Amp Camp Amp - ACA

Assembly of Japanese bicycle require great peace of mind...........

:clown:
But does it have to work? If not, then I must have great peace of mind as assembly is finished.

Letting voltage stabilize to ensure DC bias set correctly. At what point does one feel safe to hook up sources and speakers for real life test?
 

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I’m a chicken, so my first music test is always with a raw speaker salvaged from some other piece of equipment. I measure output terminals with my voltmeter to make sure I don’t have DC present, then connect a disposable test speaker. When it makes music, then I move to a real speaker. I prefer to blow up only one piece of equipment at a time :ROFLMAO:
 
edit: posted something thinking that I'm in Korg B1 thread :rofl:

@rubah - do some general reading; everything needed to connect xformer and full wave rectifier, to end with single rail supply - I already posted in my previous post

problem with reading and learning is - you need to be aware of facts and dangers working with mains voltage ........ and with that necessary level you'll be able to understand posted schematic

if you can't recognize what primary is , you're crawling in dark, waiting for disaster to happen - injury or even death

so, in short - if you're not able to deal with mains voltage based build - use switcher brick supply, as majority of ACA builders are doing
Hi ZM, thanks for your advice and I find solusinya like this psu pcb picture attachment, For my teriodal 18-0-18 🙏
 

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not good

that's twice half - wave rectifier

if you make bridge/short between two "+" at right side, then you'll have proper full wave rectification

and then you have just one "+", not two
Single rail full wave my xformer 18-0-18 to high volt after psu around 36v, to get 19v/24v i use regulator lm7819/24 + tip3055 to get stable 19v/24v - it good or not * zm?
 
solve first rectification properly, then you can do whatever you want with regulators

under load , from 18Vac you'll get something as 22Vdc to 24Vdc

36V you're mentioning are result of wrong rectification and wiring

so, no need for regs ...... nor you'll have voltage headroom to include one

take care of dots - there are connections; where no dot, no connection
 

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solve first rectification properly, then you can do whatever you want with regulators

under load , from 18Vac you'll get something as 22Vdc to 24Vdc

36V you're mentioning are result of wrong rectification and wiring

so, no need for regs ...... nor you'll have voltage headroom to include one

take care of dots - there are connections; where no dot, no connection
Thanks u MZ 🙏🙏🙏🙏🙏🙏🙏🙏🙏
 
Hi rubah,
This Full Wave Rectifier circuit is all you want. Same as Zen Mod posted at #11156.
It will give you about 24 volts DC off load from an 18 - 0 - 18 volt transformer. (You can use a bridge rectifier package and just use 1/2 of it. You leave the -ve terminal disconnected.)
If you measure more than 24/25 volts then the transformer is putting out more than 18 volts AC or you have a wiring error.

If you want 2 positive outputs (not necessary) add another resistor and capacitor shown in dotted on the second circuit.
 

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If the amp is responding properly to the potentiometer adjustment, it’s likely good.
Wow, this is my first experience with SE Class A and I am amazed at how good the sound is coming from my Heresys. No smoke from either amp or speakers, so that's a good thing. Currently running Spotify to my Schitt Modi 1 DAC directly into the ACA. No hum, dead silent with computer volume all the way up, that's a great thing. Running the volume on the Spotify app a little less than 1/3 rd of the way up with very good clean audio.

I do have a couple concerns that I could be over concerned about, but thought I would check. After hooking up DAC and speakers, I tried to let the amp come to room temperature before turning on as it was cold from the car ride to my office. When I powered it on, I heard this weird sound come from the left speaker, kind of like letting the air of a balloon. At this point the left speaker sounded light, I doubled check and it is working, just not as loud as the right. I was checking connections and decided to flip the balance/stereo/mono switch to the full down position (currently in the middle where it reads stereo). Now the left appears to be as loud as the right. Could I have the Stereo/mono switch wired incorrectly? Could that be what caused the weird sound at the beginning? At some point today I am going to incorporate a Line Stage at which time I will power down the ACA. When powering back up, I will listen to see if I notice the weird sound at first. If not, that could be the answer to my second question.

Now I have to really wonder how SE Class A will sound on my big horns at home.
 
When I powered it on, I heard this weird sound come from the left speaker, kind of like letting the air of a balloon.
Even without any wiring problems, this is a somewhat "normal" kind of thing to happen with the ACA. Mine makes this same sound at turn on and the amp is only configured for single-ended input, no output bridging, etc. It's relatively quiet, but clearly there - my understanding is that it is related to the output filter cap charging up.
 
..... I heard this weird sound come from the left speaker, kind of like letting the air of a balloon. At this point the left speaker sounded light, I doubled check and it is working, just not as loud as the right. I was checking connections and decided to flip the balance/stereo/mono switch to the full down position (currently in the middle where it reads stereo). Now the left appears to be as loud as the right. Could I have the Stereo/mono switch wired incorrectly? Could that be what caused the weird sound at the beginning? .....
The 'noise' (fart) is normal, you will get it every time you switch on in Stereo mode. It is mentioned in the build guide and numerous times in the thread.
Both sides should be the same loudness in stereo mode. If they are the same switched to 'parallel mode', switch down, make sure your inputs are equal first (swap them side to side).
If that is okay, could be the switch wiring or a resistor in the wrong place or... as Zen Mod says post some pictures so we can see too.
 
Switch wiring is fine for V1.8 build.
Switch can be either way up and no harm will be done.

Make sure your inputs are equal (you will be surprised how many one channel louder than the other problems is because of a faulty input) then check you have correct values in R11 and R12 (compare one side to the other if in doubt).
Thanks, will bring Allen wrenches tomorrow, open up and double check R11 and R12.

As for inputs being equal, can you give an example as I do understand?