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Querying - fan or heat sink - 100W amplifier

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Enzy

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Hopefully some of you guys are familiar with TDA7293 amplifier chip I have used it several times but never had to use a fan because I have never used heavy speakers on it but a guy listen to it today and said he would like me to build one for him to use on a poled box to play outdoors and they normally drive them hard for an entire dayy or night I am wondering if I could actually build a stereo setup with the TDA7293 I have a 12 center tap 10 amp transformer I plan to use a 10 amp bridge rectifier and 2 10,000uf caps on the power supply at 4 ohms load I am not sure how much wattage Rms the amp could deliver but I was wondering if that would pass 100W rms if so would I need a fan or could that run enclosed in the box just the same with only a heat sink.
 

Hi,

Power amplifier, loud, portable, low heat = low power dissipation...

This calls for a class D amplifier.

Klaus
 
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    Enzy

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Enzy said:
so would I need a fan or could that run enclosed in the box just the same with only a heat sink.
Click to expand...

A 100W amplifier with 80% efficiency means a dissipation inside equipment of about 20 watts, which sounds too much heating to manage without forced ventilation.
 
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    Enzy

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The TDA7293 datasheet shows 100 Whats but only 80 Watts at lower (but still audible) distortion. But only for a moment unless a fan and a huge heatsink are used.
The datasheet is missing graphs of distortion at various supply voltages and efficiency that is shown on almost every other amplifier's datasheet.
The heatsink and fan must never be enclosed.

I agree that a class-D amplifier IC should be used, maybe one from Texas Instruments.
 
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Ok then what are your thoughts on this amplifier.

 

I looked on Google looking for spec's on the Detex Class-D amplifier but I could not find any. Instead I found a Detex website that has lettering that I have never seen before.
Amount of power output with the amount of distortion at various audio frequencies, frequency response and signal to noise ratio would be needed.
 

Audioguru said:
I looked on Google looking for spec's on the Detex Class-D amplifier but I could not find any. Instead I found a Detex website that has lettering that I have never seen before.
Amount of power output with the amount of distortion at various audio frequencies, frequency response and signal to noise ratio would be needed.
Click to expand...

SO in other words dont build this amp?

Can you recommend me to one that I can build, I would love if it has a pcb also.
 

Hi,

Audioguru already recommended TI.
Often there are example PCB in the datasheet, or application notes, or even evaluation boards.

Klaus
 

Enzy said:
SO in other words dont build this amp?
Click to expand...
Without spec's then it might sound horrible or overheat then have meltdown.

Can you recommend me to one that I can build, I would love if it has a pcb also.
Click to expand...
Elliot Sound Products, Projects. Amplabs.com.
 

I checked but I havent found anything on their site Its my first time searching it though. All I see when I search class D amplifier is TPA3106D1 ?I wanted a DIP chip to use.
 


Audioguru said:
But only for a moment unless a fan and a huge heatsink are used..
Click to expand...

For 20W? A big heatsink fixed to the box (I assume that it is metal) will easily take care of it.

An Intel pentium (core i7) CPU easily dissipates close to 100W and that is taken care of by a big heatsink and a small fan.
 

A ducted air flow into a heat sink with narrow blades is what matters most, and pouring it toward out of the equipment ensures that the circulating air flow in the rest of the equipment will be coming in at room temperature. Finally, the geometry of the apparatus allows to compress the volume different from the old audio amplifiers with bulky external heat sinks.
 
TI and other semiconductor companies design new class-D amplifier ICs and sell millions of them to product manufacturers. They use tiny surface mounting to reduce the costs. They do not care about a few hobbyists buying only a few in DIL packages. Many old IC designs are also not made in DIL packages anymore.
 

Just to querry something I see alot of circuits online that they call bass boost circuits, my question is what does it actually do, for example when you turn it up would that lower the frequency to give you a heavier bass or would it keep the frequency at the output the same as the input but amplifies the signal going out at the same frequency?

I ask because I am wondering if I build a bass amp if it would be a good thing to use a bass boost circuit or it actually does the same thing as a volume control, or its a case I can add both because they perform different tasks.
 

Hi,

Bass boost just makes the bass louder. it doesn´t change the frequency.

****
Only some digital "sound enhancers" create new lower frequencies.

Some musicians/bands give their recorded data (usually ready to make a CD) to some digital audio studios for sound enhancing.
They use very expensive professional equippment.

Klaus
 

Enzy said:
I am wondering if I build a bass amp if it would be a good thing to use a bass boost circuit or it actually does the same thing as a volume control, or its a case I can add both because they perform different tasks.
Click to expand...
If you have a small speaker that does not produce deep low frequencies well then you can add a "bass boost circuit" that increases the gain at deep low frequencies then the speaker produces them better.

The woofers in my main home sound system are 8" and are in sealed enclosures. They play well down to 60Hz then their sound level is reduced at lower frequencies -12dB per octave. Then 30Hz is reduced -12dB. I built a bass boost circuit that plays all higher audio frequencies with no boost and no cut but the bass is boosted slightly at 60Hz then boosts +12dB at 30Hz. My guests say that the bass is very good, but ask where is the sub-woofer? I tell them I do not have a sub-woofer, instead I use bass boost.

A bass tone control is different because it boosts many low frequencies that you do not want boosted.
 

The energy density is proportional to the frequency (squared) and amplitude (squared). For both vinyl records and cassette tapes, recording low frequencies were difficult because of low energy density. (Opposite was true for high frequencies) During recording the low frequencies were boosted (so that the noise density would stay uniform) and this was "undone" during playback. However, this does not concern about the frequency sensitivity of the microphones and speakers. To produce the same energy density, the speaker will need four times the power at 50Hz when compared to 100Hz.

Individual sensitivity to low frequencies (also high frequencies) also vary markedly; it is a good idea to have some control to amplify the low frequency signals selectively. Bass boost is a god sent.
 

2 X 100 watt class D kit, includes SM power supply....for US$89, it is not bad, not bad at all.

**broken link removed**
 

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