I bought a 420W TDA8954TH chipped amp for a passive PA conversion to be powered by LifePo4 batteries.
I have bought a Wharfedale Titan Pro 8, rated at 150w RMS and 500w peak. Is the amp overkill?
I was planning to run at 23.1v, should I reduce the voltage? I understand sounds quality should at least be decent with an underutilised amp. Will reducing the voltage reduce the efficiency and if so would I be better off just buying a smaller capacity amp? Being battery powered, efficiency is key.
Set-up:
Amp: New 420W TDA8954TH Large Power Digital Audio Amplifier Board A+D Class Amp AC24V | eBay
Low pass filter as pre-amp (though looking for a standard bluetooth pre-amp): Low-pass Filter NE5532 Bass Tone Subwoofer Pre-Amplifier Preamp Board 12-24V UK 958748772515 | eBay
Speaker: Impedence 8Ω Titan 8 | Wharfedale Pro - Sound Reinforcement and Live Sound Equipment
Batteries: 23.1v LiFePo4 at 23,800 mAh (potentially 47,600 mAh further down the line for hopefully over 24 hours of battery life)
I have bought a Wharfedale Titan Pro 8, rated at 150w RMS and 500w peak. Is the amp overkill?
I was planning to run at 23.1v, should I reduce the voltage? I understand sounds quality should at least be decent with an underutilised amp. Will reducing the voltage reduce the efficiency and if so would I be better off just buying a smaller capacity amp? Being battery powered, efficiency is key.
Set-up:
Amp: New 420W TDA8954TH Large Power Digital Audio Amplifier Board A+D Class Amp AC24V | eBay
Low pass filter as pre-amp (though looking for a standard bluetooth pre-amp): Low-pass Filter NE5532 Bass Tone Subwoofer Pre-Amplifier Preamp Board 12-24V UK 958748772515 | eBay
Speaker: Impedence 8Ω Titan 8 | Wharfedale Pro - Sound Reinforcement and Live Sound Equipment
Batteries: 23.1v LiFePo4 at 23,800 mAh (potentially 47,600 mAh further down the line for hopefully over 24 hours of battery life)
Thanks but they seem underpowered for my speaker. It seems from tests TPA3116D2 will only deliver 28.1W at 24v and 8ohm. YouTube
Do you know of any amplifiers that can be powered from 24v batteries that can supply the full capacity of my speaker? Wharfedale Titan Pro 8, 150w RMS and 500w peak, 8 ohm.
I don't suppose you could swap that speaker for a 4 ohm version of the same (assuming there is one available), can you?
It's just that, in most cases, class-D amps (especially chip-amps) aren't rated for very high voltages but are easily capable of large(r) currents, so lower-impedance drivers are kinda better suited.
Sure, there are chips like the TDA898xx series, but they need split supplies, as mentioned above.
For 150W into 8 ohms, according to page 33 of the datasheet, you'd need a +/-27V supply or thereabouts. Although for subwoofer use, i've got a hunch your SPL will be rather limited by the maximum excursion of the woofer at low frequencies (especially in a vented enclosure), rather than available power.
It's just that, in most cases, class-D amps (especially chip-amps) aren't rated for very high voltages but are easily capable of large(r) currents, so lower-impedance drivers are kinda better suited.
Sure, there are chips like the TDA898xx series, but they need split supplies, as mentioned above.
For 150W into 8 ohms, according to page 33 of the datasheet, you'd need a +/-27V supply or thereabouts. Although for subwoofer use, i've got a hunch your SPL will be rather limited by the maximum excursion of the woofer at low frequencies (especially in a vented enclosure), rather than available power.
Yes, it is possible to have a center tap with a battery pack.
@eshamp:
Have a look at the page for the TDA8954TH amp. It says it is to be powered by 24V AC transformer and by the sketch (in one of the pictures) is a centertap 24V AC transformer, giving about +- 33 V DC to the TDA.
Also +- 4V tolerance gives minimum +- 28V DC to the amp. The preamp stage can use max 24V. It's going to get fiddly.
It might be a BTL configuration, but with a +- 33V supply you only going to have 120-140 watt out to the speakers. But even that should be an impressive sound volume.
@eshamp:
Have a look at the page for the TDA8954TH amp. It says it is to be powered by 24V AC transformer and by the sketch (in one of the pictures) is a centertap 24V AC transformer, giving about +- 33 V DC to the TDA.
