Hello, I'm searching for a class AB or A amp witch can be use at 24V and deliver 80W or more but less than 100W.
Here is the situation, I'm making a portable big boombox and I want it to be powered with a 24V power supply, for autonomy reasons I choose a class D amp to power my speakers. It will be a very big boombox so I made it portable for rare situation, I will thus add another better amp (class A or AB) witch will be powered by an external supply witch can deliver much more than a battery.
Finally I will have a class D amp for when I want to move outside with my boombox, and a class A or AB amp for when I will stay at home in order to have a better sound and power.
My 24V constraint is due to the fact that my battery is 24V so I can charge my batterie at the same time I power my class A or AB amp.
If 24V is not enought I can maybe use a stepdown module but I prefer not to.
Thanks a lot for helping me, I really hope that such an amp exist.
PS: since I'm french I hope I didn't make language mistakes, if so be sure to apologize^^
Here is the situation, I'm making a portable big boombox and I want it to be powered with a 24V power supply, for autonomy reasons I choose a class D amp to power my speakers. It will be a very big boombox so I made it portable for rare situation, I will thus add another better amp (class A or AB) witch will be powered by an external supply witch can deliver much more than a battery.
Finally I will have a class D amp for when I want to move outside with my boombox, and a class A or AB amp for when I will stay at home in order to have a better sound and power.
My 24V constraint is due to the fact that my battery is 24V so I can charge my batterie at the same time I power my class A or AB amp.
If 24V is not enought I can maybe use a stepdown module but I prefer not to.
Thanks a lot for helping me, I really hope that such an amp exist.
PS: since I'm french I hope I didn't make language mistakes, if so be sure to apologize^^
Hi Tanguy, fine use of the English language.
It is so that an amplifier can deliver an output power that depends on the supply voltage in the sense that all amplifiers roughly estimated deliver the same output power with the same supply voltage. That evidently depends whether the amplifier is SE or BTL coupled with the BTL coupled amplifiers delivering roughly 4 times the output power of the SE coupled amplifiers. In reality, a class D amplifier can provide a slightly higher output power than a class A or AB amplifier because the class D amplifier can go closer to the supply rails.
You want in all cases to use a 24V supply voltage.
Sound quality wise, the (real) class A amplifier is often slightly better than a class D or a class AB amplifier. The sound quality of a class D amplifier is typically about the same as that of a class AB amplifier but members on this forum often dispute that statement with different conclusions.
So, a (real) class A amplifier will give you slightly less power than the class D amplifier but may have a slightly better sound quality. Much worse, a real class A amplifier will have an idle power loss (heating) that is at least as high as the maximum output power. You can imagine your boom-box trying to get rid of 2x100W heat just in idle mode. This is why (real) class A amplifiers are not used very often. Not real class A amplifiers, often called non-switching amplifiers, are substantially class AB amplifiers.
A class AB amplifier will provide a little less output power than the class D amplifier you already have. Further, the class AB amplifier will have more heating than the class D amplifier at higher sound levels. So, if the sound quality is not considerably better than the class D amplifier, why add a class AB amplifier?
My conclusion is to use only one good (stereo or 2xmono) class D amplifier.
You say you want between 80W and 100W. That depends on your speaker impedance. 24V supply and a 4 Ohm speaker results in a clipping level of 70W. You can increase that level by turning the output further into distortion and get 90W but with a sound that is so distorted that it is of no use. You can also reduce the speaker impedance to 3.2 Ohm and get 90W at the clipping level but where do you buy a 3.2Ohm speaker? And, remember that the speaker impedance varies importantly with frequency.
70W in 4 Ohm is a practical goal. And, only one set (stereo/2xmono) of class D amplifiers.
The more ambitions you have for output power, the shorter the time the battery can supply the necessary energy before recharging. 2x70W output power may drain the battery fast.
A lot of projects end up using a TPA3116 amplifier construction, with 4 Ohm speakers often using PBTL coupling. Alternatively, with a slightly better sound and somewhat higher price you can use a TPA3250 based amplifier.
Bonne chance!
It is so that an amplifier can deliver an output power that depends on the supply voltage in the sense that all amplifiers roughly estimated deliver the same output power with the same supply voltage. That evidently depends whether the amplifier is SE or BTL coupled with the BTL coupled amplifiers delivering roughly 4 times the output power of the SE coupled amplifiers. In reality, a class D amplifier can provide a slightly higher output power than a class A or AB amplifier because the class D amplifier can go closer to the supply rails.
You want in all cases to use a 24V supply voltage.
