For the master designer a question
I am trying to imagine how to arrange the resistor and capacitor.
The three ways I could think of are drawn below:
Which, if any are what you had in mind?
The ACA switching supplies I have seen will charge a 10,000 uF cap. If they
don't there is a simple addition using a resistor and a diode to provide slow
charge for the cap.
An LC filter with lesser values of capacitance will still help with the noise figure,
so feel free to try it.
I am trying to imagine how to arrange the resistor and capacitor.
The three ways I could think of are drawn below:
Which, if any are what you had in mind?
Attachments
The diode need to be anything 50V PIV or higher and 2Amps or higher. The resistor needs to be 39 Ohms 10 Watt. The cap perhaps 100,000uF 25v. The cap charges up slowly when power is turned on. The resistor limits the current to keep the SMPS happy. When the SMPS is turned off, the diode turns on and discharges slow enough to de-thump the ACA.
Attachments
Hi, sorry I forgot to report back. I couldn't hear a difference, and sadly I've not got any audio test equipment. The ACA is driving a pair of Fostex 206EN.
I used an electronic engineers power supply unit for the B1 and then the switch mode supply for the ACA. Whether music is playing or not, the B1 draws 0.01amps (or less, it is the minimum display reading). My switch mode supply is 19vdc and 4.5amps. Normally I have been running both channels of the ACA and the B1 from this one switch mode power supply.
Its pretty easy to try, perhaps it could be a first step before investing in a separate power supply for the B1?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
My Christmas project. Will post more later. Merry Christmas to all.
About 50 degrees, I powered the mono blocks with 18v 80VA toroid and lt1083 regulator. Everything is getting very hot [emoji35]
If you can find a way to lift the heat sinks sinks up off the carpet, things should cool down a bit.
Little Bear P3 connected ACA
Well it's been a while but I've finally got myself organised and got back on the forum.
The Little Bear P3 arrived from eBay and I got the ACA from Sachu888 assembled and running. I was genuinely surprised at the sound. Running the ACA direct off my Sonos into a set of 1984 vintage JBL TLX-8's I got a nice sound. Also, given the JBL's aren't particularly sensitive, I was pleased with the sound level the 6W ACA gave me. Putting the Little Bear P3 in the loop gave the sound a little more warmth.
I've attached some pictures of the setup and the Little Bear P3. The Little Bear P3 was supposed to be a kit however basically you just wire up the transformer and put on the covers (which aren't safe if you have people who might poke fingers into it, so worth doing a nicer surround).
I also did the 6W mod to the ACA kit, photo attached. Heatsinks seem to cope however it's coming into summer here so we'll see how it goes with higher ambient temperature.
Well it's been a while but I've finally got myself organised and got back on the forum.
The Little Bear P3 arrived from eBay and I got the ACA from Sachu888 assembled and running. I was genuinely surprised at the sound. Running the ACA direct off my Sonos into a set of 1984 vintage JBL TLX-8's I got a nice sound. Also, given the JBL's aren't particularly sensitive, I was pleased with the sound level the 6W ACA gave me. Putting the Little Bear P3 in the loop gave the sound a little more warmth.
I've attached some pictures of the setup and the Little Bear P3. The Little Bear P3 was supposed to be a kit however basically you just wire up the transformer and put on the covers (which aren't safe if you have people who might poke fingers into it, so worth doing a nicer surround).
I also did the 6W mod to the ACA kit, photo attached. Heatsinks seem to cope however it's coming into summer here so we'll see how it goes with higher ambient temperature.
Last edited:
Well my ACA is nearly finished. The last step that took some time was programming the temperature controller i will be using inside the amplifier. The first ACA with an LCD screen I also made a video of how it will look like in a working conditions. Temperature was simulated with a glass of ice cubes and a burning candle.
https://www.youtube.com/watch?v=0hQdcBLgT8s
Enjoy
I also made a video of how it will look like in a working conditions. Temperature was simulated with a glass of ice cubes and a burning candle. https://www.youtube.com/watch?v=0hQdcBLgT8s
Enjoy
I have just built myself an ACA and wondering if it`s possible to increase the bias?
I have already done the 2k2 mod. Heatsinks are big so no problem there!
double mosfets
Ok? How to do that? Ekstra R5 and R6 on gate for double Mosfets, Source and Drain in parallel with existing Mosfets?
I was thinking maybe resistors in parallel with R1/R2 and R3/R4?
upper ones matched
lower ones too
or change (add) resistors , do not double mosfets - use IRFP150N instead of 240 , that will give you double everything , without need for matching
power will not increase , without increasing PSU voltage
you asked for greater Iq , and that's what you get
there must be also edited schm for increased PSU voltage , somewhere earlier in the thread
lower ones too
or change (add) resistors , do not double mosfets - use IRFP150N instead of 240 , that will give you double everything , without need for matching
power will not increase , without increasing PSU voltage
you asked for greater Iq , and that's what you get
there must be also edited schm for increased PSU voltage , somewhere earlier in the thread