Yes.
This is looks like originally :
Digital RCA > on board input > solder blob (bypass connection to pulse traffo input) > input cap
Then we change for adding a pulse traffo :
Digital RCA or Some wire > on board input > pulse traffo input (cut the blob first) > output from pulse traffo > input cap
You can see that the solder track from on board input is connected to the pulse traffo input and the output is linked to the input cap....
Which inputmass.....???
As for the under side...I just remove the connection....no issue here....I'm happy with the Newava traffo suggested in the early part on this topic...
Like Bill said, the mass/earth/ground from the input has to be seperated from the mass/earth/ground from the DAC-board by the transformer.
It looks like you didn't have to do much to do this so that is why I think this is done by disconnecting the inputconnector from top and bottom of the board. You did not check this by chance?
from what i can recall, the mass/grounding connection for the digital input is connected to the grounding of the spdf cable. i trace back the grounding track and it leads to grounding of the input pulse transformer next to it not to the board grounding....so that's right. so far i haven't experience any noise from it.... does this version is similar to any dac you have since there so many version here from the chinese supplier...
I asked the same question and they said I need to apply a hack to make it work at 192.. which is stranged becuase the seller did not mentioned anything about no hack to make work at 192khz. check post 1540 on page 154
Just picked up some 0.1uF poly caps. These things are a lot bigger than I expected(1/2"x 1 1/4") Does 0.1uF seem right? The schematic I have isn't clear(post 1567). I can't make out if it's 0.1uF or 0.1nF.
That is the right size but if it's for the digital input it should be a ceramic cap, not poly, and they are tiny compared to polys. They should be NPO, X7R type.
Thanks Bill.
I already installed it with a poly(orange drop) cap. Did a quick listen last night and it sounded good. I'll pick up some ceramics but in the meantime what are the consequences of using a poly cap?
Chas,
As respects using opamps for this big DAC kit as well as the smaller DAC kit in the output circuit; IMO the OPA2107's gave the best overall sound.
The LME49860's pretty sound similar to the 4562's; clean and fast.
The 2107's has a hint of that analog "tubey" sound; which may be good or bad, depending on your taste.
The opamp versions with the metal case have slightly lower noise.
The transformer output is the way to go with this DAC; as the tons of posts note here.
I'm still out as far as the transformers on the small DAC kit; the effect there was not so drastic as using them with the big DAC.
Cheers
My first impressions with the pulse trafo are that the bass has somehow increased. Is this possible? Details don't seem to be MIA but for a minute there it felt like I was listening to the A-20s.
I liked the balance of my DAC with the little japanese(Ramsa) trafos so I'll have to take the time and live with this new setup to see if in fact there really is more bass or if it's just my ears playing tricks on me.
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Swapped the poly cap for a ceramic one and temporarily put in a 100R(didn't have any 75Rs on hand) across secondaries.
It's sounding great. Is it better than without the trafo? I honestly don't know. One thing though - no more heavy bass - in other words balance seems to have returned to normal.
Has the trafo settled? (I know that Lundahl output trafos are notorious for having a long break in period.)
Is it the ceramic cap?
Is it the resistor?
Where my ears playing tricks on me the other day?
Was it the bass from the kids downstairs listening to hip hop that was resonating through the floor and muddying up the sound?
Whatever.
I think I might try and install one of these on my Squeezebox's digital output. Apparently it's a worthwhile(inexpensive) mod.
It's sounding great. Is it better than without the trafo? I honestly don't know. One thing though - no more heavy bass - in other words balance seems to have returned to normal.
Has the trafo settled? (I know that Lundahl output trafos are notorious for having a long break in period.)
Is it the ceramic cap?
Is it the resistor?
Where my ears playing tricks on me the other day?
Was it the bass from the kids downstairs listening to hip hop that was resonating through the floor and muddying up the sound?
Whatever.
I think I might try and install one of these on my Squeezebox's digital output. Apparently it's a worthwhile(inexpensive) mod.
@McCrackers
I thought there already is a 75 ohm resistor standard on board?
Then now your impedance is too low and you'll get some extra jitter I presume...
About the cap I understand that a ceramic has a more uniform resistance at the frequencies we are dealing with here (2x16x44kHz and higher).
Interesting the way it sounds to you!
BTW I ordered a lundahl 1572 too, hope it improves the sound still further!
Gerard.
I thought there already is a 75 ohm resistor standard on board?
Then now your impedance is too low and you'll get some extra jitter I presume...
About the cap I understand that a ceramic has a more uniform resistance at the frequencies we are dealing with here (2x16x44kHz and higher).
Interesting the way it sounds to you!
BTW I ordered a lundahl 1572 too, hope it improves the sound still further!
Gerard.
I see. In that case I'll try without the R. Hopefully I'll notice an improvement.
Theoretically - if I placed one(trafo) on my source(Squeezebox) would the one on the DAC then become redundant? If so I might just remove it and move it over to the SB.
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I know this is going to sound weird but the DAC had been unplugged since this morning so I just snipped the R away and plugged it back in. Now it seems louder and that "huge bass" is back. I have a feeling these Lundahls do need to warm up a bit before sounding their best. Either that or I need a vacation from DIY.