RTZ SDM (DSD) DAC

[ed]

Just checking Ed when you say film stencil do you mean the cut sheet for applying paste or the solder resist mask on a PCB.

I find having a metal paste stencil makes life many many times simpler when using a hot air gun. I would imagine using one and a oven would almost become trivial.

yes, the cut sheet for applying paste, the ones I'm familiar with have all been acetate but I now realise they are in metal as well. In my earlier post I used the word 'mask', it's the same thing in my vocab.

[Ray P]

Another piece of the jigsaw (and another soldering success). I'm currently listening to music via a 'DSD'it' board that I finished assembling this morning.

DSD'it is a cape for a Beaglebone and is a hardware solution to the DSD modulator question based on two ASRC chips; it takes PCM input and upsamples it to 192KHz (with an SRC4192) and then converts that to DSD256 (with an AK4137). By repute it doesn't quite match the sound quality of HQ Player but listening at the moment via a very simple RC filter DSD decoder it is sounding good.

[Ray P]

I've now successfully installed the DSD'it board and beaglebone onto the RTZ DAC.

I setup the Beaglebone firmware (based on Botic) to run Roon RAAT and I'm now streaming PCM using the Roon interface. I'm not really doing critical listening but first impressions are extremely positive and I think very close to the HQPlayer/JLSounds input I have been using with the RTZ DAC builds.

The only config change I had to make was to set the Botic mute flag to be high for mute, to match the JLSounds arrangement.



I think I'll order an AntMiner (Beaglebone derivative) from AliExpress as ppy has said his firmware is compatible and they cost less than a Beaglebone.

https://www.aliexpress.com/item/1005003 ... l9PgY&mp=1

[Ray P]

I took the opportunity of a visit to my mum (in Fareham) to drop the RTZ breadboard build at the Idler household today to give an opportunity for a decent listen.

I was also able to squeeze in a very quick listen (Hotel California) to Dave's vinyl system - very nice - before enduring a grindingly slow drive back to Somerset.

[Thermionic Idler]

Thanks Ray, we'll hopefully get an opportunity to get it installed next week sometime. Looking forward to it.

The vinyl replay was (theoretically) slightly sub-optimal, as we are taking the phono stage up to NW Analogue tomorrow and I'd reconfigured the SUT's the previous evening to 1:32 to match the DH3, so it was presenting a load of 37 ohms to the VdH, quite a bit less than recommended, and the levels going into the phono stage from the step-ups were probably a little on the hot side. Despite that, it still performed pretty well

Sorry your journey back was a bit gruesome.

[Thermionic Idler]

We got the breadboard up and running tonight and I have to say - WOW!! Admittedly I have been rather focussed on vinyl as my main source and a lot of investment has gone in that direction, but digital just took a quantum leap with this DAC. This gets pretty close to analogue for musical involvement and sheer detail ---- but if, and only if, care has been taken with the digital mastering.

Classic example - ELO's 'Time'. We pulled up the digital version that's on the Qobuz streaming service and our immediate reaction was 'where has all the bass gone'. The sound from the original vinyl LP is so much more rounded and fuller. I'm increasingly starting to suspect that 'newly remastered' is record company-speak for 'We have completely mangled the sound so that it plays better on a cheap Chinese boom-box'.

But --- if the source material is good --- this is a ruddy nice-sounding DAC. Highly recommended. I'm probably not going to bother with the Valve DAC now. It's that good.

[Paul Barker]

We got the breadboard up and running tonight and I have to say - WOW!! Admittedly I have been rather focussed on vinyl as my main source and a lot of investment has gone in that direction, but digital just took a quantum leap with this DAC. This gets pretty close to analogue for musical involvement and sheer detail ---- but if, and only if, care has been taken with the digital mastering.

Classic example - ELO's 'Time'. We pulled up the digital version that's on the Qobuz streaming service and our immediate reaction was 'where has all the bass gone'. The sound from the original vinyl LP is so much more rounded and fuller. I'm increasingly starting to suspect that 'newly remastered' is record company-speak for 'We have completely mangled the sound so that it plays better on a cheap Chinese boom-box'.

But --- if the source material is good --- this is a ruddy nice-sounding DAC. Highly recommended. I'm probably not going to bother with the Valve DAC now. It's that good.

With you on the “remastered”. Quite a few of the prog rock (my teen era and a lot of others in here) albums on Apple tv are ‘remastered’ and often with ‘bonus tracks’! Nothing endering about them at all. From memory of listening to the original vinyl on a dansette, was far better!

I might have to review my steeaming service provider…..

[Ray P]

--- this is a ruddy nice-sounding DAC. Highly recommended.

Good news Dave, I'm glad you and Meredith are enjoying it.

It is a bit special isn't it.

[Ray P]

I have one last set of PCBs (DAC and filter) for the RTZ DAC if Dave's experience has piqued anyone's interest.

If you are, but are daunted by the smd soldering it might be possible to bribe me to spend the time populating the boards - happy to discuss further.

[Tony Moore]

It is _so_ good I am going to build another one!

I don't know if people remember my Transporter based TDA1541 based DAC at the 2nd to last Owston?

Well, I didn't want to disturb that one as is sounded so nice, hence I built the RTZ DAC into the reclaimed case that my original Pedja Rogic DAC was in.

Turns out the RTZ DAC performs much better than the 1541 DAC (which was no slouch itself) so now that I have a working main unit and the Transporter is turned off I am planning to add to or replace the 1541 parts with another RTZ DAC. It will be a sqeeze(box) [pun intended] to fit all that stuff in the Transporter but I'm sure I can either fit it on top, like the supercharger on those American muscle cars, or in a separate box and use LVDS for transferring the I2S without losing quality, hopefully.

The Transporter has a much better clock and CPU & FPGA than the SqueezeBox receiver, plus it has options of digital inputs so opens up options.

I have already built a 2nd filter board (awaiting OPA1678 op-amps) and have a 2nd DAC pcb on its way from Ray! (Not the one mentioned above!)

Plus, I need to build something...

[Ray P]

I've just assembled and tested the power supplies for the digital parts of my RTZ DAC build, LT3045-based 5V supplies.

[Ray P]

I finished assembling the filter board for my own RTZ build today



The designer has also made some suggestions for a simplified filter board that removes the final op-amp stage and output capacitors (on the proviso that a small amount of DC offset on the output is tolerable) so I've been learning more KiCad skills by amending the standard filter board layout and plan to order a small batch of PCBs so that Tony, Dave and I can give it a try.

[jack]

Did you stick with the statistical regulator or drop it?

[Ray P]

Did you stick with the statistical regulator or drop it?

They weren't for this project Nick, still planning on using them on another, though I've just noticed you Mk.II thread so will watch with interest.

[Ray P]

I ordered some of the simplified filter boards and this morning I populated one of them. I'm not able to test/audition it yet as I've lent my power supplies to Mr. idler. I soldered this board using a stencil for applying the solder paste - I wish I had done it before as it makes the process much easier/quicker and, of course, you get just the right amount of paste for nice solder joints.