Sound quality wise, the (real) class A amplifier is often slightly better than a class D or a class AB amplifier. The sound quality of a class D amplifier is typically about the same as that of a class AB amplifier but members on this forum often dispute that statement with different conclusions.
So, a (real) class A amplifier will give you slightly less power than the class D amplifier but may have a slightly better sound quality. Much worse, a real class A amplifier will have an idle power loss (heating) that is at least as high as the maximum output power. You can imagine your boom-box trying to get rid of 2x100W heat just in idle mode. This is why (real) class A amplifiers are not used very often. Not real class A amplifiers, often called non-switching amplifiers, are substantially class AB amplifiers.
A class AB amplifier will provide a little less output power than the class D amplifier you already have. Further, the class AB amplifier will have more heating than the class D amplifier at higher sound levels. So, if the sound quality is not considerably better than the class D amplifier, why add a class AB amplifier?
My conclusion is to use only one good (stereo or 2xmono) class D amplifier.
You say you want between 80W and 100W. That depends on your speaker impedance. 24V supply and a 4 Ohm speaker results in a clipping level of 70W. You can increase that level by turning the output further into distortion and get 90W but with a sound that is so distorted that it is of no use. You can also reduce the speaker impedance to 3.2 Ohm and get 90W at the clipping level but where do you buy a 3.2Ohm speaker? And, remember that the speaker impedance varies importantly with frequency.
70W in 4 Ohm is a practical goal. And, only one set (stereo/2xmono) of class D amplifiers.
The more ambitions you have for output power, the shorter the time the battery can supply the necessary energy before recharging. 2x70W output power may drain the battery fast.
A lot of projects end up using a TPA3116 amplifier construction, with 4 Ohm speakers often using PBTL coupling. Alternatively, with a slightly better sound and somewhat higher price you can use a TPA3250 based amplifier.
Bonne chance!
Last edited:
Hey, thanks for your quick answer.
I already built the boom-box, so I just need a 1 way output for my amplifier. Endeed I use a passive crossover witch split the signal into 3 ways that are connected respectively to one subwoofer, one medium speaker and one twitter. Each one of this speakers are 8 Ohms ones.
Actually I already have a class D amp witch is a 50W one (DC12 24V Mono canal 50 W TDA7492MV classe D amplificateur Numerique conseil dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group).
I m not satisfied by the sound it make but I don't find another 50W one.
I understand what you said but I still want to have 2 amps, so I think I will search for another one but with a highter power so a highter voltage inpout. That will force me to use a stepdown module (for the battery charge).
I wonder if, since I will use a highter power supply with a stepdown module, a class A amp is worth. If not, I will search for a class D amp.
Do you know some class A or D (depending one the one you think is better) that is one way and around 80W.
I choose 80W because my subwoofer is a 50W but with a 100W max and I have 20W twitter and medium (if you also have advice about this I will enjoy to read them).
I already built the boom-box, so I just need a 1 way output for my amplifier. Endeed I use a passive crossover witch split the signal into 3 ways that are connected respectively to one subwoofer, one medium speaker and one twitter. Each one of this speakers are 8 Ohms ones.
Actually I already have a class D amp witch is a 50W one (DC12 24V Mono canal 50 W TDA7492MV classe D amplificateur Numerique conseil dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group).
I m not satisfied by the sound it make but I don't find another 50W one.
I understand what you said but I still want to have 2 amps, so I think I will search for another one but with a highter power so a highter voltage inpout. That will force me to use a stepdown module (for the battery charge).
I wonder if, since I will use a highter power supply with a stepdown module, a class A amp is worth. If not, I will search for a class D amp.
Do you know some class A or D (depending one the one you think is better) that is one way and around 80W.
I choose 80W because my subwoofer is a 50W but with a 100W max and I have 20W twitter and medium (if you also have advice about this I will enjoy to read them).
Hi Tanguy,
I already built the boom-box, so I just need a 1 way output for my amplifier. Endeed I use a passive crossover witch split the signal into 3 ways that are connected respectively to one subwoofer, one medium speaker and one twitter. Each one of this speakers are 8 Ohms ones.
OK, you have a mono three-way system with passive cross-over and an impedance of 8 Ohm.
Actually I already have a class D amp witch is a 50W one (DC12 24V Mono canal 50 W TDA7492MV classe D amplificateur Numerique conseil dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group).
I m not satisfied by the sound it make but I don't find another 50W one.
You can find better than TDA7492. Be aware that any amplifier (without a supply voltage booster) can maximum deliver 36W at the clipping level with a 24V supply and an 8 Ohm speaker. No 50W.
Only a 36V supply voltage leaves a clipping level of 80W in 8 Ohm.
