Hello Copenhagen,
Even if it is 3 mm thick with a lot of holes inside it will bend.
A solution could be after knowing where the mounting holes for the iron will be to add some U shaped bars from front to back that will have some holes at equal distance as the ones in bottom plate.
You could also ask a professional company to bend the four sides up and weld them at the corners. With my new power supply i just described i used 3 mm alu and between the transformer ( 11 kilo) and the two chokes (2,5 kilo each) i did add two extra 3 mm alu plates starting under the transformer and ending under the chokes. There is still some bending if you lift up the chassis on one side. But with two hands it is reduced a lot.
I am not going to modify this power supply every month so for me it is ok. BUT if you need something that can moved around or be positioned on one of the sides to do '' maintenance '' better make it sturdy.
Greetings, Eduard
Even if it is 3 mm thick with a lot of holes inside it will bend.
A solution could be after knowing where the mounting holes for the iron will be to add some U shaped bars from front to back that will have some holes at equal distance as the ones in bottom plate.
You could also ask a professional company to bend the four sides up and weld them at the corners. With my new power supply i just described i used 3 mm alu and between the transformer ( 11 kilo) and the two chokes (2,5 kilo each) i did add two extra 3 mm alu plates starting under the transformer and ending under the chokes. There is still some bending if you lift up the chassis on one side. But with two hands it is reduced a lot.
I am not going to modify this power supply every month so for me it is ok. BUT if you need something that can moved around or be positioned on one of the sides to do '' maintenance '' better make it sturdy.
Greetings, Eduard
It is for the ACA.
I use 300 VA trafo to get a stable output voltage that does not change much with load. The chokes are 2A rated but when I picked them up I got the message that they are "over dimensioned" so 2.5A is no problem and they can take high peak current without the iron saturates.
As I make them as stand alone PSU's they could also be used for other projects.
The transformer company also makes transformers for the danish railways and what was surprisind also a lot of highend audio stuff. Also tube output transformers.
For solid state PSUs they mentioned Vitus Audio and Danish Audio Design which I dit not know. When looking at Vitus Audio I can recognize the epoxy cubes trafoes he showed me. Up to 3.5 kVA trafoes which indicates some kind of class A amps. I assume.......expensive stuff.....
Hello Paris?
Yes, I could order something......but I think a thick laminated wood base plate can do it. Wood is a fantastic material! ....the stiffness is great and easy to drill holes etc. Then later a case could be built around it. Also with wood......I can forget about "safety ground"......I think.....
Wow, a long way from 19V switcher to 40 kg linear PSU. Most quiet ACA around.
I thought my 24V CRC PSU equipped with 88000 uF was overkill.
Have fun [emoji16]
It is always difficult to find out what is "overkill" in audio
I only have 66.000 uF pr. side......
The goal was less then 1 mV ripple and I think the simulation is about 0.5 mV ripple. Many thinks this requirement is overkill for a SS amp. It probably is but I had so good experience with this type of PSU in my tube amp (in this case only a RCLC filter) that I wanted to try it also for a SS amp.
Hello,
I think the best way to improve the power supply is not adding more caps. It will make life much harder for the transformer and the rectifier .Because this amp is a single rail amp you can make a choke input with just one choke .
My home cinema amp also has a single rail but i had the opportunity to buy two 127 mH chokes for cheap so i use one on each side after the rectifier. I had a single ll2733 in the attic so used that one too.
A good quality capacitor from a respectable company isnt that cheap. A choke will last a lifetime and it will give all the other power supply parts an easier and longer life. AND when done right, taking care of the minimum current through a bleeder to make it work as a choke input that is, it will sound better.
Greetings, Eduard
I think the best way to improve the power supply is not adding more caps. It will make life much harder for the transformer and the rectifier .Because this amp is a single rail amp you can make a choke input with just one choke .
My home cinema amp also has a single rail but i had the opportunity to buy two 127 mH chokes for cheap so i use one on each side after the rectifier. I had a single ll2733 in the attic so used that one too.
A good quality capacitor from a respectable company isnt that cheap. A choke will last a lifetime and it will give all the other power supply parts an easier and longer life. AND when done right, taking care of the minimum current through a bleeder to make it work as a choke input that is, it will sound better.
Greetings, Eduard
power supply
I built a PS in an old Dynaco amp chassis for the ACA. I believe I have half as much capacitance as mentioned above. Looking at my output with a scope setting of 10mv/div I see nothing to worry about, no readable noise. I did use a 300va transformer I had, unwound to disconnect the center tap to parallel the windings. I believe the ACA amp was an
easy build, good sounding project, a real gift from Papa to help those starting the audio journey. Of course do what you will to make it what you want.
I built a PS in an old Dynaco amp chassis for the ACA. I believe I have half as much capacitance as mentioned above. Looking at my output with a scope setting of 10mv/div I see nothing to worry about, no readable noise. I did use a 300va transformer I had, unwound to disconnect the center tap to parallel the windings. I believe the ACA amp was an
easy build, good sounding project, a real gift from Papa to help those starting the audio journey. Of course do what you will to make it what you want.
The ACA is an amplifier for the beginning of a journey. An amp to teach the beginners that yes, you can build this stuff, yes, it actually works, and yes, it actually sounds really, really amazing!
