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 18th April 2013, 02:23 PM   #31
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by s3tup View Post
Whoa!?!?
It's the reason the TDA could be better than the LM - it has SEPARATE input and output stage supply pins, which is great.

I wish the LM had these.
Its possible to get the output modulating the input if the output and input supplies are not seperated.
__________________
http://www.murtonpikesystems.co.uk PCBCAD50 pcb design software.
  Reply With Quote
Old 18th April 2013, 07:22 PM   #32
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Quote:
Originally Posted by s3tup View Post
Whoa!?!?
It's the reason the TDA could be better than the LM - it has SEPARATE input and output stage supply pins, which is great.

I wish the LM had these.
Well, it "could" ... but since everybody uses them joined ... even the datasheet example , I stick to my opinion.

And anyway, even if that was the original idea, they still might have used contiguous pins, so both options are easy to choose.

As is, it unnecessarily messes with the PCB layout.

In both cases they have not 1 or 2 but 5 or 6 legs in the middle.

If course, *she* also thinks that crisscrossing those tracks is no big deal:

Click the image to open in full size.
Attached Images
File Type: gif TDA7293.gif (15.0 KB, 408 views)

Last edited by JMFahey; 18th April 2013 at 07:28 PM.
  Reply With Quote
Old 18th April 2013, 08:00 PM   #33
diyAudio Member
 
s3tup's Avatar
 
Join Date: Dec 2004
Location: Israel
That's a good reason to go double-layer PCBs and reconsider the tradeoffs of trace length, inductance and current loops.

danielwritesbac,
I hope you've forgot to put quotation marks across the "non-disaster" idiom
These eBay PCBs are Good examples of Bad Layout
The main, heaviest current path is between the output stage rails, TDA's output and GND pins of bypass caps. This region should be as small loop area as possible.
What do we see on eBay (and lots of other PCBs)? The supply comes 'round the left/right edges of the board. Huh.
Bypass caps, as close to the IC as possible? Nah, they are subminiature and placed at the farthest place possible - on the opposite corners of PCB.
They are laid out for:
- Small overall footprint
- Cool/simple connectors placement
- Smallest bypass caps, because they are pricey
Yet, i have to say, they did a Great Job on cost reduction front. 10$ for 50w of power, shipped?
__________________
The missing link between lead and gold in alchemist's world was BS and commerce.
  Reply With Quote
Old 18th April 2013, 10:17 PM   #34
diyAudio Member
 
nigelwright7557's Avatar
 
Join Date: Apr 2008
Location: Carlisle, England
Quote:
Originally Posted by JMFahey View Post
Well, it "could" ... but since everybody uses them joined ... even the datasheet example , I stick to my opinion.
[/IMG]
I don't join them !

It is wrong to just join them and that is lazy and cheap design.

Its the same with random earthing of a layout and then wondering why you get hum.

PCB designs is a bit of a black art and get it wrong and your audio sounds like !"!"$
__________________
http://www.murtonpikesystems.co.uk PCBCAD50 pcb design software.
  Reply With Quote
Old 20th April 2013, 08:12 PM   #35
diyAudio Member
 
chriscam's Avatar
 
Join Date: Jul 2003
Location: Amsterdam
non disaster design

Click the image to open in full size.
  Reply With Quote
Old 21st April 2013, 02:04 PM   #36
diyAudio Member
 
s3tup's Avatar
 
Join Date: Dec 2004
Location: Israel
chriscam,
Your's PCB looks nice, especially given the restrictions of 3-channel design. What are the board dimensions? I'm thinking of something similar, but with 6 channels and 10x10cm PCB
But i may drop the 6-channel thing and go 3-4 channels if 6 won't fit.
There is a nice feature for multiway amplifiers - they don't need to be precise copies of each other - especially on power supplies. You can feed the most powerful channel with main large caps, and then feed the other channels with RC filter where R will limit the current and C would be calculated for the xover cutoff frequency. This way you get most of the power on the woofer, and delicate and clean supplies on mid/tweeter. Not to mention the reduced bypass cap sizes for mid/tweet section.

300Hz and 1ohm resistor = 680uF caps
2000Hz and 1ohm resistor = 100uF caps
These are tiny!
__________________
The missing link between lead and gold in alchemist's world was BS and commerce.

Last edited by s3tup; 21st April 2013 at 02:20 PM.
  Reply With Quote
Old 22nd April 2013, 02:48 PM   #37
diyAudio Member
 
chriscam's Avatar
 
Join Date: Jul 2003
Location: Amsterdam
Quote:
Originally Posted by s3tup View Post
Your's PCB looks nice, especially given the restrictions of 3-channel design. What are the board dimensions?
Thanks it's 100mm x 80mm, double layer with DC protection, 8000uF onboard buffer.

Click the image to open in full size.

Click the image to open in full size.

It's accompanied by a 3ch substractive 12dB xover, mfb correction & limiter in the same formfactor.

Click the image to open in full size.

Last edited by chriscam; 22nd April 2013 at 03:16 PM.
  Reply With Quote
Old 25th April 2013, 07:53 AM   #38
diyAudio Member
 
chriscam's Avatar
 
Join Date: Jul 2003
Location: Amsterdam
Default project info

For those interested in schematics, the whole project is described over here, the only gotcha is that it's dutch an englisch versionis in the making

Click the image to open in full size.
  Reply With Quote
Old 25th April 2013, 12:37 PM   #39
JMFahey is offline JMFahey  Argentina
diyAudio Member
 
JMFahey's Avatar
 
Join Date: Mar 2009
Location: Buenos Aires - Argentina
Hey!!! .... KILLER project!!!
So it's a modern upgrade for a **very** good and advanced Philips bookshelf speaker?
Cool!!!
Are you offering it here at DIY ?
It sure would raise a lot of interest.
But .... please do translate that assembly manual to English

No big problem with the Argentine version, I can ask for Maxima's help for that
  Reply With Quote
Old 26th April 2013, 05:06 PM   #40
thejohn is offline thejohn  South Africa
diyAudio Member
 
Join Date: Mar 2005
Location: Cape Town, South Africa
Ditto! I do like the look of that amp board... If boards or Gerbers were available I'd definitely be interested. I's also currently using a Connex SPMS200QR with my 3886 amps but 3 channels on one pcb would certainly make the wiring less / easier / neater!
John
  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
TDA7294 + Power Transistors AMP (TDA7293 to come also) dr frost dk Chip Amps 348 14th April 2014 07:25 PM
TDA7293/TDA7294 - by which commercial integrated Stereo Amps in use ? tiefbassuebertr Chip Amps 10 29th August 2013 08:13 PM
Differences between TDA7293 and TDA7294???? Leolabs Chip Amps 1 22nd December 2006 10:12 AM
TDA7294 TDA7293 LM3668 Spice micijanus Analogue Source 0 4th May 2002 03:13 PM


New To Site? Need Help?

All times are GMT. The time now is 11:18 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