I used an irfp140 and fqh44n10 in my premium aca and it sounds phenomenal.
Tungsten, I need your help one more time, my premium aca sounds fantastic but has some hum. Attached is the cap multiplier that I am using on each channel, should I double the capacitance on the crc? Resistors on crc are 0R1 and not 0R22 like schematic shows. That’s what Rudi had silkscreened on the board I used. Thanks for your help Mark
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Easier to double the resistance on the CRC – increase the resistors to 0R22.
Next try twisting the blue & green wires from the transformer more tightly. One side has very little twist and may be causing some hum. Also make sure that the wires to the speaker binding posts are routed next to each other.
As a general note: Capacitance multipliers need bulk capacitors on their output. It is not enough to simply claim that low output ripple is the only thing needed to power an amplifier. Even Class A amps need energy storage. In this case, see if you can find a way to connect 10,000 uF of capacitance between the CapMx and the amp.
Next try twisting the blue & green wires from the transformer more tightly. One side has very little twist and may be causing some hum. Also make sure that the wires to the speaker binding posts are routed next to each other.
As a general note: Capacitance multipliers need bulk capacitors on their output. It is not enough to simply claim that low output ripple is the only thing needed to power an amplifier. Even Class A amps need energy storage. In this case, see if you can find a way to connect 10,000 uF of capacitance between the CapMx and the amp.
For the hum, also try rotating the power transformer to find the position of least noise. Looking at the picture of the amplifier in post #1037, a bit of clockwise rotation may be beneficial.
Rotated the trannie 90 degrees getting the ac to run down the middle. Twisted the secondaries to the boards, added 18,000uf 35v cap on output of multiplier. Hum is reduced can hear 6 ft away but not from listening chair. Will call this good for now,replacing the crc resistors will be a pain. Now the big question for Tungsten, out of all the pass amps I own why do I rotate back to this premium aca with the fqh44n10 and irfp140? The soundstage is massive and all the instruments have been sprinkled with fairy dust! Everything else is good but meh in comparison. Extra H2? Bubba
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Hum at 6 feet from speaker is not good at all.
Looking at your speaker wire Out+ to the board, connecting to the power supply ground at the bridge rectifier (input side of PS) is not good. The speaker connection to the board ground should be output side of the power supply (clean power side). There looks like two possible locations on the board for a connection to clean ground. One is at the centre of the board where an off-board capacitor is connected, and the other is at the end of the board next to the Mosfet at the Mosfet source pin.
Looking at your speaker wire Out+ to the board, connecting to the power supply ground at the bridge rectifier (input side of PS) is not good. The speaker connection to the board ground should be output side of the power supply (clean power side). There looks like two possible locations on the board for a connection to clean ground. One is at the centre of the board where an off-board capacitor is connected, and the other is at the end of the board next to the Mosfet at the Mosfet source pin.
The speaker + and - are coming from where board designer intended. I will send a photo of empty board tomorrow. Off board capacitor is between cap multiplier and aca that is where you would hook up the meanwell ps if you are using it.
Another thing that I noticed was the each channel has its own power supply but both channels' ground is tied together at the CL60 ground lift. It's best to keep each channel's ground separate with each channel's ground having its own CL60 to chassis/safety ground.
Also the ground lift connection at each channel is best done at the power supply output, not at the speaker output at the back panel.
Once all of the grounding changes are made, perhaps the amplifier may be quiet enough that each channel's stand-alone capacitor that is connected at the power supply output location may be removed.
Also the ground lift connection at each channel is best done at the power supply output, not at the speaker output at the back panel.
Once all of the grounding changes are made, perhaps the amplifier may be quiet enough that each channel's stand-alone capacitor that is connected at the power supply output location may be removed.
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Ground lift was added later, it hummed before and no change after, I’ll remove it. was trying to replicate original aca grounding scheme but using a cl60 also .on the underneath of the board there is a huge ground trace that goes from c101 to c102 to speaker return and over to clean ground. Where you tap output ground along that trace will make will make a difference? i will give that a try! Tungsten wanted me to add that cap as a reservoir for the aca, put it after multiplier, is that wrong?
So the board was laid out wrong? Rudi put the ac ground after c102 right at the speaker return? C101 starts the ground trace
Regrettably, yes, the board was not laid out correctly. Ben is right about relocating the speaker return connection. Both the speaker return and the reservoir cap need to be connected at the power supply output. Try making the reservoir cap wires shorter as well.
