I noticed the images embedded into my above post are not coming thru on certain browsers ....
(Note the use of the Philips electro cap on the output. Haven't seen those in decades. New-old-stock? Does Philips still manuf. them. Or are they being "duped" by some Chinese manuf?
'Long' is relative in DAC threads - compared to ECdesigns' TDA1541A anaconda of a thread, this one's just a grass snake.
Nope. You might do me a little favour - point out which sentences in my introductory first post led you to this erroneous conclusion and I'll make some edits.
The first post contains a link to just one. That's because there is just one.
My current working hypothesis is that you've not read post #1. So I'm doubtful that amending it will indeed make the difference you suggest it will. But of course, my hypothesis might not be correct - feel free to falsify it.
My advice FWIW is to buy those designs you find most attractive. PhiDAC hex isn't for everyone.
Not that I'm aware, but its possible as I've published gerbers and schematics (and BOMs in some cases). I consider it unlikely though as the copiers tend to go for the more popular designs.
<edit> The quad-TDA1387 DAC whose pictures you're showing above is a gem of a DAC. I've bought maybe ten of these - some as kits, some just as assembled PCBs and some with boxes. They're really great and even work with a mobile phone as a source. Mods are only limited by the diminutive size of the thing. The 12MHz XTAL is needed for the CM108 interface chip to provide signal USB timing, its nothing to do with the audio sample rate.
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Is this filter -- or any of the ones shown here PhiDAC hex kits with pre-built filters -- in any of the PDF schematics you've posted? I only found this: lingDAC - cost effective RBCD multibit DAC designHere's one of my early prototypes of the 5th order filter - its not on general sale yet as I'm not sure I can make them in sufficient volume. But by all means ask if I have any available
I suppose I should break out the 'scope to measure what freq. is being pumped to the 1387's clock line (via CM108 ). Unless you've already done that and can prove a clue?
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No, the precise schematic for that filter (5th order) isn't shown anywhere. The precursor for it is here : lingDAC - cost effective RBCD multibit DAC design
The difference between that prototype and the schematic shown is only in the terminating impedance - I realized it would not be backwards compatible if it didn't feed a 47R termination. Hence the inductors got scaled down in value and the capacitors, up in the same ratio (79/47= 1.68).
As for what comes out of CM108, I've only ever replayed 44k1 material through it so have only seen 2.82MHz on the bit clock.
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So the inductor filter (daughter board) snaps in between the TDA187 out pins and your opamp-based ckt (shown in that 5-16 PDF schematic:
https://www.diyaudio.com/forums/dig...ive-rbcd-multibit-dac-design-post6209357.html ?????
I guess I don't understand why you show items that are not part of the for-sale-kit ("A couple of pictures of the DAC with the two filter options to whet your appetite are attached."):
PhiDAC hex kits with pre-built filters
Unless those inductor filters are included in the kit described in : PhiDAC hex kits with pre-built filters ?????????????
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As far as the CM108, I just looked at its datasheet:
5 DAMCLK DO, 4mA, SR 11.2896 MHz Output for 44.1KHz Sampled Data and 12.288MHz for 48KHz Sampled Data
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I got a 404 error clicking on that link. So I can only guess that the answer is 'yes'.
This is a DIY forum, this thread isn't a commercial one. Plenty of designs of mine aren't for sale, they are intended to stimulate/encourage other DIYers in their DAC journeys. The commercial thread shows two filter options and those two filter options (3rd and 7th order) are for sale. Eventually if it turns out the 5th order filter is replicable in volume then I may well add it to the 'Vendor' thread.
TDA1387s don't have any use for such a clock (256fs). S-D DACs may very well do though, I guess they don't want to limit their applications just to multibit DACs.
In the FIRST post of that Vendor's thread, post pictures of EXACTLY what the kit(s) will include. And what the final product -- after kit build -- will look like.
Even if your intentions are "pure" DIY (non-commercial), clear and concise project descriptions -- as on the Vendor or TS posts -- reflects positively on the circuit/topology itself.
If one has to dig and ask for clarification, what does that say about ultimate quality and fidelity of the circuit?
OK, fair enough. It'll need a mod to do though as attachments aren't permitted after 30mins. I'll post up a pic later on the thread and ask a mod to move it to post #1.
I'd not make a connection between them myself. You gonna reveal what your conclusion is? You've already hinted on this thread that Ali/eBay DACs look more attractive to you and I've figured you're not a likely customer for PhiDAC - after all, its a DAC for people who listen
Well, the Ali/eBay products hardly come with a sonic guarantee. A lot of marketing talk with their refs to TDA1541A-like sound.I'd not make a connection between them myself. You gonna reveal what your conclusion is? You've already hinted on this thread that Ali/eBay DACs look more attractive to you and I've figured you're not a likely customer for PhiDAC - after all, its a DAC for people who listen
That said ...
What the Ali/eBay products do well is the single-page, succinct, compact presentation that the sellers are forced to create based on standardized templates of those mega-product engines.
That is ... lotsa high-rez photos, bulleted descriptions, short-n-sweet paragraph write-up. And the full price is large font, with PayPal as payment portal.
If you (more forum sellers) follow a similar format, more diyers may try out your ideas.
No difference here then - the only sonic guarantee I give is that I love the sonics myself. PhiDAC hex is a DAC that I get a huge amount of enjoyment from. Can't say though whether my experience is transferable to others given we all have our different ways of listening.
The medium suits the message.
Increasing the quantity isn't the aim - what I'd like to do is get PhiDAC into the right hands, not just a larger number of owners. Its not a DAC for everyone. Even the extremely seasoned DAC designer Mike Moffat said something along the lines of : 'God could appear tomorrow and explain in detail to me how to build the perfect DAC. There would still be those who didn't like how it sounded.'
Promoting your wares
The ebay/Ali-sold projects are less subject to such cognitive biases .... and their actual performance (sonic fidelity) are much more statistically significant (# items sold, trending metrics, reputation of seller etc., baked into the eBay engine).
Promoting your wares in an obscure forum thread -- where only a few have actually built and tested the product -- does not really account for much.
As it is, the presentation of your projects is MESSY and CONFUSING. This thread is ~100 pages of mostly coffee talk. It's a watering hole. Hence, only a few "right hands" (your words) will listen to this project. Because of their time commitment (back and forths in this thread, and the effort/$$ to building and implementing the kit), will very readily predispose them to the sunk-cost bias. Yes, unboxing photos and "received my tracking no." updates count towards that.
The ebay/Ali-sold projects are less subject to such cognitive biases .... and their actual performance (sonic fidelity) are much more statistically significant (# items sold, trending metrics, reputation of seller etc., baked into the eBay engine).
Promoting your wares in an obscure forum thread -- where only a few have actually built and tested the product -- does not really account for much.
My "reading" of abraxalito’s history here is that he is always on the improvement and experimentation. That’s genuine diy.
On the other hand, KHashmi316’s initial comments about segregating the evolving designs and providing in situ documentation, is something I do not disagree with. But correlation with ebay pages is quite a stretch.
Then it is the other forum over Vendor’s Bazaar that is purely about the kits for sale.
George
On the other hand, KHashmi316’s initial comments about segregating the evolving designs and providing in situ documentation, is something I do not disagree with. But correlation with ebay pages is quite a stretch.
Then it is the other forum over Vendor’s Bazaar that is purely about the kits for sale.
George
Yet clearly a major part of your confusion is because you've not educated yourself with the information which is available here. Messy I would tend to agree - that's the nature of forums and also my nature (ask my wife
).The rest of your 'coffee talk' is just that.
As for the initial question regarding crystals and reclocking, I must add that it was answered correctly by both @diyiggy and @abraxalito.
Interesting things, I see a 50MHz oscilator, but don't see reclocking chip in the audiophonics design: AUDIOPHONICS I-TDA1387 TCXO DAC Raspberry Pi 3 / A+ B+ / Pi 2 / I2S - Audiophonics
It makes me thinking that when a DAC board is driven not by the RPI intefrace, but an external I2S source, this oscilator is not used at all.
@KHashmi316. In the board you have linked (4xTDA1387) you can expect working sampling rates 44.1kHz and 48kHz, as CM108 is oversampling x4 and you have to feed it with 16-bits, as 24-bits is not accepted. In the PhiDAC there is no USB/I2s interface, so you can plug anything you like and a sample rates accepted by TDA1387 chip are rated in a datasheet well above 192kHz/24bit. With a good USB/I2s converter it makes it a quite modern NOS DAC.
If you are still interested in a similar design, I suggest not DIY, but a ready product like a Nobsound 8xTDA1387 DAC/HPA: Nobsound Mini HiFi Sound Card DAC TDA1387 USB 8X Audio Decoding Headphone Amplifier DTS/AC3 Coaxial Optical Digital Output|Headphone Amplifier| - AliExpress
Interesting things, I see a 50MHz oscilator, but don't see reclocking chip in the audiophonics design: AUDIOPHONICS I-TDA1387 TCXO DAC Raspberry Pi 3 / A+ B+ / Pi 2 / I2S - Audiophonics
It makes me thinking that when a DAC board is driven not by the RPI intefrace, but an external I2S source, this oscilator is not used at all.
@KHashmi316. In the board you have linked (4xTDA1387) you can expect working sampling rates 44.1kHz and 48kHz, as CM108 is oversampling x4 and you have to feed it with 16-bits, as 24-bits is not accepted. In the PhiDAC there is no USB/I2s interface, so you can plug anything you like and a sample rates accepted by TDA1387 chip are rated in a datasheet well above 192kHz/24bit. With a good USB/I2s converter it makes it a quite modern NOS DAC.
If you are still interested in a similar design, I suggest not DIY, but a ready product like a Nobsound 8xTDA1387 DAC/HPA: Nobsound Mini HiFi Sound Card DAC TDA1387 USB 8X Audio Decoding Headphone Amplifier DTS/AC3 Coaxial Optical Digital Output|Headphone Amplifier| - AliExpress
You can ask to Ernsternst above that owns iirc the Audiophonics I linked.
I 'm not aware on how it works, bu the datasheet of the input chip might answer to you, such are little fgpa sometimes so the unique clock is the reference for them to be slaved I don't know if it's always oversampling the input signals or according the frequency detects and act dometimes as a through pass.
FGPA are less good than a dedicated exact good Xtal for the two frequencies family, bu the best one as used by Chord seems to work ! We don't know if the best FGPAs beat the best SC-Cut ocxo Xtals though... Sometimes the problem is just elswhere and what you hear for the bad is related to something else : layout, power supply, parts, all together...
I 'm not aware on how it works, bu the datasheet of the input chip might answer to you, such are little fgpa sometimes so the unique clock is the reference for them to be slaved I don't know if it's always oversampling the input signals or according the frequency detects and act dometimes as a through pass.
FGPA are less good than a dedicated exact good Xtal for the two frequencies family, bu the best one as used by Chord seems to work ! We don't know if the best FGPAs beat the best SC-Cut ocxo Xtals though... Sometimes the problem is just elswhere and what you hear for the bad is related to something else : layout, power supply, parts, all together...
