No issues at all. I have Dynaudio contour 1.3's. Single ACA was driving them with no issues at all, just truly wonderful sound. Plenty loud. These Dynaudios have pretty flat impedance; I was able to drive them with 3W SE tube amplifiers.
I also like ACA driving my HD650's directly, from the binding posts. Exceptional.
I think you many well find there is/could be a difference ...
Its something I've been looking at as I have a generic 'Laptop brick' 5 amps? which I thought I'd put to good use powering the ACA.... But I was not convinced somehow. So I wired up a Meanwell LRS-150-24v 6.5Amp (chassis type).
That was an instant fix, particularly the bottom end, bass weight and speed far superior. Might try one on each channel...
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New ACA Builder Questions
Hello all-
I am considering building two version1.6 monoblocks each powered by their own meanwell 24v supply. I’m thinking of putting both monoblocks in a single Deluxe 5U enclosure. I am also considering adding a .333 F 63V storage capacitor after each of the 24V DC power inputs from the meanwell power supplies (one cap on each 24VDC power input supply). Each monoblock will have a stiff DC supply to draw from. In order to limit inrush current, I’ll modify two of the softstart circuit PCBs for DC operation and charge the caps that way.
Questions:
Am I wasting my time with the storage caps?
Any other advice for this plan?
Any advice against this plan?
Helpful hints?
I have the caps from another project and I’m looking for a place to use them. Part # ALS70A334QS063
Hello all-
I am considering building two version1.6 monoblocks each powered by their own meanwell 24v supply. I’m thinking of putting both monoblocks in a single Deluxe 5U enclosure. I am also considering adding a .333 F 63V storage capacitor after each of the 24V DC power inputs from the meanwell power supplies (one cap on each 24VDC power input supply). Each monoblock will have a stiff DC supply to draw from. In order to limit inrush current, I’ll modify two of the softstart circuit PCBs for DC operation and charge the caps that way.
Questions:
Am I wasting my time with the storage caps?
Any other advice for this plan?
Any advice against this plan?
Helpful hints?
I have the caps from another project and I’m looking for a place to use them. Part # ALS70A334QS063
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Adding an external soft start to an SMPS is detrimental. These supplies do not generate inrush currents in the way that linear supplies do and the SMPS likes to see a normal 'raw' supply established as quickly and cleanly as possible.
Large value capacitance added to the rails of an SMPS is unnecessary and due to the way an SMPS works could even cause problems in operation. 0.33F (330,000uF) would quite likely prevent the PSU starting as it would be considered a 'shorted load'.
High value caps have little effect on reducing rail ripple at the high frequencies an SMPS operate on (because they generally have relatively poor ESR at high frequencies) and moreover they also limit the supplies ability to regulate correctly under transient load changes.
Large value capacitance added to the rails of an SMPS is unnecessary and due to the way an SMPS works could even cause problems in operation. 0.33F (330,000uF) would quite likely prevent the PSU starting as it would be considered a 'shorted load'.
High value caps have little effect on reducing rail ripple at the high frequencies an SMPS operate on (because they generally have relatively poor ESR at high frequencies) and moreover they also limit the supplies ability to regulate correctly under transient load changes.
.... But I was not convinced somehow. So I wired up a Meanwell LRS-150-24v 6.5Amp (chassis type).
That was an instant fix, particularly the bottom end, bass weight and speed far superior. Might try one on each channel...
My ACA, including two cap multipliers, draws 63W from a LRS-100-24V and I'm extremely happy. But now that you're mentioning two 150W units, I'm wondering... what if? You think there is merit in going bigger?
Edit: Just saw the two posts above. The cap multipliers that I've built into my ACA provide soft start and prevent start up noise. And also, the Meanwell is totally happy. I'd be happy to provide more info if asked.
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From my experience, SMPS do not like to "see" large capacitance in their output. You can try it but as Mooly says the SMPS will probably interpret a large capacitance as a short.
As for ripple and noise, I also agree with Mooly. I have never observed a significant improvement.
I have decided to move in my ACA to a linear psu (such as that of F2 for example). Now I am fighting with other problems
As for ripple and noise, I also agree with Mooly. I have never observed a significant improvement.
I have decided to move in my ACA to a linear psu (such as that of F2 for example). Now I am fighting with other problems
I think you many well find there is/could be a difference ...
Its something I've been looking at as I have a generic 'Laptop brick' 5 amps? which I thought I'd put to good use powering the ACA.... But I was not convinced somehow. So I wired up a Meanwell LRS-150-24v 6.5Amp (chassis type).
That was an instant fix, particularly the bottom end, bass weight and speed far superior. Might try one on each channel...
Just wondering.... did you wire that chasis type SMPS close to the ACA PCB's, i.e. inside the ACA amplifier?
If you had the laptop brick power supply wired using long (DC) cables, then that's not a fair comparison...
I noticed when powered via my bench supply (3amp) and playing music (not loud but bass heavy passages) that the over current would kick in starving the amp of current which was very noticeable.
The SMPS is external to the ACA with a 400mm long power lead. The brick lead is about 1mtr long so this may possibly be an issue. Saying that the Meanwell 5A brick also has a long lead which is why I went for the 6.5A jobbie. I did some temperature readings on the ACA and the heat sinks run at 50-55C after an hour or so, the 240's run at 42C.
After an hour running the Meanwell LRS 150-24 was at 40C. 20C above ambient at that time. I'm trying to stay away from the SMPS with cooling fans. There OK new but get noisy over time and are a point of failure.
I'm not so keen on the DC plug and socket power connection either..
There's simply no other option but to place the power supply inside the amp. I completely understand why Nelson chose to use an external 24V DC power supply - no lethal mains voltages to worry about, so that's cool and completely understandable.
I placed the 24V DC SMPS inside the ACA. The whole thing runs like a little smelting furnace, but the sound is very fast, extremely revealing and very pleasant at the same time... not easily achievable.
I placed the 24V DC SMPS inside the ACA. The whole thing runs like a little smelting furnace, but the sound is very fast, extremely revealing and very pleasant at the same time... not easily achievable.
i wonder is there any difference when putting external and internal.
sound better just placing them inside?
Thanks for the reply. I think some clarification is due on my end. So, the plan is to use the soft start circuit on the 24V output, not the AC lines. The soft start would allow me to turn on the power supply into 6-10 ohms and limit the output current of the meanwell supply to 3-4A to charge the capacitor. In that way, the power supply would not see "shorted load". After some time, the relay in the soft start would switch the power supply directly to the capacitor and 24V rail. You do bring up a good point and I would be interested to discuss the output control loop of the SMPS with the capacitor on the rail. I'll do some research today about the effect of capacitive loads on SMPS. Perhaps, I should just build a transformer based power supply from the universal power supply PCB.
Please do provide more info about the "cap multipliers". I'm not familiar with that term.
