So.. almost there.
One cap made a bid for freedom, I heard it bound off the keyboard on my lap.. so it's lost at the moment. I have two sets of resistors on back order along with the unobtanium OPAs. I found a solder short under one of the 330R resistors so I had to remove and resolver that. I'm missing some connectors (I know I didn't want to get them until I knew the height for clearance required and I only ordered 1 but not 3 of the RF connectors. I still need to source and fit the relays (Farnell I believe) plus one an extra power connector. I tested the Vishay axial caps on the scope after I fitted the first and decided they are less noisy the other way around so I need to adjust the odd one (I put the more noise sensitive outer side towards the audio side).
So I still have a way to go before first power up.
RTZ DAC with Simple DSD Modulator:
https://www.diyaudio.com/community/threads/simple-dsd-modulator-for-dsc2.370177/
Still running on bench supplies at the moment, fed from Amanero.
https://www.diyaudio.com/community/threads/simple-dsd-modulator-for-dsc2.370177/
Still running on bench supplies at the moment, fed from Amanero.
Can I ask what type of power supplies people are intending to use for the RTZ DAC please? I was intending to use a simple series pass type that I've used before on TDA1541A which has a jFET current source feeding a zener and then series pass transistor (BD139/140). It's not particularly good at a spot on regulation but it is quiet.
Or then there's the shunt type with a TL431 into a medium power transistor...
Or the old 317 of course, perhaps cascaded?
Perhaps I should just try and it and see?
Or then there's the shunt type with a TL431 into a medium power transistor...
Or the old 317 of course, perhaps cascaded?
Perhaps I should just try and it and see?
I see two supplies - analogue being probably a series and the digital switching using shunt - both with ferrites to use the IC decoupling. I need to look further but the initial will simply be just the 3080s from my ADC that can be powered by linear supply (IEC filter, toroidal, RC filter).
I already have pcbs for some positive and negative series supplies so I will see if I have enough components in to build +/- 15v this weekend, if I get time.
I have an idea to re-use a previous project's infrastructure (was my old TDA1541A DAC based on Pedja Rogic's DAC pcb (initial one), plus a Squeezebox Receiver and Kali reclocker. If I re-use the case and some of the existing stuff in it that will save a lot more expense and hassle but I'll lose that DAC forever. Choices, choices...
At the moment I have the RTZ DAC and PCM2DSD connected to a spare SB Receiver, still on bench supplies. I can't find a "mute" line anywhere on the SB to tap into however there is absolutely nothing bad happening when I switch tracks or sample rates so I have the mute defeated here, hence the hasty bodge of the resistor!
It is sounding fantastic though! It has the edge over my TDA1541A I reckon. Bass is much better, everything feels more dynamic and the soundstage is amazing. I'd hoped that wouldn't be the case but there you go. Lot's to learn and you don't know if you don't try!
I have an idea to re-use a previous project's infrastructure (was my old TDA1541A DAC based on Pedja Rogic's DAC pcb (initial one), plus a Squeezebox Receiver and Kali reclocker. If I re-use the case and some of the existing stuff in it that will save a lot more expense and hassle but I'll lose that DAC forever. Choices, choices...
At the moment I have the RTZ DAC and PCM2DSD connected to a spare SB Receiver, still on bench supplies. I can't find a "mute" line anywhere on the SB to tap into however there is absolutely nothing bad happening when I switch tracks or sample rates so I have the mute defeated here, hence the hasty bodge of the resistor!
It is sounding fantastic though! It has the edge over my TDA1541A I reckon. Bass is much better, everything feels more dynamic and the soundstage is amazing. I'd hoped that wouldn't be the case but there you go. Lot's to learn and you don't know if you don't try!
I think I used some very straightforward circuit with 78xx and 79xx voltage regulators.
Do you use hot air or a classical soldering iron? Desoldering with hot air and tweezers is straightforward once you have figured out how much you have to heat up the dual transistor and its surroundings.
It's not so straightforward with a soldering iron, but there is some trick with special low-temperature solder. I never used it, but @acg did on the valve DAC thread. If I remember well, he managed to desolder 80 pin SMD connectors with it.
As these dual transistors have only six pins, maybe you can heat all pins up simultaneously with a soldering iron and some improvized metal heat spreader. I don't know, I never tried.
It's not so straightforward with a soldering iron, but there is some trick with special low-temperature solder. I never used it, but @acg did on the valve DAC thread. If I remember well, he managed to desolder 80 pin SMD connectors with it.
As these dual transistors have only six pins, maybe you can heat all pins up simultaneously with a soldering iron and some improvized metal heat spreader. I don't know, I never tried.