Examples of such better amplifiers are:
TDA7498E 2X160 W carte amplificateur Audio double canal, prise en charge monocanal, module d'ampli de puissance stereo 24 V pour ordinateur de voiture dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
(modified to mono with PBTL as foreseen)
TAS5630 DC20 50 v Haute Puissance Amplificateur Conseil Mono 600 w Subwoofer Amplificateur de Puissance Conseil dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
I understand what you said but I still want to have 2 amps, so I think I will search for another one but with a highter power so a highter voltage inpout. That will force me to use a stepdown module (for the battery charge).
You decide but I will describe an alternative: The TDA7492 is removed and replaced with a better and stronger class D amplifier that can operate with both 24V and 36V supply. When you have net-power you operate the (better) amplifier at 36V supply and have 80W at the output. When you are mobile and do not have net-power the amplifier is operated from the 24V battery voltage and you have 35W.
Battery charging is far more complex than just applying 24V to a 24V battery!
I wonder if, since I will use a highter power supply with a stepdown module, a class A amp is worth. If not, I will search for a class D amp.
I cannot recall a single (real) class A power amplifier that is suitable for a mobile unit in any sense. Little output power and enormous heating.
Do you know some class A or D (depending one the one you think is better) that is one way and around 80W.
Class A is completely unsuited. Class AB is as such possible but very few use a single supply voltage and BTL, mainly car amplifiers that can operate with up to 22V supply. I see class D as the only feasible option.
I choose 80W because my subwoofer is a 50W but with a 100W max and I have 20W twitter and medium (if you also have advice about this I will enjoy to read them).
I haven´t made speakers for a very long time. This forum has real specialists. One small detail - “twitter" is where energetic politicians tell the world about their talents, a “tweeter” is a speaker unit for high frequencies.
I already built the boom-box, so I just need a 1 way output for my amplifier. Endeed I use a passive crossover witch split the signal into 3 ways that are connected respectively to one subwoofer, one medium speaker and one twitter. Each one of this speakers are 8 Ohms ones.
OK, you have a mono three-way system with passive cross-over and an impedance of 8 Ohm.
Actually I already have a class D amp witch is a 50W one (DC12 24V Mono canal 50 W TDA7492MV classe D amplificateur Numerique conseil dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group).
I m not satisfied by the sound it make but I don't find another 50W one.
You can find better than TDA7492. Be aware that any amplifier (without a supply voltage booster) can maximum deliver 36W at the clipping level with a 24V supply and an 8 Ohm speaker. No 50W.
Only a 36V supply voltage leaves a clipping level of 80W in 8 Ohm.
Examples of such better amplifiers are:
TDA7498E 2X160 W carte amplificateur Audio double canal, prise en charge monocanal, module d'ampli de puissance stereo 24 V pour ordinateur de voiture dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
(modified to mono with PBTL as foreseen)
TAS5630 DC20 50 v Haute Puissance Amplificateur Conseil Mono 600 w Subwoofer Amplificateur de Puissance Conseil dans Amplificateur de Electronique sur AliExpress.com | Alibaba Group
I understand what you said but I still want to have 2 amps, so I think I will search for another one but with a highter power so a highter voltage inpout. That will force me to use a stepdown module (for the battery charge).
You decide but I will describe an alternative: The TDA7492 is removed and replaced with a better and stronger class D amplifier that can operate with both 24V and 36V supply. When you have net-power you operate the (better) amplifier at 36V supply and have 80W at the output. When you are mobile and do not have net-power the amplifier is operated from the 24V battery voltage and you have 35W.
Battery charging is far more complex than just applying 24V to a 24V battery!
I wonder if, since I will use a highter power supply with a stepdown module, a class A amp is worth. If not, I will search for a class D amp.
I cannot recall a single (real) class A power amplifier that is suitable for a mobile unit in any sense. Little output power and enormous heating.
Do you know some class A or D (depending one the one you think is better) that is one way and around 80W.
Class A is completely unsuited. Class AB is as such possible but very few use a single supply voltage and BTL, mainly car amplifiers that can operate with up to 22V supply. I see class D as the only feasible option.
I choose 80W because my subwoofer is a 50W but with a 100W max and I have 20W twitter and medium (if you also have advice about this I will enjoy to read them).
I haven´t made speakers for a very long time. This forum has real specialists. One small detail - “twitter" is where energetic politicians tell the world about their talents, a “tweeter” is a speaker unit for high frequencies.
Last edited:
With 24 V available, the highest you can get is 24 V peak-to-peak swing to the load. 48 V peak-to-peak in a bridged/BTL configuration.
