What's the block diagram of?
It doesn't look the same as the CM108 diagram I have. But still, its showing the audio clocks being generated by 'PLL2' and 'PLL3' which is what I said in post #119. The crystal's jitter barely matters when there's a PLL generating those audio clocks.
It doesn't look the same as the CM108 diagram I have. But still, its showing the audio clocks being generated by 'PLL2' and 'PLL3' which is what I said in post #119. The crystal's jitter barely matters when there's a PLL generating those audio clocks.
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That's the CM108 I just grabbed from a download from Cmedia site. I think you only have to look at the arrows to understand the input clock is feeding the 3 PLLs and that this one clock is used to time the whole device. I don't understand why you think the PLLs would be immune from jitter on this clock. It's not the kind of device that can generate a clock from the incoming data alone, as some DACs can. PLL2 makes that fairly clear I think.
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Nope, its used as a frequency reference for the array of PLLs. It might be responsible for timing of some digital logic though, I am not sure.
I don't understand why you think I think that. Could be you're lacking some basic understanding of how PLLs operate and also have a misunderstanding of how adaptive USB works in terms of generating the timing of the audio clocks.
Because you've shown yourself to be relatively immune to being educated on some techie matters on this very thread (presumably because you don't much like the look of big dicks?) I'm right now unclear whether its worthwhile to set things out for you. Let's start with a question - does the concept of oscillator Q have any resonance with you?
You're right. My bad. And it won't sound any better if the reference has lower jitter. Of course not. Crazy ignorant me. ;-)
In the theory vs experience discussions that play out on this site, the above is another example of a post intended to patronise someone in order to dismiss/denigrate/etc their tested experience. It's especially sad in this case because Abraxalito previously stated he doesn't do this.
Unfortunately, replacing the xtal with an xo to improve a PLL is something that has been done before with CMedia gear, and there is evidence it works. RMAA results and pictures of the improved scope trace were posted here on Diyaudio about 6 years ago. I found it and could re-post it in this thread but I'm going to leave that as an "exercise for the reader". It isn't great evidence but at least there's some. I also found a lot of this on Head-Fi where people have done this with a wide range of devices.
So, no easy link for ya, as part of my love of the X-Files, I'm just going to say the truth is out there. You have to want to find it.
Also, having been listening and testing DACs for a while now, I've decided on 4x ES9038q2m for the Minidsp project. $ for $ it is by far the best quality sound on the market today imo.
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In the theory vs experience discussions that play out on this site, the above is another example of a post intended to patronise someone in order to dismiss/denigrate/etc their tested experience. It's especially sad in this case because Abraxalito previously stated he doesn't do this.
So you're saying I intended to patronize you and dismiss your experience with this post? Where's the evidence please?
In an earlier version of this post (which I received through the email notification system) you'd asked me a question. The question contained your perception of what I think about XO replacement. My answer to that question is 'no' which is the opposite to what you perceived as my position. With your perception as 'yes' its easy to see why you consider what you quoted as dismissive and patronizing.
Which particular CMedia chip was that? CMedia make a variety of ICs for USB interface and not all operate in the adaptive mode for USB audio.
Yeah I love X files too. Like 'trust no-one'So, no easy link for ya, as part of my love of the X-Files, I'm just going to say the truth is out there. You have to want to find it.
Yeah I love X files too. Like 'trust no-one'
When I hear that phrase I think of Herod Agrippa in I, CLAUDIUS.
It may not be "nice" but it certainly is good advice while living on Earth.
The BBC series is a great example in how good a production can be when you don't throw money at it for no good reason.
Heads up about that seller - the goods are returned by SF Express but he's refusing to sign for them so he can avoid giving a refund. Seems a bit of dirtbag.
I finally got around to hooking up this board this weekend. I agree with Hugh, it sounds pretty good, better than the "little giant" TDA 1387 board from the same maker. Ran it for about 2 hrs nice vocals but can't hear into the music background much. Like you can't really hear the recording venue well in the background of recordings. I'll bypass the output caps next to see what improvement it brings. so far it hasn't burnt up yet so I'll keep my fingers crossed.
Hi I am encasing the single TDA1387 board from that seller. Replaced the 22 µF 16V bipolar electrolytic caps for Wima 22 µF 16V MKS2-XL film caps which I happen to stock. These are the largest value film capacitor in 5 mm pitch.