Also +- 4V tolerance gives minimum +- 28V DC to the amp. The preamp stage can use max 24V. It's going to get fiddly.
It might be a BTL configuration, but with a +- 33V supply you only going to have 120-140 watt out to the speakers. But even that should be an impressive sound volume.
Because watts = voltage ^2 / ohms
(The "current" in your equation being voltage / impedance)
Sorry for such beginner questions!
What about briefing 2 X 24v amps?
So I think bridging class D amps is probably too much of a headache, so potentially a step-up converter instead. Efficiency is key in this battery powered speaker, will a step-up converter introduce too much inefficiency?
Re: bridging, it's not necessarily complicated - most, if not all class-D amp chips contain at least one full-bridge internally.
It only depends on the board design whether you're allowed to (easily*) configure them in bridged more or not.
---
* Easily, as in, via switches or jumpers already on the board, as opposed resorting to "medieval" methods (ie. running wires and "creating" configuration jumpers yourself)
It only depends on the board design whether you're allowed to (easily*) configure them in bridged more or not.
---
* Easily, as in, via switches or jumpers already on the board, as opposed resorting to "medieval" methods (ie. running wires and "creating" configuration jumpers yourself)
Cost being a factor I have narrowed it down to these four amps. One is rated for higher voltages than the other three. Am I correct in assuming the higher rated amp will have an easier time (produce less heat and less distortion at 150W) running my speaker than the other two (which will need to have a power supply close to their max)?
All are based on the IRS2092S chip.
+-30v - +-80v
+-42v - +-58v
+-30v - +-60v
+-33v - +-55v
All are based on the IRS2092S chip.
+-30v - +-80v
+-42v - +-58v
+-30v - +-60v
+-33v - +-55v
Last edited:
Because you need high voltage over a given resistance to have high wattage.
Se Watts/Volts/Amps/Ohms conversion calculator for a good example.
Additionally the output from the amplifier is to be considered AC voltage, so the peak voltage from the amplifier needs to be at least 1.4 times higher than the calculated value for a given wattage.
Nearly every cheap class D amplifier specifies the output power in 2 ohm, so just divide by four.
Have a look at this page for a good sounding Amp that can be used with 24 volt DC. At the end of the page is a table listing power supply range and products.
http://store3.sure-electronics.com/1-x-300-watt-class-d-audio-amplifier-board-compact-t-amp
Se Watts/Volts/Amps/Ohms conversion calculator for a good example.
Additionally the output from the amplifier is to be considered AC voltage, so the peak voltage from the amplifier needs to be at least 1.4 times higher than the calculated value for a given wattage.
Nearly every cheap class D amplifier specifies the output power in 2 ohm, so just divide by four.
Have a look at this page for a good sounding Amp that can be used with 24 volt DC. At the end of the page is a table listing power supply range and products.
http://store3.sure-electronics.com/1-x-300-watt-class-d-audio-amplifier-board-compact-t-amp
Ok I understand.
I am really keen to convert a single, good PA speaker
This is because of portability and c alreadyase design/weatherproofing being done. This speaker will be carried long ways.
Pretty much all PA speakers are 8ohm. So I am restricted to an 8ohm setup.
Would a step up transformer to 40ish volts introduce too much of an efficiency loss Vs building a halfinator type speaker from scratch?
Another less preferable option is just switching the driver I'm a prebuilt speaker to 4ohm.
I am really keen to convert a single, good PA speaker
This is because of portability and c alreadyase design/weatherproofing being done. This speaker will be carried long ways.
Pretty much all PA speakers are 8ohm. So I am restricted to an 8ohm setup.
Would a step up transformer to 40ish volts introduce too much of an efficiency loss Vs building a halfinator type speaker from scratch?
Another less preferable option is just switching the driver I'm a prebuilt speaker to 4ohm.
you give yourself partly the answer
P = U*i or P = U^2 /R
as high your impdance of your speaker e.g. 8 ohms you need more "Voltage" to get more power..
RMS values/power
125W = U^2 / 8....125*8 = U^2...... SQRT(125*8) = U -- 31,6V rms on the Speakers...
so Upeak (...needed psu) 31,6 *1,4 = 44,24V
here is an excellent way how to calculate the psu
https://www.diyaudio.com/forums/class-d/104822-favorite-threads-posts-class-forum-2.html#post5683013
chris
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.
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.