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Moving from 9038Q2M to a 9028Pro board
Moving from 9038Q2M to a 9028Pro board
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Old 4th July 2018, 12:00 AM   #101
Mikett is offline Mikett  Canada
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Join Date: Aug 2003
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OK, Who let the dogs(Sound) out? Yeah. First impressions listening to Diana Krall Live in Paris. Yeah this SRC does work well. It is like moving from an MP3 to a FLAC. It is not that subtle if yoor system resolves it. A level of veiling is removed. Soundstage depth is distinctly improved same for width. Essentially it regains more dimensionality. Is it just the highs. Heck No. Is it the midrange. No. So what about the Low end.....It does it everywhere. The sense of dimensionality, the applause is more real though applause is HARD to reproduce, the timing and little details come out just as when I changed over the AVCC from the LT1963 to the LT3042. Everywhere you say? Yes. Now maybe the output of the SRC has less jitter but whatever it is doing it is making it better at this time.
Now one warning though. If your DAC still has too much sheen and has edginess, I think this SRC could splash that in your face too much.

I will give more listening but it appears to do what it does well. It is able to retrieve more information on the recording than what we thought was there. Pretty amazing that it can be done.

At first I could not get it to run off the USB on my PC. My motherboard has a couple USB ports that is supposed to put out a cleaner 5V for USB based dacs. So I used it on a USB phone adapter.

Me thinks that I will build a dedicated 5V linear source using a 317 from my box and see how much more this thing can pump out. Maybe I will order another LT3042 to power this thing.
So Markw4, so far so good. It is not a cureall but possible one of the last steps.
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Old 4th July 2018, 04:07 AM   #102
Mikett is offline Mikett  Canada
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OK, been listening. Then checked the temps on the heatsinks for AVCC. Much warmer than they were before the up sampling. So one needs to pay attention to the increased current demand. My guesstimate is that the increased current might have doubled or tripled.

This DAC is getting so much better I've decided to go all in and put in a SuperReg for the IV stage PS. The final install will take longer.

I'm also now beginning to look for a superior clock.
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Old 4th July 2018, 05:11 AM   #103
Markw4 is offline Markw4  United States
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Quote:
Originally Posted by Mikett View Post
If your DAC still has too much sheen and has edginess, I think this SRC could splash that in your face too much.
Looks like you are hearing a very slight remaining amount of distortion that comes out of SRC4392, although as you say, it helps a lot and once you hear it you would rather have it there than not.

However, the good thing about AK4137 is it doesn't have that little thing you are still hearing. That effect is replaced with a more detailed yet more easy and natural sound. The difference takes no effort to hear, if you tried it you would definitely keep the AK4137 and replace the SRC4392.

Isn't it interesting how it keeps getting better than expected because you never had any way of knowing all the information that is really on a CD, you just thought you did. It gets better as more of that information becomes audible and and turns out to be good sounding. No idea mastering ADCs were that good.

Last edited by Markw4; 4th July 2018 at 05:22 AM.
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Old 4th July 2018, 12:50 PM   #104
Mikett is offline Mikett  Canada
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Well, not only us but PS Audio has been touting that there is more information on a CD than we thought. They upsample PCM via an FPGA to DSD and then output it using transformers on their top end DAC. Their DAC jr. does the output with SS. Both are in totally different snack brackets. The AK4137 might be doing something similar in some fashion but it sure looks like when upsampling is done right, it works. Why? that is a mystery because it would seem that they are creating bits out of nowhere but not really. The algorithm is likely a form of SWAG. Sophisticated Wild As Guessing.
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Old 5th July 2018, 12:48 AM   #105
Markw4 is offline Markw4  United States
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Upsampling seems to be doing more than one thing. One thing has to do with reconstruction filter transition band space, but there seems to be something else too. It may have to do with jitter, but I think it would probably take some very good test equipment to get a better understanding of it. I do know that DAC-3 only upsamples to 211kHz and it still sounds a little better than by modded DAC at 960kHz. But, they aren't using a 100MHz clock with it's higher jitter either. They do have a some nice test equipment at Benchmark and they have done a lot of measuring to help guide their design, we know that. And they say they have designed to get jitter (horizontal time axis errors) and digital processing errors (vertical amplitude axis errors) as low as they can.
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Old 6th July 2018, 07:36 PM   #106
Mikett is offline Mikett  Canada
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Well over the last period, I've connected the 4392 SRC converter to a different power supply. I elected to use a very simple solution. I used a rechargeable phone power pack with a USB output for 5V.

