Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

Moving from 9038Q2M to a 9028Pro board
Moving from 9038Q2M to a 9028Pro board
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 22nd June 2018, 03:47 AM   #41
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Quote:
Originally Posted by Markw4 View Post
The 9028PRO board with the 'golden clock' you can buy on ebay for about $10 (only the clock, not the board) is not a low phase noise clock so far as anyone has been able to show.

The IV stage doesn't use quality thin film resistors and C0G caps in the signal path.

The voltage regulators, some of them anyway, probably need to upgraded.

The AVCC supply is one regulator for both left and right channels, so stereo separation is probably affected as would be expected.

It still does't have any way to upsample, either. My current recommendation for that may be changing from an SRC492 to an AK4137. I made some comments as to why in another thread, but I can post a link here if anyone is interested. I will have more to say about it later anyway after some more tests. The basic rationale for upsampling, which is the reason Benchmark and Crane Song use it, is to fix reconstruction filter issues that are a part of all hi-res DAC chips currently made (according to Benchmark).

Bottom line, I would agree it appears the 9028PRO board is better as-built than the 9038Q2M board. I don't know how much work or if it would even be possible to make the 9028PRO board sound as good as my modded 9038Q2M board. That remains to be seen. If the AVCC issue can be fixed then it can probably be made as good as my modded board, but the end cost will be more because there is still a lot to fix to make it the best sounding DAC it can be.

As far as the question of how good is good enough, I would say that I have been encouraging people to mod a headphone amp to go with the DAC mods. An high quality HPA would be pretty cheap to do, a whole lot less expensive than a power amp, and it will let you know how good your DAC actually sounds. Getting back to how good is good enough, it may depend on how good you have heard. Too much listening to a really good system risks making you want one. The safest protection is never listen to a good system, then you won't know how good it sounds and you can remain satisfied with whatever you have right now. For myself, I guess I can listen to a some car stereos, but not all, and I can listen to iPhone audio some, but none is good enough for a main stereo. Since I know what a good one sounds like (potentially habit forming), that's what I want to have. I also want it to be able to serve some utility function such as be usable to mix a record with if the need arises, which it does now and then when people track me down asking me to do it for them.
Lest we forget that we need to put all of this into a case at the end. That was when it hit me that some kind of compromise will be needed because fitting a mish mash of a ton of boards into a case is not easy and the amt of metalwork is huge. When I saw that a decent case was available that fit this exact dac board and I estimated just enough space to fit everything in, including possible mods, that sealed the deal. I hate doing intricate metalwork, and when you have a display, it needs to "look" right. PLUS it has a remote.

Yeah, the upsampling, reconstruction and THD compensation etc. will be missed but I think even the Buffalo series does not have this either. I guess there are three levels, things like the 9038Q2M, boards like these, then things like what Twisted Pear is doing. I was intentionally trying to avoid too much serious modding on the replacement DAC board. Remember that caused the smoke to escape on my last DAC.

And in the end I keep reminding myself that this DAC will cost less than the taxes I would have to pay on a DAC3 purchase!
  Reply With Quote
Old 22nd June 2018, 04:09 AM   #42
Markw4 is offline Markw4  United States
diyAudio Member
 
Join Date: Jul 2016
Location: California
IIRC, I think the Buffalo DACs have an SRC4392 for SPDIF inputs only. Don't know if they use it to upsample at all.

But, the main thing is I wouldn't necessarily do something or not just because of what someone else does. The only thing I would really encourage people here to do would be to mod a HPA, invest in some accurate headphones and use those things as test instruments and for enjoyment. Once you can hear what you are doing then you can decide if your DAC is good enough or not. If you can't even hear what you have, how you can make a decision about what to do next?

Also, because of the expense of SRC and because most people aren't familiar with what they do I have offered to loan one out to somebody who has done the other mods and wants to hear what the SRC can do for the sound as a final mod. In fact, I think I might offer to send you one to try out since I have a spare that can serve as a loaner and your 9028PRO DAC already sounds not-too-bad as-is. Would you be interested?
  Reply With Quote
Old 22nd June 2018, 08:03 AM   #43
Sergelisses is offline Sergelisses  France
diyAudio Member
 
Join Date: Nov 2003
Location: Near PARIS
Quote:
Originally Posted by keilau View Post
The $140 ES9028PRO board seems to have most of the quality features we would like to upgrade to. The 3 totally separated PS, I/V output and a better clock. I estimate adding USB input, PS source and a pre-drilled case will add up to about $300. The sound would have been good enough for most of us without further board upgrade.

The SU-5 assembled ES9038Q2M DAC has I/V and ready to run at $200. A good quality linear PS box will add about $30. I am waiting for Markw4's assessment on how good it sounds as is and quality of the parts, including clock used.

I have an assembled ES9038Q2M DAC with TFT display, USB for $120. I am about done upgrading it to LDO dual linear PS. But it has no I/V and the clock is not so good. It sound pretty good to me and like the filter adjustment, but I do not have a reference for high quality DAC.

Two low end, commercial ES9038Q2M DAC, Pro-Ject Pre Box S2 Digital and Topping D50, both get very good reviews without the I/V. But they get good separate PS. I am facing the question of how good is good enough. I am very tempted to get the SU-5 DAC if it sounds better than the ES9038Q2M board that started the ES9038Q2M thread. Any first hand input on comparison of the above mentioned 3 options is appreciated.

Hello

If had any advice to give

Change the power supply step by step to see the impact on the sound .
In fact I changed the 3 at the same time and I do not know if the 3 are
really necessary!

Serge
  Reply With Quote
Old 22nd June 2018, 11:32 AM   #44
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Yes, I plan on doing just that with the OP amp PS first but I am waiting for some 797s for the last stage of the IV before I start that journey.
  Reply With Quote
Old 22nd June 2018, 02:56 PM   #45
keilau is offline keilau  United States
diyAudio Member
 
Join Date: Mar 2013
Location: Windy City, US
Quote:
Originally Posted by Mikett View Post
Lest we forget that we need to put all of this into a case at the end. That was when it hit me that some kind of compromise will be needed because fitting a mish mash of a ton of boards into a case is not easy and the amt of metalwork is huge. When I saw that a decent case was available that fit this exact dac board and I estimated just enough space to fit everything in, including possible mods, that sealed the deal. I hate doing intricate metalwork, and when you have a display, it needs to "look" right. PLUS it has a remote.
Well said.

When I first start the DAC project, I purchased this enclosure that was specifically pre-drill for the VR1.06/1.07 ES9038Q2M board.
MINI aluminum chassis case for ES9038Q2M DAC DSD Decoder | eBay
I still have it on my shelf. (PM me if you are interested) But it does not have the cutout for the display. So I ended up purchased the fully assembled DAC with the Q2M board, USB and display.

Last edited by keilau; 22nd June 2018 at 03:00 PM.
  Reply With Quote
Old 25th June 2018, 02:22 AM   #46
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Update. I did install the Sulzer Borbeley Power Supply first.
I will show step by step details.
Turned it on and discovered something. Uh Huh... I was always told to watch out for this. Fixed it.
Then I listened and listened and the conclusion will come later.
Then I went for it and decided to install a couple of LT3042 boosted to 1 amp.
I modified each LT3042 board with a Cset of 47uF Tantalums + whatever was already on the board. I then crossed my fingers that the slower ramp up would not cause issues.
None. Turn on was smooth as silk.
Listened and listened. Wow....this time the LT3042s sounded great in the low end unlike my experience I had with them on the 9038Q2M. There it probably was not the LT3042 but something else.
Bass is fantastic. Chorals...superb, Brass with real bite. Pianos will pound your chest when the player wants. But when you want soft vocals, the sound could indeed seduce. Yah.
I'm a fan of PRAT and this has it all in spades let me tell you.

Advance thanks for MarkW4 whose work on the 9038Q2M board inspired me to get into better digital and I am glad I did follow his guidance. Learning that smoke indeed runs ICs. I am keeping it inside this one!

Over the next few days I'll post pictures and outline everything and my impressions. What the analog supply effect is. What the AVCC effect is.
But not to keep you waiting....this board, IMO is a much better base to start from despite it having some compromises. I will outline why I feel so and the decision which direction to go for those sitting on the fence will be up to you but you need to know the pros and cons.

This weekend is going to force me to upgrade my crossover network for my subwoofers and I will tell you what I found there as well.

Last edited by Mikett; 25th June 2018 at 02:28 AM.
  Reply With Quote
Old 25th June 2018, 01:45 PM   #47
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
While I had the board out I would show the undersides.
The lighting was adjusted as best I could to enhance the line shadows.
Attached Images
File Type: jpg IMG_1088.JPG (957.5 KB, 148 views)
File Type: jpg IMG_1089.JPG (929.3 KB, 142 views)
File Type: jpg IMG_1090.JPG (662.2 KB, 138 views)
File Type: jpg IMG_1091.JPG (942.9 KB, 138 views)
  Reply With Quote
Old 25th June 2018, 02:00 PM   #48
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Now we begin the mods.
First we remove the 317/337 regs.
Since the regs were removed, there was no need for the voltage dividing resistors to the adjustment pin so I elected to remove those as well as the decoupling cap.
Then a thought occurred to me...... I could put in some pilot lights in there by reusing the 2.4K resistors and some LEDS. That way I can easily tell when my regulator has output.
Next stroke of luck was that there was a large plated hole for the ground point. I grabbed some 12 gauge wire and used that for joining ground to my Sulzer Borbeley PS.
Attached Images
File Type: jpg IMG_1092.JPG (915.7 KB, 135 views)
File Type: jpg IMG_1093.JPG (881.6 KB, 49 views)
File Type: jpg IMG_1095.JPG (974.8 KB, 44 views)
File Type: jpg IMG_1096.JPG (884.7 KB, 44 views)
File Type: jpg IMG_1097.JPG (959.6 KB, 44 views)
File Type: jpg IMG_1098.JPG (867.1 KB, 40 views)
File Type: jpg IMG_1099.jpg (220.7 KB, 43 views)
File Type: jpg IMG_1101.JPG (957.1 KB, 44 views)
File Type: jpg IMG_1103.JPG (878.1 KB, 43 views)
  Reply With Quote
Old 25th June 2018, 02:12 PM   #49
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Now comes the shutting down of the LT1963s.
One LT1963 feeds the AVCC lines, the other LT1963 feeds the Clock and other voltage requirements of the DAC via two AMS 1117s.
Since space was going to have to be minimized to fit into the custom case I also purchased from Ebay to fit this DAC. I started to think about compacting everything.
I believe in preregulation rather than brute force capacitance. So the Ebay LT3042 modules I had to needed to be reduced in footprint since space was going to be an issue. I'll let you know later why I did what I did and what it means down the road.
So I removed the large Capacitors on the LT3042 module and installed some more compact input caps and also removed the rectifying diodes as that work will be carried out on a 317 preregulator. ( you could reuse the 317 removed in the first step to fab a preregulator or do what I did purchase an inexpensive 317 single reg board from ebay for about $2...upgrade caps though.)
I then modified the 1A Current boosted LT3042 module to 3.3V and then installed a 47uF tantalum capacitor as Cset. Why 47Uf and not 22uF. This was left over when I was trying to build the op amp AVCC and my 9038q2m was fried in the process.

