That would keep it on the noisy side of the DAC board, definitely. But I worry it would contaminate the clean side of the USB interface back through the I2S ground. [EDIT] Unless the Serial and I2S are separately isolated? I admit I didn't actually test it, just assumed the 'dirty' side was all connected. [/EDIT]. I mean, I know it sounds like audio nervosa... but I just can't stress how noisy the USB is from my Lenovo docking stations, and the noise does only seem to need the ground to ride on. I have no idea how they screwed it up so badly.
Thankfully, any noise is completely inaudible once isolated, so I'll just have to pop the lid if I want to tinker. Might encourage me to just listen more rather than futz around!
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That's ok, you can remove Andrea from your ignore list, for now on 😀.
Nice build, BTW, is that a custom enclosure?
Isn't there any 60Hz mag field leak to the analog side? I get chill bumps when seeing free air toroids that close to sensitive analog circuitry...
It's a HiFi2000 Galaxy 2U 330x280mm. Available here and here. Also has the perforated steel baseplate. Very old school and pricy versus what you can get out of Asia these days, but I like the classic look and they are very solid.
Dead silent, even with my most sensitive IEMs. The transformers are only 7VA and 5VA, not even close to their maximum loading. That said, I am probably going to buy a custom toroidal transformer - magnetically shielded and with a screen between primary and secondary - just to better nail the voltages. As it stands, the ±9VDC is intended to be fed from 12+12VAC but is sitting at over 15VAC, meaning the power supplies generate way more heat than necessary.
Same stuff! Technically HiFi2000 is the brand name, Modushop.biz is the name of their online store. Also available at diyaudiostore.com of course.
FWIW, I've ordered from both stores, and Modushop works out cheaper for us here in Canada.
Hi guys,
I have a question, if it was discussed earlier then I kindly ask you to point me (1000+ pages is really hard to browse quickly).
Is here anybody knows what is the best load (impedance) for dam1121' raw output? Does 640 Ohms of output impedance means that the best loading impedance should be x10-20 times more (6-13k)? Have anybody tried to load 1121 on to the output equal impedance (640 Ohm) or even to load it on to low impedance like 1-10 Ohms? And finally to be maximally streight in question - is it dangerous to short the + and - of channel output at all?
All I have found is this promt within the user manual (on page 5): "There is no requirement for a specific load, but low impedance loads will reduce the output voltage."
Reducing the output voltage - is clear, but what about THD/IMD changes within different load impedances?
Thanks!
Ivan.
I have a question, if it was discussed earlier then I kindly ask you to point me (1000+ pages is really hard to browse quickly).
Is here anybody knows what is the best load (impedance) for dam1121' raw output? Does 640 Ohms of output impedance means that the best loading impedance should be x10-20 times more (6-13k)? Have anybody tried to load 1121 on to the output equal impedance (640 Ohm) or even to load it on to low impedance like 1-10 Ohms? And finally to be maximally streight in question - is it dangerous to short the + and - of channel output at all?
All I have found is this promt within the user manual (on page 5): "There is no requirement for a specific load, but low impedance loads will reduce the output voltage."
Reducing the output voltage - is clear, but what about THD/IMD changes within different load impedances?
Thanks!
Ivan.
I haven't tried, but do adhere to having a 10-100x or higher impedance on the amp input, so that there is voltage matching and the DAC doesn't need to "drive" the amp.
Well, my question relates more to DAC's SQ (THD/IMD at least), while pairing it with the next stage is another task. Important too, but another task.
Actually, this is not the dam1121 thread, but anyway, the R-2R network in all my dams and dacs is a perfect voltage source with a resistive output impedance, in most cases 625 ohm. So ohms law apply, no side effects.
Thank you Soren@soekris (Soren)
Over the last couple of weeks have listened to two builds of this module, built by enthusiasts here locally. I liked the "fluid" presentation of music this DAC brings to the game. Recently, I had to start wearing hearing aids due to mild hearing loss. The present rig started sounding a bit shrill/harsh with hearing aids. DAM1021 presentation is more pleasant, I feel.
Going to try a build with DAM1021-12. Waiting for boards to be procured in US and hand carried to India, now that travel has resumed.
Could you please update DAM1021 document on your website w.r.t rev7 changes and usage. It would be helpful to noobies like me to have as a reference.
Thanks,
Raghu
Over the last couple of weeks have listened to two builds of this module, built by enthusiasts here locally. I liked the "fluid" presentation of music this DAC brings to the game. Recently, I had to start wearing hearing aids due to mild hearing loss. The present rig started sounding a bit shrill/harsh with hearing aids. DAM1021 presentation is more pleasant, I feel.
