have many uses. Try dissipating 300w+ of heat from from a computer...

17th December 2001, 12:30 AM	#14
AudioFreak Warp Engineer On Holiday Join Date: Oct 2001 Location: Queensland, Australia	Yes i understand that ... but they do have their uses ... and below ambient is nice but then humidity becomes a problem ... its just a matter of which compromise you prefer.

17th December 2001, 03:32 AM	#15
downhere diyAudio Member Join Date: Oct 2001	Yeah peltiers are just used for overclocking, it may improve the sound I guess, by producing a steady temperature, but peltiers introduce their own problems. E.g condensation, you have to insulate practically everything around the peltier, high heat on one side of the peltier, and watercooling the peltier, which is a huge problem by itself.

17th December 2001, 03:55 AM	#16
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	A peltier wouldn't exactly produce a steady temperature. A rise in heat output of the device being cooled would result in a rise in heat being transfered from the cold side to the hot side of the peltier, therefore also increasing the amount of total heat having to be dissapated. While I may seem to be putting peltiers in a bad light, they do have their uses and are excessively usefull in some applications. They do for one work rather well if you ever intend to build a DIY mini-fridge .

17th December 2001, 05:04 AM	#18
JoeBob diyAudio Member Join Date: Nov 2001 Location: Montreal, Canada	Ya, I'm aware of it's output into 4 and 8 ohm speakers. But I already have my speakers built, it was my previous project, now the amp comes secound.