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

Vendor's Bazaar Commercial Vendors large & small hawking their wares

Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
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 2nd January 2018, 09:02 PM   #6841
fedde is offline fedde  Netherlands
diyAudio Member
 
Join Date: Jul 2002
Location: Eindhoven, the Netherlands
Quote:
Originally Posted by zfe View Post
The problem is that the gain is set in dB so you do not get an exact factor 2 this way.
You have a point here, indeed -6 dB is not exactly a factor of two...
(depending on the implementation though. the multiples of 6 dB gains could have been rounded to factors of two to reduce distortion at LSB).

In the meantime, my DAM package has arrived at the local post office. I can pick it up tomorrow...
__________________
http://www.fedde.nu, gainclone, non-oversampling DAC and open baffle audio projects...
  Reply With Quote
Old 3rd January 2018, 03:08 PM   #6842
nige2000 is offline nige2000  Ireland
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by ynmichael View Post
It's amazing how little I actually know about the DAM DAC... There's just so much hidden in the electrical circuits and components that could affect the performance, completely hidden away from non-majors behind the pretty abstractions... Let alone the fact that we don't really know the full dam1021 schematics...

I found out after studying all 77 pages of Soekris Dam Dac - Tir Na HiFi where Nigel and friends went for (and got VERY far) the ultimate dam1021, destroying a few boards now and then of course.

First of all, correcting my last post, the power regulation on the dam1021 is more likely:
AC/DC -> Bridge rectifier -> PWR A+/-
PWR A+ -> 3.3V Regulators-> Digitals (FPGA, oscillator and microprocessor)
PWR A+ -> 1.2V Regulator -> ?
PWR A+/- -> +/-5V Regulator -> +/- 5V DC -> Op-amps -> 4V vref -> shift registers
PWR A+/- -> Output buffer op-amps
[Probably still missing some but better than last...]

With this, now I can answer my own questions...:
(1) Digital/analog separation in the ground plane, or power in general, is probably not perfect. There is no conclusive evidence but the fact that Nigel and friends believe the vref battery mod was the most significant among all the mods which they A/B tested gives some hint. The mod basically provides independent power supply to the analog circuits (with output buffer already removed...).
(2) One could go all out on battery/externally regulated power supplies for all voltages/major components on-board, as a few did. And replace the 1.2V switch-mode regulator which seems to be noisy by an LDO counterpart... Here's my current idea of a reasonable and accessible mod, if the output buffer is not needed:

i. Supply PWR A+ with 5-7V DC, replace 3.3V regulator with Sparko discrete regulator, wire the VCC on the oscillator directly to the regulator for improved performance.
ii. Replace 1.2V switch-mode regulator with LDO.
iii. Supply ~4V (such as 3.3V with LiFePo4 battery) to shift registers, bypass op-amps. If done with batteries capacitors can be left out, but if done with (here I'm very much not sure...) regulators, supercapcitors might be needed. A possible regulated supply is perhaps Regulated DC -> 4* 4V Sparko Regulators. Sparkos are rated at 3uV ripple, 1.5% voltage precision, and 1A output, which should be enough for the shift registers (??).
iv. Supply future Soekris add-on buffer/headphone amp with the same regulated DC as the Sparkos for the shift registers. Or use an existing buffer kit.
v. (optional?) Swap out certain on-board ceramics for better caps / bridge more caps at places if there's room.

This should provide a higher level of digital/analog separation, better regulated voltage for critical components, and doesn't go as far as using battery supplies. Ideally, this should only require one transformer with two sets of secondaries for digital and analog respectively. one dual-rail linear regulator for analog and one single-rail linear regulator for digital. The enclosure would also have a quality buffer/head-amp built-in.

Does this sound reasonable? If so I might consider doing it next year when I have more time... also ideally after Soren releases the head-amp board so I can stack it with the balanced dam1021's....

This is just a naïve attempt at a decent mod... please offer critiques of any kind!

Happy New Year!
the last board i modded was a revision three which was much better sound than the revision 1

when we started into modding this the boards were cheaper in the rev1 days

consider the risk of ruining boards and the amount of work involved in the part removal
it is probably more suited to experienced compulsive diyers

the rev 4 will be a decent performer as long as its not fed an ac power supply
  Reply With Quote
Old 3rd January 2018, 04:26 PM   #6843
matt_garman is offline matt_garman  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Chicago, Illinois, USA
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
How good of a power supply do you think is good enough? I'm not talking about pulling the on-board regulators, just feeding the board normally. Seems everyone agrees regulated DC is better than unregulated AC. But there's quite a spectrum on regulated DC, from basic lm317 up to (for example) Salas shunts... Seems that going better than the on-board regs might be well in the overkill territory.

