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Old 26th April 2010, 07:03 AM   #1501
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Quote:
Originally Posted by fredlock View Post
Andrea,

Sorry, I meant L1 and L2 was omitted as well as C4, C5, C9 and C10.

Would this heater power supply for the phono preamp applicable to the DACend? The 2.2ohms resistors and the bridge rectifier are too hot, can't stand it. This might be better that the original one. Please advise.
In thí circuit, I don't use C-LC before LT1084.
That is good!
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Old 26th April 2010, 07:59 AM   #1502
adamus is offline adamus  United Kingdom
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its almost the same, so i dont see much point in changing.

the 2.2r gets too hot, reduce them to 1ohm or use jumpers. use a big heatsink on the regulator, and a heatsink on the bridge.

Last edited by adamus; 26th April 2010 at 08:27 AM.
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Old 26th April 2010, 12:09 PM   #1503
Ekkeri is offline Ekkeri  Finland
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Quote:
Originally Posted by adamus View Post
Match cheap yellow or green leds to 3.8v for two in series (9v battery > 1k2 resistors > led, measure voltage over led, look for closest to 1.9v, then test them in series too for 3.8.
What LED did you use? I measured a few yellows and greens that I had, all 1.95-2V so pretty hard to get 3.8V from those..
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Old 26th April 2010, 01:18 PM   #1504
adamus is offline adamus  United Kingdom
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3.9v is fine. I just had a bag of really cheap yellows. you are testing with a series resistor too arent you?
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Old 26th April 2010, 01:30 PM   #1505
Ekkeri is offline Ekkeri  Finland
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Quote:
Originally Posted by adamus View Post
3.9v is fine. I just had a bag of really cheap yellows. you are testing with a series resistor too arent you?
Yep, ~5V & ~470ohm, so should be ~6mA. Those are really cheap 3mm yellows also, maybe I will find the lowest ones..

Is those R30-R33 needed in the I/V stage?
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Old 26th April 2010, 01:33 PM   #1506
adamus is offline adamus  United Kingdom
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r30-33 are not needed if you remove the inductor from the dac board and replece it with a wire jumper. They are needed if you have the inductor.
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Old 26th April 2010, 07:50 PM   #1507
Jogi is offline Jogi  Germany
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hi all,

as I have started to build, questions arise naturally...well, here is the first one, and maybe its already answered in the depths of this thread.
Its about the 33r resistors for the low voltage salas shunt, do they really have this value? I remember vaguely that there was a change, but I could be wrong also. Ernst ordered for these 3 places ( R1,7,13) 22R, but according to Andreas list its two 33 and one 27R, in Quanghao's list its two 33 and one 8-10 ohm..
So what comes in finally?

And I'm planning to use the HV Shunt as well, has anyone experiences with this? For example, how to set it up with a 250V transformer?
And, finally, is it enough cooling for those fets when they are bolted at the bottom of a steel enclosure ?

Thanks alot, also for the very helpful pics and posts of the lucky ones, who have finished the whole thing already.

Juergen
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Old 26th April 2010, 07:59 PM   #1508
adamus is offline adamus  United Kingdom
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for the analogue ps sections 33ohm should be fine, although i would use 27r and heatsinks on the fets.

for the 5v dig i settled on 11r. Too high resistance will mean the reg will drop out and you wont be able to adjust the voltage enough to give the tl431 enough headroom (you want to dial in 5.3v at least, 5.6 max, 5.5v optimum)

Best check is to ensure vgs on the second fet is not 0, if it is then no shunt current is flowing and poor regulation.

HV shunt you are on your own until completed builds come out.

Steel is not a fantastic conductor of heat, but you may get away with it. The heater reg gets very hot, and do heatsink the diode bridge. Its the hottest part on the build.
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Old 26th April 2010, 09:02 PM   #1509
Jogi is offline Jogi  Germany
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Adamus, thanks for this very helpful information.

With the shunt I will see, together with Ernst I will hopefully manage to get it together.
Will report,when everything is running.
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Old 27th April 2010, 02:43 AM   #1510
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Quote:
Originally Posted by Jogi View Post
hi all,

as I have started to build, questions arise naturally...well, here is the first one, and maybe its already answered in the depths of this thread.
Its about the 33r resistors for the low voltage salas shunt, do they really have this value? I remember vaguely that there was a change, but I could be wrong also. Ernst ordered for these 3 places ( R1,7,13) 22R, but according to Andreas list its two 33 and one 27R, in Quanghao's list its two 33 and one 8-10 ohm..
So what comes in finally?

yes you use 8-11R for one Salas shunt for Cs8414 and 74HC04.

And I'm planning to use the HV Shunt as well, has anyone experiences with this? For example, how to set it up with a 250V transformer?

Yes you use Ac 250 v for SSHV , and R 1 = 47R for set curent SSHV
Not V in only at 300V, and you can adjust V-out 270V for I/V tube 5687


And, finally, is it enough cooling for those fets when they are bolted at the bottom of a steel enclosure ?

Thanks alot, also for the very helpful pics and posts of the lucky ones, who have finished the whole thing already.

Juergen
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Group buy DAC-END R (ES9018) full assembled board
update 06/14/2013 :http://www.audiodesignguide.com/DAC32/index2.html

Last edited by quanghao; 27th April 2010 at 02:47 AM.
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