Go Back   Home > Forums > >

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
Old 24th October 2019, 09:21 PM   #341
snax is offline snax  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Cheers Marcel.
  Reply With Quote
Old 31st October 2019, 07:42 PM   #342
Trajan is offline Trajan  United States
diyAudio Member
 
Join Date: Apr 2014
Quote:
Originally Posted by nautibuoy View Post
Anyway, moving on from frivolous stuff like LEDs, as the build is now inderway I'm starting to think about the output filter boards, however, I'm a bit reluctant to spend several hundred pounds on the parts for the filters I would ideally build (with the DON Audio filters and Lundahl transformers) without getting a feel for what the Valve DAC can do so I'm looking at some cheaper interim arrangements. If all works well I can replace them with the optimised filter boards later.

I was initially thinking about using the JLSounds filter boards but on reflection I think it is probably better to build some filters that are closer to those Marcel has designed.To that end I want to assemble an interim filter based on Marcel's third order schematic.

For the output transformers these look to fit the bill; they're copies of Lundahl LL1527s which themselves are essentially smaller, cheaper variants of the LL1684s;

R24 imitation Swedish LUNDAHL1527 Lunda cattle 1+1:1+1 audio isolation transformer microphone line input-in Transformers from Home Improvement on Aliexpress.com | Alibaba Group

It's a bit more difficult when it comes to the inductors though as, obviously, there are no standard products with precisely the correct value, however, these seem to be fairly close;

RFS1317-185KL Coilcraft | Mouser United Kingdom

and I'm wondering if they would be too much of a compromise or if they could be accomodated by adjusting the filter?

Thoughts?
I question the ethics of someone buying obvious knock-offs. good luck with that.
  Reply With Quote
Old 31st October 2019, 08:02 PM   #343
nautibuoy is offline nautibuoy  United Kingdom
diyAudio Member
 
nautibuoy's Avatar
 
Join Date: Jan 2010
Location: Somerset, England
Quote:
Originally Posted by Trajan View Post
I question the ethics of someone buying obvious knock-offs. good luck with that.
I always find that posession of all the facts helps in reaching a judgement;

Valve DAC from Linear Audio volume 13

Click the image to open in full size.
  Reply With Quote
Old 31st October 2019, 09:18 PM   #344
snax is offline snax  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Quote:
I question the ethics of someone buying obvious knock-offs. good luck with that.
I tend to try everything first hand and make my own judgements...

Those Chinese "components" are excellent! just my opinion.

Its my own home brew that I question...
Attached Images
File Type: jpg 2019-10-31_211629.jpg (221.3 KB, 189 views)
  Reply With Quote
Old 31st October 2019, 09:30 PM   #345
nautibuoy is offline nautibuoy  United Kingdom
diyAudio Member
 
nautibuoy's Avatar
 
Join Date: Jan 2010
Location: Somerset, England
Hi Dan. What are your plans for the reconstruction filters?

I've got four of the Don Audio custom RM8 inductors on the way (in transit currently) and the LL1684s and I'm aiming for the balanced 3rd order filter Marcel designed using the Lundahls to go to single-ended for the final outputs. I've started setting out a PCB for them and you'll be welcome to a pair if they'll suit?
  Reply With Quote
Old 31st October 2019, 10:42 PM   #346
snax is offline snax  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Hey Ray,

I am winding my own inductors as per Marcels instructions… In for a penny.

I bought the Epcos Pot Cores and they are next on my list of things to do…. You can see an empty one in the photo above. It’s the matching to at least 1% that is going to get me….

I was going to ask about the MCLK via the u.FL press studs… they were tricky to solder.

I have opted to go via a AK4137 board to generate / convert the PMC into a DS254 signal and output it to the I2S header on the DAC board. This has a MCLK output on it but I know there is an external input via the u.FL on the DAC board.

I’m struggling to understand the number of clocks (BCLK, FSCLK, MCLK).
  Reply With Quote
Old 31st October 2019, 11:05 PM   #347
MarcelvdG is offline MarcelvdG  Netherlands
diyAudio Member
 
Join Date: Mar 2003
Location: Haarlem, the Netherlands
The FSCLK is used as the right channel DSD data line, so it is no clock at all. The funny naming is due to the fact that interface boards such as the Amanero use the same pins for I2S and raw DSD interfaces.

Of the other two clocks, only one should actually be connected. I'm not sure whether master clock or bit clock will work best in practice, so for the Amanero-compatible connector, I just reserved space so you can connect one or the other by placing the correct 0 ohm resistor.

When you use the U.FL connectors rather than the Amanero-compatible connector, you can just experiment with it without soldering or removing any 0 ohm resistors. In this case, it is in fact best not to place any of the 0 ohm resistors that connect the Amanero-compatible connector to the rest of the circuit, in order to avoid possible data-to-clock crosstalk of the Amanero-compatible connector (as the Amanero pin-out is a bit silly; clocks sandwiched between data lines).
  Reply With Quote
Old 1st November 2019, 12:03 AM   #348
snax is offline snax  United Kingdom
diyAudio Member
 
Join Date: Jun 2007
Again, Marcel to the rescue,

You are correct that I am looking at the 2x 10pin header and getting confused by the labelling.

I have the Amanero board but realised that I can output I2S from my RPi onto an AK4137 board… from China, to do my conversion. This will up the frequency and has an board clock to provide the synchronisation. It will then output to another 2x 10pin header.

I suppose my confusion lay in I2S is only three of those 20 pin outs.

Am I having a moment of Sobriety or shall I return to the isopropanol?
  Reply With Quote
Old 3rd November 2019, 11:38 AM   #349
Zoran is online now Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
Quote:
Originally Posted by MarcelvdG View Post
I still had to post the expected timing for the data and clock input section. Referring to the attached picture, this is what I calculated (with the SN74LVC2G86 connected, so without the clock division):

From A to B and Bi: 3.4 ns to 8.6 ns of delay, B in phase with A and Bi in antiphase
From A to D: data clocked in at the rising edge, delay between 1 ns and 9 ns
E and E': data transitions between 22.1 ns and 31.6 ns after the rising edge of Bi
C and C': rising clock edges between 1 ns and 4.1 ns after B and Bi, respectively, at minimum potmeter setting, between 10 ns and 17.3 ns after B and Bi, respectively, at maximum potmeter setting
Maybe there is mistake on the schematic? How iti is seems like MCK and BCK outputs from USB-I2S/DSD interface are shorted? Cut out the line/connection after RS8 and RS9 at the input of the circuit?
cheers.
__________________
###
  Reply With Quote
Old 3rd November 2019, 01:21 PM   #350
ticknpop is offline ticknpop  Canada
diyAudio Member
 
Join Date: May 2005
Location: toronto
Valve DAC from Linear Audio volume 13
For 3000pf = 2200pf +820 pf LCR make them in 1% polystyrene at reasonable prices
  Reply With Quote

Reply


Valve DAC from Linear Audio volume 13Hide this!Advertise here!
Thread Tools

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
13.8V 80A Linear PS circuit design analysis for Ham Radio Use FJHookah Power Supplies 71 27th October 2019 02:52 PM
Is it tradition that we use linear PSUs for valve amps? Paul Uszak Power Supplies 9 2nd September 2016 10:58 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 01:25 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki