I can always add a second PSU in the future since I got the extra boards. At what point does it make sense to have each channel on their own PSU?
With any amplifier and listening room combination there are several things to evaluate and experiment with to achieve the most pleasing sound for one’s preferences. The power supply in the amp is just one part of the overall setup.
Speaker locations in the room, amount of toe-in, distance to listening position and other factors will likely have greater impact in the sound presentation than power supply choices, at least initially. Starting with a simple amp build, it is best to evaluate the other physical configurations first. Once the fundamentals are in place, then one may try shared supply vs dual-mono and other variations thereof.
The link I provided above has the story of how I built my F5m. I have worked on other configurations with other amps that I built, including full dual-mono in my F6 with soft regulation in the form of capacitance multipliers. Different a amps will respond differently to choices with the power supply.
Speaker locations in the room, amount of toe-in, distance to listening position and other factors will likely have greater impact in the sound presentation than power supply choices, at least initially. Starting with a simple amp build, it is best to evaluate the other physical configurations first. Once the fundamentals are in place, then one may try shared supply vs dual-mono and other variations thereof.
The link I provided above has the story of how I built my F5m. I have worked on other configurations with other amps that I built, including full dual-mono in my F6 with soft regulation in the form of capacitance multipliers. Different a amps will respond differently to choices with the power supply.
Good to know. I'll ensure I order 2 4U/400mm cases with slightly over-sized heat-sinks. I'll have enough room for the 2 supplies, if I ever get to that point. Bigger heat sinks will be a plus for the initial build.
Are there any alternatives to 'PASSDIY 4U/400 Deluxe Chassis'? They are back in stock in Sept. but no pre-order so not certain I can get two.
Could I maybe just order the heat sinks and panels and drill the holes myself? I know JLCPCB does CNC now but not sure how much it would cost for a 10mm 400mm 4U front aluminum panel. ( they could drill the LED holes ) I've done other panels with them.
Are there any alternatives to 'PASSDIY 4U/400 Deluxe Chassis'? They are back in stock in Sept. but no pre-order so not certain I can get two.
Could I maybe just order the heat sinks and panels and drill the holes myself? I know JLCPCB does CNC now but not sure how much it would cost for a 10mm 400mm 4U front aluminum panel. ( they could drill the LED holes ) I've done other panels with them.
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I’ve recently built a stereo ACA with premium parts, and want to share my experience.
Someone once said: “the ACA has no right to sound this good”. In my experience, the premium parts mod has elevated that to deserving of even higher praise. I was blown away and still am, when I listen to it in near field in my office where I spend a large part of my day. And I’m not just saying this, I’ve compared the modded ACA, using the same preamp and speakers, to my M2 (Teabag’s boards with Toshiba Jfets). I still can’t believe that I now prefer the ACA over the M2, which I just adore. I’m in love with the sonic beauty of the sound. It's intimate in a headphone-like way, but with an exceptional soundstage, imaging and beautiful bass and a completely dark background.
@TungstenAudio, thank you so much for this incredible achievement and for sharing it with us greedy boyz.
To everyone who are maybe still undecided whether to do the Premium Parts mod: Go for it!!! Otherwise, you’ll never know what you’re missing.
Components used: (refer to Tungstenaudio’s comments re use of these parts)
C1: Nichicon KG series (fast becoming unobtanium, so be quick)
C2, C4: Organic Polymer
C3: Elna SILMIC II (now probably unobtanium, I used the last 2 left over from my M2 build)
Q1, Q2: IRFP140PBF
R1 .. R3: KOA Speer
R4: Stackpole Elect
R11: RN65
R12: RN60
Other resistors: KOA Speer
Note:
Stereo ACA V1.6 on 20V. I’m using one Cap Multiplier per channel running off a single Meanwell LRS-100-24 SMPS.
Disclaimer: I’m using this amp in near field. It certainly doesn’t have the Watts to compete power-wise, with the M2 in a bigger room, but it still does sound better there.
Someone once said: “the ACA has no right to sound this good”. In my experience, the premium parts mod has elevated that to deserving of even higher praise. I was blown away and still am, when I listen to it in near field in my office where I spend a large part of my day. And I’m not just saying this, I’ve compared the modded ACA, using the same preamp and speakers, to my M2 (Teabag’s boards with Toshiba Jfets). I still can’t believe that I now prefer the ACA over the M2, which I just adore. I’m in love with the sonic beauty of the sound. It's intimate in a headphone-like way, but with an exceptional soundstage, imaging and beautiful bass and a completely dark background.
@TungstenAudio, thank you so much for this incredible achievement and for sharing it with us greedy boyz.
