Hi, I await my F5 parts kit. When it arrives, I will stuff the boards, and then start on a power source. I am good enough with electronics to follow directions, solder well, and not usually start fires. So, my question is...
Since the F5 needs 18 volts per channel to operate, and my ACAs use 18 volts, would it be possible to power the F5s with computer power supplies like the ACAs are powered?
I'm guessing that the answer is no because of needed capacitance or not enough magic smoke pressure.
I humbly await your wise and knowledgeable answers.
Since the F5 needs 18 volts per channel to operate, and my ACAs use 18 volts, would it be possible to power the F5s with computer power supplies like the ACAs are powered?
I'm guessing that the answer is no because of needed capacitance or not enough magic smoke pressure.
I humbly await your wise and knowledgeable answers.
First off, F5 uses a 18+18 transformer, rails will be 24 volts or so. That said, I don't see why it couldn't be done at 18, but not as it was designed. I really don't know if a similar power supply to ACA has enough umph or not...I would just build the Standard Pass First Watt power Supply.
Russellc
Russellc
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There are no stupid questions. 
Yes, what you suggest is actually possible, though you'd want to use 24v laptop supplies.
The reason you don't see it commonly has to do with 2 reasons,
1) there's a rather large problem if one supply fails, you'll see the entirety of the remaining DC supply on the output, essentially full power of the amp trying to suck the speaker all the way back, or push it all the way out until something in the speaker burns out. That's not a great failure mode. Similar happens if they don't power-up evenly, but not over as much time.
2) Although the modern supplies are getting quieter and quieter, and are absolutely good enough for the application, putting two in series is going to make for very interesting issues with the (independent) switching frequencies interacting and the beats falling down into the audio range. dT=1/(f2-f1) I know that Nelson looked into this, and it became the biggest reason to not jump in and do it.
That said, I could see an interface board, something in the amplifier that would switch off the power to the amp PCBs if there was a big DC imbalance on the output, but am not sure if there is an easy solution to the frequency beat interactions.
Yes, what you suggest is actually possible, though you'd want to use 24v laptop supplies.
The reason you don't see it commonly has to do with 2 reasons,
1) there's a rather large problem if one supply fails, you'll see the entirety of the remaining DC supply on the output, essentially full power of the amp trying to suck the speaker all the way back, or push it all the way out until something in the speaker burns out. That's not a great failure mode. Similar happens if they don't power-up evenly, but not over as much time.
2) Although the modern supplies are getting quieter and quieter, and are absolutely good enough for the application, putting two in series is going to make for very interesting issues with the (independent) switching frequencies interacting and the beats falling down into the audio range. dT=1/(f2-f1) I know that Nelson looked into this, and it became the biggest reason to not jump in and do it.
That said, I could see an interface board, something in the amplifier that would switch off the power to the amp PCBs if there was a big DC imbalance on the output, but am not sure if there is an easy solution to the frequency beat interactions.
If I try building as 6L6 describes, I would prefer to build as 2 separate mono blocks. I have not pulled out my F5 boards since I bought them, and I am at work, so it will have to wait. I believe there are either 2 boards for the F5, 1 per channel. I will take a look at things and post later.
A point of clarification, as I’m re-reading the thread, I want to make sure you’ll need 2 laptop supplies per power supply.
If you are wanting to make monoblocks, the first step is to determine what you use for chassis and get two of them. Then you can figure out what you’ll need to do for PSU and what will fit.
Also, I’m not actually suggesting that you use laptop bricks for this project, due to the bipolar (dual rail) configuration of the PSU, in contrast to the ACA’s single rail.
If you are wanting to make monoblocks, the first step is to determine what you use for chassis and get two of them. Then you can figure out what you’ll need to do for PSU and what will fit.
Also, I’m not actually suggesting that you use laptop bricks for this project, due to the bipolar (dual rail) configuration of the PSU, in contrast to the ACA’s single rail.
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