RTZ SDM (DSD) DAC

[Leon]

I don't know where this evening has gone!

I prefer the JLSounds USB board to the Amanero but it would complicate matters with connections to the PCM2DSD module. I made some interface boards to hook a JLSounds board to a ValveDAC that I bult for a friend (Marcel's designs use the Amanero pattern header on their inputs) and it worked really well but that used HQPlayer for upsampling. The interface board also has sample rate indicators for the DSD rate and whether the data is 44.1KHz or 48KHz family.

I have found these are very good power supplies for my Decoder projects, Salas shunt regulators didn't give any discernible improvement so I think in this context low-noise is the important thing to consider. These supplies are very space efficient too.

https://www.ldovr.com/category-s/114.htm

I think the most scope for exploring improvements with the RTZ is the output filter and when I get back to the RTZ (currently working on several amplifier projects) I want to try some different arrangements - top of my list is the circuit in post #7 of this thread, using 6SN7s.

Just some quick thoughts.

I think that most evenings Ray good thing with these threads , we can add anything whenever its convenient .

Love the look of that Beagelbone black , I need to look into that tbh I was expecting a huge PC was needed to run HQ player .

I'm definitely preferring running the Amanero from a separate supply ,even a basic LM317 would probably be better than the USB supply .

Thanks for the regged PSU links, the LT3045 are nice and compact certainly take less space up compared to what I'm using now . I tried one of Salas shunts years ago although it was one of the older versions , I preferred the PH Z1A's but they was quite expensive .

After I've tried swapping out the NE5532's to OPA1678 and having a listen I'd like to try bypassing the last stage of Dac3filter too , think details for that on diyaudio .
Look forward to seeing how you get on with the valve output stage , did you ever try the discrete version of the CD enhancer ? I tried it with a Pioneer PDS904 quite a few years ago

[MistyBlue]

Hi everyone,

Thanks to the generousity of Tony, I am about to join the RTZ builders club - a surprise parcel arrived today with much more that I expected to be in it.

....And so it begins.

RTZ Surprise.jpg (143.97 KiB) Viewed 1762 times

[Leon]

Hi everyone,

Thanks to the generousity of Tony, I am about to join the RTZ builders club - a surprise parcel arrived today with much more that I expected to be in it.

....And so it begins.

RTZ Surprise.jpg

Your in for some fun Look forward to seeing how you get on

[Leon]

I've removed the NE5532 and fitted the OPA1678's (Thanks Tony)
Got to say guys just my opinion but I found the OPA's are noticeably better , its opened the sound up and sounds less compressed , better attack . Its obviously fiddly changing smd parts so caution if wanting to try it .

Next thing to try is running separate wire from the output of first OPA1678 (tagged on input of C13/40) then through resistor to separate phono sockets, I didn't have 49.9R so used 56R . I can then try it without the last stage and coupling caps . It's not ideal having the last section powered and still in circuit but it allows quick easy comparison .

[Tony Moore]

Just to say that I suspect most people did build with the OPA1678 and the only reason I built with NE5532 at the time was due to supply issues and huge lead times. (which is why Marcel specified them in the drawing/BOM)

I did buy some OPA1678 from Ebay at the time but didn't trust them so when Mouser finally had them in stock I used them for the subsequent builds.

Sorry you had to change them out Leon, I'd completely forgotten. Luckily I found those 4 in another box I'd squirreled away. All gone now though.

Edit: ps Steve's unit has OPA1678 fitted.

[Leon]

Just to say that I suspect most people did build with the OPA1678 and the only reason I built with NE5532 at the time was due to supply issues and huge lead times. (which is why Marcel specified them in the drawing/BOM)

I did buy some OPA1678 from Ebay at the time but didn't trust them so when Mouser finally had them in stock I used them for the subsequent builds.

Sorry you had to change them out Leon, I'd completely forgotten. Luckily I found those 4 in another box I'd squirreled away. All gone now though.

Edit: ps Steve's unit has OPA1678 fitted.

It was actually great to be able to compare them so thanks for that Surprising what differences these things can make

[Ray P]

I think that most evenings Ray

Seems to be!

Love the look of that Beagelbone black , I need to look into that tbh I was expecting a huge PC was needed to run HQ player .

You do need a powerful PC for HQ Player, mine is getting a bit old now but still benchmarks at something like 11000. The Beaglebone is just an HQPlayer network endpoint - basically it renders the DSD data that HQPlayer streams to it, so all the heavy lifting has already been done.

[Ray P]

I've removed the NE5532 and fitted the OPA1678's (Thanks Tony)
Got to say guys just my opinion but I found the OPA's are noticeably better , its opened the sound up and sounds less compressed , better attack . Its obviously fiddly changing smd parts so caution if wanting to try it .

Next thing to try is running separate wire from the output of first OPA1678 (tagged on input of C13/40) then through resistor to separate phono sockets, I didn't have 49.9R so used 56R . I can then try it without the last stage and coupling caps . It's not ideal having the last section powered and still in circuit but it allows quick easy comparison .

I've built filter boards with both the 5532s and OPAs and seem to remember a conversation at the time along the lines of the 5532 sounding surprisingly good (that was all you could get at the time!) but OPAs improved things once you could get hold of them. There's a filter section PCB sans the final stage and also a passive output filter board.

[Ray P]

Look forward to seeing how you get on with the valve output stage , did you ever try the discrete version of the CD enhancer ? I tried it with a Pioneer PDS904 quite a few years ago

Not tried the discrete CD Enhancer but will have a look.

[Leon]

Added another pair of regs for the active filter board

[Leon]

Thanks to Tony for the closely matched Vishay/Beyschlag Melf , I've removed the 3k01 Susumo RR and given the Melf a try . I can only go by listening tests to well known tracks but the highs seem to be a little more clear ,not huge but noticing more with cymbals so to me was worth the time and effort

[Tony Moore]

More "experiments" on the RTZ DAC. This is an experimental filter board built to fit the RTZ DAC using the circuit published on DIYAudio by Bohrok2610 utilizing the opa1632 fully differential op-amps.



I have installed it in my DAC:



and I am letting it run in. I am using the Lundahl 1588 transformers to convert from differential to SE.

Initial impressions are very good. There is a lot more gain here which suits my amp and I like the way it is handling bass / lower mids. This is probably only the first stage in an obsessive (what? Me?) path.

[MistyBlue]

I like it!

I will be watching this with keen interest.

[Leon]

Excellent work with the board Tony, must say its way better than my butchered TPA IVY3 board using OPA1632's, I'm finding this stage sounding very good at the minute .More weighty sound compared to the original active stage so will be interesting to see if Bohrok does any tweaking to the filters

[iansr]

@Ray P: Hi Ray, I sent you an email a few days ago. You may just be busy of course but it occurred to me that it may have landed in your spam folder? Cheers, Ian