Rudi has enjoyed trying a number of different ideas for the ACA over the last couple years. He does board layout as a hobby. This particular one is not his best work with regards to getting good performance.
Rudi has enjoyed trying a number of different ideas for the ACA over the last couple years. He does board layout as a hobby. This particular one is not his best work with regards to getting good performance.
Bubba177, The symbol used for Q7 is an N-Channel mosfet, but the part number is that of a P-Channel part. The way the part is drawn, there is no connection to the Drain. Please correct the schematic.
Tungsten, Ben, we have success. Deleted ground lift. Took speaker return from clean power supply output, shortened reservoir wires. I have to stick my head in 108 db horn to hear a tiny buzz. Thank you so much for all your help, very very much appreciated.
bubba, Great news!
However, when you said you deleted the ground lift, did you delete the CL60 but kept the power supply grounds connected to safety ground? Or did you delete the power supply grounds to safety ground entirely?
The power supply grounds should be connected to safety ground. My previous point was that you have a separate power supply for each channel but their grounds were joined together before they were connected to safety ground. For better separation of the two channels it is better to connect each channel's ground to its own CL60, and then connect the CL60s to safety ground.
If both power supply grounds are connected directly to safety ground and you have no hum, then no further changes need to be made.
However, when you said you deleted the ground lift, did you delete the CL60 but kept the power supply grounds connected to safety ground? Or did you delete the power supply grounds to safety ground entirely?
The power supply grounds should be connected to safety ground. My previous point was that you have a separate power supply for each channel but their grounds were joined together before they were connected to safety ground. For better separation of the two channels it is better to connect each channel's ground to its own CL60, and then connect the CL60s to safety ground.
If both power supply grounds are connected directly to safety ground and you have no hum, then no further changes need to be made.
Ben I was going to ask that, I deleted it all but will add another cl60 and have both channels to safety ground via their own cl60. Thank you so much bubba
Hi everyone, this is actually my first post after doing quite a bit of research about ACA DIY project that I'm considering undertaking in the near future.
First of all I must say I admire the wealth of knowledge and the dedication of so many of you members of the forum.
I have limited experience in electronics building, but I feel that with guidance and support of the community, ACA could be a perfect project for me to undertake. I love music and i like to listen to it at moderate volumes so I'm not concerned about the amps power.
After reading through the debate about all the improvements, I've decided I would like to build the latest (sonically improved version by TungstenAudio).
Here are my questions:
Can I make the upgrades directly on the 1.8 board or I should get the modified/upgraded one?
Do you recommend buying the regular kit first (I believe the current version is 1.8) and to buy the upgraded components separately or I'm better off just buying everything seperatly?
In that case, does anyone have a complete list of components at hand (TungstenAudio latest version)?
I've also noticed the case normally used in this project is currently unavailable. Are there any good alternatives that open the possibility for the future upgrades (also interested in aleph j)?
I'm based in Europe, Spain.
What would you do if you would want to start this particular project as soon as possible implementing all the upgrades from the start?
I thank you all in advance for all your input.
First of all I must say I admire the wealth of knowledge and the dedication of so many of you members of the forum.
I have limited experience in electronics building, but I feel that with guidance and support of the community, ACA could be a perfect project for me to undertake. I love music and i like to listen to it at moderate volumes so I'm not concerned about the amps power.
After reading through the debate about all the improvements, I've decided I would like to build the latest (sonically improved version by TungstenAudio).
Here are my questions:
Can I make the upgrades directly on the 1.8 board or I should get the modified/upgraded one?
Do you recommend buying the regular kit first (I believe the current version is 1.8) and to buy the upgraded components separately or I'm better off just buying everything seperatly?
In that case, does anyone have a complete list of components at hand (TungstenAudio latest version)?
I've also noticed the case normally used in this project is currently unavailable. Are there any good alternatives that open the possibility for the future upgrades (also interested in aleph j)?
I'm based in Europe, Spain.
What would you do if you would want to start this particular project as soon as possible implementing all the upgrades from the start?
I thank you all in advance for all your input.
You can buy case directly https://modushop.biz/site/index.php?route=product/product&product_id=792.Its faster and cheaper then from USA.