OLD THREAD DAC End by Andrea Ciuffoli

[adamus]

yep pefect

[Salas]

I am no use anymore then.

[adamus]

its odd, if i cut all the 10ohm dac resistors out, then add them back in one by one the voltage from the reg drops and drops, until it bottoms out at 5.15ish

with just one 10ohm in the 10ohm drops 250mv. this is without dac chips so i dont know whats loading. the other oddity is that the reistance between the gnd and 5v digital is only 400 ohms. MEasureing the current between reg and board, its sits pretty much at the max the reg is set for, hence it dropping out of regulation i think.

Cant see a short. next thought is a leaky cap or a short somewhere.

[apelizzo]

************************************************** ****************
DAC end succesfully tested. All voltages are spot on 5.0V <10mV difference between all 5V voltages

No problem with relay EVERYTHING works really well.

Tested sound -> very well balanced and natural.
Best sound obtained with Sprague PIO HyperQ 1uF 300V, also Russian PIO OTK is ok (nice detail) but I have to say both are for me better then Obbligato 1uF 630v MKP. I noticed Obbligato somehow sounds with no soul, the detail is grainy. I don't like it, that's just my taste.
PIO Sprague sound "exciting", very relaxed and pleasant and reserve "surprises" to the sound that gives very nice sound stage.
************************************************** ****************

[adamus]

good to hear.

Interesting comments re obbligato. When you say grainy i say resolving. I always find russian pio a bit.... warm and relaxed (as you say).

ALl my voltages are spot on at 5v.... i just cant get +5.5v on the digital reg.

Could you do me favour and measure the resistance between the digital + and ground on the dac board. it could help help me.

bizarre thing is it sounds wonderful, yet something must be wrong.

[apelizzo]

Originally Posted by adamus

good to hear.

Interesting comments re obbligato. When you say grainy i say resolving. I always find russian pio a bit.... warm and relaxed (as you say).

ALl my voltages are spot on at 5v.... i just cant get +5.5v on the digital reg.

Could you do me favour and measure the resistance between the digital + and ground on the dac board. it could help help me.

bizarre thing is it sounds wonderful, yet something must be wrong.

I adjusted all Salas shunt at 5.3V. All the voltages on DAC chips are 5.0V with <10mV differences due probably to some tolerances on 1K resistors and or TL431. When I ordered the TL431 I was confused because there are some at 4.9V . I bought those 5V for this project.

Can you be more specific about your request. Which resistance you want me to measure?

[adamus]

with it off, literally measure the resistance between the 5vdig input and the ground (terminal block).

[apelizzo]

Originally Posted by adamus

with it off, literally measure the resistance between the 5vdig input and the ground (terminal block).

372 Ohms 373 Ohms with two different multimeters

[adamus]

me too, exactly.

that rules out a short or leaky cap i think. You know what, i think i will just leave it. The 5v lines look clean on the scope, nothign is gettign hot. If i adjust the salas shunt just below its max then it regulates well. Sounds great.


My thoughts on the sound

With jan phillips its a warm dac, no doubt about it. Bass has more presence than my cambridge audio dac magic. So much so i had to pull the speakers from the wall a little further.

Mids are typically nice for a tube stage

Highs and detail are there. Not as crisp as the dacmagic, but AB'ing between them (which you can do with dacmagic, it has a spdif pasthrough, so i have daisy chained them) the dacmagic doesnt sound as natural. This is with the 120uh filter in, so i may remove it and retest.

The Dacend is a relaxing listen, no fatigue at all (which i can get with the dacmagic).

image is definatley more coherent with the dacend. Speakers dissappear more easily.

[apelizzo]

Break-in setup, I still have to find out how to install the large Sprague.

The only criticism to this project is for the power supply for the heater is a little too compact. In Australia in summer it will get very hot then reliability becomes an issue.
Look the heatsink for DC power to heater on my previous AD1865 DAC (using 6n6P as rectifier, 5670 and 6n6p cathode follower).