420W TDA8954TH Overkill? Lithium powered project

[eshamp]

Yes, a step up converter will work. They have more or less 90% efficency, so that shouldn't be a problem. But if you buy on ebay or Ali, make sure that you read the specification with a critical eye, they are suspiciously cheap and max power can often only be used with additional cooling.
Still, you can't input more than 40V DC to a TDA8954 unit, so max output still applies.

Thanks, this is really helpful! They certainly are suspiciously cheap.

I think I will have to ditch the TDA8954 as it seems too niche or convoluted (and inefficient) to step up and convert DC from a battery to dual AC as required by the TDA8954, which is a shame as I already bought this amp.

Can you recommend a reasonably priced/quality alternative amp that will run on DC at 40-45 volts?

 

[Old'n'Cranky]

Why so much effort to reinvent the wheel ?

Small cheap car audio class d amp, 12 volt battery, job done.

 

[eshamp]

I have searched for suitable car amps. Most of the ones with enough power to drive over 100w RMS at 8ohms are AB class. I need the system to be as energy efficient as possible.

 

[chermann]

....

Can you recommend a reasonably priced/quality alternative amp that will run on DC at 40-45 volts?

maybe here...:

200W IRS2092 Amp for $20

chris

 

[eshamp]

maybe here...:

200W IRS2092 Amp for $20

chris

That one's also dual voltage.

 

[chermann]

That one's also dual voltage.

ahh... sorry my fault

maybe a TPA3255 chinese board?

 

[strongbow60]

Have a look at this board http://store3.sure-electronics.com/...udio-amplifier-board-compact-t-amp-sta-516-be. Up to 50 volt with a lot of batteries .

The T-AMP versions sounds really nice, I have one of those stereo amps and they are perfect for a home theatre system. Lot of bass and a very catchy sound.

Not as neutral as the TPA3255, but overall nice.

 

[eshamp]

Thanks for the replies. I think I accidentally ordered a TAS5630 but if they let me cancel (it's not been shipped) then I'm thinking of this BT TPA3255.

The STA516 also looks good, but there are less around and seem more expensive.

 

[chermann]

Thanks for the replies. I think I accidentally ordered a TAS5630 but if they let me cancel (it's not been shipped) then I'm thinking of this BT TPA3255.

The STA516 also looks good, but there are less around and seem more expensive.

hi eshamp

you want a ready amp or board?
if you want to have a TPA3255 ready amp...here and pages before are some discussions: anatoliy was at the beginning not really happy..but read...
https://www.diyaudio.com/forums/class-d/287470-tpa3255-diy-discussion-design-etc-107.html#post5739410


the TAS board i an digital chip baord- so i guess you have an additionally DA conversion on that board....its not needed.


TPA3255 board stand alone:
1PC New Arrival Class D TPA3255 MINI HIFI AUDIO Digital Amplifier Board 300W + 300W DC50V Module-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

thread:...pages before are interesting too
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-30.html#post5499268


chris

 

[eshamp]

hi eshamp

you want a ready amp or board?
if you want to have a TPA3255 ready amp...here and pages before are some discussions: anatoliy was at the beginning not really happy..but read...
https://www.diyaudio.com/forums/class-d/287470-tpa3255-diy-discussion-design-etc-107.html#post5739410


the TAS board i an digital chip baord- so i guess you have an additionally DA conversion on that board....its not needed.


TPA3255 board stand alone:
1PC New Arrival Class D TPA3255 MINI HIFI AUDIO Digital Amplifier Board 300W + 300W DC50V Module-in Integrated Circuits from Electronic Components & Supplies on Aliexpress.com | Alibaba Group

thread:...pages before are interesting too
https://www.diyaudio.com/forums/class-d/309813-wrong-tpa3255-30.html#post5499268


chris

Banggood won't let me cancel so TAS it is. I'm not sure what you mean by DA conversion?

 

[chermann]

Hi

i meant AD conversion- forget it..because....i mixed with an other TAS chip which are with digital input...sorry my fault.

 

[eshamp]

Ah yes, I follow now. Thanks.

 

[xrk971]

Take a look at TPA3255.

Run two 24V for 48V...no need to split supply.

TPA3255 will run 18V to 50+V

Is there a limiter switch setting on the TPA3255? I set mine up with a 53v 600w DC-DC powered by a large 12v Pb-acid deep cycle UPS backup battery. Using a 200w 4ohm load resistor, I was only able to get 40vpp before clipping. This is not even as high as the rail voltage, I monitored that and it did not sag below 53v setting.

 

[chermann]

Is there a limiter switch setting on the TPA3255? I set mine up with a 53v 600w DC-DC powered by a large 12v Pb-acid deep cycle UPS backup battery. Using a 200w 4ohm load resistor, I was only able to get 40vpp before clipping. This is not even as high as the rail voltage, I monitored that and it did not sag below 53v setting.

just an idea: without experience...sorry i am not an expert



DC-DC converter has an efficiency of about 85% at this power output....=> 53V *0,85 = 45V
this 45V with an efficiency of 90% of the amp = 40,5V


chris

 

[ICG]

DC-DC converter has an efficiency of about 85% at this power output....=> 53V *0,85 = 45V
this 45V with an efficiency of 90% of the amp = 40,5V

That's not how it works. The voltage stays the same until it's exceeding the current limit of the PS (SMPS, transformator, battery, whatever). If a PS or DC converter got an efficiency of 85% that means the remaining 15% of the 100% are going to be heat. That means, they will draw 15% more power than they will supply, the input current is higher than the output current. It does not change the output voltage, at least not if the input does not sag because of the current.

 

[chermann]

That's not how it works. The voltage stays the same until it's exceeding the current limit of the PS (SMPS, transformator, battery, whatever). If a PS or DC converter got an efficiency of 85% that means the remaining 15% of the 100% are going to be heat. That means, they will draw 15% more power than they will supply, the input current is higher than the output current. It does not change the output voltage, at least not if the input does not sag because of the current.

ok. i was tooo quick in thinking. yes you are right. thx

but now i am interesting....what could the reason of the voltage sag??

 

[ICG]

but now i am interesting....what could the reason of the voltage sag??

It could be the power source not being stable enough, serial resistances of the wires, switches, relays, fuse, transition resistance, current limiter or protective circuits, lack of heat dissipation.

 

[chermann]

It could be the power source not being stable enough, serial resistances of the wires, switches, relays, fuse, transition resistance, current limiter or protective circuits, lack of heat dissipation.

Just follow:

Voltage drop is 13V (53-40).
Load: 200w ,4R = > P= I^2 *R........I= about 7,07A

Voltage drop R = u/I 13/ 7 = 1,83ohms "loss" serial resistance?

chris

 

[ICG]

Just follow:

Voltage drop is 13V (53-40).
Load: 200w ,4R = > P= I^2 *R........I= about 7,07A

Voltage drop R = u/I 13/ 7 = 1,83ohms "loss" serial resistance?

Since power supplies also got inner resistances and there are likely also contact resistances at the cable mounts involved, that sound pretty feasible. The dimensions of the buffer capacitors and the ripple/ESR play a factor too. And don't forget, no PS works without losses.

 

[chermann]

Since power supplies also got inner resistances and there are likely also contact resistances at the cable mounts involved, that sound pretty feasible. The dimensions of the buffer capacitors and the ripple/ESR play a factor too. And don't forget, no PS works without losses.

thanks for sharing your experience