Hi,
Anyone here using 2x20v instead of 2x18v transformer?
Considering it will have a voltage drop during filtration, especially for the bridge diodes.
(18v x 1.4142)-2.4v = 23v
(20v x 1.4142)-2.4v = 25.8v
2.4v is commonly voltage drop after bridge diodes (1.2v per diode)
If aleph J need 25v then 2x20v transformer will be better I think.
Anyone here using 2x20v instead of 2x18v transformer?
Considering it will have a voltage drop during filtration, especially for the bridge diodes.
(18v x 1.4142)-2.4v = 23v
(20v x 1.4142)-2.4v = 25.8v
2.4v is commonly voltage drop after bridge diodes (1.2v per diode)
If aleph J need 25v then 2x20v transformer will be better I think.
Finished collecting some stuff
Any suggest for the output transistors?
Some people consider FQA series better than IRFP
What do you think?
If you don't me saying, you have been a bit shy with the solder, you should have a good joint on both sides of the PCB with a 2-sided layout.
The similar F5 works fine at 20V x 1.414, the outputs just get a bit hotter.
18V is the normal transformer break point here in the UK. 9V then 12V then 15V then 18V then 24V then skywards.
It is double sided through holes
I think one side solder is fine for through holes
So, it is only because no 20v transformer at the market right?
I am planning to order a custom transformer for aleph J.
Jean - For heatsink size, the 4U chassis from the store should be considered the absolute minimum. These amps do get hot.
Wengtech - A 20+20V transformer will be fine. It's going to run a bit hotter, but you can always turn down the bias a bit if needed.
Your soldering looks fine... although you are missing some transistors...
Wengtech - A 20+20V transformer will be fine. It's going to run a bit hotter, but you can always turn down the bias a bit if needed.
Your soldering looks fine... although you are missing some transistors...
Wengtech - A 20+20V transformer will be fine. It's going to run a bit hotter, but you can always turn down the bias a bit if needed.
Your soldering looks fine... although you are missing some transistors...
Thank you for clean answer. Got it now. Playing with bias.
And yes you are right, it is hard to find original j74 today, china market still have plenty but not sure for originality.
Do you know what is the difference between original and fake one? In measurement for example, or in the sounding for sure.
Check with Spencer for genuine J74's or try the Linear J74's from the store.
FET Audio | Hi-End Audio Projects
Jim beat me to it.
FET Audio | Hi-End Audio Projects
Jim beat me to it.
Aleph J from scratch - part 1
so... I started my build, and i would like to show, how i made my pcb's real diy (just kidding).
I start off, drawing the schematic into diptrace(pcbmaking software).
Sometimes i have to make my own parts, with footprints so that the parts fit to my needs. Eventually i made a 2sj109 cause i am so lucky that i got 4 of them.
The layout is then printed, mirrored and cut out.
In progress :
Final. Next move is to etch the pcb.
SUCCESS !
This layout is a bit trickey, as i have to make it double sided...
When i make double sided i drill the holes surrounding the top layers, so as to avoid shorts...
Here final picture today... Toplayer of pcb.
I will post again, when i move on...
// Jesper
so... I started my build, and i would like to show, how i made my pcb's real diy (just kidding).I start off, drawing the schematic into diptrace(pcbmaking software).
Sometimes i have to make my own parts, with footprints so that the parts fit to my needs. Eventually i made a 2sj109 cause i am so lucky that i got 4 of them.
The layout is then printed, mirrored and cut out.
In progress :
Final. Next move is to etch the pcb.
SUCCESS
!
This layout is a bit trickey, as i have to make it double sided...
When i make double sided i drill the holes surrounding the top layers, so as to avoid shorts...
Here final picture today... Toplayer of pcb.
I will post again, when i move on...
// Jesper