I have numerous T and D and AB low power amps in my parts bin.
I am seeking to make a 12V powered portable guitar amp and only need 10 watts or so. A TDA7297 (so cheap they are almost free) would do fine. But I only need one channel. I could just earth one channel input and leave it unused. I probably will.
But, I wonder, is there a low cost 10-20W single channel amp board/module/chip I should look at ?
I am seeking to make a 12V powered portable guitar amp and only need 10 watts or so. A TDA7297 (so cheap they are almost free) would do fine. But I only need one channel. I could just earth one channel input and leave it unused. I probably will.
But, I wonder, is there a low cost 10-20W single channel amp board/module/chip I should look at ?
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The TDA7297 data sheet I'm looking at says a 12 volt power supply will give you about 6 watts out. In your living room 6 watts can get you evicted, but in anything more than a pretty small club not so much. Google:
data TDA7297
One way to go would be to use both channels, feeding two speakers, which would give much better sound distribution anyway. Or perhaps channel A for an instrument, channel B for voice or a second instrument, somebody sitting in? This would double the load on the 12 volt battery, of course.
This is for a portable performance rig? Busker or such, maybe everything mounted on a hand cart? Any way you could spring for two batteries (Walmart highly recommended)? Two batteries would give you either 24 volts, or +/- 12 volts, either way opening up lots of options, such as the LM1875.
Remember that batteries have to be both stored and transported right side up, they can never be turned on their sides.
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The TDA7297 data sheet I'm looking at says a 12 volt power supply will give you about 6 watts out. In your living room 6 watts can get you evicted, but in anything more than a pretty small club not so much. Google:
data TDA7297
One way to go would be to use both channels, feeding two speakers, which would give much better sound distribution anyway. Or perhaps channel A for an instrument, channel B for voice or a second instrument, somebody sitting in? This would double the load on the 12 volt battery, of course.
This is for a portable performance rig? Busker or such, maybe everything mounted on a hand cart? Any way you could spring for two batteries (Walmart highly recommended)? Two batteries would give you either 24 volts, or +/- 12 volts, either way opening up lots of options, such as the LM1875.
Remember that batteries have to be both stored and transported right side up, they can never be turned on their sides.
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The TDA2040 can be used at 12V.
https://www.google.co.uk/search?q=1...om%2Fcar-stereo-circuit-using-tda2040;816;508
https://www.google.co.uk/search?q=1...om%2Fcar-stereo-circuit-using-tda2040;816;508
Thanks Bentsnake.
Yes, the plan is for the smallest possible, lowest power guitar amp that might just make 100dBA peak with a 94dB/W driver. Will run on rechargeable AA batteries (!) but should be powerable from a vehicle if necessary. The single channel option was hoping to eliminate quiescent dissipation from the unused channel.
cheers,
blakkie
Curious that. I have TDA2030 amps and the spec for that chip is min +/_ 6volts, while the TDA2040 and 2050 are in +/- 4.5V.
With a 12v rail, you get around 10v peak to peak output swing with an 8 ohm load. This is a 3.54v rms output swing which means you get 1.56 watts max. With 4 ohm load you get a little less than 3 watts. If you can increase rail to 15v, you can reach about 5 watts @ 4 ohms and this will get to 100db with a bit of room to spare. I'd use 10 C or D batteries as voltage will sag fast with AAs.
I'd skip BTL (bridge amps) because they are quite a draw on batteries. Also skip the TDA 2030, 40, 50 or LM1875 as their output swing is not optimized for low voltage use, Even though they work at 12v. For example, the LM1875 puts out 1 watt with 12v supply, where a TDA2003 will make 1.6.
One interesting chip is the LA4425. it is a 5 pin chip, but feedback is set internal so there are less parts. TDA2003s are disco'ed and authentic ones are hard to find.
I'd skip BTL (bridge amps) because they are quite a draw on batteries. Also skip the TDA 2030, 40, 50 or LM1875 as their output swing is not optimized for low voltage use, Even though they work at 12v. For example, the LM1875 puts out 1 watt with 12v supply, where a TDA2003 will make 1.6.
One interesting chip is the LA4425. it is a 5 pin chip, but feedback is set internal so there are less parts. TDA2003s are disco'ed and authentic ones are hard to find.
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I wish people would quit talking about voltage output of amplifiers, because the concept is meaningless. Voltage when? When the percussion section is playing the triangle solo, or when they're firing the canon for the 1812 Overture? Oh and by the way what's the frequency, because your meter is only accurate at 50-60 Hz.
Well, while they're heating up the tar I'll just chime in to say that johnr66's LA4425 sounds about as close to what you need as you're likely to get.
But also to remind that Walmart carries lawn mower/tractor batteries. They're about the size of 3 books stacked up. The advantage would be much longer running time between recharges, and much less voltage drop when the canon goes off. The one I had before now lasted about 7 years.
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I wish people would quit talking about voltage output of amplifiers, because the concept is meaningless. Voltage when? When the percussion section is playing the triangle solo, or when they're firing the canon for the 1812 Overture? Oh and by the way what's the frequency, because your meter is only accurate at 50-60 Hz.
Well, while they're heating up the tar I'll just chime in to say that johnr66's LA4425 sounds about as close to what you need as you're likely to get.
But also to remind that Walmart carries lawn mower/tractor batteries. They're about the size of 3 books stacked up. The advantage would be much longer running time between recharges, and much less voltage drop when the canon goes off. The one I had before now lasted about 7 years.
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Most dual channel amps (musical instrument or pro audio) can run bridged mono.Crate CPB 150 Power Block Amp Head.it's 150W mono/75W stereo. I've used it for bass powering 2 Acoustic Image Contra extension cabs (4 ohms each), and for guitar powering a single Chinese
Celestion (8 ohms).
That just needs 4W, if both your specifications are for 1m listening distance.
If you listen at 2m, then that power target jumps from 4W to 16W and for 3m increases to 36W
Meaningless? No it is not. Why not just give a fictitious PMPO rating? Often, people ask for (for example) a 25 watt amp to drive their 8 ohm speakers and they want to use a 12 volt battery. They're not getting anywhere close to that unless they include a DC-DC step up converter and a power source that can deal with the load.
Sure, my normal listening level is probably under 1 watt, but I have selected a more powerful amp for a reason.
No, PMPO is easy to calculate. Just take the true output power of the amp and multiply that by the square root of the age of the kid who thinks is car stereo is cool.
John,
you omitted a factor.
The extra factor is how many tens of thousands are you expected to flog?
Say they plan to produce 100,000 amplifiers and then close the factory and change their name before the lawyers arrive to sue them for misrepresenting their product.
They end up with PMPO = sqrt(con artist's age) * 100000/10k * (sum of all the channels for peak instantaneous output power)
eg.
con artist age = 49years,
Production target = 100k
2.1 amp (3 channels)
single channel maximum output = 4W, peak instantaneous output = 12W
PMPO = sqrt(49)*10*{12*3) = 2520W
you omitted a factor.
The extra factor is how many tens of thousands are you expected to flog?
Say they plan to produce 100,000 amplifiers and then close the factory and change their name before the lawyers arrive to sue them for misrepresenting their product.
They end up with PMPO = sqrt(con artist's age) * 100000/10k * (sum of all the channels for peak instantaneous output power)
eg.
con artist age = 49years,
Production target = 100k
2.1 amp (3 channels)
single channel maximum output = 4W, peak instantaneous output = 12W
PMPO = sqrt(49)*10*{12*3) = 2520W
you are doing the PMPO alculation wrong.
((supply voltage - 2)^2) * number of channels.
so for any amp that has a rail voltage of 12 volts, and is a stereo one, it comes out as:
(12-2)(12-2)(2) = 200 watt PMPO.
get Your facts stright before posting such nonsense 😀
((supply voltage - 2)^2) * number of channels.
so for any amp that has a rail voltage of 12 volts, and is a stereo one, it comes out as:
(12-2)(12-2)(2) = 200 watt PMPO.
get Your facts stright before posting such nonsense 😀
Thanks all for your suggestions.
I will look into them and get back to you.
ps. I am running on 12 x 1.2V NiMH AA's which claim to be 2450mAH so I think we can make target power OK.
I will look into them and get back to you.
ps. I am running on 12 x 1.2V NiMH AA's which claim to be 2450mAH so I think we can make target power OK.
within reasonable powerlevels You will find it may take literally a full day (24 hours) to deplete those batteries.
try a TDA 1557q or similar chip.
basicly to make it "work" it will need (three) capacitors only.
100nf across supply + and gnd, and an input cap of around 470 uF or larger.
film type caps only. anything rated to at least 16 volts will do.
and You will need something around 2000 uF or larger 16 V rated electrolithic cap to be sure across Your battery pack. thisone may even be ommitted.
you allso need a switch, and wires. and a potmeter to adjust volume.
piece of cake.
wire those AA s in series to get a decent 14.4 pack and its good to go.
try a TDA 1557q or similar chip.
basicly to make it "work" it will need (three) capacitors only.
100nf across supply + and gnd, and an input cap of around 470 uF or larger.
film type caps only. anything rated to at least 16 volts will do.
and You will need something around 2000 uF or larger 16 V rated electrolithic cap to be sure across Your battery pack. thisone may even be ommitted.
you allso need a switch, and wires. and a potmeter to adjust volume.
piece of cake.
wire those AA s in series to get a decent 14.4 pack and its good to go.
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