small correction on: "This will draw a bit more current from the dac " ...
The DAC has a current source as output. This means another value of R will only result in another DC bias and AC output. The current never changes. it is fixed. So IF there is a change in sound it has not do with this.
what will happen, is that the d2 component of distortion goes down as you lower the resistor (other direction when it gets larger of course) I would suspect this more as a sound changer. but the same effect is, wehn you play a track with low recorded sound level...
yes one load to keep DC bias up. Now between POS and NEG you will see very low DC offset difference so you can hook up to next amplifier.
remeber, ONE LEG of the DAC is now at GROUND... be very carefull with ground loops in your system now, may be HUMM, may be you will blow the DAC if your Main Grounds are not looped behind your equipmet to each other... I know antenna cables or cable-TV sometimes have like 100 Volt AC between their ground and your mains ground. wehn connected this is gone of course.
but I know some DAC owners have done this succesfully, without any problems...
Just now i use my DDdac to a diy Pass Aleph 1.7 pre..--seem to work fine together--xlr wiring direct from Dac to input (there are caps on the input of the Aleph )it is the most quiet combination i ever had
maybe i should try lower the I_V resistor ..just to hear the sound from that---there are a lot of gain in the Aleph..
Best Bjarne
maybe i should try lower the I_V resistor ..just to hear the sound from that---there are a lot of gain in the Aleph..
Best Bjarne
i will do testing the coming weeks or so as mentioned before and I will do all possible variations. Till then I will not recommend anything as it would not be based on real experiance , only suspicions and speculations if it might be better based on General ideas or results in other situations. Not what I like to do.
but how can I get gnd loops when the dac only is hooked up to a TVC and nothing in the circuit or psu is hooked up against the ac?
ac gnd will only be hooked up to chassis, but dac circuits will "float" inside cab...
or did I miss something ?
best
Leif
Thanks for your addition/ correction.
The sound becomes thinner (less bass) as you lower the resistor value. This might combine nicely with the sound balance of your set, or it might not...........
I have done the same. Just keep the primary of the tvc unconnected to ground, that way you will benefit from balanced driven dac outputs. If you tie one of the primaries of the tvc to ground the balanced operation will be gone.
Please let us know how you experience the sound.
in the mean time I´ll check choke input psu feeding your psu´s
as well as a couple of others......
no measurements....just experienced ears and good system
mvh
Leif
Hi leif,
I missed something
with a TVC you will have NO problem. On the contrary.... balanced out is definitively the way to go when a TVC is behind!
Ok, I'd left out Ra/b on the Neg sides since I wasn't using these for the time being, but I'll put them in for this reason.
Last night I finished my breadboard build of the new “S” mainboard with a single DAC board. First impression is already excellent, a step up from my old but also (imo) respectable Sabre chip based DAC, with run of the mill(ish) Auricap output caps & and cheap Chinees knock-off regulated power supplies, & not yet burned in ... . So still lots of scope for improvement and some idea’s to play around with different I2S input options.
I have an ever so faint high frequency (what seems to me like) white noise coming from the speakers, well above >10Khz. (Only when the DAC is switched on, my amp is inaudibly silent). Doede has drawn in and accomodated for optional HF filtering caps. Do people use these? I obviously want to retain as much as possible from the audio sound in de audible spectrum. Could the SNR improve, i.e. lower the noise floor, with more DAC boards as Ra/b become lower (possibly better PSU’s as well but that’s an obvious area of improvement and not a question)?
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