I have 10uf capacitors because of headphone amp input impedance (10k). Needed to be sure to avoid phase shift
aha ! yes, RC is the thing, not uF only....
so 10uF with 10K gives the same as 2uF with 50k (which is some what typical for hifi)
so 10uF with 10K gives the same as 2uF with 50k (which is some what typical for hifi)
I used 4.7uF for a 30k input impedance of the preamplifier. Now I use an output transformer. In principle, the advice is that the -3dB point with capacitors be below 2Hz, so that there is no phase shift at 20Hz. There is a simple online calculator where it is easy to check.
RC Low-pass Filter Design Tool
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I want to say a word about the previous post about 7.5V analog voltage... It seems burn in has done its part very sneakily. After some time parts have gone through burn in process and now i have 8V supply and it is better than 7.5V. Nice hobby we have 😀
Maybe a little bit off topic, but can somebody please tell me if it is possible to change the standalone tent shunt modules from 8V (DDDAC version) to 5V and how to do that? I've two modules here which I have originally used on an old DDDAC board. Have switched to the new DDDAC boards and would now like to use the tent shunts modules for the 5V DDDAC Mainboard supply.
I would be very happy if you could give me a hint via PN. Thank you!
I would be very happy if you could give me a hint via PN. Thank you!
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Doede, is it okay to ask here about your old TUMOS project, I got two pairs of Toshiba 2SJ50/2SK135 I would like to spend them on some small A class amplifier. Or maybe there is something more interesting with the mosfet transistors I have?
Last night my friend brought to my home his brand new Chord Hugo TT and M-Scaler which costs approx £8,000.
We first listen to my Signature DDDAC which is supported by Ian Canada solutions, Andrea clocks and high quality PSUs. My friend stated this was the best sound he has ever heard and he stated he felt the Chord should be better as a major brand 😊
So we quickly swapped the Chord in replacing my DDDAC and everything else was the same and same music all via Roon.
We listened to a few tracks and he stated nothing for sometime. he then stated to me that he was shocked that with the Chord the sound was not as good and was a very noticeable difference. 😀
We switched back to the DDDAC solution and both of us agreed MUCH MUCH better sound! Its amazing what this DIY community can design and deliver to us all
A HUGE thank you to Doede, Ian and Andrea for there amazing dedication, skill and effort they give for all our benefits!
😀
We first listen to my Signature DDDAC which is supported by Ian Canada solutions, Andrea clocks and high quality PSUs. My friend stated this was the best sound he has ever heard and he stated he felt the Chord should be better as a major brand 😊
So we quickly swapped the Chord in replacing my DDDAC and everything else was the same and same music all via Roon.
We listened to a few tracks and he stated nothing for sometime. he then stated to me that he was shocked that with the Chord the sound was not as good and was a very noticeable difference. 😀
We switched back to the DDDAC solution and both of us agreed MUCH MUCH better sound! Its amazing what this DIY community can design and deliver to us all
A HUGE thank you to Doede, Ian and Andrea for there amazing dedication, skill and effort they give for all our benefits!
😀
I just posted the final clock blog.
it covers the Andrea Mori clocks with and without doublers and the Ian Canada SinePi and ReclockPi as well
have a nice read 🙂
Doede
Link to Post of the final clock reviews
http://blog.dddac.com/clock-switch-project-clock-series-part-6/
http://blog.dddac.com/clock-switch-project-clock-series-part-6/
it covers the Andrea Mori clocks with and without doublers and the Ian Canada SinePi and ReclockPi as well
have a nice read 🙂
Doede
Link to Post of the final clock reviews
http://blog.dddac.com/clock-switch-project-clock-series-part-6/
http://blog.dddac.com/clock-switch-project-clock-series-part-6/
Thanks for your answers regarding output caps.
I have attached a few pictures. I am very happy with DDDAC sound. Boards are v3.0, mainboard is the latest version. For now I use WaveIO and I am very happy with it. In the future, I will look for Amanero with IAN Ultimate FIFO reclocker etc.
But, main goal are the output transformers. I am asking for a feedback about Audio Creative O.P.T. Silver & Gold for DDDAC and Sowter OPTs. Price is very different. I read somewhere that even Cinemag 15/15B are good, but 🙂
Thanks in advance
I have attached a few pictures. I am very happy with DDDAC sound. Boards are v3.0, mainboard is the latest version. For now I use WaveIO and I am very happy with it. In the future, I will look for Amanero with IAN Ultimate FIFO reclocker etc.