24 V peak-to-peak (12 V peak) is enough for: 12^2/(2*4) = 18 W into 4 Ω.
48 V peak-to-peak (24 V peak) is enough for: 24^2/(2*4) = 72 W into 4 Ω.
Thus, without using a boost converter to get higher rail voltage, you will not reach the 80 W that you require. Also note that above calculations assume zero voltage drop across the amplifier output stage which is obviously not going to happen in practice. Thus, in practice you'll definitely need that boost converter.
Tom
24 V peak-to-peak (12 V peak) is enough for: 12^2/(2*4) = 18 W into 4 Ω.
48 V peak-to-peak (24 V peak) is enough for: 24^2/(2*4) = 72 W into 4 Ω.
Thus, without using a boost converter to get higher rail voltage, you will not reach the 80 W that you require. Also note that above calculations assume zero voltage drop across the amplifier output stage which is obviously not going to happen in practice. Thus, in practice you'll definitely need that boost converter.
Tom
I understand what you both said, thanks again for your answers.
Your idea of using only one amp with different voltage is really good I will considere it first.
I'm using a BMS to charge my battery if it is what you are worry about (I thought it was enought but tell me if I'm wrong).
You said that 24V cannot deliver 50W, I wonder why the amp description is describing it as a 50W one, is that a lie to make me buy it ? because if I can't trust that, how can I trust the seller about al the caracteristic of my amp?!
Thanks again for taking time to answer me, I really appraciate it.
Your idea of using only one amp with different voltage is really good I will considere it first.
I'm using a BMS to charge my battery if it is what you are worry about (I thought it was enought but tell me if I'm wrong).
You said that 24V cannot deliver 50W, I wonder why the amp description is describing it as a 50W one, is that a lie to make me buy it ? because if I can't trust that, how can I trust the seller about al the caracteristic of my amp?!
Thanks again for taking time to answer me, I really appraciate it.
Hi Tanguy,
If you really want 80W you can get 36V E-bike batteries. They are not cheap. Make a calculation of how long the battery will last before recharge if you really use that kind of power. Many have reduced their ambitions concerning power after having made this estimation. A 36V battery is better than a 24V battery and a voltage booster.
The "BMS" is probably fine. Many believe a Li-Ion battery can be treated like a lead battery which is not the case.
Remember that the amplifier must stand the maximum voltage of the battery, when charging and just before being fully charged.
ST promises for TDA7492 2x50W in 6 Ohm with a 25V supply voltage. You use 8 Ohm and the power will be less. The board manufacturer reduced the operating voltage to 24V but kept the 50W. One of the smallest exaggerations in the audio world where Tom's Neurochrome is one of few reliable. Try to look in the high power car audio business if you want to see exaggeration.
Always remember that output power depends on the amplifier configuration, the supply voltage and the load impedance. Often the claimed output power is in a very low load impedance that is not realistic.
If you really want 80W you can get 36V E-bike batteries. They are not cheap. Make a calculation of how long the battery will last before recharge if you really use that kind of power. Many have reduced their ambitions concerning power after having made this estimation. A 36V battery is better than a 24V battery and a voltage booster.
The "BMS" is probably fine. Many believe a Li-Ion battery can be treated like a lead battery which is not the case.
Remember that the amplifier must stand the maximum voltage of the battery, when charging and just before being fully charged.
ST promises for TDA7492 2x50W in 6 Ohm with a 25V supply voltage. You use 8 Ohm and the power will be less. The board manufacturer reduced the operating voltage to 24V but kept the 50W. One of the smallest exaggerations in the audio world where Tom's Neurochrome is one of few reliable. Try to look in the high power car audio business if you want to see exaggeration.
Always remember that output power depends on the amplifier configuration, the supply voltage and the load impedance. Often the claimed output power is in a very low load impedance that is not realistic.
Last edited:
Welcome to Marketing World.
Are you really that naïve to straight believe what sellers claim, specially on EBay or Ali Baba and similar?
You are in for a rude awakening.
Tanguy,
Do not allow yourself to get too distracted by numbers.
To a human being, 80 watts into a speaker will be imperceptibly louder than 72 watts. ?You will never hear the difference.
My advice would be to get a decent bridge tied load amplifier (either stereo or two mono).
If you REALLY want to make a huge difference, and to get massively more volume from the boombox, then put an active crossover in there.
If you have 2 * 72W (or 80W) for bass, and 2* 72W for highs, with say a crossover of 200-400Hz (assuming the speakers are close together - I dont know how your speakers are set up) you will get a massive increase in available SPL in most cases.
Do not allow yourself to get too distracted by numbers.
To a human being, 80 watts into a speaker will be imperceptibly louder than 72 watts. ?You will never hear the difference.
My advice would be to get a decent bridge tied load amplifier (either stereo or two mono).
If you REALLY want to make a huge difference, and to get massively more volume from the boombox, then put an active crossover in there.
If you have 2 * 72W (or 80W) for bass, and 2* 72W for highs, with say a crossover of 200-400Hz (assuming the speakers are close together - I dont know how your speakers are set up) you will get a massive increase in available SPL in most cases.
Ok, thanks again, I have a last question for you all, I have dificulties to find a mono 80W-(24 and 36V) class D amp, I think I will take a stereo one and use PBTL.
However I never did such a think so I don't know how it works, especialy I don't know the output power after a PBTL, is it double or not ?.
I don't know either what kind of filter I have to make.
I search in this forum a topic about that but I didn't find one, so if you know one I would be glad to watch it.
thanks
However I never did such a think so I don't know how it works, especialy I don't know the output power after a PBTL, is it double or not ?.
I don't know either what kind of filter I have to make.
I search in this forum a topic about that but I didn't find one, so if you know one I would be glad to watch it.
thanks
Hi Tanguy,
I included two links in posting #4. The first is to a TDA7498E board that is foreseen for modification into PBTL (mono). This thread describes the modification: 7498E BTL Mode Question
The second link is to a TAS5630 based mono amplifier that is stated to handle 20Vdc-50Vdc.
Perform searches in Google including "diyaudio" if you want to find your way around in this forum.
I included two links in posting #4. The first is to a TDA7498E board that is foreseen for modification into PBTL (mono). This thread describes the modification: 7498E BTL Mode Question
The second link is to a TAS5630 based mono amplifier that is stated to handle 20Vdc-50Vdc.
Perform searches in Google including "diyaudio" if you want to find your way around in this forum.
Totally OT, but I couldn't let this pass. FF, you have a way with words, whether technical or otherwise:
Unfortunately the world now accepts and celebrates politicians mostly talking, rather than doing.
Unfortunately the world now accepts and celebrates politicians mostly talking, rather than doing.
You proposed me the TAS5630 DC20 50 v amp,
My bad I didn't see that the output power (600W) was given for 2 Ohms speakers, however I think that even with 36V the output will be higher than 100W for 8 Ohms, witch is too much for me.
Endeed they predict 200W for 8 Ohm with 50V DC so if we divide by 2 it will be 100W with 8 Ohm for 25V DC, so I will be at the limit of my speakers with only the minimum I want to get.
Plus, if I choose this one I will have to deliver a lot of intensity, they endeed said that "the proposed range is the best 24-45V, current 6A or more (the bigger the better)",it is really too much form my battery, even 3A would be too much.
Thanks
My bad I didn't see that the output power (600W) was given for 2 Ohms speakers, however I think that even with 36V the output will be higher than 100W for 8 Ohms, witch is too much for me.
Endeed they predict 200W for 8 Ohm with 50V DC so if we divide by 2 it will be 100W with 8 Ohm for 25V DC, so I will be at the limit of my speakers with only the minimum I want to get.
Plus, if I choose this one I will have to deliver a lot of intensity, they endeed said that "the proposed range is the best 24-45V, current 6A or more (the bigger the better)",it is really too much form my battery, even 3A would be too much.
Thanks
Endeed it is a bit excessive, I wanted the greater sound possible no matter what the size of the boombox had to take. I came with these speakers :
-Visaton TW 6 NG, 8 ohm
-FaitalPRO 3FE22
-Monacor SPH-210
I wanted to do it even if I knew that the autonomy was low (bc remember that I will mostly use it on a fix place). My batterry is 2 packs in parallele of 6 18650 li-ion in series.
Actually I expect arround 3 hours as runtime.
-Visaton TW 6 NG, 8 ohm
-FaitalPRO 3FE22
-Monacor SPH-210
I wanted to do it even if I knew that the autonomy was low (bc remember that I will mostly use it on a fix place). My batterry is 2 packs in parallele of 6 18650 li-ion in series.
Actually I expect arround 3 hours as runtime.
Hi Tanguy,
It may not be what you want. Just remember what I wrote before - any BTL coupled class D amplifier gives the same output power with the same supply voltage. Thus, also this amplifier gives 80W in 8 Ohm with 36V supply and 35W i 8 Ohm with 24V supply. The change in output power is not proportional to the supply voltage, it increases with the square of the supply voltage (double supply voltage -> 4 times the output power).
Last edited:
- Status
- This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.