Compact USB DAC/Integrated LM1875 Amp - Page 7 - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 16th April 2008, 07:29 AM   #61
e-mos is offline e-mos  Norway
diyAudio Member
 
Join Date: Jun 2004
Location: gvarv
hey,

interesting project..

according to the datasheet of this usb dac it has a hid interface and spdif output. have you considered a second version using the hid interface and/or the spdif?
maybe just add a pinheader for later use?

one more question what pcb program have you used and are there any posibilety for sharing your pcb files??


-emesto-
  Reply With Quote
Old 16th April 2008, 03:45 PM   #62
dfdye is offline dfdye  United States
diyAudio Member
 
dfdye's Avatar
 
Join Date: Dec 2005
Location: USA
There is a d-out pin currently, but I didn't put a jumper in to control it!

But, to answer your question, I am currently drawing up a PCM2707/PCM1794 USB DAC, potentially with selectable inputs for the DAC. This is, of course, not anywhere close to new territory! Russ White has a supposedly excellent solution for this combo already (I only say supposedly because I personally haven't heard it, but I am sure it is high quality!) The point of my new combo will be to drive a set of to-be-built active crossovers/speakers, so I don't think I will put an on-board amp with that DAC.

That being said, I can EASILY modify my current board layout to enable SPDIF output, but that sort of defeats the whole point of having the on-board amp! If you are looking for SPDIF outputs, I would defer to a dedicated USB DAC and not waste the amplifier portion of this project since that adds considerable cost and complexity. Check out the Opus DAC if you are just looking for a USB to SPDIF solution. Also, I have heard GREAT things about Peter Daniel's USB DAC, which you can get information about by e-mailing him directly. Either of these would be better for getting SPDIF.

Finally, I used Dip Trace for the board layouts, and I believe I have posted pretty much everything I have done up to this point! I have found this to be much more intuitive and user friendly than Eagle, plus they have a nice hobbiest version for pretty cheap ($125 I think). Check back through the thread and you should be able to recreate the project pretty easily if you want to make modifications. I will be happy to stick Gerbers of the revised version correcting the minor goofs when I get it finished.
  Reply With Quote
Old 20th April 2008, 07:38 AM   #63
dfdye is offline dfdye  United States
diyAudio Member
 
dfdye's Avatar
 
Join Date: Dec 2005
Location: USA
To wrap things up for this project, here is the revised PCB layout to correct a few mistakes. There hasn't been a request for boards since the beginning of this thread, so I am assuming there isn't an interest in a group buy. As such, if anybody wants Gerbers or B&W artwork to make a set of boards for yourself, just e-mail me and I'll be happy to send them along.

I have NOT built this revised board, much less populated it to make sure everything is in fact fixed, so if you want to re-create this project be sure to double check that you know what is what before you start. It should use the same BOM as posted earlier, with the addition of 500 ohm grounding resistors (R27 & R28) which may or may not be necessary depending on whether this input voltage offset is reproducible (I honestly have NO idea what is causing it!) Also, I changed R13 & R14 to 0 ohm resistors.

Regardless, this amp has been running fine for about a week with zero signs of distress, so I'll call it done until it blows up!
Attached Images
File Type: jpg top-rev2.jpg (74.4 KB, 279 views)
  Reply With Quote
Old 20th April 2008, 07:40 AM   #64
dfdye is offline dfdye  United States
diyAudio Member
 
dfdye's Avatar
 
Join Date: Dec 2005
Location: USA
And the bottom.
Attached Images
File Type: jpg bottom-rev2.jpg (85.4 KB, 265 views)
  Reply With Quote
Old 20th April 2008, 07:51 AM   #65
dfdye is offline dfdye  United States
diyAudio Member
 
dfdye's Avatar
 
Join Date: Dec 2005
Location: USA
I can't resist one last picture of the amp since I finally got off my tail and ran down the machine shop to knock out a knob. I had to trim down the pot a little to get the proportions right, but I think it finally looks like a finished project now!
Attached Images
File Type: jpg dsc_2714.jpg (58.2 KB, 278 views)
  Reply With Quote
Old 20th April 2008, 08:18 AM   #66
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally posted by dfdye
There hasn't been a request for boards since the beginning of this thread, so I am assuming there isn't an interest in a group buy. As such, if anybody wants Gerbers or B&W artwork to make a set of boards for yourself, just e-mail me and I'll be happy to send them along.
I think that a similar thing could be quite popular as a group buy, if. . . well, there's just two things:
1). To appeal to more people, it would need hole-thru components and the chip attached via socket--or just something considerably easier-looking to solder.
2). You could leave off the power amp so that it could work with a variety of amplifier projects.

One optional device. . . I've noticed several dc blocking caps in the signal path, and, if possible, it would be great if that function could be re-located to the output of the preamplifier, for accomodating personal taste (and a sure-fire way of blocking that dc).

The resulting device, a high quality, easily built, connection from a computer's USB to any amplifier. . . could be more effective than an expensive sound card.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 20th April 2008, 03:39 PM   #67
dfdye is offline dfdye  United States
diyAudio Member
 
dfdye's Avatar
 
Join Date: Dec 2005
Location: USA
Daniel,

1) Through hole parts made this project too big for my taste, as mentioned in the beginning of this thread.

2) The whole point of this project was to have an integrated solution with DAC and amp on one board that fits neatly into a compact case, so leaving off the amp wouldn't serve my design goals.

3) There is ONE cap in each signal from the 2707 to the 2134, not
several, and they are more than sufficient for my needs (Coincidentally, these are the Nichicon ES caps mentioned in another thread). Facilitating multiple cap options (other than those that fit within the reasonable footprint provided) would compromise space considerations. Bypassing is easily achieved on the bottom of the boards by connecting film caps p2p if you really must use them.

4) The "resulting device" you describe has been built and distributed by a number of members of this forum in versions far more refined that what I care to attempt. Look under the "Digital" forum for USB DAC and you will find more options that you can shake a stick at. If you are interested in purchasing such a device, as I have said before in this thread, several DIY kits are offered for sale by Twisted Pear and Peter Daniel to name two. I do not have much interest rehashing something that these guys have already pulled off pretty well.
  Reply With Quote
Old 16th July 2010, 10:18 PM   #68
diyAudio Member
 
Join Date: Apr 2009
Send a message via MSN to chchyong89
can i have the part number for
-PCM2707 *TQFP-32
-SRC4192
-WM8741
in diptrace?

was tired searching over and over again from bottom to top and vice versa for the same pattern chip
__________________
~.~

Last edited by chchyong89; 16th July 2010 at 10:22 PM.
  Reply With Quote

Reply


Hide 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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Integrated LM1875 PCB Nordic Chip Amps 8 8th September 2010 11:18 AM
compact lm1875 amplifier Jamh Chip Amps 9 25th August 2009 12:50 AM
Compact Sub Suggestions lgchristianson Car Audio 4 19th May 2007 11:05 PM
Compact sub DocLorren Subwoofers 11 8th January 2005 12:34 AM
Compact subwoofer Vatos Subwoofers 0 20th March 2003 08:17 AM


New To Site? Need Help?

All times are GMT. The time now is 02:55 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2