To everyone who are maybe still undecided whether to do the Premium Parts mod: Go for it!!! Otherwise, you’ll never know what you’re missing.
Components used: (refer to Tungstenaudio’s comments re use of these parts)
C1: Nichicon KG series (fast becoming unobtanium, so be quick)
C2, C4: Organic Polymer
C3: Elna SILMIC II (now probably unobtanium, I used the last 2 left over from my M2 build)
Q1, Q2: IRFP140PBF
R1 .. R3: KOA Speer
R4: Stackpole Elect
R11: RN65
R12: RN60
Other resistors: KOA Speer
Note:
Stereo ACA V1.6 on 20V. I’m using one Cap Multiplier per channel running off a single Meanwell LRS-100-24 SMPS.
Disclaimer: I’m using this amp in near field. It certainly doesn’t have the Watts to compete power-wise, with the M2 in a bigger room, but it still does sound better there.
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Help with ACA build.
I finally finished up my ACA with premium parts last night. I had completed the PCBs 4 months ago and then life got in the way. Anyway, when I powered it on I got what sounds like an electronic fart, which I think is normal, but have very low volume. For testing purposes I have a Korg B1 as the pre and Sonos port for streaming and Lii F15 speakers which are very efficient. With the Korg turned all the way up I can hear the music but just loud enough for very close listening. Clearly something is not right. I took resistance measurements based up the ACA build guide and most of them are low. Both PCBs test similarly so whatever error I made appears to be consistent. I printed out the ACA guide and wrote in the measurements. I am hoping I get input as to how to diagnose my build issue.
I finally finished up my ACA with premium parts last night. I had completed the PCBs 4 months ago and then life got in the way. Anyway, when I powered it on I got what sounds like an electronic fart, which I think is normal, but have very low volume. For testing purposes I have a Korg B1 as the pre and Sonos port for streaming and Lii F15 speakers which are very efficient. With the Korg turned all the way up I can hear the music but just loud enough for very close listening. Clearly something is not right. I took resistance measurements based up the ACA build guide and most of them are low. Both PCBs test similarly so whatever error I made appears to be consistent. I printed out the ACA guide and wrote in the measurements. I am hoping I get input as to how to diagnose my build issue.
The voltage gain of the ACA is very very low and determined by R12/R11 (so about 3.9 numerically). I suspect that is all you are noticing, the low gain. A preamp is needed for many users needs. Most power amps have voltage gains in the 20 to 40 range.
Not disagreeing with Mooly re: the relatively low gain of the ACA...
However, your Liis should play much louder than very quiet when using a Korg B1 as the pre-amp and with the volume turned all the way up.
Did you build the ACA as a standard build before you did the "premium parts" updates or did you start with the premium parts?
I added the premium parts as part of my initial build. I tend to agree with you regarding the Korg. While I built it primarily out of curiosity, in the times I have had in my main system it has no issue driving loud volumes. That is why I assume I have a build problem.
^ I don't have all the resistor values memorized, but assuming a few missing k's ... that looks fine. Just double check the values against the schematics. Post exactly what mods you made.
There's so many things that can lead to what you're describing. Next thing is to post a set of really good pics of both completed boards and all your wiring.
In the interim... to rule out some of the easy stuff, I'd recommend checking to make sure the full input signal is reaching the amplifier boards. The "mode" switch along with input wiring trips up a lot of people... and those switches can melt. Check both RCAs and the XLR and check it with the switch in the appropriate operating setting for each. Also... just to rule out the obvious... the Sonos is sending a full signal, yes? No digital attenuation?
I assume everything in the guide went to plan through the initial power up etc., yes?
There's so many things that can lead to what you're describing. Next thing is to post a set of really good pics of both completed boards and all your wiring.
In the interim... to rule out some of the easy stuff, I'd recommend checking to make sure the full input signal is reaching the amplifier boards. The "mode" switch along with input wiring trips up a lot of people... and those switches can melt. Check both RCAs and the XLR and check it with the switch in the appropriate operating setting for each. Also... just to rule out the obvious... the Sonos is sending a full signal, yes? No digital attenuation?
I assume everything in the guide went to plan through the initial power up etc., yes?
I second what IAMH said. The correctness of the build needs to be verified.
Some useful voltage measurements (both channels):
1. Power supply voltage at board when turned on.
2. Voltage drop across resistor R9.
3. Voltage drop across resistor R2.
4. Voltage at pad between R2 and R4 relative to Ground.
Some useful voltage measurements (both channels):
1. Power supply voltage at board when turned on.
2. Voltage drop across resistor R9.
3. Voltage drop across resistor R2.
4. Voltage at pad between R2 and R4 relative to Ground.
I am not sure I did this correctly. Had the ground probe connected to the ground wire at back of unit and used the other probe to connect at the below points. Voltage drop was done by touching the resistor on both sides.