Just wondering what everyone thinks is a good balance between cost+complexity vs diminishing returns.
  Reply With Quote
Old 3rd January 2018, 05:05 PM   #6844
nige2000 is offline nige2000  Ireland
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by matt_garman View Post
How good of a power supply do you think is good enough? I'm not talking about pulling the on-board regulators, just feeding the board normally. Seems everyone agrees regulated DC is better than unregulated AC. But there's quite a spectrum on regulated DC, from basic lm317 up to (for example) Salas shunts... Seems that going better than the on-board regs might be well in the overkill territory.

Just wondering what everyone thinks is a good balance between cost+complexity vs diminishing returns.
because of all the onboard regulation and capacitance there is a certain point where the input ps quality will not matter then they will become the next weakest link

in your case i assume your benchmark will be that tda1387 your working on,
ive done some experiments with that chip too it is indeed very good sounding with a good power supply and good clean i2s signal
you may have to mod the dam 1 a bit more in depth to surpass it

which revision of the dam do u have?
filters matter too, something i havent kept up to speed with

btw i got some of your tda1387 pcbs manufactured

hopefully ill get round to it soon
  Reply With Quote
Old 3rd January 2018, 07:26 PM   #6845
matt_garman is offline matt_garman  United States
diyAudio Member
 
Join Date: Feb 2008
Location: Chicago, Illinois, USA
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Quote:
Originally Posted by nige2000 View Post
in your case i assume your benchmark will be that tda1387 your working on,
ive done some experiments with that chip too it is indeed very good sounding with a good power supply and good clean i2s signal
you may have to mod the dam 1 a bit more in depth to surpass it

which revision of the dam do u have?
filters matter too, something i havent kept up to speed with
The goal isn't so much one versus the other, but more just to finish a project that's been in a not-quite-completed state for too long. I've got two rev3 dam1021 boards (for balanced dual-mono). Currently fed i2s from a RPi, powered by the DIYINHK lt3042 regulators, all glued together with Normunds PCB. I've posted pics in this thread if you search for my posts.

I don't think the DIYINHK lt3042 is really ideal for the dam1021, at least not in balanced dual-mono mode: I was having problems with either board randomly loosing sync whenever the mains voltage would sag (e.g. running a paper shredder). Plus the choke gets really hot, making me think the pair of boards pull more current than the regulator was designed to supply.

In short, I'm trying to think of what PSU to use with the pair of dam boards. I have an unbuilt Salas BIB shunt regulator, but I'm thinking that might be overkill... maybe something smaller/simpler will do the trick... hence the question.

Also, the Normunds PCB doesn't allow independent UART control of the two dam1021 boards, it "chains" output from the RPI to the dam boards. That's fine for volume control and filter selection, but won't work for firmware upgrades, changing filter packs or making config changes to one but not the other... so I'm thinking about designing a board similar to the Normunds one, but with a pair of USB to UART chips, or something similar, so that the dam boards can be controlled independently (and can be chained via software). I could also put a power regulator on the board too, if I found something fairly simple (lt3042 is nice, but physically too small for me to solder).

The tda1387 stuff is mostly just me following Abraxalito's lead, and playing with something simple enough for me to fit my head around.
  Reply With Quote
Old 3rd January 2018, 07:53 PM   #6846
nige2000 is offline nige2000  Ireland
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by matt_garman View Post
The goal isn't so much one versus the other, but more just to finish a project that's been in a not-quite-completed state for too long. I've got two rev3 dam1021 boards (for balanced dual-mono). Currently fed i2s from a RPi, powered by the DIYINHK lt3042 regulators, all glued together with Normunds PCB. I've posted pics in this thread if you search for my posts.

I don't think the DIYINHK lt3042 is really ideal for the dam1021, at least not in balanced dual-mono mode: I was having problems with either board randomly loosing sync whenever the mains voltage would sag (e.g. running a paper shredder). Plus the choke gets really hot, making me think the pair of boards pull more current than the regulator was designed to supply.

In short, I'm trying to think of what PSU to use with the pair of dam boards. I have an unbuilt Salas BIB shunt regulator, but I'm thinking that might be overkill... maybe something smaller/simpler will do the trick... hence the question.

