I believe the B+ is an American term. When tube radios (valve wirelesses) ran on batteries they were marked:
A+ for the filament cell or battery
B+ for the high tension battery
C+ for the Grid Bias battery
To make connecting them up easier.
In the UK
B+ is called the HT+ (High Tension +)
A+ is called LT+ (Low Tension +) and the C+ is just called Grid Bias.
In lower voltage situations it is more common to use V+ for the positive supply. Eg 18V+ or 36V+.
A+ for the filament cell or battery
B+ for the high tension battery
C+ for the Grid Bias battery
To make connecting them up easier.
In the UK
B+ is called the HT+ (High Tension +)
A+ is called LT+ (Low Tension +) and the C+ is just called Grid Bias.
In lower voltage situations it is more common to use V+ for the positive supply. Eg 18V+ or 36V+.
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welcome, i post based on actual experience and what i was telling all along is that this ACA amp will work the first time if you got construction right....
i too have my share of failures with other builds, but never with this one...
an open mind surely helped me.... not be too dismissive of what you do not understand...
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were it not for this pandemic, we could have built more than a hundred of these boards in Manila.....
Nelson Pass came up with a winner here, single ended design, class A, what is not to like?
i built a 48v version of this ACA, bridged, and i am very happy with the results....
the design was culled from inputs coming from Zen Mod and other members here...
board layout was done in the middle east by filipino engineers, and board fabricated in china.....
it has become my reference amp for now....until i can find another one that sounded better to my ears...
this was our first session held in a local cafe......
Nelson Pass came up with a winner here, single ended design, class A, what is not to like?
i built a 48v version of this ACA, bridged, and i am very happy with the results....
the design was culled from inputs coming from Zen Mod and other members here...
board layout was done in the middle east by filipino engineers, and board fabricated in china.....
it has become my reference amp for now....until i can find another one that sounded better to my ears...
this was our first session held in a local cafe......
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I was thinking - if you have more pics, just open new thread
and I'm completely happy with this pictures being here
🙂
and I'm completely happy with this pictures being here
🙂
Maybe a thread for Amp Camps. In other words, events where people get together to build ACAs
I have photos of the original Amp Camp! And I know Jan Didden did one
Tony, How many events that include building ACAs have you done?
I have photos of the original Amp Camp! And I know Jan Didden did one
Tony, How many events that include building ACAs have you done?
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My mind struggles to comprehend pictures of so many people, not relatives, no one wearing a mask! We certainly live different realities in different places. Here I hardly see my parents, let alone attend something like that!
I looks like so much fun! Congrats!
that was in late October of 2018, our first build out/tech-ins, not yet pandemic thus the pictures...
one in late 2018, and about four in 2019, nothing in 2020...after this pandemic we will do other events..
i have my pictures stored in my FB account and also in my hardrive....
when two guys approached me in June of 2018 and asked me to do a buildout teach-in, i selected the ACA because of its ease in construction and is guaranteed to work the first time, and the sound will not disappoint....
thanks, i have the bride of zen preamp, and the Aleph 3 boards done, waiting for the day that we can resume doing build out events...
The ACA makes a funny "burp" when powering up. In XLR-bridged mode, this disappears completely - I guess the burps in the two channels perfectly track each other. (This is with the stock Meanwell dead rat PS)
This must be different capacitors charging up to their respective operating points. Does anyone have anymore insight as to what exactly the sequence of events is, and if there is any potential for fine-tuning the parameters/components such that the power-up happens without oscillations in the audible band? I have read somewhere here there are no power-up noises with a linear PS and a soft-start circuit.
This must be different capacitors charging up to their respective operating points. Does anyone have anymore insight as to what exactly the sequence of events is, and if there is any potential for fine-tuning the parameters/components such that the power-up happens without oscillations in the audible band? I have read somewhere here there are no power-up noises with a linear PS and a soft-start circuit.
The output coupling capacitors are charging. You don't hear it when outputs are bridged as the speaker isn't attached to ground, and you don't hear the difference between the charging cap(s) and ground.
Yes, that's what I mean by "the channels track each other": Both output caps charge in-sync, providing no net current/voltage across the speaker.
Nevertheless, the caps don't charge in a smooth, continuous way. There is some oscillation happening. I can also see some oscillations on the voltmeter when adjusting the bias: When I connect the voltmeter and then turn on the amp from cold, the voltage oscillates until it settles around 12V.
So my noob question is: What causes this oscillation? And is there a way to get rid of it, for cosmetic reasons if nothing else 🙂
PS: Thanks for the quick reply.
Nevertheless, the caps don't charge in a smooth, continuous way. There is some oscillation happening. I can also see some oscillations on the voltmeter when adjusting the bias: When I connect the voltmeter and then turn on the amp from cold, the voltage oscillates until it settles around 12V.
So my noob question is: What causes this oscillation? And is there a way to get rid of it, for cosmetic reasons if nothing else 🙂
PS: Thanks for the quick reply.
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Have a look at this:
A possible approach to adding a silent start/shutdown to the ACA
Post #32 might be the easiest diy solution.
A possible approach to adding a silent start/shutdown to the ACA
Post #32 might be the easiest diy solution.
much as i would like to help, i am not sure i get you without seeing your setup...
it takes a few seconds to charge the output caps that is terminated to ground with a 1k resistor, i have no idea how it will oscillate....i have no such issues as yours...