There lack stop resistors in the output of the output stage. From L and R a 47 Ohm resistor should be used to the L and R output RCA to prevent the opamps from oscillation with capacitive loads i.e. cables.
Not listened yet but board design and choice of regulators both seem fine.
There lack stop resistors in the output of the output stage. From L and R a 47 Ohm resistor should be used to the L and R output RCA to prevent the opamps from oscillation with capacitive loads i.e. cables.
Not listened yet but board design and choice of regulators both seem fine.
Most likely I was unlucky and got one with a damaged/used/fake dac ic but I would run yours for more than 2 hours (mine died after 4 iirc) continuously and check temperatures to be sure. Besides, this breaks in the caps and gets the DAC ready for evaluation. I hope it's good!
I decided to go with AD1862 but I have yet to get round to making it. I found a seller with an AK4137 ASRC that uses low frequency clocks (under 17MHz), another seller with a logic shifter/buffer to split left/right, truncate to 20 bits etc, and then another seller who sells allegedly paired and genuine AD1862NJ chips. I shall hack them together at some point. I am curious about using TPA6120 current feedback amp as I/V followed by a 3rd order passive filter. The TPA can easily drive a 32 ohm load making a passive filter with a low impedance possible. I hope. ;-)
One circuit aspect responsible for flat sound IME is opamps. They do this by virtue of their classAB output stage creating noise on their power supply. It can be reduced by classA biassing the opamp's output (use a 2 or 3mA current source to the -ve rail) and decreasing the supply impedance (use polymer capacitors on the rails as these have very low ESR).
I've not tried TPA6120 but I do plan on trying the nearest ADI equivalent to it, the AD815. Its super-cheap here, even on Aliexpress its about $1. So far the clear winner on I/V is the AD811, streets ahead of AD8017. The clear difference between these two though almost disappears with a CLC filter before the I/V.
If using TPA6120 to drive a low impedance load, be sure to classA bias it.
TPA6120 is hard to hear - it's really very good at reproduction in every bit of gear I've listened to. I just bough a cheap kit to try for US$3 TPA6120 ???HIFI TPA6120A2????????????????-???
It costs only slightly more than the headphone protector kit ?ZEROZONE?E12-I??????????????????--??-???
Here's the link for the AK4137
AK4137 I2S/DSD?????? ??PCM/DSD?? ??DOP??-???
And the R2R I2S converter
NOS DAC/I2S?? NOS????????I2S?????????-???
And the AD1862 (no idea if this seller is reliable tho)
AD1862N-J ??{???}??(??100?)-???
TPA6120 ???HIFI TPA6120A2????????????????-???It costs only slightly more than the headphone protector kit ?ZEROZONE?E12-I??????????????????--??-???
Here's the link for the AK4137
AK4137 I2S/DSD?????? ??PCM/DSD?? ??DOP??-???
And the R2R I2S converter
NOS DAC/I2S?? NOS????????I2S?????????-???
And the AD1862 (no idea if this seller is reliable tho)
AD1862N-J ??{???}??(??100?)-???
An externally hosted image should be here but it was not working when we last tested it.
bypassed the two electrolytic output caps, sounds better, more detail. I like this DAC sounds nice. I need to run it in for a few more hours but so far so good, board runs nice and cool. I have this in a test box that I can easily swap out this board for the tda1387 "little giant" to compare the two. I'll try some of Jean Paul's suggested mods to the 1387 and compare.
Hello all,
What do you think of this DAC?
AD1865 decoding finished board r2r decoding nos mode DAC hifi audio good-in Digital-to-Analog Converter from Consumer Electronics on Aliexpress.com | Alibaba Group
EDIT. The thread almost immediately digressed into one about TDA1387 (from post 8 on) and then later into op amp in the I/V for TDA1387. Sorry.
And then when my DAC eventually arrived, it was faulty, and was returned. See post 96.
And the saga went on... the seller refused to sign for the faulty goods so he could "negotiate" a partial refund.
No need to apologize for the topic sway, many dac threads taper off rapidly after the diyer has determined that bypassing the I/V stage is “best”. Then there are no more posts, as things have gone, well, quiet, so to speak.
I haven’t attempted any returns, sorry about the bad experience with that...
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