Or is it black magic. 🤣
I can't remember now if the PCM1702 ran at 384k. I think so, but I could be wrong.
I can't remember now if the PCM1702 ran at 384k. I think so, but I could be wrong.
Last edited:
@eclipsevl You know how they quaranteed this specification on AD1865. They made testing on slower BCLK, only 18-bit FS LRCK (768 kHz * 18 = 13.8 MHz for BCK) - only mono.
So does the AD1862, 16x oversampling in datasheet ... that is 768 kHz * 20fs (only mono) = 15.36 MHz for BCK
So does the AD1862, 16x oversampling in datasheet ... that is 768 kHz * 20fs (only mono) = 15.36 MHz for BCK
One thing, it is states it's minimum clock rate 13.5Mhz for ad1865 😉 So they left quite a large questwork of maximum frequency. In ds, figure 13, there is 16.9344Mhz xin with cdx1244 digital filter. So higher is definitely possible.
Fired it up. Plays music. But only through the Left channel. Measured AC voltage out from the D1 RCA's out, I can see a half volt on the left and negligible on the left. Thinking I may still not have the JLS I2s over USB pins correct.
Resolved dead left channel. My error, neglected to solder the # nine female receiver header pin on the underside of the DAC board. Next step, burn in and optimization. Need to try changing R4 on the D1 from 1k8R to max 2kR, as my system is low gain.
He is using NP D1. Such a drastic change will affect the operation of the other area of the circuit, and there are other resistors to be changed in the correct ratio. Iirc, there is also a need to raise the bipolar voltage to somewhere like 40V to maintain the drain current of the MOSFETs to allow higher IV resistors.
I changed a few things that were mentioned in my last previous posts. I'm still experimenting with r8 r9 and c15 c25 etc. It's better but the differences are subtle. I'm using Burson V7 Classic. I'm thinking about a tube stage. Will it give me a noticeable improvement? Is it worth messing with? Or which solution to test first? Something simple to build.
Please share the group buy / swap meet link if/when you sell. I've got a pair of PCM63P-K that need a home. 🙂
Was it on this thread that I saw some noise measurements of different opamps? Can not find it anymore 🙁
I tried both an op-amp and a tube stage (ECC40) out of my PCM56 board. The tube stage had a nice smooth sound, but in the end I preferred the op-amp stage for its slightly better focus and micro detail. My shortlist was AD843, AD845 and AD797 and I'm currently using AD797. I preferred all three to a pair of Burson V7 Vivid, which did have better treble but a rather hollow midrange and a lack of fullness - not a balanced sound to my ears. I haven't tried the AD811 or AD844 but those are favourites here, especially the AD811 which has been preferred to even a good tube stage.
I've never listened to tubes. Tubes are praised and I'm very curious about this topic, but if I'm going to put the effort, time and money into building a tube I/V stage only to later go back to op amps, then it's a waste of time. I'm not such a passionate DIY electronics guy that I'm only doing it out of curiosity. I want to get the most out of the Ad1862, but sitting for hours trying to get 0.00001% thd difference that I won't hear anyway doesn't interest me. So far I've only had the OPA134PA, Burson V7 Classic and V7 Vivid, and out of these three, the Classic works best for me. I wonder how much more can be improved in this DAC. If I compared it to a commercial product for $50,000, would the difference be astronomical or rather just nuances... So far I've replaced capacitors and resistors and by ear the differences are quite small. Is there an improvement or solution that will significantly affect the quality of sound? Is all this fun in developing this DAC just a delicate refinement of the sound to suit your taste? The worst thing is that every change changes something but the brain doesn't remember so well whether in configuration x it sounded better than in configuration y or z etc. Every time I change something I compare the sound to the fiio k11 r2r as a reference point. I think I'll try other opamps but I'm tempted by a tube 🙂
I built two mostly identical copies of Miro's AD1862 DAC. Tried a bunch of IC opamps and found that I preferred a Sparkos discrete opamps by a good margin. I then fitted one with a "Dark" IV and analog filter from Abraxilito and lived with both DACs for a few months. Eventually ended up getting another "Dark" and ditched the Sparkos. I found the sound quality to be better with the filtering on the Dark IV. Cleaner, a bit more focused.
Note to reader. The following contains elements of humor which may get lost in translation...
@Tommar Tubes are fun and can sound fantastic. Tubes are another rabbit hole with infinite permutations to try, think designs/PSU types/tube types - and then you start collecting NOS tubes...
I am no expert on the topic, but in my limited experience, it seems you can make tubes sound like solid state and the other way around. As far as I gather, this depends on the harmonic distortion profile of the circuit. So one can ask oneself, what am I pursuing...particular sonics, new builds, tube glow... There is no wrong answer in my opinion.
I listen to music all day and just felt bad wasting finite 'tube life' so the tube stuff ended up not being used much.
In short, you likely need to try tubes for yourself 😆
@Tommar Tubes are fun and can sound fantastic. Tubes are another rabbit hole with infinite permutations to try, think designs/PSU types/tube types - and then you start collecting NOS tubes...
I am no expert on the topic, but in my limited experience, it seems you can make tubes sound like solid state and the other way around. As far as I gather, this depends on the harmonic distortion profile of the circuit. So one can ask oneself, what am I pursuing...particular sonics, new builds, tube glow... There is no wrong answer in my opinion.
I listen to music all day and just felt bad wasting finite 'tube life' so the tube stuff ended up not being used much.
In short, you likely need to try tubes for yourself 😆