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Old 5th February 2010, 07:42 AM   #501
adamus is offline adamus  United Kingdom
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Quote:
Originally Posted by audiodesign View Post
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?
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Old 5th February 2010, 08:05 AM   #502
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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.
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Old 5th February 2010, 08:20 AM   #503
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[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!
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Old 5th February 2010, 08:24 AM   #504
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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.
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Old 5th February 2010, 09:51 AM   #505
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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)
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Old 5th February 2010, 09:53 AM   #506
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165 looks low to me.
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Old 5th February 2010, 10:26 AM   #507
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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
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Old 5th February 2010, 10:40 AM   #508
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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.
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Old 5th February 2010, 10:46 AM   #509
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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).
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Old 5th February 2010, 11:39 AM   #510
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Default Power transformers - idea

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
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Last edited by apelizzo; 5th February 2010 at 11:59 AM.
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