Sure but fans cost money and make a noise. They're also moving parts so decrease the overall reliability.
I'm willing to bet that the average plate amp isn't so conservatively engineered as here. They'll often use undersized transformers for example. They almost certainly will NOT use 2 * LM3886T in bridged into a 4R load as this is way suboptimal. If it were me building this, I'd opt for a 6 * TDA2030a bridged/parallel approach as they'll be more efficient, cheaper and use a smaller heatsink - having 6 packages to spread out the heat is an advantage too. The TDA2030a is really unbeatable in terms of watts per yuan here.
Sure, why not. I would like to go for TDA2030a x 6 Packages. Any application notes available ?
using TDA2030 makes more sense. Thanks for clicking this to me. come here I I'll treat you
Sure, why not. I would like to go for TDA2030a x 6 Packages. Any application notes available ?
I'll post up a schematic soon as I have an 8 amplifier version I'm playing with. Just need to chop out two devices.
Tribal TDA2030a
Well here's the schematic.
A few caveats:
1) I haven't tested this as a subwoofer amp, only as bass/mid in my digital active system. This means I've not run it into clipping so can't vouch for how well it behaves when over driven. I recommend a soft-clipper (like the one Bob Cordell shows in his new book) to prevent hitting the rails and potential instability.
2) Its set up to give only 6dB of gain, with a balanced input. More on this in my blog shortly. Gain setting resistors (30k, 15k) must be 0.1% matched or better.
3) Its using the amp chips in inverting mode for lowest distortion, with 'gain stealing' to keep them stable with such a low gain. Its DC coupled with low offset because of the low DC gain. The gain stealing components (2n and 1700R) are not optional - this most certainly will oscillate if you omit them.
4) The input signal is floating. A non-floating input would need some attention paying to the grounding as the opamp ground (active supply splitter) won't be able to cope.
Well here's the schematic.
A few caveats:
1) I haven't tested this as a subwoofer amp, only as bass/mid in my digital active system. This means I've not run it into clipping so can't vouch for how well it behaves when over driven. I recommend a soft-clipper (like the one Bob Cordell shows in his new book) to prevent hitting the rails and potential instability.
2) Its set up to give only 6dB of gain, with a balanced input. More on this in my blog shortly. Gain setting resistors (30k, 15k) must be 0.1% matched or better.
3) Its using the amp chips in inverting mode for lowest distortion, with 'gain stealing' to keep them stable with such a low gain. Its DC coupled with low offset because of the low DC gain. The gain stealing components (2n and 1700R) are not optional - this most certainly will oscillate if you omit them.
4) The input signal is floating. A non-floating input would need some attention paying to the grounding as the opamp ground (active supply splitter) won't be able to cope.
Attachments
You mean more efficient as in less power consumption for the same output power? If so, how much more efficient are they? And is that valid for all output power levels from 0 to 100 %?
No, I meant less power wasted overall, when listening to music. In fact, if measured at identical output power from the same voltage power supplies, the TDA2030a solution would be less efficient overall as there are 6 chips drawing quiescent (32mA each, measured cold) versus 2 chips drawing 50mA each (from the datasheet). The TDA solution is more efficient overall at turning mains electricity into sound overall, for music signals.
Hard to say, given that the TDA2030a datasheet is fairly sparse and it depends on the music being listened to. I've estimated that the saturation voltage is going to be around 3.6V into the 6R load, compared to 5V into 2R for the LM3886. The upshot is the TDA solution will play a bit louder for the same input power because less will be going into the heatsink at higher levels.
No, its not valid at the lower power levels because of the higher quiescent. If you're keeping the volume down low all the time then the LM3886 solution is going to be better from the pov of efficiency. It remains a considerably more expensive solution though.
That means the TDA may achieve a 1,4 V higher output swing, not that the resulting higher power output comes for free.
I don't see higher efficiency at any power level. Power dissipation is voltage drop x (output current + quiescent current). Voltage drop and output current are the same for any given output power and the quiescent current of 6 TDAs will always be higher than that of 2 LMs, not only at low power levels.
Well, sure. Did I say that anything 'comes for free' ?
If you choose to see things in that way, then I agree. But reality isn't constrained by your particular choice of perspective. The TDA solution is capable of a higher maximum power level, so its not a reasonable way to compare amps.
That's all correct, but doesn't change the result - the TDA solution is more efficient in practice. If you believe otherwise, then do show why. After all, I haven't done the detailed calculations myself so I could be wrong here. Have you done them? If you show me I'm wrong I'll take back my claim that its more efficient. I'll still recommend that solution though because its cheaper (in silicon and, I reckon in aluminium too) and likely to be lower distortion.
Since the 1,4 V higher output swing was your answer to my question how much more efficent the TDAs are, it seemed you wanted to say just that.
Then please enlighten us about the different perspectives of efficiency and why it is not reasonable to compare amps that way.
I did explain why in post #55. Since you claim (or hypothesize?) that the TDA is more efficient in practice, it's your turn to prove it.
I see. So now we've cleared up that misperception, no?
Have already done so in earlier posts. For example, way back I explained that the LM suggestion fell far short of the theoretical maximum efficiency of a class B amp. At that time, I didn't put up the figure for the TDA version but since I've told you my estimate of the saturation voltage, you might be able to calculate that for yourself now.
As a more general point, enlightenment is not something I can do for you. As Morpheus says to Neo 'I can only show you the door, you have to walk through it'. So do some work for yourself - have a look at a graph of efficiency vs output level for a theoretical class B amp. Then ponder on how it reaches a maximum at maximum output. Then ask yourself - if an amp never reaches maximum output (the case where it has a significant saturation voltage) what happens to its average efficiency?
And I've already responded to that post. In that you did not explain why you chose to compare at identical power levels when in fact there's a mismatch between the number of power levels available in the two amps. What happens to the power levels which are available to the TDA amp and not available to the LM? I'd like your suggestion for how to handle those. For me, I'd take them as having zero efficiency in the LM case as it can't produce them under any circumstances.
I would need convincing that its important enough first. As I've already said, even if this hypothesis turns out to be wrong, my advice won't change. Feel free to persuade me though - just claiming 'its your turn to prove it' doesn't do that.
Yes, but not what the answer really had to do with the question, then.
Somehow it doesn't come as a surprise to me that you would compare yourself to the heathen god of dreams Morpheus.
Ah, no, you are talking Matrix. That is interesting, because I would be Neo in that comparison? The hero that needs your guidance? Sorry, neither the hero, nor the person who needs your guidance are roles I assume.
In this case, where the output power is current limited by the SMPS, neither amp will reach its saturation voltage, so there is no...
If the efficiency is not important, why did you bring it up in post #41?
@Acousticraft
The flaw in posts #12 and #13 seems to have gone unnoticed so far. BTL into the same load will of course give four times the output power, not only twice. You could expect 128 W into 4 Ohm from a BTL amp with those SMPS. Good news for you?
Hey Blue,
I was already thinking in that direction.but didn't dare to make that statement here. Logically when 4 Ohms is connected in BTL mode then each half bridge sees it as a 2 Ohms which makes Wattage 2X and the same is the same thing happens at the other half bridge. so the total power is 4X.
Correct if my simple logic is wrong.
I was already thinking in that direction.but didn't dare to make that statement here. Logically when 4 Ohms is connected in BTL mode then each half bridge sees it as a 2 Ohms which makes Wattage 2X and the same is the same thing happens at the other half bridge. so the total power is 4X.
Correct if my simple logic is wrong.
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