I think you all can imagine my level of excitement. I even misspelled the word...lol 🙂
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Yes! You chose a very good one for your first ! I am anxious to know how it sounds when you get it playing.... When you have a minute to tell us. Thanks!
Yes we are. Your spelling is perfectly good enough considering English is not your native language. I think 99 percent of us understand what you were trying to say. Most of us that speak English make as many mistakes ourselves.
Thanks for understanding.
I left it powered on for an hour or so. I think it was thermally stable by then. The heatsink was not too warm. Will connect it to my main setup tonight. Let's see what happens. Will update accordingly.
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I left it powered on for an hour or so. I think it was thermally stable by then. The heatsink was not too warm. Will connect it to my main setup tonight. Let's see what happens. Will update accordingly.
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Finished both the amps. Bias is showing 10.05v for both the channels after 2 hours. The heatsinks I am using measures 195mmX100mmX32mm. It became very hot after 2 hours of contentious playback. At room temperature, I could not not put my fingers on them for more than 10 seconds. Btw, the weather is very hot in my city (41-42 deg celsius).
After I turned on the AC, the temperature of the heatsinks went down.
Should I upgrade the sinks?
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After I turned on the AC, the temperature of the heatsinks went down.
Should I upgrade the sinks?
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The sinks need to have airflow, raise them off the flat surface and temps should drop.
10 seconds isn't too bad.
If you can raise them up a little so that air can circulate underneath them as well you will be fine, no worries
Edit: Sippy beat me to it!
If you can raise them up a little so that air can circulate underneath them as well you will be fine, no worries
Edit: Sippy beat me to it!
The Pass rule is 5 seconds. I would not worry with 10 seconds. Sounds normal for a Class A amp.
Thanks @sippy, @JRKO, @wdecho. I've placed some carrom coins below the heatsinks. Now there is a small air gap at the bottom end. This worked well. I have to test the temperature after long listening hours though.
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One more change that should help keep temp. down is to invert the heat sinks so that the side where the mosfets are mounted is at the bottom meeting the fresh air first.
Regards
Regards
Good eye. Yes they do need inverting. Heat rises and the rule is to mount transistors on the bottom 1/3rd of the heat sink. You have them mounted about 1/3rd but now at the top 1/3rd. Invert as cochleus noticed.
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I've built a few ACAs. Each one has sinks that are about 200mm wide by 80mm tall and 40mm deep. The mosfets are attached at the bottom of the sinks (inverted from what you've shown in your image) and the chassis elevates the bottom of the sinks about 1-2cm above the table top, so this improves airflow through the sinks a bit. Both run quite well at about 45-50c in a room that is about 25c. If you want cooler sinks, you'll need larger ones. Some people use Class A amps more in the winter months than during the summer. Of course, you've found a viable solution as well...
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Thanks a lot @cochleus, @wdecho, @Eric for your feedback. I've inverted the MOSFETs and kept some air gap at the bottom of the cabinet. Results are pretty obvious (read good). Now heatsinks are not getting that hot.
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So I'm building my ACA (turbo) as dual mono with 32volt supplies. My original plan was to have the PSU in a separate housing with a single transformer with dual secondaries feeding separate unregulated CRC filters. The same housing would have a 12v transformer for the cooling fans. xrk971 recommended a single 32v SMPS and tapping into the main rail supply with a 7812 regulator to deliver the power for the fans. I like the simplicity of that, but I would rather have separate supplies for the channels.
The question is, will tapping into one of the supply rails risk introducing noise or have other detrimental effects on the amp's performance?
The question is, will tapping into one of the supply rails risk introducing noise or have other detrimental effects on the amp's performance?
Well done.
Maybe some vent holes in the case bottom (and top, of course) as there will be some heat build up inside, even though the sinks now have enough air moving around them.
Maybe some vent holes in the case bottom (and top, of course) as there will be some heat build up inside, even though the sinks now have enough air moving around them.
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Great to hear that it is working better now! The ACA is a great little amp and I like the emphasis on "little" - you can get great sound from a very small package!