I also added an LED to the board again to show power to the board was good.
You'll notice I am using through hole stuff to mount on SMD intended pads. It's all good but you need to take your time and I also used all kinds of contraptions to hold everything in place before soldering. This was nearly as complicated as created making my custom 744-811 module on an 8 pin DIP over 20 years ago.

In the end all good.
Attached Images
File Type: jpg IMG_1105.JPG (875.7 KB, 63 views)
File Type: jpg IMG_1106.JPG (902.7 KB, 69 views)

Last edited by Mikett; 25th June 2018 at 02:15 PM.
  Reply With Quote
Old 25th June 2018, 02:26 PM   #50
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Can we provide separate feeds for AVCC L and AVCC R. Looking at the board closely I do believe it can be done. It would involve cutting some traces and making wire runs directly to the L and R reference voltages and to two decoupling caps for AVCC.

Will I do this? I'll think about it but the limitation I had stated up front as regards AVCC lines is likely not there anymore but will depend on how much modding one wants to get into. As it is now, I can easily remove all the mods and return the board to stock. So there was no invasive modding at this point.

What more could have been done? Of course Clock changes......could be in the works.
Another LT3042 separate voltage feed for the clock...another $15 and SPACE and crystal......Never changed crystals before.

Upgrade decoupling caps.

Install shielded wire runs from the LT3042 feeds to the DAC board. Same for Analog. PS. Remember only one side of shield to be connected

Finally, I am thinking of removing the LT1963s from the board and use the rectifying circuit on the board. Its output will feed the LT3042s but each LT3042 board will have its own preregulator. This WILL then allow enough space in the case to fit possibly 4 - LT3042 modules into the case.....thus AVCC L. AVCC R, Clock, and feed to AMS1117s.
This would require invasive modding....remember I did not have to fabricate any boards myself.

I could also upgrade the resistors on the board to higher quality metal films.

At this time the sound is excellent in my opinion and I need to look at something else.

For those thinking of this DAC, while I did not fabricate any boards the analog power supply board is also very important. I had some left over from the early 80s and to this day they still sound excellent. These can be bested like I did to my preamp by Jung Super Regs or even his newer Shunt regs using similar design. ( Other low Z low noise regs can also be used but I can't comment on their performance) I have been a keen follower of Walter Jung since the early 80s and really appreciate his contributions to the audio world. Boards for the Super Reg can be purchased from the DIY Audio store and will indeed be better than the SULZER Borbeley. How much better will depend on how low your system can go and how much air your system can move. I am using VMPS Larger subs driven by Leach Amps with fully regulated power supplies and they do not poop out. The Super Regs add a sense of space that only the lower octaves will provide. If your system does not dig that low, I am not sure there will be a difference between the Super Reg and the Sulzer Borbeley.
I am now really thinking about going to the DIY Audio store.

Last edited by Mikett; 25th June 2018 at 02:38 PM.
  Reply With Quote

Reply


Moving from 9038Q2M to a 9028Pro boardHide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
ES9018K2M, ES9028Q2M, 9038Q2M DSD/I2S DAC HATs for Raspberry Pi iancanada PC Based 632 17th September 2018 02:52 PM
Moving day jackinnj The Lounge 12 26th January 2016 01:32 PM
Moving Pots from the PCB georgebrooke Construction Tips 10 15th September 2013 10:01 PM
The Hazards of Moving KBK Everything Else 1 2nd February 2004 10:44 AM


New To Site? Need Help?

All times are GMT. The time now is 09:09 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki