an other thing is heat, and getting rid of it.
and a bridged tda7294 can take full blast at 4 ohms, no rpoblem as long as you can keep it cool. and that is a problem of its own.
but seen it done, even my self have done it, did not burn anything, no operating problems.
and its a dirty methood, and unadviced. use BPA for better results.
but the thing is yess, it can be done. even safely.
and no, that alone does not mean it should be done at all.
i can even give a vendor who makes this bridged amplifier board, and will not advice against the 4 ohm load, does not restrict the rail voltage, but in exchange makes a bit fat ugly and pricy cooling solution mandatory to use. and ift used, then there is no problem.
and a bridged tda7294 can take full blast at 4 ohms, no rpoblem as long as you can keep it cool. and that is a problem of its own.
but seen it done, even my self have done it, did not burn anything, no operating problems.
and its a dirty methood, and unadviced. use BPA for better results.
but the thing is yess, it can be done. even safely.
and no, that alone does not mean it should be done at all.
i can even give a vendor who makes this bridged amplifier board, and will not advice against the 4 ohm load, does not restrict the rail voltage, but in exchange makes a bit fat ugly and pricy cooling solution mandatory to use. and ift used, then there is no problem.
Only so much power can go Into a chip amp, and after that point, the power is split by the efficiency ratio, between the speaker and heatsink. Since heavier loading worsens the efficiency and since bridged also doubles the loading, then most of the power goes into the heatsink, and not available to the speaker.
Although bridging could be useful, this example doesn't show it.
Just a note: 127W bass dynamic for the bridge amp or 180W bass dynamic for the parallel amp. Linearity does it. Same parts count; however, with an efficiency difference, the parallel is cheaper at the transformer because it is much cheaper at the heatsink.
In practical bass dynamic measuring, distortion is allowed to exceed 1%, only momentarily, specifically for a duration same or less than the bass beats expected of popular music, and with the average distortion also not higher than 1%. It is a fun way to consider subwoofer amplifiers, and full-bandwidth concert types as well.
For bass dynamic power, the voltage output superiority of the bridge amplifier didn't win because it takes current to move the woofer, and higher current capacity is what parallel amplifiers do.
So, basically, if you wanted more power at better quality, you'll have to spend less.
Perhaps, comparing the wrong way to do a bridge amp, with a decent parallel amp, is an unfair comparison? However, I thought it relevant.
P.S.
When doing a bridge amp, you swamp the quality costs by starting with an amplifier that has minimized distortion and a vast amount of unused capacity. . . before bridging. And, that's when bridging works.
Typically, making enough room in the tolerances involves under-volting.
SO, actually, this chip can be bridged, IF done at the smallest scale (involving a 14+14vac transformer, at most; and, the datasheet's minimum published gain setting), resulting in a bridge amp with approximately 20W to 4R. Well, when bridging the TDA7294, the choices are limited to either really bad consequences, or a Tiny scale amplifier with very little power.
So, I'm not saying that you can't bridge it--I'm just saying that bridging it nicely, is stunningly unlikely.
All things in proportion, it would make an incredibly loud table radio. 😀
Although bridging could be useful, this example doesn't show it.
Just a note: 127W bass dynamic for the bridge amp or 180W bass dynamic for the parallel amp. Linearity does it. Same parts count; however, with an efficiency difference, the parallel is cheaper at the transformer because it is much cheaper at the heatsink.
In practical bass dynamic measuring, distortion is allowed to exceed 1%, only momentarily, specifically for a duration same or less than the bass beats expected of popular music, and with the average distortion also not higher than 1%. It is a fun way to consider subwoofer amplifiers, and full-bandwidth concert types as well.
For bass dynamic power, the voltage output superiority of the bridge amplifier didn't win because it takes current to move the woofer, and higher current capacity is what parallel amplifiers do.
So, basically, if you wanted more power at better quality, you'll have to spend less.
Perhaps, comparing the wrong way to do a bridge amp, with a decent parallel amp, is an unfair comparison? However, I thought it relevant.
P.S.
When doing a bridge amp, you swamp the quality costs by starting with an amplifier that has minimized distortion and a vast amount of unused capacity. . . before bridging. And, that's when bridging works.
Typically, making enough room in the tolerances involves under-volting.
SO, actually, this chip can be bridged, IF done at the smallest scale (involving a 14+14vac transformer, at most; and, the datasheet's minimum published gain setting), resulting in a bridge amp with approximately 20W to 4R. Well, when bridging the TDA7294, the choices are limited to either really bad consequences, or a Tiny scale amplifier with very little power.
So, I'm not saying that you can't bridge it--I'm just saying that bridging it nicely, is stunningly unlikely.
All things in proportion, it would make an incredibly loud table radio. 😀
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http://bolthely.hu/kepek/mikroshop/00537.jpg
had a few of these boards too my self.
full blast with 4 ohm rated load and no magic smoke.
+-42 volt rails.
i'd still be more confident with a bridge-paralell application, but if you need cheap power than this is it.
had a few of these boards too my self.
full blast with 4 ohm rated load and no magic smoke.
+-42 volt rails.
i'd still be more confident with a bridge-paralell application, but if you need cheap power than this is it.
A bridged pair of amplifiers gives double the power into double the impedance. That rule never changes.
Using that knowledge one can work backwards from the target power to find what amplifiers one needs when bridging a pair of amplifiers.
Target = 300W into 8ohms.
Each single amplifier needs to deliver half of 300W, i.e. 150W
Each single amplifier needs to operate with half the load impedance of 8ohms, i.e. 4ohms.