The improvement was very easy to discern once again. The soundstage increased and imaging was much more stable. Some of the extra sibilance or distortion the little that the SRC imparts was reduced a bit but was not clear of the issue. Markw4, informs me that the AK4137 does not have or has much less of this distortion, so that will need to be sampled in the future. He is currently waiting to evaluate another AK4137 that is priced very attractively.

In the next while I will continue to use the DAC at the stage it is right now while I acquire a new crystek clock and await the SuperRegulator power supply PC board to arrive. When these two items have arrived, I will then case up the project.

I added some additional heatsinking for one of LT3042 because the high upsampling frequency is causing the Digital lines of the DAC to consume significantly more current. I will also have to drill some vent holes directly below and above the heatsinks to keep the components cool.

So far this DAC is now at a stage where every change is resolved very quiickly. It is a revealing DAC without harshness, in fact, if a component does introduce some distortion like the 4392 SRC converter, it will reveal it. The nice aspect to me is that all the components to bring it here are pretty much off the shelf. The only real construction will be the SuperRegulator Power Supply which is readily available at the DIYAUDIO store. Thus this can be a straighforward project for the intermediate builder.

Last edited by Mikett; 6th July 2018 at 07:38 PM.
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Old 11th July 2018, 07:24 PM   #107
Markw4 is offline Markw4  United States
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Just wondering if anybody has decided to work with the same board here that Mikett has been modding? Has anybody placed an order for one, or maybe even received one yet?
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Old 18th July 2018, 04:15 PM   #108
Mikett is offline Mikett  Canada
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Since the last posting I am still listening with the SRC. Each time I listen I come back in awe of what I am now hearing.

Does it get better. Yes. I will be ordering a new Crystek oscillator. The nice thing is that underneath the current oscillator, there should be SMD pads that allow easy mounting of the Crystek 575 oscillator. YEAH. That WAS a nice discovery.

Next thing I would do instead and about to do....I will put the 317/337 regulators for the op amps back in and will use them as preregulators for the SuperRegulator power supply that I am now in the process of building. So If I had to start again, all I would need to do is replace one resistor on each channel that sets the regulator output voltage and then cut traces of both outputs of the regs and lead those to my SuperReg PS boards. Since the SuperReg PS boards feature remote sense, my wiring back to the PS will be accomodated in the feedback, but still good wiring to there is warranted.

Next thing I will do is this. I will remove the LT1963 for the AVCC, the left one. and use the rectified DC circuit built on the DAC board. The LT1963 built onto the board will be sufficient for the Vdd signals for the DAC. and will be retained. However, since I already have 2 LT3042s, I will then cut the trace that leads from the activated LT1963 and branches out to the oscillator/clock. This will now be fed directly from a dedicated LT3042. Retain the ferrite bead in the path as this helps with filtering very HF hash on the line. The pads from the removed LT1963 will then lead to my LT3042s which will both be fitted with their own LT317 preregulators.
And I also decided to get a nice case for the power supply box.
When the SRC converter is used, the currents demanded on the Vdd lines (1.2V) increase dramatically.
It will I hope only get better.
In the meantime, I might be experimenting rolling op amps in the final stage. However my tube based Balanced to Single ended converter is beckoning.

This is turning out to be much better than I had anticipated.
Attached Images
File Type: jpg crystal mount.jpg (145.1 KB, 267 views)

Last edited by Mikett; 18th July 2018 at 04:19 PM.
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Old 28th July 2018, 09:36 AM   #109
terry22 is offline terry22
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Nice! Every mod looks to be easier on this big board than on the little 9038q2m..
Please share some pictures of your future mods.
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Old 30th July 2018, 08:33 AM   #110
Sergelisses is offline Sergelisses  France
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Quote:
Originally Posted by Mikett View Post
In the meantime, I might be experimenting rolling op amps in the final stage. However my tube based Balanced to Single ended converter is beckoning.
Hello Mike
I am experimenting also different op amps on final stage and i have a question

The final stage is a simple op amp and i would like to test a double amp on the final stage .
What to do with the op amp no used ..... how to connect the inputs non used

Thanks for your help

I have received two samples AD797 from analog devices and the results are very good ...better than the LME49710 ( Final stage )

Serge

Last edited by Sergelisses; 30th July 2018 at 08:36 AM.
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