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output power calculation TDA2030A 12V DC

Thread starter #1
Recently ordered one of these little guys. Really cute and apparently well made. http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=390569664754&ssPageName=ADME:X:AAQ:US:1123

They advertise 15W off a single 12V supply. Is 15W possible for this analog design with a 12V DC power supply into 4Ω or 8Ω?

What power could be expected with a 12V DC 1.75A power supply into 4Ω and 8Ω? I don't know how to calculate it.

Does anyone have experience with this board?

How about a schematic? I contacted the seller and they do not have a schematic for the board.

Thanks
 

dougy83

Well-Known Member
#2
No, it doesn't appear that 15W is possible with either 4Ω or 8Ω, see figure 6 (http://www.electro-tech-online.com/custompdfs/2013/07/CD00000129.pdf). The schematic will be along the lines of that in figure 4, although there are obviously many differences; you could scan/photo/trace the pcb tracks to work out the schematic. The incoming power on the board you ordered appears to be a half-bridge rectifier, so there may be a fair bit of ripple if feeding with an AC supply.
 

dougy83

Well-Known Member
#3
They advertise 15W off a single 12V supply. Is 15W possible for this analog design with a 12V DC power supply into 4Ω or 8Ω?
This is a 12V single supply configuration, therefore equivalent to ±6V; if the amplifier output voltage could reach ±6V (which it can't), then the max output power for a sine wave is V²/R/sqrt(2)=6²/4/1.414= 6.36W into 4 ohms and 6²/8/1.414= 3.18W into 8 ohms.
What power could be expected with a 12V DC 1.75A power supply into 4Ω and 8Ω? I don't know how to calculate it.
As above, but instead of ±6V, put in the output voltage swing of the TDA2030A (if you can find it). The power will be less than calculated above
 
Thread starter #5
Hey, thanks guys.

Your input suggests I take another road. I bot that board's bigger brother http://www.ebay.com/itm/370759055327?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649

BTW here is a neat blog on that board http://atoomnet.net/tda2030a-amplifier-diy-kit-schematic-and-soldering-howto/

I can unwind one of my toroids and supply the big brother board's bridge with sufficient AC to get 12X12V DC and get around 12W (prob 10) at 8Ω. Just the ticket. I only need a couple watts. I will measure speakers and don't want to lug around a big amp.

With the big brother board I need only activate one channel of the circuit, pop on a moderate heat sink and be on my way. I will be doing tone bursts, pulsed FFT (MLSA), and occasional freq sweeps and stepped freq sweeps. So the HS requirements should not be too bad. Besides, the chip has a shutdown mode for over heating.

Two questions:

What AC Voltage in should I have (center tapped into the bridge shown in the blog schematic) so that I put ±12V DC on the board after the bridge?

What are the equations for current requirement for a given output power? The toroid I have in mind is good to about 3.5A That should be plenty, but it is nice to check.

Thanks for your help.
 
Last edited:

audioguru

Well-Known Member
Most Helpful Member
#6
To make plus and minus 12VDC the transformer must have a center-tap and be 9VAC-0V-9VAC. The center-tap is connected to 0V and a full-wave bridge rectifier and two large filter capacitors are used.

The datasheet for the TDA2030A shows that the output power is 6W into 8 ohms or 10W into 4 ohms at 0.5% distortion when the supply is a total of 24V.
One amplifier is about 55% efficient so when the output is 6W then the power drawn from the power supply is 11W.
11W/24V= 0.46A.
 
Thread starter #7
Thanks,

This board accepts 24V AC CT and has a full wave rectifier and PS caps on board.

I figure that means 12V X 1.414 = +-16.968 VDC shud be on the PS caps. But there is loss in the bridge. I guess the loss is about 1.4 v so the actual V is 16.968 - 1.4 or +- 15.568VDC.

Am I right so far?

So, (15.568 X 15.568)/8/1.414 = 21W into 8Ω

and (15.568 X 15.568)/8/1.414 = 42W into 4Ω

Taking the worst case (4Ω load) and an efficiency of 50% for convenience, then the xformer must put out 82W. Then 82W/24V = 3.417A is current required.

And the HS must handle 42W for constant max amplitude output.

I guess at idle there is very little current and virtually no heat generated.

Did I get it right?
 

audioguru

Well-Known Member
Most Helpful Member
#8
I figure that means 12V X 1.414 = +-16.968 VDC shud be on the PS caps. But there is loss in the bridge. I guess the loss is about 1.4 v so the actual V is 16.968 - 1.4 or +- 15.568VDC.
The rectifier bridge has high peak currents when the amplifier is producing its maximum power so the loss in the bridge rectifier is about 2V. Then the total supply to the TDA2030A amplifier is 32VDC.