You need two power amplifiers each capable of 150W into 4ohms.
Bridging those two amplifiers you will get 300W into 4ohms.
Now go and find some power amplifiers that meet that brief of 150W into 4ohms
If your target changes to 450W into 4ohms then you need two 225W into 2ohms amplifiers.
Using that knowledge one can work backwards from the target power to find what amplifiers one needs when bridging a pair of amplifiers.
Target = 300W into 8ohms.
Each single amplifier needs to deliver half of 300W, i.e. 150W
Each single amplifier needs to operate with half the load impedance of 8ohms, i.e. 4ohms.
You need two power amplifiers each capable of 150W into 4ohms.
Bridging those two amplifiers you will get 300W into 4ohms.
Now go and find some power amplifiers that meet that brief of 150W into 4ohms
If your target changes to 450W into 4ohms then you need two 225W into 2ohms amplifiers.
i think the topic is a bit more about if the tda7294 can take 4 om load in bridged mode.
or may i say, if tda7294 can coop with a 2 ohm load.
by datasheet it will engage its protection mechanism and thats about it.
in real life if you keep it cool it *could* be done,and its IS done, but its not adviced, nor should be done.
or may i say, if tda7294 can coop with a 2 ohm load.
by datasheet it will engage its protection mechanism and thats about it.
in real life if you keep it cool it *could* be done,and its IS done, but its not adviced, nor should be done.
Exception: Double the load, ruins the efficiency and linearity of output devices tiny enough to fit inside chip amplifier casings. You can get at least three times the heat output. So, then double the audio output power is not realized due to the (ruined) efficiency.
It can push a two ohm load, if under-volted enough to stay within thermal maximum specs. In that case the protection will still managed to skim/attenuate/omit the very lowest notes and the output device linearity won't be good enough to use with tweeters. So, poor bass and poor treble--it can push the 2 ohm load, but at minimum quality.
That protection circuit related bass problem with loading can be effectively reversed by adding big pairs of output devices to buffer the chip, in which case, the much lighter loading of the chip, also has the chip doing really good bass, as seen the thread for it: http://www.diyaudio.com/forums/chip-amps/206591-tda7294-power-transistors-amp-tda7293-come-also.html
I don't agree.
If one uses an amplifier capable of driving a load impedance, then when it is bridged into double that impedance the efficiency of that amplifier is exactly the same. The amplifier sees the same load impedance and delivers the same current and has the same losses and thus from all those "samenesses" it has the same efficiency.
I don't know where you got your lower efficiency statement from.
The increased loading cripples it.
Efficiency statements are verifiable by every datasheet.
Cheers!
There is no increased loading if you double the load impedance with two amps.
Its the same as two amps driving half the load.
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there's no increased loading, there's no increased current demand, there's no decrease in efficiency.
If you are interpreting some datasheet as such then you are reading it incorrectly.
A bridged pair of amplifiers delivers double the power into double the load impedance. That rule never changes !
let it be then.
take an amplifier that has a voltage swing of 10 volt, and can supply 10A no rpoblem.
then take your load, witch is for the sake of experiment a 10 ohm ohmic load. just for kicks.
10 volt swing, 10 ohm load, 1 A current required. 10 watts. nice.
so , we bridge this amplifier.
got now 20 volt swing, 10 ohm load, 2 A current required. 40 watts. nice.
"A bridged pair of amplifiers delivers double the power into double the load impedance. That rule never changes !"
and allso,
A bridged pair of amplifiers delivers quadrouple the power into the same load impedance, untill it can supply enough current. That rule never changes !
as long as it can keep up with the current demand, and the load is not changed, a bridged amp will deliver 4x the power. even if you don't want it.
surely if you double the load impedance it will deliver only double the power.
so what.
take an amplifier that has a voltage swing of 10 volt, and can supply 10A no rpoblem.
then take your load, witch is for the sake of experiment a 10 ohm ohmic load. just for kicks.
10 volt swing, 10 ohm load, 1 A current required. 10 watts. nice.
so , we bridge this amplifier.
got now 20 volt swing, 10 ohm load, 2 A current required. 40 watts. nice.
"A bridged pair of amplifiers delivers double the power into double the load impedance. That rule never changes !"
and allso,
A bridged pair of amplifiers delivers quadrouple the power into the same load impedance, untill it can supply enough current. That rule never changes !
as long as it can keep up with the current demand, and the load is not changed, a bridged amp will deliver 4x the power. even if you don't want it.
surely if you double the load impedance it will deliver only double the power.
so what.
bridged into double the load impedance. 1A into 20r, not 2A into 10r !
I know of no briged arrangement that can achieve 4 times the power into the single amplifier's rated load impedance. Most will blow up within a few minutes/hours of trying to attempt that feat.
That rule is rarely if ever true !!!
No it won't.
That is precisely what a bridged amplifier can do reliably. The two amplifiers deliver exactly the same total power as the bridged pair of amplifiers. No magic, no extra power, no unreliability. Just double the power into double the impedance. It's what any reasonable user would expect from using double the number of amplifiers.
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then i suggest you to hook up a single tda729x to a 16 ohm speaker, and measure the power at full blast.
then hook up the verry same 16 ohm load to a bridged tda 729x amp, and measure the power at full blast.
surprise surprise, 4x the power.
now you know an arrangment where it works 100%.
then hook up the verry same 16 ohm load to a bridged tda 729x amp, and measure the power at full blast.
surprise surprise, 4x the power.
now you know an arrangment where it works 100%.
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