Experience with this DIY DAC ?

Re: Re: LL1690 diagram and capacitor

legarem said:


Cirrus use a 50 khz low pass filter on their own evaluation board so I tried this low pass filter with my dac and loved it. The tonal balance is better with the 50khz low pass frequency

Simply use two 100 ohms and a .015 uF cap and it gives a 53 khz low pass frequency.


I have been doing some listening with different filters on my Tamuras.

On the primary, I have tried;

A - 270 Ohm resistors from each DAC output (+ & -) with 2000pF cap in between primary inputs (= 147kHz cutoff, like Jensen circuit, louder)
B - 2 x 1K resistors from each DAC output (+ & -) with 470pF cap in between primary inputs (= 169kHz cutoff, legarem's original recommendation, quieter)

On the secondary I have tried;

C - 1K resistor in series with 1200pF cap, between the secondary outputs (+ & -) (as close as I could get to Jensen circuit, which is ~50KHz cutoff filter)
D - 680 Ohm resistor only, between the secondary outputs (+ & -)

I like B and C together - it's the most organic combo in my setup so far.

I can't help feeling there is more to squeeze out of this DAC - any more ideas welcome!
 
I never thought using the USB input of this dac

Yesterday, I bought a Mac mini and tried many encodings for ripping cds

I will probably become an addict of music server soon. My CEC TL51X transport is 'perhaps' outclassed by the Mac mini.

I'm still amazed because before yesterday, I had great doubts about this technology.
 
Using the Tamuras, I am currently using 680ohm resistors on each of the DAC inputs with a 2200pf cap across them - F = 51Khz, and a 680ohm across the secondaries.

I really like this configuration. I had previously used the 1Kohm resistor with a 4700pf cap, but I was getting lots of dropouts.

Now I have no dropouts, and I discovered more detail in my music.
:)


BTW - I am using the SMD version of this board with the CS4397

I might try a few different brand resistors. I am currently using Allen Bradley 1/2 watt. I'd like to try the Mills and also some Kiwames.

Thanks to all who have contributed here I have a very nice little DAC.
 
fordgtlover said:
Using the Tamuras, I am currently using 680ohm resistors on each of the DAC inputs with a 2200pf cap across them - F = 51Khz, and a 680ohm across the secondaries.

I really like this configuration. I had previously used the 1Kohm resistor with a 4700pf cap, but I was getting lots of dropouts.

Now I have no dropouts, and I discovered more detail in my music.
:)

fordgtlover, 2 questions!
1 - What are dropouts?
2 - What is purpose of the 680 Ohm resistor on the secondaries? I tried it but wasn't sure why I was doing it!
Thanks
 
hoverdonkey said:


fordgtlover, 2 questions!
1 - What are dropouts?
2 - What is purpose of the 680 Ohm resistor on the secondaries? I tried it but wasn't sure why I was doing it!
Thanks


1 - The dropouts are when the music would dropout briefly - usually only for less than maybe half a second, but it was annoying. I'm not sure what caused it, but it has now stopped. The only thing I changed were the resistors and the cap on the primary.

2 - Perhaps there is someone here with far more knowledge that I have who can explain this.
 
hoverdonkey said:

What is purpose of the 680 Ohm resistor on the secondaries? I tried it but wasn't sure why I was doing it!
Thanks

As the transformer is a 600 to 600 ohm transformer, the 680 ohm resistor shunting the secondary is the optimal load for this transformer and you get near 600 ohm of impedance in the primary.

I never experienced the 'dropout' mentionned when I used 1K resistors. With 1K, resistors, the gain is a little on the low side.
 
Bill Fuss said:
The secondary load is supposed to eliminate ringing(resonance) but an RC filter does a much better job without loosing as much signal.
Read some of Jensen's white papers on their website, secondary loading is not beneficial to OP transformers.

Bill


With the Tams, I tried many secondary loads with a scope and by ear.

Near 600 ohms I got the best results.

How to calculate a RC filter to correct the ringning ?

I search about this topic and it seems that this is not an easy task to design.
 
well, i have 680R across the outputs of the tamura, i have to admit that i am still not happy with the sound, althought all i have to compare it to is a lite audio dac 60 which used the burr brown 1704 and a tube output. however i have a tube preamp now and did not feel the need to go down the tube output route for this dac.

i will say that i have not connected the black ground lead from the tamuras, will this make a difference? i guess i should just try it, but i have read conflicting reports about the overall grounding of this dac, i currently have no ground from the mains connected to the dac, i read that mains earth could be connected to the center of the 15, 0 15 rails. And then where would i take the ground from the tamuras to? other than the signal ground?
and would the type of resistors used in the tamura output and input affect the sound massively?

i don't know what it is about this dac but it just seems a little weak the way i have it configured at the moment, i know i must have done somethng wrong as i keep hearing great things about this dac in this thread, and i trust you all!!

cheers stuart
 
surfstu said:
legarem:

i used your original circuit for the tamuras (without connecting the black wires from tamura), which i appreciate by the way.....

but am i to beleive you have changed the low pass filter now?

stuart

Here is my new setup

Can you describe what's wrong with the sound ?
 

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New version

Seems there is a new version of this kit:
NEW Version 24bit/192Hz DAC DA CONVERTER W/ USB Kit,
it now looks identical to gigaworks module as far as I can see. and now has the Daughter Board design for the CS8421 and USB support but apart from that I can not see anything to justify the near $50 price hike over the plain NEW BIG 24bit/192Hz HI-FI DAC DIY KIT,ASSEMBLED MODULE. can anyone see any other differences, is the Daughter board the way to go, "i will be using it in up sampling mode".

Thanks