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.

Valve DAC from Linear Audio volume 13
Valve DAC from Linear Audio volume 13
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 19th October 2017, 05:41 PM   #21
leadbelly is offline leadbelly  Canada
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Hi, just noticed this thread. This is very interesting to me, but the pcb prices seem so high compared to Chinese manufacture. Marcel, if you have Gerbers I can run a group buy. I ran one here quite a few years ago, but still remember the in's and out's.
__________________
Prove all things 1 Thessalonians 5:21
  Reply With Quote
Old 19th October 2017, 08:28 PM   #22
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
It indeed uses sigma-delta (or delta-sigma, that's the same) modulation. In fact you can choose between three sigma-delta algorithms, a seventh-order chaotic sigma-delta and two fifth-order sigma-deltas with a kind of embedded pulse width modulator with randomly rotated pattern. These last two have the advantage that they are dithered according to dither theory, which eliminates the tonal behaviour that many sigma-delta modulators have. You can also do a blind ABX test, I've included a state machine for that.

The complete design database including Gerber files, KiCAD database and FPGA files (source code and synthesized + implemented) can be downloaded for free from the downloads section of the Linear Audio website, Downloads | Linear Audio. You have to scroll down to "Design data package for Marcel van de Gevel's Valve DAC from Vol 13".

The article that explains the ideas behind the design can also be downloaded, but that will cost you almost half a euro, see Linear Audio | your tech audio resource

I rather like buying things that are not made in China every now and then, but of course you can have the PCB manufactured in China or wherever you like. Some component values may have to be adapted when the prepreg thickness is very different from the 360 um that Eurocircuits uses, but that can be done.

Last edited by MarcelvdG; 19th October 2017 at 08:41 PM.
  Reply With Quote
Old 19th October 2017, 09:03 PM   #23
leadbelly is offline leadbelly  Canada
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
Originally Posted by MarcelvdG View Post
I rather like buying things that are not made in China every now and then, but of course you can have the PCB manufactured in China or wherever you like. Some component values may have to be adapted when the prepreg thickness is very different from the 360 um that Eurocircuits uses, but that can be done.
Thank you very much for this contribution!

Even if you have made the package freely available, it would not be ethical for me to even start a group buy without your agreement. I would plan on Chinese manufacture of the boards, looking for best price and also previous experience on this forum. I would start by opening a thread in the group buy forum to gauge sufficient interest. Let me know your thoughts.
__________________
Prove all things 1 Thessalonians 5:21
  Reply With Quote
Old 19th October 2017, 09:48 PM   #24
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
Don't worry, I'd consider it an honour if you started a group buy for this. I would like to warn you, though, that the PCB is not the only expensive part, see also posts 8 and 9.
  Reply With Quote
Old 19th October 2017, 09:54 PM   #25
Trajan is offline Trajan  United States
diyAudio Member
 
Join Date: Apr 2014
But how does it sound?
  Reply With Quote
Old 19th October 2017, 09:59 PM   #26
leadbelly is offline leadbelly  Canada
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
Originally Posted by MarcelvdG View Post
Don't worry, I'd consider it an honour if you started a group buy for this. I would like to warn you, though, that the PCB is not the only expensive part, see also posts 8 and 9.
Yes, of course. That is the beauty of a group buy, if there is enough interest even parts other than PCB's can be sourced at lower cost. It really just depends on interest more than anything else.
__________________
Prove all things 1 Thessalonians 5:21
  Reply With Quote
Old 19th October 2017, 10:01 PM   #27
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
Quote:
Originally Posted by Trajan View Post
But how does it sound?
See post 235 of this thread:

DAC gallery
  Reply With Quote
Old 20th October 2017, 03:36 PM   #28
leadbelly is offline leadbelly  Canada
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Marcel, I am starting to get some questions back from the PCB houses, and I have some of my own:

The filter PCB gerber files do not include silkscreen or solder mask.

What about PCB specification itself: substrate, thickness, surface finish, etc.? What are they for your prototypes, can we use this, or do you have suggested improvements?

You mentioned that there is a error with the transformer solder pads. Is this because the software library assumed a different Jensen form factor? This may be important if we seek a substitute supplier such as Cinemag.

You mention that the transformer is optional. The schematics in the design package don't show that option. Is it to be found somewhere?
__________________
Prove all things 1 Thessalonians 5:21
  Reply With Quote
Old 20th October 2017, 10:20 PM   #29
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
Quote:
Originally Posted by leadbelly View Post
Marcel, I am starting to get some questions back from the PCB houses, and I have some of my own:

The filter PCB gerber files do not include silkscreen or solder mask.
True, the filter PCB was targeted for the Eurocircuits naked proto process which has no silkscreen or solder mask.

Quote:
Originally Posted by leadbelly View Post
What about PCB specification itself: substrate, thickness, surface finish, etc.? What are they for your prototypes, can we use this, or do you have suggested improvements?
FR4, about 1.55 mm total thickness, single-layer filter board, four-layer main board with 360 um prepreg thickness. I'll look up the other data soon.

Quote:
Originally Posted by leadbelly View Post
You mentioned that there is a error with the transformer solder pads. Is this because the software library assumed a different Jensen form factor? This may be important if we seek a substitute supplier such as Cinemag.
I simply made a stupid mistake entering the footprint. That mistake is fixed in the layout data on the Linear Audio site.

Quote:
You mention that the transformer is optional. The schematics in the design package don't show that option. Is it to be found somewhere?
There is a pdf file in the zip with the design package that shows the various filter options.
  Reply With Quote
Old 20th October 2017, 11:06 PM   #30
leadbelly is offline leadbelly  Canada
diyAudio Member
 
leadbelly's Avatar
 
Join Date: Dec 2002
Location: Calgary, Alberta
Quote:
Originally Posted by MarcelvdG View Post
FR4, about 1.55 mm total thickness, single-layer filter board, four-layer main board with 360 um prepreg thickness. I'll look up the other data soon.
Thanks! It would be appreciated if you could look up the other data as well. Always better to copy a successful prototype.

I was surprised at 1.55mm thickness. With this large a board, 4 layers, and the need to survive multiple tube socket insertions and removals, I would have thought that thicker would have been the way to go. Any comment?
__________________
Prove all things 1 Thessalonians 5:21
  Reply With Quote

Reply


Valve DAC from Linear Audio volume 13Hide 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
Is it tradition that we use linear PSUs for valve amps? Paul Uszak Power Supplies 9 2nd September 2016 10:58 PM
13.8V 80A Linear PS circuit design analysis for Ham Radio Use FJHookah Power Supplies 69 14th June 2016 02:46 PM
Audio Valve Eklipse volume pot value? Ki Choi Tubes / Valves 0 27th March 2015 05:22 PM
Londog Audio VDt1 Valve Output 24/192 DSD DAC mainscablesrus Mains Cables R Us 1 1st October 2013 06:52 PM
Audio Note DAC 2.1x valve DAC juancho Swap Meet 0 6th July 2005 09:16 PM


New To Site? Need Help?

All times are GMT. The time now is 01:00 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