Yes a version with LME49990 and fancy resistors, I'm sure some of us here would like to buy two boards and blind test the difference.
If you want, you can set it up that way. The audio signal, direct from the DAC, can be fed into any self-invented amplifier. No separate versions will be produced, as I understand.
Soekris wrote LME49724 earlier, I think rredline was asking about LME49990 instead of LME49724, since LME49990 has lower THD and IMD specs.
If this is pure Current out, then there should be no LME49724.
A quite large percent of this forum believes resistors sound different, so if they are Carbon, metal-film, Tantalum, Silver and so on is a tech consideration IMHO.
If this is pure Current out, then there should be no LME49724.
A quite large percent of this forum believes resistors sound different, so if they are Carbon, metal-film, Tantalum, Silver and so on is a tech consideration IMHO.
IMHO, it's a metallurgical question (metal to metal voltage & current), how the connections to the internal substrate and whether you have a inductive free internal design & trimming; followed the soldering of the resistors to your PCB.
It may be optimal to have all resistors in one ceramic substrate & laser trimmed.
Finally the RF question rises, while the Analog is not fully isolated against the digital... while a RF wave signal does not stop on the end, it will emit... source & sink dependent. Not only internally also it will flow source & sink dependent over connection wires to other equipments.
This is not an easy task to solve analog & digital shielding .. just my experiences using electric & magnetic near field probes 😱
Just my 2 cents
Hp
Since the thread has moved into the Vendor's Bazar section, everyone is free to buy or not this DAC as is, the Vendor made the design choices....
... but, I find just curious that everyone can discuss Scott's design
http://www.diyaudio.com/forums/solid-state/156474-yet-another-discrete-op-amp.html (also John's and Nelson's design), while noone can do the same about Soekris's project....
Maybe, I'm living in the World 1.0 too ....
Andrea
When the direct output is used (not the opamp output )..shall we use a caps on this direct out ??
He may have ordered 2400 resistors already, alright then, I'll just buy two and change all resistors on the second. Blind tests coming in 2015.
Next topic.
agree 100%
I hope Kastor L has already checked the price of 0.01% resistors and the availability in the several types... I guess he'll need a (sub-prime) mortgage 😀
EDIT: available types (0.01%) are only various metal film types. Prices (piece) range from €7,42 (@ 50+ pcs) to €36,45 (@ 50+ pcs) ... LOL ... prices, sales tax excluded
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I should have music though it in a couple of weeks, my references are not that fancy, an older Sony ES series CD player and a Cambridge DacMagic Plus, plus a Sennheiser HD-650. But don't expect me to be objective 🙂
Since the opamps are not really stressed, unlike most DAC I-V circuits, I feel the used parts are perfect for the needs, although I also have considered a LME49990 on the highest grade version.
But I do also like building discrete circuits, so later on a version with fully discrete output amplifiers might come out.... See a couple of my older post that never got anywhere:
http://www.diyaudio.com/forums/soli...er-mosfets-2sk3497-2sj618-little-testing.html
http://www.diyaudio.com/forums/soli...-amplifier-non-feedback-production-ready.html
http://www.diyaudio.com/forums/solid-state/156674-my-take-buildable-discrete-op-amp.html
Actually I would love competent input on the digital filters, seems to be plenty opinions around whats best, from no oversampling/filters, to very long FIR filters, or to FIR filters. Preferable supported by objective test or papers....
The direct resistor string output has zero DC offset, filtering only per personal preference...
Thankfully I'm not buying resistors the same place as you 🙂
Is it possible to add u.fl pads for the i2s input?
Very interesting design, but I think I will wait a bit for later discrete output stage. 🙂
Very interesting design, but I think I will wait a bit for later discrete output stage. 🙂
Check out John Swenson's thoughts:
Upsampling Impressions
and in this thread:
Are we just kidding ourselves? - Page 5
And an observer's thoughts on the results:
http://bottlehead.com/smf/index.php/topic,4086.msg54324.html#msg54324
Greg in Mississippi
As you probably understood, those are prices we DIY'ers have to pay. The prices mentioned are prices from mouser.