So, (15.568 X 15.568)/8/1.414 = 21W into 8Ω
Absolutely not! The amplifier also has voltage loss and the datasheet shows that its output into 8 ohms is only 12W when the total supply is 32VDC.
Then its maximum output swing is the root of (12W x 8 ohms)= 9.8V RMS which is (9.8 x 1.414)= 13.9V peak.

and (15.568 X 15.568)/8/1.414 = 42W into 4Ω
No again.
The output into 4 ohms is 18W so its output swing is the root of (18W x 4 ohms)= 8.5V RMS which is (8.5V x 1.414)= 12.0V peak.
The total voltage loss of the amplifier is 8V.

I guess at idle there is very little current and virtually no heat generated.
The datasheet shows that the idle current is 80mA max so it heats with 32V x 80mA= 2.56W which is not much compared with its heating of 14.5W when playing loud.

With a 4 ohm load the max output is 18W. It is about 55% efficient so the transformer must deliver 32.5W. The max current from the transformer is (32.5W/24VAC)= 1.35A.
 
Thread starter #9
Thanks $scrooge,

What are the possibilities if the amp was set up for BTL operation? The board has that option. How would the numbers work then and how could it be made safe for loudspeaker testing given that measurements will be made by a sound card with an unbalance input vs the groundless output from BTL? Would it have a problem driving 4Ω or 8Ω loudspeaker loads?

I am guessing that transformer current demands will be doubled?
 

audioguru

Well-Known Member
Most Helpful Member
#10
What are the possibilities if the amp was set up for BTL operation? The board has that option. How would the numbers work then and how could it be made safe for loudspeaker testing given that measurements will be made by a sound card with an unbalance input vs the groundless output from BTL? Would it have a problem driving 4Ω or 8Ω loudspeaker loads?

I am guessing that transformer current demands will be doubled?
The datasheet shows a BTL amplifier (figure 16) that has an output of 34W into 8 ohms with a plus and minus 16V supply. But it says no specs about it so it might be clipping its head off with high distortion. The output current will be too high if the speaker is 4 ohms.
The power supply current is probably almost 3 times a single amplifier since the output power is almost 3 times (double the voltage swing times double the current swing equals 4 times as much power) but the weak amplifiers have high losses.

The input for the BTL amplifier is unbalanced.
 
#11
TDA2030A can't work properly or give high power at single 12Volts coz it's designed for split supply. Also, since the company has discontinued it's production, it's fake version is manufactured by some companies which doesn't meet the safety standards as the original. So it gets burnt even at 12-0-12 volts, 1A transformer operation. It's available online at Amazon but the quality is not 100% guaranteed that it's original. It's really very sad. I really miss this IC as my home theater contains this IC.
 

ronsimpson

Well-Known Member
Most Helpful Member
#12
A sales person will not give audio power in rms.
More typical is peak power or P-P power.
Measured at a very low resistance and high distortion level.
6 watts peak = 12 peak to peak.
 

Nigel Goodwin

Super Moderator
Most Helpful Member
#13
A sales person will not give audio power in rms.
Only in uncivilised countries :D

Although to be fair a sales person will quote what it says on the box, and in-car equipment quotes particularly imaginary figures, and sound bars are going the exact same way.

But any decent quality equipment will give proper RMS power output, at a specified distortion and frequency range.

As I've said throughout this thread, it's absolutely trivial to calculate the approximate (but far more accurate than the usual ludicrous claims) power from the power supply voltage and speaker impedance.
 

Reloadron

Well-Known Member
Most Helpful Member
#15
Off Topic:
Why do new members gravitate to old threads? I have always wondered about that. With all of the new and current threads available on current material why, in a case like this would a new member make a first post in an old dead thread.

As I've said throughout this thread, it's absolutely trivial to calculate the approximate (but far more accurate than the usual ludicrous claims) power from the power supply voltage and speaker impedance.
Nigel, you lost me with that. I see this as your first post in the thread? What am I missing here? :)

Ron
 

Nigel Goodwin

Super Moderator
Most Helpful Member
#16
Off Topic:
Why do new members gravitate to old threads? I have always wondered about that. With all of the new and current threads available on current material why, in a case like this would a new member make a first post in an old dead thread.


Nigel, you lost me with that. I see this as your first post in the thread? What am I missing here? :)

Ron
Sorry Ron, bit of 'thread confusion' :D

But the reply still stands, it's trivial to calculate power output.
 

Reloadron

Well-Known Member
Most Helpful Member
#17
Otay, I was just a little lost and agree absolutely as to power output.

Thanks
Ron
 

Reloadron

Well-Known Member
Most Helpful Member
#19
Go to a search engine and type "how do I ___fill in the blank___ electronics" and you get this forum (with out concern of date). I think the search looks for the key words and not dates.

"How do I make a coffee maker with a 555?"
Yeah, I have noticed that, pretty sure its key word search. That has to be it. :)

Ron
 

ronsimpson

Well-Known Member
Most Helpful Member
#20
Why? I think many people come here, find what they need and leave with out a word. Some leave a thanks and are gone. Then a old grump jumps them for responding to an old thread.

I do not want to be the one to respond to "old thoughts". But once opended up and new questions asked ... why not?

Do we want to deleat 100s of "blink LED 555" threads and have to start over from zero every week?

RonTheGrump,
 

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