This is the second implementation of the GIC filter in the DAC circuit.
Previously I have using this GIC filter in the non-oversampling TDA1541 DAC and the result is smoother sound and micro detail reveal. The sound quality from this TDA1541 DAC is now extraordinary.
Then in this today post, I will do the same in my Ultimate AD1865 DAC that I've previously built here. This DAC is oversampling using CXD1144 and the low pass filter using unity-gain Sallen-key LPF. Because this Ultimate AD1865 DAC built is intended for future upgrade, so the board inside are separate into 4 module. What I will do right now is built the new analog output module using the GIC filter and replace one of the board with this new module.
The new GIC filter will build on the universal PCB and all components are connecting by point-to-point.
As usual, I remove the old board and take few components that I will still use it in the new board, especially for the output transformer.
This new GIC filter using Styrene capacitor which have the best performance for the signal filter circuit like this. The value that I am using right now is 2700pf. It is quite large and I think the cutting frequency will be bellow 40kHz.
It didn't take so much time to do all connection in this GIC module. I start to familiar with this complicated GIC filter schematic.
The next part that I will install is the output transformer. This will isolated the output from the LPF circuit to the RCA output of this DAC. I start to using this output transformer since the sound quality result also so much improved. This output transformer has several function such as: DC blocking, additional low pass filter, and signal isolated.
This new GIC filter is now install into the DAC chassis.
Once I finished with this new GIC filter, I start to put this DAC into my audio system.
The major difference when using this GIC filter is the smoother sound and micro detail more reveal.
The difference using this GIC filter in the oversampling DAC like this is not as large when it applied on the non-oversampling DAC like what I previously built. But there is still an improvement in sound quality.
I am now really happy to have the most advanced DAC built and I am enjoying the sound quality from this Ultimate AD1865 DAC with the GIC filter installed.
The music playing while I am writing this blog is Solitaire by Sofia - I believe.
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Finally, you did the GIC filter build with the AD1865!
ReplyDeleteSo may I know whether the TDA1541 GIC DAC scales up to this AD1865 build?
I have been asking about the TDA1541 DAC build specifically because I had a pair of the chip but haven't found them yet (lost in my stash).
Supposed that they scale up to the ultimate AD1865, I am planning to also build the ultimate TDA1541 DAC.
I am also interested in designing PCB for them.
If you don't mind, can I consult you on the build preferably through messaging app such as Telegram or WA?
Thank you beforehand!
The Ultimate AD1865 is already far ahead from ordinary TDA1541. Put the GIC on this ultimate AD1865 slightly give improvement on micro detail and smoothness.
DeleteThe TDA1541 GIC sound really good, as good as the ultimate AD1865 but a little bit lack of smoothness and soundstage presentation
Thank you for the brief comparison!
ReplyDeleteSeems like I will stick with TDA1541 based on your impression.
Can I inquire you on DAC build (like the one for Mr. J) through your Tokopedia?
Thanks!
Yes please
DeleteHello. I have a Nakamichi DAC 101. I admire the work you have done with yours. Is there any chance I can have mine serviced by you? Please let me know. Thank you.
ReplyDeleteThank you for your compliment, really appriciated 🙏
DeleteFor servicing, hmn.. I don’t think I can handle it since I work based on my spare time and with today covid slowing down, my primary job demanding me more😀
I understand! Is there a way to exchange emails in case in the near future you change your mind? Like I said I admire your work and I know I would like for my Nakamichi DAC to sound its best.
DeleteSure, you can catch me on my instagram, please search orronoco. Thank you.
DeleteI ran a noise simulation on the GIC filter (as found in PCM1702 datasheet) and boy, it is noisy. If you use the OPA2604 (a very noisy JFET opamp) as shown in the schematic it gets even worse. Noise in post-DAC stages is an issue I've found, if you want an 'airy' sound you do need low noise.
ReplyDeleteby the way, your work impresses me with its neatness. I don't think any of my work on protoboard comes up to your level. Very nice indeed.
ReplyDeleteThank you 🙏
DeleteHi, sound of AD1865/AD1864 for my point of view shine only when it is non oversampling. Oversampling is ok, but tired me after long sessions. Old chips with oversampling not far away from new delta sigma in my opinion. Still better than delta sigma, but at the end of the day you feel than sound its unnatural and digital.
ReplyDeleteYes and no, It rally depends on the oversampling IC. Naturally NOS will give more warm midrange but sometimes it will lack of smoothness. I tried using SM5813 and CXD1144, they completely different league to compare. Please try one if you have a chance to get those IC’s
Delete