1. Power supply voltage at board when turned on. 23.93 for each PCB
2. Voltage drop across resistor R9. 5.7 to 5.17 and 5.06 to 4.2 (Clearly a problem)
3. Voltage drop across resistor R2. 12.86 to 12.49. 12.98 to 12.62
4. Voltage at pad between R2 and R4 relative to Ground.R4 was 12.49 and 12.60. Taken by connecting to right side of R4 resister next to R2. Suspect that is not what you were asking for. Not sure what you meant by pad.
Will put together a parts list of premium parts tomorrow and re-review the PCB for the parts i soldered to the board. Been 4 months since I did this so I want to recheck everything.
Pics of build below:
1. Power supply voltage at board when turned on. 23.93 for each PCB
2. Voltage drop across resistor R9. 5.7 to 5.17 and 5.06 to 4.2 (Clearly a problem)
3. Voltage drop across resistor R2. 12.86 to 12.49. 12.98 to 12.62
4. Voltage at pad between R2 and R4 relative to Ground.R4 was 12.49 and 12.60. Taken by connecting to right side of R4 resister next to R2. Suspect that is not what you were asking for. Not sure what you meant by pad.
Will put together a parts list of premium parts tomorrow and re-review the PCB for the parts i soldered to the board. Been 4 months since I did this so I want to recheck everything.
Pics of build below:
@ItsAllInMyHead
The Sonos streamer is at full volume in its settings and not with a limit. One of the first things I checked last night. In regard to the switch, I don’t have an XLR to test that input. However nothing changes when I flick the switch in any of the 3 positions. . Both speakers still work. Is that correct?
The Sonos streamer is at full volume in its settings and not with a limit. One of the first things I checked last night. In regard to the switch, I don’t have an XLR to test that input. However nothing changes when I flick the switch in any of the 3 positions. . Both speakers still work. Is that correct?
Voltage drop across resistor is measured by one probe on one side of the resistor and the other probe on the other side of the resistor.
So for please remeasure voltage drops across R9 and R2.
Voltage at pad between R2 and R4 relative to ground: one probe on pcb solder pad that is between R2 and R4 and one probe on the circuit Ground.
So for please remeasure voltage drops across R9 and R2.
Voltage at pad between R2 and R4 relative to ground: one probe on pcb solder pad that is between R2 and R4 and one probe on the circuit Ground.
Voltage drop
R9 L: 395.7 R: 389.0
R2 L: 5.28 R: 5.17
Voltage between R2 and R4:
L: 12.73
R: 12.84
R9 L: 395.7 R: 389.0
R2 L: 5.28 R: 5.17
Voltage between R2 and R4:
L: 12.73
R: 12.84
Always include unit of measure! Volt? milliVolt?
The Voltage drop numbers look mixed up. Assuming the R9 numbers are mV and the R2 numbers are V, the numbers as shown do not make sense. They do make more sense if they were reversed.
If R2 Voltage drops were 396mV and 389mV, then Iq was approximately .39V/.235 Ohm=1.66A, which is reasonable.
If R9 Voltage drops were 5.28V and 5.17V, they were a bit high, but perhaps not unreasonable.
This is all assuming the numbers were mixed up and reversed. So please check those measurements.
The Voltages between at the point between R2 and R4 appear reasonable.
You can also check the gain of the amplifier. Go to the web and download a file of a 1000 Hz sine wave. Play it through the amplifier and measure the AC Voltage at the amplifier input and at the amplifier output. The gain of the ACA is supposed to be approximately 9dB, which is 3.8X.
The Voltage drop numbers look mixed up. Assuming the R9 numbers are mV and the R2 numbers are V, the numbers as shown do not make sense. They do make more sense if they were reversed.
If R2 Voltage drops were 396mV and 389mV, then Iq was approximately .39V/.235 Ohm=1.66A, which is reasonable.
If R9 Voltage drops were 5.28V and 5.17V, they were a bit high, but perhaps not unreasonable.
This is all assuming the numbers were mixed up and reversed. So please check those measurements.
The Voltages between at the point between R2 and R4 appear reasonable.
You can also check the gain of the amplifier. Go to the web and download a file of a 1000 Hz sine wave. Play it through the amplifier and measure the AC Voltage at the amplifier input and at the amplifier output. The gain of the ACA is supposed to be approximately 9dB, which is 3.8X.
I did mix up R9 and R2 when I posted the measurements. Sorry about that. I will see if I can test the gain later today.