Surely 'Chassis Ground' is made at the DC input socket? Assuming you use the full kit and install it correctly (steps 29 - 31).
No secret - just preparation.
Make sure the tags or scoop are perfectly clean. Now wipe the soldering iron tip and 'tin' it, wait a second or two and then load a small 'blob' of solder on the tip - now the blob increases the surface area and thermal conductivity when it touches the parts to be soldered. Apply solder to the joint as normal.
Find a spare RCA plug and fit it to the socket you are soldering. This helps keep the plastic parts in shape if it all gets a little too warm...
C2 will not be the cause of this fault. It allows the AC output voltage to add to the DC voltage used to drive the gate of Q2. Its a very old technique called bootstrapping.
So no click, no noise.
The DC voltages may be correct but lets confirm the current is flowing. Did you try this ?
You should be seeing around 0.4 volts across R1 and R2 and around 0.55 volts across R3 and R4. The FET's should be hot. I think your measurements above are showing that but lets be sure.
With the amp OFF you should be able to measure your speakers DC resistance by measuring the resistance across R14. This check will go a long way to confirming the speaker is physically connected to the correct points on the PCB. This value will be low, perhaps just 4 to 10 ohms and should be identical to the value you see measuring across the speaker alone.
Lets see what those tests show.
Thanks for you answers!
I will do some measurements at work to see the difference for the smps and CM.
I use pure silver 999 for this. It does not have the emphasis on high freq like sterling silver has. I also use multi strands of 0,5mm wire. Four or more. That gives a lot more body to the sound. Adding a strain of pure gold also does some magic to every aspect of the music.
I changed it to a brass one just to be safe and to keep both amps the same. It didn’t feel right seeing the ground connected to the eyelet of the pcb and no connection to the chassis. Also the difference between the two amps, one with and one without a brass pin feeled odd.
Ok....
Just now i decided to make the final test to my ACA, to plug it in to my pre and load frequency on it!
And what i can say?
1st of all i almost cried.... as told before, i have been dreaming about having a class a for i would say 16-17 years now. For one or another reason i could not make it.
But now, when i can afford it, and went for it, even if is a spoon fed build, i am so happy that words can match it.
I never thought i would solder and make things work at 1st time, i was sure it would blow up as my electronics level is basic at best. I can look and understand a circuit but no idea on it's dark magic and do more than drawn by the author.
So now i am listening to my beloved jazz in my poor man system and i am defiantly amazed on how this "little" ,"low power" amazing piece of engineering is able to throw out.
My speaker system, for now, is an old Bowers and Wilkins Solid Ovale that i am sure can not make it to the definition of this amp, but for me, nevertheless, with my ACA it is already a noticeably upgrade. They are 87db sensitivity and freq response from 57-20khz but i am sure when i plug in a real set of speakers it will be magic.
So hands down to Mr Pass and all involved in this ACA project.
I can not vouch more for you, i am deeply touched by you all and keep in mind you just made a person happier in earth!
Next projects:
- i think that the bride of zen is the pre i want to build. I will need to speak to people about it but i think is the right path.
- then its speaker time, or maybe at same time of the pre, dont know... the speaker project is something i will do in the near future for sure. I know nothing about wood working but i will learn and make it!
- i have bought like 5-6 years ago the parts for the F5 but not the chassis yet.
Now that the diy power amp bug bitten me i can't stop When pre and speakers are done, comes the time to finish my F5
Just now i decided to make the final test to my ACA, to plug it in to my pre and load frequency on it!
And what i can say?
1st of all i almost cried.... as told before, i have been dreaming about having a class a for i would say 16-17 years now. For one or another reason i could not make it.
But now, when i can afford it, and went for it, even if is a spoon fed build, i am so happy that words can match it.
I never thought i would solder and make things work at 1st time, i was sure it would blow up as my electronics level is basic at best. I can look and understand a circuit but no idea on it's dark magic and do more than drawn by the author.
So now i am listening to my beloved jazz in my poor man system and i am defiantly amazed on how this "little" ,"low power" amazing piece of engineering is able to throw out.
My speaker system, for now, is an old Bowers and Wilkins Solid Ovale that i am sure can not make it to the definition of this amp, but for me, nevertheless, with my ACA it is already a noticeably upgrade. They are 87db sensitivity and freq response from 57-20khz but i am sure when i plug in a real set of speakers it will be magic.
So hands down to Mr Pass and all involved in this ACA project.
I can not vouch more for you, i am deeply touched by you all and keep in mind you just made a person happier in earth!
Next projects:
- i think that the bride of zen is the pre i want to build. I will need to speak to people about it but i think is the right path.
- then its speaker time, or maybe at same time of the pre, dont know... the speaker project is something i will do in the near future for sure. I know nothing about wood working but i will learn and make it!
- i have bought like 5-6 years ago the parts for the F5 but not the chassis yet.
