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.

ES9038Q2M Board
ES9038Q2M 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 14th July 2019, 01:54 PM   #4671
Markw4 is online now Markw4  United States
diyAudio Member
 
Join Date: Jul 2016
Location: California
Looks like DigiKey has created an order page for AK4499, although they show it as back ordered. Maybe they are tired of people asking about it?
https://www.digikey.com/products/en?...%09974-1192-ND
  Reply With Quote
Old 14th July 2019, 03:49 PM   #4672
kaytata is offline kaytata  India
diyAudio Member
 
Join Date: Mar 2012
Hi Mark,
Ah ha! I didn't know that. I listened after I reconnected the mcu. I need to put a volume pot in my amp in that case, which I didn't do yet. So it seems I might have listened to the same settings! Okay I'll do and report back. Thanks for pointing that out.
Kay
  Reply With Quote
Old 14th July 2019, 04:03 PM   #4673
kaytata is offline kaytata  India
diyAudio Member
 
Join Date: Mar 2012
Hi eziitis,
Sorry I commented it wrongly, I mean to say the background seems darker. I could not hear any noise as it is, even with the ear by the speakers.
Regards,
Kay
  Reply With Quote
Old 14th July 2019, 05:41 PM   #4674
Markw4 is online now Markw4  United States
diyAudio Member
 
Join Date: Jul 2016
Location: California
Quote:
Originally Posted by kaytata View Post
I need to put a volume pot in my amp
There are registers to control the volume. There is also a bit you can set somewhere to control the volume of both channels using only one register. The registers actually turn down the volume, so I guess one might call them attenuators.
  Reply With Quote
Old 14th July 2019, 06:27 PM   #4675
zenonn67 is offline zenonn67
diyAudio Member
 
Join Date: Nov 2018
Hi Markw4,
what kind of capacitor (C2; C3), would recommend for AVCC_LR?

Space in the box is very, very limited, so MKP is not an option, I think.

Regards,
Ivo
Attached Images
File Type: jpg ADA4898-2 VCC_L&R.JPG (39.0 KB, 273 views)
  Reply With Quote
Old 14th July 2019, 09:08 PM   #4676
Markw4 is online now Markw4  United States
diyAudio Member
 
Join Date: Jul 2016
Location: California
Hi Ivo,
ESS has some info on that type of AVCC circuit on the downloads page of their website: http://www.esstech.com/files/4514/40...PCB_Layout.pdf

They just used 10uf or 47uf elctrolytics. That's what I used for an earlier dac too. Those should probably be fine, IMHO.

Also perhaps worth mentioning about some good opamps to use, IME. I have been using OPA1612 for everything as of recent (AVCC, I/V, differential summing). They and many other opamps tend to sound better with some several uf of film caps from each of the +-15v rails to ground. Some people have reported better sound quality with as little as 15uf of film caps per rail. Similarly good results may obtainable from using high gain audio-friendly voltage regulators such as Jung-Didden, or especially if cost and or size is an issue, perhaps Nazar regulators. We can probably provide some more info about the latter if you are interested.

Another opamp that is very good for AVCC is AD797. However, those particular opamps usually work better with no film caps on the +-15v rails. Too much low ESR capacitance on the power rails can cause stability issues in that case, IME.

However, film caps are probably worth a try if using other good audio opamps such as OPA1612 or LME49720/LME49860. The caps tend to help get rid of the last bit of graininess in the sound that may perhaps be most easily noticeable for things such as cymbals.

Also if interested, the AVCC schematic we use can be found attached to post #3003 in this thread.

-Mark

Last edited by Markw4; 14th July 2019 at 09:16 PM.
  Reply With Quote
Old 15th July 2019, 03:47 AM   #4677
laserscrape is offline laserscrape
diyAudio Member
 
Join Date: Dec 2017
Thanks for offer Mark, I dont understand the target of 1.65V for vref (which as we noticed does vary slightly higher and lower in some implemenations).

For one, you could get higher output levels from the I/V while remaining in Class A with a higher reference voltage.
  Reply With Quote
Old 15th July 2019, 04:29 PM   #4678
Markw4 is online now Markw4  United States
diyAudio Member
 
Join Date: Jul 2016
Location: California
Quote:
Originally Posted by laserscrape View Post
Thanks for offer Mark, I dont understand the target of 1.65V for vref (which as we noticed does vary slightly higher and lower in some implemenations).

For one, you could get higher output levels from the I/V while remaining in Class A with a higher reference voltage.
1.65v = AVCC/2 and is the quiescent and average output voltage of the dac. Using it for Vref makes the dac output current = 0ma on average. Whether or not that is optimal in all ways is not something that ESS has said.

Some people may like to adjust the Vref voltage divider so as to make the average I/V output voltage = 0v. In that case, low level audio signals will be operating right in the area where opamp output crossover distortion sits. Maybe not so good for small signals coming out of the I/V stage, but maybe better for the differential summing stage. Distortion in the differential summing stage may be lower if the quiescent or average input common mode offset is = 0v. So, we could adjust Vref for lowest distortion coming out of the differential summing stage.

Another possible source of distortion with bipolar opamps we use for audio, such as OPA1612, is related to input bias currents. The bias currents are large enough that dc input resistance looking out through the opamp inputs combined with the bias current will create a voltage drop, which is an error source. If we can't keep dc resistance really low as seen by both opamp inputs, we should at least make the dc resistance of both of them look the same. That way the bias error is mostly due to the input bias offset current. However, none of the commonly seen Vref voltage dividers makes the noninverting input see the same dc resistance as the inverting input. The voltage divider might have to have a source resistance that looks more like 400-ohms for that. Then again, maybe the error is only a dc offset error, not a dynamic one affecting sound quality. Although there is a graph in the OPA1516 data sheet showing distortion as a function of input resistance, the test circuit they use is not the exact same circuit we are using. If unsure, probably best to run a suite of measurements with an AP to see what changes and to what makes distortion better or worse. Doing a measurement only at 1kHz and one input level is probably not adequate, IMHO.

What it means, I think, is that there are many possible sources of distortion in modern, ultra-low distortion SD dacs. There are no Self or Cordell books on dacs with lists of all sources of known distortion to look out for. People are still finding more everyday, it seems like.

Also, despite the fact that we know about many sources of distortion, such as clock jitter, inappropriate power supplies, improper use of ground planes, etc., lots of people are still going ahead doing wrong things like there won't be any bad effect from it.

What can you do? People behave like people do.

Last edited by Markw4; 15th July 2019 at 04:41 PM.
  Reply With Quote
Old 16th July 2019, 09:13 AM   #4679
zenonn67 is offline zenonn67
diyAudio Member
 
Join Date: Nov 2018
Quote:
Originally Posted by Markw4 View Post
Hi Ivo,
ESS has some info on that...
Thank You Mark!

Regards,
Ivo
  Reply With Quote
Old 16th July 2019, 02:25 PM   #4680
Mikett is offline Mikett  Canada
diyAudio Member
 
Join Date: Aug 2003
Location: Toronto
Quote:
Originally Posted by Markw4 View Post

What can you do? People behave like people do.
Yes, it is the human condition. It's what makes the audio world keep going forward yet at the same time in circles.
  Reply With Quote

Reply


ES9038Q2M 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
My Cambridge 500SE, needs an output board (to replace internal DAC Board) slbender Digital Source 1 11th July 2018 02:43 AM
JLSounds XMOS USB board + AK4396 board + Direct DSD PCB ravid Swap Meet 1 29th December 2016 11:36 AM
Unknown Board DC12V TPA3116 amplifier board DIY L163-9 AUS Ben Class D 0 8th December 2016 04:05 AM
FS: Ian FIFO i2s-to-PCM board, Single XO clock board trung224 Swap Meet 3 26th November 2016 02:18 PM
Lost 1 Zv4 ckt board..looking to buy 1 circuit board Blues Pass Labs 1 22nd March 2004 10:09 PM


New To Site? Need Help?

All times are GMT. The time now is 03:20 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki