OLD THREAD DAC End by Andrea Ciuffoli

[adamus]

Originally Posted by audiodesign

The secondary for the filaments should be 8v 3A instead of 9v 1A.

and the 2 x 2.2ohm 3w resistor should be 2.2ohm 5w

3A seems high. are the regulators really that lossy?

[adamus]

I am going to order a customer toroid for this. It will work out cheaper than buying several R-cores.

Are these specs right

HT 0-230 @ 0.15 amps
filament 0-9 @ 3A
salas1 0-12 @ 0.5A
salas2 0-12 @ 0.5A
salas3 0-12 @ 0.5A

Thanks

Adam.

[quanghao]

[QUOTE=adamus;2074424]I am going to order a customer toroid for this. It will work out cheaper than buying several R-cores.

Are these specs right

HT 0-230 @ 0.15 ampsanh dang ban la chat nhe

filament 0-9 @ 3A

salas1 0-12 @ 0.5A
salas2 0-12 @ 0.5A
salas3 0-12 @ 0.5A

THat is Ok

But R-cores 3 A is not good! not enough mA, because it is less, I see that!

[adamus]

yes. if you went the ebay Rcore route then you'll need three transformers. Shipping would get very expensive.

I had a quote from a british firm for £75 for a custom toroid.

I just Pm'ed a guy from the ukraine for a price, i get back to everyone with the result if favorable.

[vzs]

Isn't the transformer used by Andrea Ciuffoli in DAC End good for this one as well?

DIYCLUB
R26-90 primary 115 X2 :0-165V(0.1A); 0-9V X2(1A)

[adamus]

165 looks low to me.

[audiodesign]

Yes, 165V is too low.

In the DAC End ver. 1 are necessary only 200V dc because all the power supply voltage go on tube anode.

In the DAC End ver. 2 we must use 265-275V to get a low distortion because many voltage are lost on anode resistors and on the anode there are about 180v.

See in previous page my choice for the transformers.


Here another good source for OS-CON
V.A. Hi Fi www.VocativeAudio.com The advanced Hi-Fi shop in China-Hong Kong

[audiodesign]

If you are searching a good custom trasformer manufactor I suggest the Italian Bartolucci

Ricerca e Sviluppo - Bartolucci Transformers - Products List - Power Transformers Toroidal

The price and the characteristics are very interesting.

I have payed more the 2 Chine r-core.

[audiodesign]

To get the best performance by this DAC project it is necessary use on DAC output module a 200ohm MK132 Caddock resistor.

For all the other resistor on the signal path has been considered good a parallel of two normal 1% metallic oside resistor with inverted phase to compensate some of their inductance.

Also the four 2w resistors must be connected with invereted phase (colors).

[apelizzo]

In my project I will use the following 6 caged PCB potted transformers (easy to find, compact and doesn't look messy):

1) 30VA PCB toroid 240pri 9+9sec parallel connected to 2) 9+9 parallel to get 240VAC for HT. (PRI-SEC-SEC-PRI)

3) 30VA (same as 1) PCB toroid 240pri 9+9sec parallel for DC HEATER

4) 10VA PCB toroid 240pri 9+9sec parallel to SALAS DIGITAL

5) 10VA PCB toroid 240pri 9+9sec parallel to SALAS ANALOG +5

6) 10VA PCB toroid 240pri 9+9sec parallel to SALAS ANALOG -5