Now that the diy power amp bug bitten me i can't stop
When pre and speakers are done, comes the time to finish my F5 
I just looked at "bride of ZEN". I don't think it is a good match with ACA if you have the vol. control at the output (as in the original schematic). ACA needs a pre-amp with low output impedance. If not the amount of NFB will be affected. At least I think you should make the "bride of ZEN" with vol. control at the input (which seems to be a real option to do that).
Another ACA build completed and working first time! No pictures as it looks pretty much like all the others. Just one channel at the moment as I didn't have the patience to finish wiring up the second one - but it sounds lovely in mono powering a Linn 140.
UK import duty was a nasty shock, but hey, ho - pride of ownership in a self-build (even such a simple one) and a sweet Class A sound are worth it.
Thanks to Mr Pass and all who made this possible.
UK import duty was a nasty shock, but hey, ho - pride of ownership in a self-build (even such a simple one) and a sweet Class A sound are worth it.
Thanks to Mr Pass and all who made this possible.
I agree.
fred0,
If I were you in your position with your level of experience I would happily build a BA-3 as a preamp. That would go well with not only your current ACA but your future F5 aspirations. Besides, there is already a build guide and support here:
http://www.diyaudio.com/forums/pass-labs/258022-ba-3-preamp-build-guide.html#post3968063
Best,
Anand.
It was termed 'duty' - could have been VAT I suppose. The whole system is a lottery - skewed by the courier or Royal Mail earning a collection fee. Refund claims are usually obstructed until you give up.
Ok....
i have bought like 5-6 years ago the parts for the F5 but not the chassis yet.
Now that the diy power amp bug bitten me i can't stop
Congratulations on the ACA build!! Nice they you are enjoying it
The F5 is a very good amplifier and well worth the build, I built one and it is my favourite amplifier.
Regards,
Matt
In my country Belgium import duty is approx 6% or so, but on this value a sale tax of 21%, and approx 25 euro customs cost. Under approx 22 euro, there is no extra cost. I think it would be cheaper to ship the components in 5 packages of 20 euro each. On the case we pay Italian vat, 22% i think.
monitor ct225
Congrats FredO for successful build ACA.
I like a little speaker, resonable priced, for listen voices, jazz or brass music that sort was engaged and dynamic played. I know as all ways any better possible.
The kleiner Schreihals "little squaller" called also 87dB, but starts at 70Hz .
You can add a little Sub like FT7.
FirstTime 7 - Ausgabe 1 2008 - Lautsprecherbau-Magazin 2008 | Lautsprecherbau - Lautsprecher selber bauen
Congrats FredO for successful build ACA.
I like a little speaker, resonable priced, for listen voices, jazz or brass music that sort was engaged and dynamic played. I know as all ways any better possible.
The kleiner Schreihals "little squaller" called also 87dB, but starts at 70Hz .
You can add a little Sub like FT7.
FirstTime 7 - Ausgabe 1 2008 - Lautsprecherbau-Magazin 2008 | Lautsprecherbau - Lautsprecher selber bauen
Attachments
Thanks a lot for all the people that posted ideas about speakers and explain me the cons of the pre i was thinking about.
For the pre i will carefully start now to learn why and what to do based on some posts and the info i will research here.
As for speakers i would like to ask one thing:
Dont really know why but i like the idea of a Fostex fe206 and the proposed cabinet.
Later i would add the fostex tweeter to them.
Do there speakers perform well with most class a amps like aca, f5, etc?
Are they worth the effort to build the cabinet and people that build them are really happy with them?
Do they rock @ jazz music?
For the pre i will carefully start now to learn why and what to do based on some posts and the info i will research here.
As for speakers i would like to ask one thing:
Dont really know why but i like the idea of a Fostex fe206 and the proposed cabinet.
Later i would add the fostex tweeter to them.
Do there speakers perform well with most class a amps like aca, f5, etc?
Are they worth the effort to build the cabinet and people that build them are really happy with them?
Do they rock @ jazz music?
Dumb question... pretty much done with my mono blocks, built a lightbulb dim tester... time for the moment of truth... electricity!
Assuming the magic smoke stays inside... I assume I should bias them with the switch on back DOWN so they are stereo amps... or can you bias in either mode as well? Aka switch on back UP for mono block. I chose the front power switch option
Assuming the magic smoke stays inside... I assume I should bias them with the switch on back DOWN so they are stereo amps... or can you bias in either mode as well? Aka switch on back UP for mono block. I chose the front power switch option
Second Question: I powered up through a dim lightbulb tester. I took hot from mains into hot on bulb, then neutral out of bulb into hot of power receptical, then neutral back to mains. Also hooked up the ground.
On both amps using a 40w and a 60w halogen incandescent bulbs... neither bulb lights up and stays on, but both 40w and 60w bulbs flicker or pulse....
Am I in trouble? Are things ok? Please advise, thanks
On both amps using a 40w and a 60w halogen incandescent bulbs... neither bulb lights up and stays on, but both 40w and 60w bulbs flicker or pulse....
Am I in trouble? Are things ok? Please advise, thanks