But, main goal are the output transformers. I am asking for a feedback about Audio Creative O.P.T. Silver & Gold for DDDAC and Sowter OPTs. Price is very different. I read somewhere that even Cinemag 15/15B are good, but 🙂
Thanks in advance
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Hi. If this has was answered before, do direct me to that entry or article.
I spent some time looking at OS and NOS yesterday and realized that if you take the PCM1794A chip and you bypass the OS, what you are left with are the lower 16 bits, or the true bits if you like. The x8 interpolation is bypassed.
Now... since it's in the 16 bit operational mode and this is a Sigma-Delta architecture or what TI likes to call it Advanced Segmented DAC, this got me thinking... something one shouldn't do .. LOL. Burr-Brown produced lots of chips
back in the day and some of them are still in production, like the PCM1794A but also the PCM56 (monolithic) which is a true 16 bit Multibit (R2R) chip.
My question is: Why go through all the trouble of bypassing the oversampling part of a sigma-delta chip when you can go straight to a 16 bit Multibit chip ? ... #ultimatedac
And pleas, if "its cheaper" in the context of this dac is a valid argument, don't reply... LOL. The chip cost is eclipsed by the rest of the the build, and so in the grand scheme of things, the extra hurdle is not that big of a jump. But rather,
there has to be some quality's of the PCM1794A which does not come through via the datasheet or in some other form which is easy to grasp. I went over Doede's DDDAC and can't find any reference to 16 bit or other chips.
I spent some time looking at OS and NOS yesterday and realized that if you take the PCM1794A chip and you bypass the OS, what you are left with are the lower 16 bits, or the true bits if you like. The x8 interpolation is bypassed.
Now... since it's in the 16 bit operational mode and this is a Sigma-Delta architecture or what TI likes to call it Advanced Segmented DAC, this got me thinking... something one shouldn't do .. LOL. Burr-Brown produced lots of chips
back in the day and some of them are still in production, like the PCM1794A but also the PCM56 (monolithic) which is a true 16 bit Multibit (R2R) chip.
My question is: Why go through all the trouble of bypassing the oversampling part of a sigma-delta chip when you can go straight to a 16 bit Multibit chip ? ... #ultimatedac
And pleas, if "its cheaper" in the context of this dac is a valid argument, don't reply... LOL. The chip cost is eclipsed by the rest of the the build, and so in the grand scheme of things, the extra hurdle is not that big of a jump. But rather,
there has to be some quality's of the PCM1794A which does not come through via the datasheet or in some other form which is easy to grasp. I went over Doede's DDDAC and can't find any reference to 16 bit or other chips.
Hi Oneminde. Not the first time we go through this, but with a long thread like this very understandable. Key point was that with the the way I implement the pcm1794 (8 volt analog power, no digital filtering and passive I/V) you will get high voltage signal output without the need for an extra amplifying stage which you need with the R2R chips, which output just 10s mV or a few 100mV at best. Secondly the PCM1794 is a mix of multi it and bitstream and just sounds very very good in this setup. The ease of paralleling outputs and the NOS sound you get from it came on top.
Hi. I have not tried any of transformers you mention. But i am using these ones for a week: https://it.aliexpress.com/item/32810421236.html
I bought them because they were used in STAR PURE DSD dac by Andrea Ciuffoli and Pavel Pogodin at www.audiodesignguide.com.
They said that those are better than many others costing much more. You can see transformer testing here: http://www.audiodesignguide.com/DSC2/OPT/index.html
Anyway, they are excellent, much better than capacitors. Sound stage is bigger and voices are so natural that i somethimes think i can feel a singer in front of me. Bass is more tighter and stronger. I always thought that transformers will kill some of bass, but not these ones. And that is with one deck!
These transformers are not an usual "aliexpress yellow transformer".
They cost 55eur (pair) and i highly recommend them to someone on budget or anyone else.
Also i would recommend to look at Ivan Bisesik transformers: https://www.diyaudio.com/community/threads/output-transformers-for-dacs.327794/
According to forum, they are better and bit cheaper than cinemags.
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I hear a very quiet hum at full wolume (headphone destroying volume). I need to isolate them with copper foil and i need to put an L metal profile between power and signal transformers. With metal piece between them noise is non existant. It came out very well considering the size of dac.
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Great,
but I have 4 boards. Don't know if those transformers can handle the current ...
Regards
There is no large DC current through the output transformers if the DC offset at the DDDAC output is small. So that transformer can be applied. I tried one similar, on 4 boards, on the same core, just wound as 600: 600 ohms. The sound is not something special, but again, maybe that 10k: 10k sounds better. I will rewind it bifilar, with thinner wire and more threads, it’s sure to sound better that way.