If the output mosfets are biased to to draw current, the capacitors should discharge fairly quickly. If the LED is installed that would also give a visual indication of the capacitor being discharged.
Just checking the schematic, the LED would only indicate discharged capacitors if the power supply is unplugged and the power switch is left on.
Just checking the schematic, the LED would only indicate discharged capacitors if the power supply is unplugged and the power switch is left on.
2 channels up and running (heating)
17.27 / 0.360 and 17.34 / 0.366 V.
It feels a little hotter today, starting to get uncomfortable after about 5 seconds or so.
And the psu is also (as expected) heating up, but not as much as the amps.
Mine needs at least 10 to 15 minutes to reach stable temps and voltages.
All wires are in, will probably hook it up tomorrow.
But Nelson - green leds (???)😉
17.27 / 0.360 and 17.34 / 0.366 V.
It feels a little hotter today, starting to get uncomfortable after about 5 seconds or so.
And the psu is also (as expected) heating up, but not as much as the amps.
Mine needs at least 10 to 15 minutes to reach stable temps and voltages.
All wires are in, will probably hook it up tomorrow.
But Nelson - green leds (???)😉
Loving the progress on your build perj!
I'm not satisfied with the LEDs either. They're 490 nm, which in theory is cyan, but in person they do just look green unless there's a normal green LED nearby to compare.
In the past I've used LEDs that cycle through several colors over time.
What do the cool kids use? Blue?
I'm not satisfied with the LEDs either. They're 490 nm, which in theory is cyan, but in person they do just look green unless there's a normal green LED nearby to compare.
In the past I've used LEDs that cycle through several colors over time.
What do the cool kids use? Blue?
I use purple. Jameco used to carry them but I haven't seen them on their website lately. Lighthouse LEDs sells purple LEDs, and a dazzling variety of other colors & functions.
And we have music !
Unfortunately on a very low volume and with my expendable test speakers, so I cant really say anything about the sound. Hopefully I will be able to hook up another set of speakers next week.
Also, the green leds are far to bright, so I will do my usual led-routine: hook up a potmeter to one of the led wires, turn to full resistance, power-on, slowly turn the pot until it looks about right, power down, unhook the pot without turning, measure pot, find a resistor with about the same value, solder inline with one of the led wires, cover with some heatshrinktubing.
And it is quite, i can barely hear a faint hum if i put my ear 1 cm from the tweeter...
Unfortunately on a very low volume and with my expendable test speakers, so I cant really say anything about the sound. Hopefully I will be able to hook up another set of speakers next week.
Also, the green leds are far to bright, so I will do my usual led-routine: hook up a potmeter to one of the led wires, turn to full resistance, power-on, slowly turn the pot until it looks about right, power down, unhook the pot without turning, measure pot, find a resistor with about the same value, solder inline with one of the led wires, cover with some heatshrinktubing.
And it is quite, i can barely hear a faint hum if i put my ear 1 cm from the tweeter...
FINNALLLLY has someone spotted the Sun box !
Or should I say, finally has someone shown their true age 😁 This is an old Sun SCSI box, I saved a couple of these + a couple of smaller ones from the dumpster. Thought they might could be to some use.
I gutted the internal in this one, and now it has a couple of switched mode psu's and a couple of 3255 power amp modules. Used together with a Minidsp 2x4 (to the right of the box) in an active "shoebox" and subwoofer setup...
Or should I say, finally has someone shown their true age 😁 This is an old Sun SCSI box, I saved a couple of these + a couple of smaller ones from the dumpster. Thought they might could be to some use.
I gutted the internal in this one, and now it has a couple of switched mode psu's and a couple of 3255 power amp modules. Used together with a Minidsp 2x4 (to the right of the box) in an active "shoebox" and subwoofer setup...
