I am thinking to use single chassis of 4U size for two ACA mono-blocks, but will power through two separate SMPS as I already bought them and I have following doubts:-
- Can I use common power switch for both SMPS power supplies?
- Is there any common wiring which I can do for both the amps as they will be in same chassis? (I will use bridge or parallel mono mostly)
- I will use heat sink of 250mm width x 40mm wave profile x 165mm height and place both the PCB on same heat-sink, is it fine or any interference can be caused or any suggestions to avoid such issues?
Question 1. Are you switching the mains AC or the 24 volts DC? Mains switching should be okay, but we do not know the switch on surge your SMPSs have. You have to try it this is DIY.
Question 2. Not really. Build them as 2 amps.
Question 3. Where ever suits you. Better thermal dissipation if you mount them symmetrically at the mid height point, but after an hour or so it will all be much the same temperature...
Question 2. Not really. Build them as 2 amps.
Question 3. Where ever suits you. Better thermal dissipation if you mount them symmetrically at the mid height point, but after an hour or so it will all be much the same temperature...
Question 1: I will use two Meanwell 24V SMPS so it will be two 24v DC sockets as per wiring diagram of ACA v1.8
First do not connect the 2 Meanwell supplies together in parallel. Keep them separate. You can switch them at the same time if you use a double pole switch rated at at least 5 Amps. A rocker or toggle switch will be fine depending on what you find locally. Ask if you need a diagram. Just an example https://www.digikey.co.uk/en/products/detail/e-switch/R5CBLKREDEF0/1805333?utm_adgroup=Rocker Switches&utm_source=google&utm_medium=cpc&utm_campaign=Shopping_Product_Switches&utm_term=&productid=1805333&gclid=CjwKCAjw5NqVBhAjEiwAeCa97TTnuNFSL1XEP8AxrWQRXbhONTryqJzDfuHKyL2VptT9a7jUugaaNBoCtLYQAvD_BwE
Or https://www.retroamplis.com/DPDT-Toggle-switch-ON-ON/en
The rear switch could be combined too if you can find a 4 pole 3 position (on-off-on) switch locally. An example again here: https://uk.farnell.com/multicomp/1m...ING-PMAX-Medium_ROAS-Test915&gross_price=true
Or https://www.retroamplis.com/DPDT-Toggle-switch-ON-ON/en
The rear switch could be combined too if you can find a 4 pole 3 position (on-off-on) switch locally. An example again here: https://uk.farnell.com/multicomp/1m...ING-PMAX-Medium_ROAS-Test915&gross_price=true
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I noticed today that if I tried putting my stock ACA on a pair of 6ohm/92dB speakers that I get the right channel LED slightly pulsing (mostly with the music). I saw this one other time on the same channel with a very easy to drive set of speakers, then it stopped. It only does it with music playing. I don’t notice any noise or difference in volume. Any ideas what to check? I know those 6 ohm speakers are not gonna work, but was curious to see.
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What power supply are you using? Is it a suitable SMPS?
The LED changes brightness because of a change in LED current and that can only be because the power supply voltage is being modulated by the music. Although the ACA is Class A the rail current is not a constant.
I did that the first time I saw it happening 6 months or so ago. All the voltages checked out fine against the build documents. I'll check all the voltages again tomorrow. Thanks.
Those voltages are critical because they tell us how much current the ACA is drawing.
I've no experience of the ACA beyond the theoretical and working from the circuit diagram so perhaps others could say whether they have ever noticed this effect or not on their builds using the Meanwell PSU.
I've no experience of the ACA beyond the theoretical and working from the circuit diagram so perhaps others could say whether they have ever noticed this effect or not on their builds using the Meanwell PSU.
As it is the same right channel each time it suggests there is a 'high' resistance connection from the switch to the board? It might be 0.1s of an ohm, but at 1.5 amps it will show. Measure carefully the +ve to -ve voltage at the faulty board, does it fluctuate with music? If it is stable check the LED wiring perhaps?
This is just a shot in the dark, but have you tested your AC line for voltage? You might have a drop in voltage on the actual line itself.
It only happens on the right channel. When I measured it with music playing the voltage at the boards never changed, but the LED would very slightly pulse, so I don’t think it’d be the mains. I’ve never measured it below 120V. Usually it’s 122-124V. I don’t hear it affecting the sound at all. It might be just a flaky LED? It’s just annoying as I notice it when I’m listening and staring at the stereo rack. Maybe some black tape 😁
Thanks, those voltages all look good and show the basic current draw is fine.
Try what Nelson suggests and I'm also going to add to try swapping the speaker load from left to right just to eliminate anything weird with the right channels load.
I would doubt that really, particularly if the brightness responds to the music and volume level.