Going to try a build with DAM1021-12. Waiting for boards to be procured in US and hand carried to India, now that travel has resumed.
Could you please update DAM1021 document on your website w.r.t rev7 changes and usage. It would be helpful to noobies like me to have as a reference.
Thanks,
Raghu
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Guys, I'm using DAM 1021 since April 2015, the first version, it's already upgraded with Vref mod, I'm not using the output opamps, installed polymer low ESR decoupling caps on the supply rails, recently also replaced the main DAC PSU with Salas shunt regulator.
Together with DAC, I am using Logitech Squeezebox (10+ year-old wireless Wi-Fi player) to provide the I2S signal (3.3V if I remember well) to the DAC. They sound great together, I think better than any multi-bit DAC I ever tried so far.
I use it and keep the PCBs for years on a... shelf... yeah I know 🙂 well, it's time to put it in a nice enclosure.
But before I do that... before I order a specific transformer and chassis I'm wondering if there is anything else to improve, for example in terms of the master clock/FIFO buffer - actually, a few years ago I purchased one from Ian and never used it. Squeezebox has an 11.2896MHz clock, I'm not sure if adding a low jitter clock there will change anything?
Guys, from your personal experience and successful improvements any ideas that I should definitely consider before it will be too late or difficult to implement before ordering the parts? 🙂
Together with DAC, I am using Logitech Squeezebox (10+ year-old wireless Wi-Fi player) to provide the I2S signal (3.3V if I remember well) to the DAC. They sound great together, I think better than any multi-bit DAC I ever tried so far.
I use it and keep the PCBs for years on a... shelf... yeah I know 🙂 well, it's time to put it in a nice enclosure.
But before I do that... before I order a specific transformer and chassis I'm wondering if there is anything else to improve, for example in terms of the master clock/FIFO buffer - actually, a few years ago I purchased one from Ian and never used it. Squeezebox has an 11.2896MHz clock, I'm not sure if adding a low jitter clock there will change anything?
Guys, from your personal experience and successful improvements any ideas that I should definitely consider before it will be too late or difficult to implement before ordering the parts? 🙂
Improving PSU
IMO little modifying in the PSU brings noticeable improvement.
Change cheap R1 wirewound in the Salas to better one (I use Ohmite AG5 5W wirewound, but any good one better than average WW).
If you have final power transformer, the appropriate Quasimodo values (Cx, Cs, Rs) also helps.
IMO little modifying in the PSU brings noticeable improvement.
Change cheap R1 wirewound in the Salas to better one (I use Ohmite AG5 5W wirewound, but any good one better than average WW).
If you have final power transformer, the appropriate Quasimodo values (Cx, Cs, Rs) also helps.
Thanks for your reply. I'm not sure how replacing one wire-wound resistor with another wire-wound resistor in this particular place would make any difference?
How?
https://www.tme.eu/Document/1d010f0222836cb51567e6715d044023/ROYALOHM-KNP.pdf
Even if the resistor I used has some inductance it can only help to reduce HF noise.
Hi all, i am waiting for my soekris package to arrive. Can i please learn your r core connection experiences for power supply? Actually i dont have toroid transformer for now..
Non magnetic materials, ceramic core, welded constructions, tight temperature coefficient (for example 50ppm/C), versus not marked materials, 400ppm/C.
Try both.
audiodiyers.hu • Tema megtekintese - Salas SSLV 1.3
"This circuit is very sensitive in terms of sound quality to the type of current limiting resistor R1. I deliberately didn’t write quality because who knows what quality means here ?! I made the 2 + and 1 - panels, one + with 1.2 ohms, the other + and - with 3.3 ohms. On the very first try, the 1.2ohm Mills12W and the 3.3ohm Ohmite 5W. Hmmm, it sounded pretty nice. Then of course came the fix effect on it and I bought a 1W metal layer of Takmans because to my surprise it was 3.3 ohms, the 1.2-meg was assembled from 2.4 ohms. And the surprise came. Everything has shifted up quite a bit, the mids and highs have become hyper-defined, the shots that tend to hiss or are close to it have now started properly. The deepest section went on vacation.
Did I wait - or 2 weeks? - see if the picture changes, but all that changed was that I took out the Takmans and soldered the Mills and Ohmites back. It was already back on the first record I heard before taking Takman.
I can’t comment on the other components, but that series resistance really matters. "
Hi all, i finally got my dam1021 and made all connections using 12dcv power supply, amanero i2s and raw output. I've checked j2 header, all voltages are ok. Green link is stabilised while amanero connected via pc. But unfortunately i dont get any sound from speakers.. What could be the problem? I've read old posts and made amanero firmware upgrade.. But i dont understand where to look at next.