Also, the Normunds PCB doesn't allow independent UART control of the two dam1021 boards, it "chains" output from the RPI to the dam boards. That's fine for volume control and filter selection, but won't work for firmware upgrades, changing filter packs or making config changes to one but not the other... so I'm thinking about designing a board similar to the Normunds one, but with a pair of USB to UART chips, or something similar, so that the dam boards can be controlled independently (and can be chained via software). I could also put a power regulator on the board too, if I found something fairly simple (lt3042 is nice, but physically too small for me to solder).

The tda1387 stuff is mostly just me following Abraxalito's lead, and playing with something simple enough for me to fit my head around.
have you tried alternate sources of i2s ?
rpis dont have a great i2s out but it should still be stable

lt3042 arent as bad to solder as yould think, tin one pad then solder pin to it then do the others

if the opamps were removed it would be easier to power too
youll have less noise also
you could parallel the lt3042 either
  Reply With Quote
Old 3rd January 2018, 09:06 PM   #6847
Dimdim is offline Dimdim  Greece
diyAudio Member
 
Join Date: Sep 2008
Location: Athens
Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 Khz
Or use lt3045s..
__________________
http://www.dimdim.gr
  Reply With Quote
Old 4th January 2018, 12:53 AM   #6848
Pegasus123 is offline Pegasus123  United States
diyAudio Member
 
Join Date: Aug 2014
Quote:
Originally Posted by matt_garman View Post
How good of a power supply do you think is good enough? I'm not talking about pulling the on-board regulators, just feeding the board normally. Seems everyone agrees regulated DC is better than unregulated AC. But there's quite a spectrum on regulated DC, from basic lm317 up to (for example) Salas shunts... Seems that going better than the on-board regs might be well in the overkill territory.

Just wondering what everyone thinks is a good balance between cost+complexity vs diminishing returns.
I have only seen one real comparison between the dam1021 and the dam1121. Post 288 of the link below. The user states that despite the differences his ear couldn't discern a difference. Plus the dam1021 has the easy to implement AudioZen OLED board (which was my Christmas gift).
Building with the Soekris dam1121

I'm sure the dam1021 has very good regulation and the differences might not even be audible. That being said some of the Salas regulators are known as the best for a reason.

Søren's Audiophile line is doing well and has very good measurements from what I have seen. The DIY dam1021 line is a very good all in one solution which is easy to build for any DIY'er.

Sadly I'm not sure the OEM dam1121 is doing as well. It's just too cost prohibitive especially stateside. For a fully balanced build it would cost $569 for the .02% version and $804.48 for the .01% + international shipping + 6 power supplies. Honestly I think Søren would be surprised how well a DIY line dam1121 with op-amp balanced outputs would sell. Added bonus if it has analog control too (but not necessary).
  Reply With Quote
Old 4th January 2018, 04:36 AM   #6849
Flikoman is offline Flikoman  Croatia
diyAudio Member
 
Join Date: Jan 2010
Quote:
Originally Posted by nige2000 View Post
if the opamps were removed it would be easier to power too
youll have less noise also
you could parallel the lt3042 either
I have rev. 2 board that has 2 opamps per channel, so I remove both, right? Salas PSU is waiting for better days, don't have enough time to try it.

So, if I remove both opamps, how much voltage is enough just for raw outputs?

Regards
  Reply With Quote
Old 4th January 2018, 07:54 AM   #6850
nige2000 is offline nige2000  Ireland
diyAudio Member
 
Join Date: Jun 2013
Quote:
Originally Posted by Flikoman View Post
I have rev. 2 board that has 2 opamps per channel, so I remove both, right? Salas PSU is waiting for better days, don't have enough time to try it.

So, if I remove both opamps, how much voltage is enough just for raw outputs?

Regards
theres a 5v and -5v reg on there pre regulation for v-ref
just look up their data sheet for the minimum voltage its probably around +/-7v

mine runs with +/- 3.3v and 1.2v as ive replaced all onboard regulation and removed or replaced most caps
  Reply With Quote

Reply


Reference DAC Module - Discrete R-2R Sign Magnitude 24 bit 384 KhzHide 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
e18 DAC - 8 channels at 32bit /384 kHz exa065 exaDevices 30 29th June 2012 05:11 PM
384 Khz DAC? SunRa Digital Source 8 1st October 2009 11:14 PM
24 bit/192 kHz via USB? gentlevoice Everything Else 3 22nd December 2008 06:24 AM
sign magnitude DAC Bernhard Digital Source 0 30th January 2007 01:40 PM
24 bit / 192 kHz Tube DAC questions Overlord Digital Source 4 29th April 2003 05:14 PM


New To Site? Need Help?

All times are GMT. The time now is 12:27 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki