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.

lingDAC - cost effective RBCD multibit DAC design
lingDAC - cost effective RBCD multibit DAC design
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 24th March 2020, 10:37 AM   #711
abraxalito is online now abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Quote:
Originally Posted by Grarea View Post
I see that you have organised kits before.
When you offer the kits.
I can imagine that they are an awful lot of work to sort out.
Too right! Which is why last time we made up kits in batches of 10, not a lot more work to do that than make a single one. This time though I think 10 will be too many as the BOM cost is significantly higher - in the region of $10 rather than $3 as last time. So I'm wondering (not decided by any means) if batches of 3 or 4 might be appropriate.

Quote:
Do you limit the number you are willing to sort (I for sure would) and limit the people you give them to.
For sure yes. Last time we took at stab at a number which was about 70 and created 7 lots of 10-batch kits. I don't think we have many left, if any. This time I dunno how many we'll do. The ideal way to distribute them would be to have a small number of people willing to do some of the kitting work to serve people in their geographical area. So then I (though its normally my wife) send out bags of components and the local kitter sub-divides and allocates these. That seems to me to be one way to share out the more boring work

Quote:
I am very aware that my feedback would essentially be useless.
I can't think why that would be. Anyone's feedback is welcome.

Quote:
But I also assume that I could source the parts myself anyway eh?
Most of them you can yes, though if you go through the usual channels for semis you'll pay a lot more (e.g. AD744 here is about 7 for $1, on Mouser over $5). That's because the semis I buy are pulls from old boards. On C0G ceramic caps, Mouser's prices are considerably higher and that's comparing new vs new. The inductors might be hard to source - Mouser does have some cores but I'm not sure they're the right ones.

Quote:
With your designs, are all the difficulties (once designed) all about constructing them.
I've not come to any firm decision about the filter board yet - it might turn out that's too tricky to get right without a capacitance meter and tweaking cap values. In which case I might sell it as a finished board. But other than that, yes there's nothing too hair-raising.

Quote:
Or will i need more tools other than the DMM to measure things for example?
You might need a DMM which can measure capacitance fairly accurately but that feature's pretty common these days on DMMs.

Quote:
Sorry for all the questions, I am so intrigued and impressed.
I like the questions, apologies for them aren't necessary
__________________
I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant - Alan Greenspan
  Reply With Quote
Old 24th March 2020, 11:08 AM   #712
Grarea is offline Grarea  United Kingdom
diyAudio Member
 
Join Date: Dec 2019
Location: Cornwall
Excellent.
Thanks for that reply.

I like the idea of a few for sure.
Might be able to get one right by the last one perhaps.

I would be willing to join in and do my bit if needed. (am in the UK) Well, if it is deemed that I am capable of making them anyway.

I guess my feedback would be useful in the way of 'how little amount of knowledge is required to put one together' type thing
I suspect I am right on the cusp. (well, somewhat below the line currently so take your time)
"looks up capacitance meter" - doesn't look like mine has that. Might be time to upgarde a tool
Sounds like a useful tool to have.

OK, seems like the steps are not too far away.
Just need a bit of time to practice mostly.
Thanks.
I shall continue to be bemused by your threads

If it needed five years of experience beforehand, I might have turned my attention elsewhere.
  Reply With Quote
Old 24th March 2020, 12:35 PM   #713
abraxalito is online now abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
If you're (or anyone is) interested in a top-of-the-line meter for a very affordable price, this is the one I'd recommend. Its incredible what they've packed in for so little money (at least in China, its 160RMB or about $23) - when I was a schoolboy I used to drool over Fluke meters which were less functional than this at over 10X the price in 1970s dollars.

https://item.taobao.com/item.htm?spm...ucket=4#detail
__________________
I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant - Alan Greenspan
  Reply With Quote
Old 24th March 2020, 03:12 PM   #714
Grarea is offline Grarea  United Kingdom
diyAudio Member
 
Join Date: Dec 2019
Location: Cornwall
lol, yes, I can imagine you now.
Stuff is so amazingly cheap now.

Thank you for that.
Impossible for me to work out what is good and bad given all of the options. I have no idea what i am looking for.
Mine does more than I can presently but it doesn't measure capacitance. (I think.)
HAs done me fine for the limited amount I have needed it.
This is mine (nearly)
DIGITAL MULTI METER 987AA1770

I seem to recall that I can't buy from Taobao from the uk.
But this is the one right?
ZOYI ZT219 Digital Multimeter 19999 Counts True Rms Multimeter Transistor Tester Voltimetro Profesional Capacitance Meter|Multimeters| | - AliExpress

That would be an accurate enough capacitance meter for this would it?
  Reply With Quote
Old 25th March 2020, 02:32 AM   #715
abraxalito is online now abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Quote:
Originally Posted by Grarea View Post
I seem to recall that I can't buy from Taobao from the uk.
Yes I think you'd need to employ an agent to get it for you.

That is indeed the right one, but the price is a bit higher than on Taobao. I couldn't help but scroll down that page and found this one :

ANENG Handheld Digital Multimeter Voltmeter Ammeter Ohmmeter Voltage Multimeter Volt Tester Meter AC DC Tester Meter Portable|Multimeters| | - AliExpress

Looks to have identical specs just a different name at the top and its cheaper by about $5. Though it depends on a promotion.

Quote:
That would be an accurate enough capacitance meter for this would it?
Good question - the spec says 2% (mid ranges) but I will compare mine with my dedicated LCR meter and see if its any better than that in practice.
__________________
I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant - Alan Greenspan
  Reply With Quote
Old 26th March 2020, 07:01 AM   #716
abraxalito is online now abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
Default Passive filter daughter board

Here's the PCB rendering of the filter board. The bulk of the capacitors making up the filter are on the reverse side.

Also here is the FR plot (from LTspice) for the NOS filter. If some end-users were going to use 2X oversampling to drive their PhiDAC Quad then a different filter design may well be more appropriate as with 2X OS (running at 88.2kHz) there's no need for such a steep slope as images won't begin until 68.2kHz. In giving up some steepness, deeper stop-band rejection can be achieved as in the second FR plot. 2XOS allows a 'textbook' response where rejection at 68.2kHz and beyond can be >96dB.
Attached Images
File Type: png LCdaughter.png (65.5 KB, 96 views)
File Type: jpg filter.jpg (157.0 KB, 95 views)
File Type: jpg 2Xfilter.jpg (156.1 KB, 94 views)
__________________
I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant - Alan Greenspan

Last edited by abraxalito; 26th March 2020 at 07:04 AM.
  Reply With Quote
Old 26th March 2020, 07:25 AM   #717
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
Textbook is suppression of images by filtering at Fs/2. In your basic implementation, it's only 25-30 dB down and your second filter don't help here - right? And for Fs 88,2 the "textbook frequency" is not 68,2, its 44,1 - no? So ~70 dB down. There will be imaging distorsion in this DAC but the question is if it's less bad than the impact of a steep digital filter. I believe you think so or you wouldn't build it like this!?

Will you publish measurements?

//
__________________
More distortion to the people!
  Reply With Quote
Old 26th March 2020, 07:35 AM   #718
abraxalito is online now abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
The NOS implementation suppresses the lowest possible image (24.1kHz) by around 30dB and higher frequencies by more. So yes there's imaging distortion in this DAC, it will typically be around 0.05%. In the 'textbook' version with 2XOS the imaging distortion will be below the DAC's quantization noise.

I'm not following your math @TNT - to find the first (lowest) image frequency, subtract the highest audio frequency from the sample rate. At 44.1kHz its 44100-20000 = 24100. At 88.2kHz its 88200-20000 = 68200.

Happy to show measurements when I have a prototype up and running though they won't be comprehensive ones as I have no AP or equivalent equipment. Just a USB ADC.
__________________
I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant - Alan Greenspan
  Reply With Quote
Old 26th March 2020, 08:37 AM   #719
TNT is offline TNT  Sweden
diyAudio Member
 
Join Date: Apr 2003
Location: Sweden
OK!

//
__________________
More distortion to the people!
  Reply With Quote
Old 26th March 2020, 08:55 AM   #720
abraxalito is online now abraxalito  United Kingdom
diyAudio Member
 
abraxalito's Avatar
 
Join Date: Sep 2007
Location: Hangzhou - Marco Polo's 'most beautiful city'. 700yrs is a long time though...
I'm not one of those guys incidentally who thinks imaging distortion is preferable to a steep roll-off filter. I'm building it without a digital filter because I can't see a way to add one while keeping the design cheap and yet robust. An ARM chip can do the job but I'm not experienced enough yet with their foibles to put a design using one out for public consumption. Adding firmware to a hardware design increases the complexity considerably. Hopefully I'll get there eventually though.
__________________
I know you think you understand what you thought I said but I'm not sure you realize that what you heard is not what I meant - Alan Greenspan
  Reply With Quote

Reply


lingDAC - cost effective RBCD multibit DAC designHide 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
Extremely cost-effective and professional PCB Layout design service Kevmeister Vendor's Bazaar 0 30th June 2013 05:27 AM
Most cost effective way to store cd's jerryo Digital Source 9 31st December 2009 09:13 AM
Cost-effective audio cap relycap Vendor's Bazaar 0 27th September 2009 03:56 PM
Most cost effective active set up ? jerryo Class D 0 20th November 2007 03:56 PM
Cost effective upgrades Pan Solid State 4 9th April 2003 12:09 AM


New To Site? Need Help?

All times are GMT. The time now is 04:52 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2020 DragonByte Technologies Ltd.
Copyright ©1999-2020 diyAudio
Wiki