In order to produce that small output power to the speakers, the ACA requires multiple times that power from the outlet. The ACA circuit is a “Single ended class A amplifier” This type of circuit requires a lot of power to create a small amount of output i.e. “not efficient” but it does sound very good. The excess power turns into heat which is why this amp has relatively large heatsinks for its power
Every build or just mine can’t remember how I managed to end up with 300VA but a bit of surplus power is good. Full shielding makes it even bigger.
This is why - I used an ultra low ripple board that came with the following recommendations for transformers.
View attachment ULN-PS7-E.pdf
View attachment ULN-PS7-E.pdf
RafaPolit
Thanks for the replies. I guess I should have been clearer about what I'm intending to do.
I want to build a Mono amp going in to a single Jamo centre
speaker Ebay cheapie (from a surround setup ). It'll basically
be like a big crude Bluetooth speaker except mains-powered
and no bluetooth.. Well bluetooth optional.
So 1 ACA and 1 speaker
When I wrote 10 watts I meant for it to be easier to understand because people usually would think of the ACA
as stereo with 2 x ACA.
So really it should be 5 Watt output.
But as you've all pointed out; The circuit itself is far more power hungry and as I am intending to use a 7818 voltage regulator in the power supply that should gobble up a couple of watts as well.
Rafapolit pointed out that the original ACA used a
switchmode PSU brick thingy at 5 Amps into 24V.
So we're in the territory of around 125 Watt max draw.
Quite a bit beyond my hopes and dreams of 20 watt.
Does anyone know what the measured power draw for 1 channel is(roughly)?
I actually have a 300VAC transformer but I'd rather use it for a more ambitious build.
Thanks for all the kind answers.
Variac
Steve Luck
Thanks for the replies. I guess I should have been clearer about what I'm intending to do.
I want to build a Mono amp going in to a single Jamo centre
speaker Ebay cheapie (from a surround setup ). It'll basically
be like a big crude Bluetooth speaker except mains-powered
and no bluetooth.. Well bluetooth optional.
So 1 ACA and 1 speaker
When I wrote 10 watts I meant for it to be easier to understand because people usually would think of the ACA
as stereo with 2 x ACA.
So really it should be 5 Watt output.
But as you've all pointed out; The circuit itself is far more power hungry and as I am intending to use a 7818 voltage regulator in the power supply that should gobble up a couple of watts as well.
Rafapolit pointed out that the original ACA used a
switchmode PSU brick thingy at 5 Amps into 24V.
So we're in the territory of around 125 Watt max draw.
Quite a bit beyond my hopes and dreams of 20 watt.
Does anyone know what the measured power draw for 1 channel is(roughly)?
I actually have a 300VAC transformer but I'd rather use it for a more ambitious build.
Thanks for all the kind answers.
I'm a little confused too, but here are some facts.
Each ACA board draws approximately 1.5 Amps so 36 Watts dissipation - as heat. (1.5A x 24volts = 36 watts) Class A amplifiers are very inefficient at less than 25%.
Always design a power supply to have more current (amps) than the total draw by at least 1.5 times and 2 times even better. Every thing will run cooler and with less stress. That is why the Meanwell SMPS is rated at 5 Amps, not 3 Amps.
Not sure the 7818 voltage regulator is what you want? Aim for 24 volts at 2.5 Amps to get nearly 8 watts of output from a single ACA.
We can all dream...
Yes without question. Linear PSU is my entry in to electronics
It's what I understand and it's better than a SWMPSU for audio anyway.
It's all about learning for me.
Linear PSU's was first. Next is audio amplifier circuits.. Tomorrow the world!
Thanks I'll check it out.
Awesome answer. It's everything I needed to know.
So the new plan is a 7824 regulator and I just bought
a 160VA Torroid transformer.. Actually I bought 2 after realizing another project of mine is underpowered in the same fashion.
Attached is a rough drawing of the PSU.
The best dreams are the ones that come true.. Except for nightmares of course.
Attachments
The SMPS is by far the best approach for the ACA on technical grounds.
That will never power an ACA, not even 1 channel.
The ACA is probably the most unsuitable amp you could choose based on your requirements
It has to be said... just so you know.A bridged chip amp would deliver many times more power and have next to nothing quiescent current draw.
The SMPS is by far the best approach for the ACA on technical grounds.
That will never power an ACA, not even 1 channel.
The ACA is probably the most unsuitable amp you could choose based on your requirements
A bridged chip amp would deliver many times more power and have next to nothing quiescent current draw.
Do you know who wrote that?
It seems that whoever wrote that, also designed the "Amp Camp Amp"
That person seemed far more concerned with the safety of the participants of the event than any 'technical' benefits that might be gained from using a switchmode powerbrick..
What? An ACA with a linear power supply?
Get over it – it works fine.
I could keep quoting Nelson here. Especially concerning
your suggestion of using a 'chip amp' but I'm not going to.
It seems to me that the spirit of the ACA is to teach
people how to build and very crucially, to understand how an
amplifier works. That's not going to happen by buying an off the shelf powerbrick and an IC.
If this is about some audio purist indignation at me not
buying the Audio store brushed aluminium kit then
all that makes me want to do is to mount the whole design
in a giant pickle jar and call it the ACA tube amp, complete
with blinking LED's. I'll make the thing look like a brothel.
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Who wrote what? I have no connection with anything in that second block of text you quote.
I'm say the SMPS is the best PSU for the job here. It wins on cost, size and performance.
You need to look at the PSRR of an ACA before deciding to go down the linear route. Yes, a linear supply can offer excellent performance but its no small task to end up with a result that will be a as quiet as the SMPS.
If you want to learn about design then that is to be applauded but do make sure you understand all the pros and cons of each PSU approach first.
I'm say the SMPS is the best PSU for the job here. It wins on cost, size and performance.
You need to look at the PSRR of an ACA before deciding to go down the linear route. Yes, a linear supply can offer excellent performance but its no small task to end up with a result that will be a as quiet as the SMPS.
If you want to learn about design then that is to be applauded but do make sure you understand all the pros and cons of each PSU approach first.
I find it astonishing that you do not know who Nelson Pass is.
Or that he wrote this small essay
https://www.firstwatt.com/pdf/art_amp_camp_1.pdf
before he took part in the Amp Camp event.
I strongly and thoroughly recommend you read it.
It is the baseline for anything to do with this topic.
Or that he wrote this small essay
https://www.firstwatt.com/pdf/art_amp_camp_1.pdf
before he took part in the Amp Camp event.
I strongly and thoroughly recommend you read it.
It is the baseline for anything to do with this topic.
SMPSU's are universally known as being noisy compared
to Linear PSU's. I don't care what circuit they're feeding
by their very nature they are prone to introducing oscillations.
It seems to me that you've all accepted SMPSU as being superior just because it was part of the original design.
when the real reason had nothing to do with it being better
and everything to do with it being safer and easier. Sheesh
read the thing for yourself..
https://www.firstwatt.com/pdf/art_amp_camp_1.pdf
to Linear PSU's. I don't care what circuit they're feeding
by their very nature they are prone to introducing oscillations.
It seems to me that you've all accepted SMPSU as being superior just because it was part of the original design.
when the real reason had nothing to do with it being better
and everything to do with it being safer and easier. Sheesh
read the thing for yourself..
https://www.firstwatt.com/pdf/art_amp_camp_1.pdf
I did read it. Many moons ago. Please show the ripple you have calculated for your power supply. Without those calculations all your words are just some noise. Please feel free to build your supply and test it. This is just audio nothing more. To learn more about the ACA and the modifications that have been successful, look for the thread titled "ACA with premium parts".
The new V fet amp that all of us have lusted after employs a SMPS PSU chosen by Nelson Pass himself. Maybe they are not as bad as you believe.
The new V fet amp that all of us have lusted after employs a SMPS PSU chosen by Nelson Pass himself. Maybe they are not as bad as you believe.
Maybe they aren't and maybe my very standard regulated linear supply design isn't that bad either.
You're 100 percent correct The best way to find out is to build it.
And test it.
I'll check out the aca premium parts thread as well.
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It seems like you just joined diyaudio forum. Based on your posts, you got lot to learn. If I were you, I would listen to older members, specially Mooly. Very knowledgeable and helpful gentleman.
Everyone around here knows who NP is.