Hello Doede,
I am presently building a V3 version and wonder what voltage value transformer to buy for the PSU. In any case it will be minimum 50VA as I already heard the effect of more power in the transformer on my current 8 decks DDDAC (V1 V2 mix).
As I had to tweak, with you help, the old PSU when I went to 8 boards, Today I prefer asking before buying my transformer. (Toroidy supreme audio grade in mind)
From PSU Building instructions:
Optional chokes
Suggestions are between 50mH and 1H – as long as the DC resistance is below 4 Ohm. This applies, when used with the DDDAC1794MK3 board (1 or 2 boards)
Maximum current output
The PSU can deliver easily 1A or more. But with the delivered heatsinks it is intended for maximum two DDDAC1794MK3 DAC boards, where redominantly the analog section (9 Vdc) is drawing up to 200mA per Board. Two boards are below 400mA and perfectly safe when a 12 Vac transformer is being used. For higher currents increase of heatsink size is necessary! This is DIY experiments…
My understanding:
A 4 Ohms choke will add 1.5 Volts ( 0,22 resistor out ≈ +0,1V) drop for 2 boards and 3,1V drop for the silly boys like me who may use 4 boards.
In the chapter about old PSU tweaking you stated a 5,5V headroom is needed.
Guessing it is still same requirement, needed headroom is 8,6V with four boards if I am correct.
My question is:
Will a "powerful" 2X12V transformer still do for the task when switching to 4 boards or do I need a bit more voltage?
Thank you for advising.
PS: The kits are a pleasure to build with amazing board quality. Thanks!
I am presently building a V3 version and wonder what voltage value transformer to buy for the PSU. In any case it will be minimum 50VA as I already heard the effect of more power in the transformer on my current 8 decks DDDAC (V1 V2 mix).
As I had to tweak, with you help, the old PSU when I went to 8 boards, Today I prefer asking before buying my transformer. (Toroidy supreme audio grade in mind)
From PSU Building instructions:
Optional chokes
Suggestions are between 50mH and 1H – as long as the DC resistance is below 4 Ohm. This applies, when used with the DDDAC1794MK3 board (1 or 2 boards)
Maximum current output
The PSU can deliver easily 1A or more. But with the delivered heatsinks it is intended for maximum two DDDAC1794MK3 DAC boards, where redominantly the analog section (9 Vdc) is drawing up to 200mA per Board. Two boards are below 400mA and perfectly safe when a 12 Vac transformer is being used. For higher currents increase of heatsink size is necessary! This is DIY experiments…
My understanding:
A 4 Ohms choke will add 1.5 Volts ( 0,22 resistor out ≈ +0,1V) drop for 2 boards and 3,1V drop for the silly boys like me who may use 4 boards.
In the chapter about old PSU tweaking you stated a 5,5V headroom is needed.
Guessing it is still same requirement, needed headroom is 8,6V with four boards if I am correct.
My question is:
Will a "powerful" 2X12V transformer still do for the task when switching to 4 boards or do I need a bit more voltage?
Thank you for advising.
PS: The kits are a pleasure to build with amazing board quality. Thanks!
Looks like their site is a bit erratic. Sometimes it works, sometimes it times out. Oh well.
Thanks for the feedback Tristan (and your patience with the small error in your kit
)You are correct with two boards. The double boards draw 400mA, hence the 1.5V drop with 4 Ohm choke.
Without choke, with a solid 2x12Vac transformer, you will have a (measured by me) headroom of 7,7V. so when using a choke with 1,5V drop there is 6,2 left over which is OK (!)
BUT.....
If you are now doubling the boards again to 4 boards, you are getting into the critical area of too little headroom (4.7V).
My suggestion would be, IF you want to go for 4 boards (like the "old 8-deck"), you should use two PSU.
In that case you could actually do a true 2x mono set-up "PSU1-2xboards-Right" and "PSU2-2xboards-Left"
But for now, you should be fine with a 50VA transformer 2x 12Vac