I've made some progress with my amp. Ran into a little problem on assembly though. I ordered my parts from Newark, who don't stock the power switch listed in the BOM. So I ordered a very similar switch, also made by E-Switch. The biggest difference being it's a threaded mount switch. Which turns out won't work with the ACA front panel. So, I've now placed an order with Digikey for the correct switch. I ordered some flux remover too, so I can give the board a good scrub before final assembly. Finally I got some hours using my regular small "shoebox" speakers.
Compared to my other amps (China 3255, Quad 606, modified Hafler, original ACA's etc) it is a sweet sounding little amp. No, it wont drive the speakers to very high levels. But these speakers cant play very loud anyway.
For better words, it is "ear friendly". I can listen to it for a long time without any fatigue at all.
Cymbals and guitars has a "softness" of some sort, they are not "hard" or "harsh" in any way.
"Friday night in San Francisco" was really nice.
"Romantic Warrior" as well.
Setup was Wiim streamer, Topping D50s dac and Seas / ScanSpeak drivers in a mini monitor box.
Compared to my other amps (China 3255, Quad 606, modified Hafler, original ACA's etc) it is a sweet sounding little amp. No, it wont drive the speakers to very high levels. But these speakers cant play very loud anyway.
For better words, it is "ear friendly". I can listen to it for a long time without any fatigue at all.
Cymbals and guitars has a "softness" of some sort, they are not "hard" or "harsh" in any way.
"Friday night in San Francisco" was really nice.
"Romantic Warrior" as well.
Setup was Wiim streamer, Topping D50s dac and Seas / ScanSpeak drivers in a mini monitor box.
The time has come. Pioneer kits are up on the store!https://diyaudiostore.com/products/aca-minmax-bundle
Kits in future batches will have test point loops and stickers for rear panel mods, plus corrections for any issues we discover together.
Happy building!
So many happy builders are on the horizon. I look forward to seeing all the great builds. Thank you to all involved!
I love mine! Sounds just superb! If you are on the fence, just buy it, nurture it....It's gonna make you proud someday!
I love mine! Sounds just superb! If you are on the fence, just buy it, nurture it....It's gonna make you proud someday!
Got me a kit ordered which will make 2 minmaxes in total. If I get my butt moving, might be the first to try balanced.
The typical MinMax build will have higher voltage and bias (exact values up to you). More bias gives lower distortion (at both jumper settings) and better low end response, especially when driving low efficiency or complex impedance speakers that the mini can struggle a bit with. The Mini has been compared to the F5 by several people, and in my opinion the MinMax sits somewhere between the two.
Here's a post where I compared two bias settings against THD. There's more discussion in that thread from people who increased the bias and gave their impressions. If you don't know, there's an option when you use the search bar to only search that thread which I find helpful when navigating the 1000+ post epics.
Here's a post where I compared two bias settings against THD. There's more discussion in that thread from people who increased the bias and gave their impressions. If you don't know, there's an option when you use the search bar to only search that thread which I find helpful when navigating the 1000+ post epics.
I had a pair of ACA chassis sitting in my basement for a couple years so I figured I’d give one of these kits a try. Just got it up and running. Very nice little amp! It’s a pretty significant step up from the regular mini IMO. A lot more power for the typical multi driver speaker. So I just ordered another one for my second ACA chassis. These deserve to be monoblocks. 🙂 Any word on how these will drive 4ohm loads in its balanced mono configuration?
Nelson Brock sells ACA monoblock kits, search for "ACA Redux". His design uses a round heatsink with a large number of cylindrical pin-fins, thus fondly referred to as The Hedgehog. Before that, I briefly sold bare PCBs for "RACAM -- Round Amp Camp Amp Monoblock" but those require extreme dedication from the builder because sourcing the heatsinks was a never ending game of Whack A Mole. Sellers keep appearing and disappearing, wasting the builder's time and money, and aggravating her tremendously.
I don't have any 4 ohm speakers in my usual rotation so I can't speak from direct experience, but on paper, parallel mono would do better than balanced mono because it doubles the available current (rather than the voltage). The good news is that it's easy to try both and see which you like best 😀