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ES9038Q2M Board
ES9038Q2M Board
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Old 23rd January 2019, 09:04 PM   #3711
kaytata is offline kaytata  India
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Join Date: Mar 2012
Hi Mark,
Regarding the balanced output schematic you advised, is it like the attached diagram?

Kay
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Old 23rd January 2019, 11:44 PM   #3712
bisesik is offline bisesik  Kazakhstan
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Join Date: Sep 2008
I have spend hours trying make it work... It works now, but not as I expected. It is needed to re-pull MU-pin every time when freq is changed. If MU-pin is always on the GND, then I need to re-select USB-input to actualize freq. AUDMUTE (and DACRST too) which are on XMOS board are not help. There is "NOT LOCKED" promt until MU pin is not grounded at least for one time. I can actualizate freq manually by pulling MU to GND every time after freq of music changed. But to make it automatically "more or less" I can only by pulling MU-pin to DATA of I2S through 3kOhm. If more than 3k, then freq may not changed (depends on music). To avoid problems in SQ of music, I think that this resistor should be as much as can, because I don't want to solder any active splitter. If MU is connected to LRCK, then the freq is wrong (what "he" is doing there when showing me wrong freq ??? ), if connect to BCK\MCK - not works at all. Stupid method, but it works
I have wrong version of old XMOS pins functionality, but thanks of you Mark, you made me believe in myself

Last edited by bisesik; 23rd January 2019 at 11:50 PM.
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Old 24th January 2019, 12:11 AM   #3713
bisesik is offline bisesik  Kazakhstan
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Unfortunately, there are some pops in music becsuse of that connection of MU to DATA. Most easiest way is to change XMOS to some modern version, OK
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Old 24th January 2019, 12:29 AM   #3714
Markw4 is offline Markw4  United States
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Join Date: Jul 2016
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Not sure if changing the board type between Amanero and XMOS might help. Don't know if it uses the mute pin for both. On the other hand, the low cost AK4137 doesn't even use a mute pin. And, they only cost around $35, so maybe one option if all else fails.
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Old 24th January 2019, 12:36 AM   #3715
Markw4 is offline Markw4  United States
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Join Date: Jul 2016
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In other news, finally got the clock divider board working. Figured out how to program it, and now ES9038Q2M is dead stable with DPLL set to 1. The 100MHz dac clock is divided by 4 to make 12.5MHz, a little bit high for DSD256, but it works. In particular it is outputting 12.5MHz DSD on the DSD256 setting with 16/44 PCM input from a CD rip. Don't know about that table in the AK4137 data sheet suggesting it wouldn't upsample 44.1Khz to DSD256. It works for me.

In addition to having to write bit-banging SPI code to program the divider, also found that at first the divider was outputting 75MHz instead of 12.5MHz. That turned out to be because of harmonic distortion in the LVDS inputs, which was due to no termination of the short u.fl cables. Added some 50 ohm loads at the input connectors of the clock divider board to fix that.

So far, I have only listened with headphones driven by the output stage line level output. That always adds some distortion, so I need to get the whole test setup into the test chassis and playing through the AHB2 power amp. Only then will I know how it really sounds.
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Old 24th January 2019, 02:04 AM   #3716
Markw4 is offline Markw4  United States
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Just noticed a possibly confusing description in the last post. The 100MHz dac clock is divided by 4 to produce a 25Mhz clock signal, which replaces the 22.5MHz clock that was on the AK4137 board. That in turn, will cause AK4137 to produce 12.5MHz DSD when set to DSD256 mode. To make it a little more clear, I marked up a copy of the block diagram posted by redjr (thanks!). The 22.5MHz clock is the one the AK4137 board firmware always selects when the board is set for outputting DSD. Also, it may help to know that the 100MHz clock signal that drives the clock divider is actually output on one of the ES9038Q2M GPIO pins.
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File Type: jpg DAC_Block Diagram2.jpg (89.1 KB, 283 views)

Last edited by Markw4; 24th January 2019 at 02:16 AM.
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Old 24th January 2019, 05:57 AM   #3717
bisesik is offline bisesik  Kazakhstan
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Selecting Amanero lead to "lock" freq to OTHER (always), but works the same manner through MU-pin.
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Old 24th January 2019, 07:10 AM   #3718
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by kaytata View Post
Hi Mark,
Regarding the balanced output schematic you advised, is it like the attached diagram?

Kay
Hi Kay,
Yes, that is the way shown in one schematic I posted. The inverting opamp can take its input from the output of the non-inverting opamp, or the the inputs of both inverting and non-inverting opamps can be in parallel as shown in the schematic below. When it comes right down to picking one way or the other, I guess I would probably prefer the version with the inputs in parallel, as below. That is, I would prefer it if the source impedance of whatever drives the two opamp circuits is reasonably low, such as another opamp. If the circuit could be loaded down significantly by the resistors of the inverting circuit, then that could be a problem. In that case the resistors could be made sufficiently large, or the opamps could be connected as shown on the other schematic. Since with our dacs the output impedance is usually pretty low, the parallel input circuit would probably win out.

Mark

EDIT: If you are only driving balanced lines a short distance to your power amp inputs, most likely you would not notice any difference whichever schematic version you choose.
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File Type: gif !BalancedOut2.gif (13.1 KB, 264 views)

Last edited by Markw4; 24th January 2019 at 07:24 AM.
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Old 24th January 2019, 07:46 AM   #3719
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by Terry Demol View Post
The part you mention above appears to be unobtainium. If there is an alternative you know of offhand that is available from Mouser or Digikey I might be willing to give that approach a try.

Otherwise, clock divider chips appear to be what can be reasonably obtained.

Assuming tests over the next few days show good effects on sound quality, then a low cost, easy to find and use solution that does the dividing would be probably be worth spending some time searching around for. Otherwise, some kind of circuit boards would be needed for ball-grid-array parts, or other cook-on-solder-pad parts.

Last edited by Markw4; 24th January 2019 at 07:54 AM.
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Old 24th January 2019, 02:33 PM   #3720
PJN is offline PJN  United States
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Join Date: Dec 2004
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Hi Mark,

I took your advise using my DMM to check my output stage, found two mistakes that are easily fixed. In the meantime I added extra capacitance to the AVCC rails as suggested. I removed the existing 100 uF caps and put 2000uf on each rail. I had a good listen before the mod and after the mod. I have to agree that it is well worth doing, it is an easy, low risk mod that audibly increases sound quality. Sound is more liquid, the glare that can be present on high frequencies is greatly reduced, definitely sounds better. Next step straighten out the output stage and give it a whirl, need to modify my case to add some new rca outs first. Here are some pics of the cap mod, the wimpy original caps are shown in the one pic for comparison.


Paul
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