Ok so I have all the parts picked out. I have the toroids coming and i got the lm3875's for free as I'm a electrical engineering student. I'm getting the boards fabed by advanced circuits for free but I want to make sure theres is nothing i need to change at the last second.
So here is the schmatic for the amp its self
Here is the board for the psu
and here is the board for the cap bank (caps are 100nf poly film, then 1000uf, 2200uf, 3300uf, 2200uf, 1000uf, 100nf poly film)
So here is the schmatic for the amp its self
An externally hosted image should be here but it was not working when we last tested it.
Here is the board for the psu
An externally hosted image should be here but it was not working when we last tested it.
and here is the board for the cap bank (caps are 100nf poly film, then 1000uf, 2200uf, 3300uf, 2200uf, 1000uf, 100nf poly film)
An externally hosted image should be here but it was not working when we last tested it.
On the cap's PCB there is a small trace missing in the lower left corner.
Do you expect anything in particular from the first increasing and then decreasing capacity values?
Do you expect anything in particular from the first increasing and then decreasing capacity values?
hello.
r2=1k and c5=22uf give you a high pass filter around 7hz.
with a 47uf (non polarised) elcap you can get around 4hz......
greetings............
r2=1k and c5=22uf give you a high pass filter around 7hz.
with a 47uf (non polarised) elcap you can get around 4hz......
greetings............
i think so:
the -3db cutoff frequency should be far away (5times......10times)
from the lowest (bass )frequency you want to hear without attenuation........so 30hz gives you 6hz.........to 3hz and so on.
at least that all depends on your imagination of sounds......
greetings....
the -3db cutoff frequency should be far away (5times......10times)
from the lowest (bass )frequency you want to hear without attenuation........so 30hz gives you 6hz.........to 3hz and so on.
at least that all depends on your imagination of sounds......
greetings....
Putting all the parts on one board will make for easy assembly, but is not always the most optimum for reducing size. Start with approximately what size of enclosure you want and use that to optimize layout of parts. It is often optimum to split the circuit into two boards, with one mounted on top of the other.
I'm custom making all of the cases. The actual amp is very small. The power supply is going to be much larger. I'm waiting to get the toroids to start drawing up the cases. I may split the cap bank in half to reduce size but i still need to get the toroids in hand first. I'm just worried about the amp's schematic
I think an AC coupled amplifier needs DC blocking caps on both the NFB lower leg and on the input.star882 said:
A DC coupled amplifier should have neither, but needs other systems to protect the output load from damage.
does the chipamp manufacturer have any recommendations for additional circuits to ensure stability and minimising noise and interference?
Do you recognise the difference between signal ground and decoupling ground and power ground and speaker ground and mains ground?
Do you recognise the difference between signal ground and decoupling ground and power ground and speaker ground and mains ground?
well on the noise side of things I'm using a filtered ac input module and the physical devices are going to be enclosed in metal (most likely a thin sheet of aluminum) then with another material (non metalic) around it. So the only exposed metalic surfaces would be the audio terminals which are grounded, the power switch, and the head sink which is at the very least isolated from the lm3875.
My ground system will consists of two parts. In the psu case the star point will be a bolt into the aluminum shell to which the ac ground, in case power ground, and the ground from the powercon conector from the amp (which is the ground like between the psu and amp).
In the amp I have the power ground and all of the power decoupling and bulk caps together while the input ground is connected to them via a 805 smd resistor on the pcb. The speaker return ground is just connected to the powercon ground connector. The only question that I have is should I have the ground from the feedback loop on the amp connected with the input ground or just with the power ground? And is there anything else I should do to the ac ground?
My ground system will consists of two parts. In the psu case the star point will be a bolt into the aluminum shell to which the ac ground, in case power ground, and the ground from the powercon conector from the amp (which is the ground like between the psu and amp).
In the amp I have the power ground and all of the power decoupling and bulk caps together while the input ground is connected to them via a 805 smd resistor on the pcb. The speaker return ground is just connected to the powercon ground connector. The only question that I have is should I have the ground from the feedback loop on the amp connected with the input ground or just with the power ground? And is there anything else I should do to the ac ground?
Hi,
why don't you wire it point-to-point first? There are virtually no parts 😀
That's done in a morning and in the afternoon you can already enjoy your amp 😉
Have fun, Hannes
why don't you wire it point-to-point first? There are virtually no parts 😀
That's done in a morning and in the afternoon you can already enjoy your amp 😉
Have fun, Hannes
Well i have 4 chips coming. I may bread board it but i really don't like point to point wiring. If i'm going to do something i'm going to do it right
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