temperature heatsinks ?
I completed the ACA build today. I'm surprised by the quality of sound.
But i'm worried about the high temperature of both heatsinks. I could mine hands on it but just on. Both heatsinks the same. Is this a normal temperature of the ACA ? or is this due a fault in the build. I checked everything twice.
Regards
John
I completed the ACA build today. I'm surprised by the quality of sound.
But i'm worried about the high temperature of both heatsinks. I could mine hands on it but just on. Both heatsinks the same. Is this a normal temperature of the ACA ? or is this due a fault in the build. I checked everything twice.
Regards
John
Hi John,
And welcome to the world of Class A. Yes, heat and lots of it is normal and so your amp is almost certainly fine and operating perfectly.
Around 1.5 amps is flowing in each channels output transistors and so if you multiply that by the 24 volt supply you get a power dissipation of about 36 watts. And that's just one channel. So its HOT
Enjoy your amp.
And welcome to the world of Class A. Yes, heat and lots of it is normal and so your amp is almost certainly fine and operating perfectly.
Around 1.5 amps is flowing in each channels output transistors and so if you multiply that by the 24 volt supply you get a power dissipation of about 36 watts. And that's just one channel. So its HOT
Enjoy your amp.
Well done.
All is normal. Each heat sink is 'loosing' 36 watts to the air. Being able to touch it even briefly is proof it is working OK. That is the cost of Class A operation.
Just check / adjust the 12 volt bias again when it is fully warmed up, 30 minutes or so.
Alan
Sorry, everyone is posting at the same time. At least we all have the same answer...
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I think that is normal for a good DAC/preamp. My preamp can simultaneously drive two sets of 8v SE and two sets of 16v xlr preamp outputs. “scotty, I need more power!”
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Both of the NuPrime DACs: DAC 9 and DAC 10 are capable of 4v through RCA outputs. I'm using the 10 with the ACA to great success!
Thanks for all the help everyone. Another question. In my kit, the thin green and blue wire are not solid core, they are stranded. I thought I read they should all be solid core now. Will this change things? For example when I make a twisted pair out of green and white for the rca connections, is it ok that white is solid core and green is stranded?
I just finished the first of my two ACA 1.6s. Worked the first time and plays music! Very good guide. I did find what I think is a bad instruction text in step 37:
XLR - pin 2 is connected via black wire to the white RCA pin, Pin 3 is connected via red wire to the red RCA pin.
The pictures clearly shows the red wire connected to Pin 2 (hot) and black wire connected to Pin 3.
I followed the pictures and everything is fine.
I also wish that specific lengths of wire be included. I ran out of red wire between the front panel switch wiring and the red connections to the PC so I had to use my own substitute wiring for this task.
Thanks so much for all the efforts of the creators.
-CB
Well, one of my two is up and running very nicely. Running it from my 6sn7 based tube pre amp into Audio Note speakers. Certainly sounds different to the EL34 Push/Pull that it has replaced. Not better, not worse, different.
Now to trouble shoot the other one ... proably a bad solder joint somewhere.
Now to trouble shoot the other one ... proably a bad solder joint somewhere.
•The round "front switch" comes in all kits. So you can make a hole to one side of the rear panel, perhaps centered with the RCA input and centered between the 2 speaker posts. A stepped drill bit would help tremendously with this.
•Consider whether you need a power switch. Many people I know just plug their amps (even ones with a power switch, which they leave on) into a power strip and switch them there. That allows you to use the paddle switch for the 2ch/mono bridged setup.
•Consider whether you need a power switch. Many people I know just plug their amps (even ones with a power switch, which they leave on) into a power strip and switch them there. That allows you to use the paddle switch for the 2ch/mono bridged setup.
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Just curious... do you use that 6sn7 pre-amp to drive the EL34 amp as well?
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Yes, I do/did/will. The EL34 is a Bob Latino based Dynaco style amp.
The next experiment will be running it with a couple of other pre's. Have an Audioengine D1 and a A&K flac/wav player to try. Enjoying the different sound of the ACA with the tube pre currently so not in a huge hurry to swap around.
What I found is that ACA will present what it sees at its input, with a great resolution, speed, presence and maybe just a hint of warmth. It portrays the low-frequency spectrum the way it actually should sound - clear, defined, precise while the speaker cone energy is dissipated into the air the way, for example, the bass guitar strings vibrate - amazing. You would expect this from a two-gain stage, single-end class A amplifier. A few days back I compared it with a 3 gain stage amp with push-pull output - I liked lower distortions of that amp a lot! So, it seems the logical thing would be to build bigger ACA with much lower distortions.
I wonder if M2X would provide (even) more pleasing sound due to no feedback and "magnetic" voltage gain... instead of a semiconductor-based...
I wonder if M2X would provide (even) more pleasing sound due to no feedback and "magnetic" voltage gain... instead of a semiconductor-based...
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I assembled 4 ACA kits (love the red chassis) some time ago with the 2.21K mod. Have been enjoying them since.
Based on the newer kits, I upgraded to the Meanwell 24v supply and rebiased. I am really impressed how low noise they. I am using 2 ACA's to drive JBL compression drivers with no pad, just a protection cap. I have to put my ear inside the waveguide to hear the tiniest bit of hiss and no hum whatsoever. A significant improvement over the old 19v supplies which were a crap shoot for noise.
They get Crikey Hot, but I sure love the sound!
Based on the newer kits, I upgraded to the Meanwell 24v supply and rebiased. I am really impressed how low noise they. I am using 2 ACA's to drive JBL compression drivers with no pad, just a protection cap. I have to put my ear inside the waveguide to hear the tiniest bit of hiss and no hum whatsoever. A significant improvement over the old 19v supplies which were a crap shoot for noise.
They get Crikey Hot, but I sure love the sound!
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