The PSU is it's own pre-made unit to greatly simplify the process, but that's not a big sacrifice as switchers are getting better and better everyday.
The circuit is simple, to make it easy to build and understand. Is this done at the cost of some performance? One could argue that it is, but the reality of the sound and performance is that real Class-A has a quality all it's own that is impossible to reproduce with other topologies. That's the true magic of the ACA - it's small compromises are there to give you a performance unobtainable in any other way.
Does a M2 or Aleph J or BA-3 or whatever Firstwatt project sound "better?" In my opinion, yes... exactly as one would expect for the significant difference in time and effort, power, expense, etc... BUT Does that mean the ACA sounds "worse?" Unequivocally no. It's not worse, it's just smaller. It's got the magic. (But it's still just a 4W amp...)
Remember, when comparing Firsrwatt amps it's analogous to standing in a garage full of Ferraris and asking the question, "What is the most Italian sports car?"
They all are.
The PSU is it's own pre-made unit to greatly simplify the process, but that's not a big sacrifice as switchers are getting better and better everyday.
The circuit is simple, to make it easy to build and understand. Is this done at the cost of some performance? One could argue that it is, but the reality of the sound and performance is that real Class-A has a quality all it's own that is impossible to reproduce with other topologies. That's the true magic of the ACA - it's small compromises are there to give you a performance unobtainable in any other way.
Does a M2 or Aleph J or BA-3 or whatever Firstwatt project sound "better?" In my opinion, yes... exactly as one would expect for the significant difference in time and effort, power, expense, etc... BUT Does that mean the ACA sounds "worse?" Unequivocally no. It's not worse, it's just smaller. It's got the magic. (But it's still just a 4W amp...)
Remember, when comparing Firsrwatt amps it's analogous to standing in a garage full of Ferraris and asking the question, "What is the most Italian sports car?"
They all are.
Ok.....I will see when I have finished my ACA project. Looking just at the schematic compared with other FirstWatt project I would say that the Output cap and amount of NFB is a weakness compared to the other constructions. But in some way I like the output cap as this ensures no DC at the output. Also if something goes wrong I don't get the rail voltage at the output. In the old days NFB was a natural and a good thing to get lower distortion and lower output impedance. Since then everybody has tried to tell me that it is a bad thing to correct errors this way and not make every stage perfect from the begining. But if amp can deliver near perfect square wave from 10 to 100 kHz and has low 2nd harmonic as most dominant distortion I don't know what to believe......
Ok.....an obvious weakness is probably the relative low output power but I will get more than 4W as I go for a 24V PSU. The ACA requires the right speaker.
Italian sports car......Ferrari of course......but I like a Swedish Koenigsegg better......that is the ACA......I hope......then the M2 can be the Ferrari.
Ok.....an obvious weakness is probably the relative low output power but I will get more than 4W as I go for a 24V PSU. The ACA requires the right speaker.
Italian sports car......Ferrari of course......but I like a Swedish Koenigsegg better......that is the ACA......I hope......then the M2 can be the Ferrari.
I have had the ACA in full use since I completed it and cannot imagine a practical, audible upgrade from here. Coupled with excellent speakers it is really tough to beat. I'm using it as designed other than this benchtop 24V meanwell supply. No noise whatsoever with both blocks running off the same supply.
Given the right speaker, perhaps upward of 93db sensitivity and a wide ranger, the ACA is hard to beat by any Class AB amp. The magic in the vocal range and coherence through the spectrum of a Single Ended Class A can scarcely be matched by any other topology and configuration.
Only the bottom end may not be as "taut" as to your liking, but some folks prefer it that way.
Other FirstWatts in Nelson's offerings are the higher range of Ferraris in the garage.
Only the bottom end may not be as "taut" as to your liking, but some folks prefer it that way.
Other FirstWatts in Nelson's offerings are the higher range of Ferraris in the garage.
Hello,
The French in the past had a 8 watt called the monster. Sounded very nice with the right power supply and the right speaker. 93 db is low compared to the speakers the french are using.
High sensitivity and small amps with huge power supplies always sound nice to me.
Greetings, Eduard
The French in the past had a 8 watt called the monster. Sounded very nice with the right power supply and the right speaker. 93 db is low compared to the speakers the french are using.
High sensitivity and small amps with huge power supplies always sound nice to me.
Greetings, Eduard
I have had the ACA in full use since I completed it and cannot imagine a practical, audible upgrade from here. Coupled with excellent speakers it is really tough to beat. I'm using it as designed other than this benchtop 24V meanwell supply. No noise whatsoever with both blocks running off the same supply.
I rebuilt mine with one Meanwell LRS-100-24 for both channels, everything on same box. 24v unmodified. Completely silent. One week working, no problem at all and wonderful music.
I rebuilt mine with one Meanwell LRS-100-24 for both channels, everything on same box. 24v unmodified. Completely silent. One week working, no problem at all and wonderful music.
I'm also using the same Meanwell LRS-100-24, but running it through a cap multiplier to get even better channel separation. Even with the 4V drop in the cap multiplier, max draw is only 61W. So, the 100W PSU is a perfect match for the ACA - and cheap too, plus only one is needed for both channels.
