Optimizing TDA7294 Output - Page 35 - 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 23rd February 2013, 01:52 AM   #341
diyAudio Member
 
Join Date: Jan 2011
when I turn off power one of the LED glows longer than the other,the other LED turn off instantly in my PSU,,is that a sign of illness in my psu ?.I think tda7294 needs a pre amp if played from a mobile hanset.
  Reply With Quote
Old 23rd February 2013, 02:02 AM   #342
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
Did you do the DIY power supply?
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 23rd February 2013, 03:40 AM   #343
diyAudio Member
 
Join Date: Jan 2011
Quote:
Originally Posted by bcmbob View Post
Did you do the DIY power supply?
yes the same psu like you,how about you ,does the LED turn off instantly.
  Reply With Quote
Old 23rd February 2013, 12:18 PM   #344
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
Both the PS and the amp LEDs on my build fade out. None of the four turn off instantly. The on-board LEDs are more sensitive and take longer but even they showed discharge after about 4 seconds . I did some timings this morning and found having just one amp with the new cap arrangement greatly influences the discharge time. The amp LED now fade first at ~ 4 -6 seconds. The modded amp side shows the presence of a charge up to 24 seconds. (on the PS only)

If you have two stock builds I would suggest swapping them to see if one of the amps is causing the discrepancy. A few posts back Daniel did remark he thought even my stock amp pair was a little slow discharging. Try the swap and let us know what you find.
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 24th February 2013, 12:29 AM   #345
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally Posted by bcmbob View Post
I did some timings this morning and found having just one amp with the new cap arrangement greatly influences the discharge time. The amp LED now fade first at ~ 4 -6 seconds. The modded amp side shows the presence of a charge up to 24 seconds. (on the PS only)
Those times look appropriate but I'd need some more information.

It is important to compare when using the same model of speaker so that the load compared is the same.

Since the bass bandwidth is different between the two amplifiers, it is more useful to compare non-audio workload, and therefore we'd need to have the source connected, powered on, and the volume set to minimum (input dampening but no input signal).

In this condition, which amplifier takes longer to drain the power supply board?
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 4th March 2013, 08:12 PM   #346
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Default The next step. . . Optimize Pin 2

Parameters:
1). Feedback resistor within the range of: 25k to 110k
2). Feedback-shunt resistor within the range of: 1.3k to 3.0k
3). NFB-shunt cap sized to fit Feedback-shunt resistor value so we don't accidentally make a bass blur/blocker.
4). Gain settings within the range of 20x to 42x--Simply divide the two resistor values and then add 1, to find your gain value. Gain also affects compensation so be sure to observe temperature and aim for cool.

If you need some gain for either fun dynamics and/or so that a PC or digiplayer doesn't strain, here's a couple of possibilities.
75k with 2.2k for a gain of 35x or
60k with 1.8k for a gain of 34x.
In these two examples, the gain factor is nearly identical but the feedback current is different so the audio will be different (while driving a real speaker).

Choosing by observation:
Maximize the soundcast width of a single (mono) speaker, since the bigger presentation usually represents higher resolution of micro detail.
Maximize the baritone range clarity, especially Cello/Piano, because this is the harmonic range that allows you to hear bass in normal size rooms.

Those two audible parameters are adjusted mainly with these two resistors: Feedback resistor and Feedback-shunt resistor.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.

Last edited by danielwritesbac; 4th March 2013 at 08:33 PM.
  Reply With Quote
Old 6th March 2013, 02:09 AM   #347
diyAudio Member
 
Join Date: Jan 2011
I have played with gain of 24,32,40,50,60X but all of them are so weak and dull without a preamp.
  Reply With Quote
Old 7th March 2013, 12:44 AM   #348
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Quote:
Originally Posted by simply14prem View Post
I have played with gain of 24,32,40,50,60X but all of them are so weak and dull without a preamp.
Fascinating! Is the source a tape head, phono cartridge, microphone or direct feed from a tuner? What music source do you have there?
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  Reply With Quote
Old 7th March 2013, 12:53 AM   #349
bcmbob is offline bcmbob  United States
diyAudio Member
 
Join Date: Dec 2009
Location: Bay City, Michigan
I'm feeling really bad/guilty.

I'm trying to finish up a couple other things and will get back to this effort soon. I'll probably move over to a breadboard format with pins to be able to try all the suggestions.
__________________
Bob M.
"Arrange Whatever Pieces Come Your Way."
  Reply With Quote
Old 7th March 2013, 08:57 AM   #350
diyAudio Member
 
danielwritesbac's Avatar
 
Join Date: Nov 2007
Well there's just 5 things, some of which are location sensitive, so breadboard won't help. Just remember, you're also optimizing the sound of a given board. The easiest or fastest thing to do is actually use the printed circuit boards.

1. Feedback resistor trackside, onto the chip, from pin 2 to pin 14
2. Feedback-shunt resistor trackside (for easy swapping)
3. NFB-shunt caps and bypass caps mounted on pins (for easy swapping)
4. Input cap--mount helper/bypass cap trackside (for easy swapping)
5. Rail2Rail power filter cap (or RCR) at amp board V+, V- terminals

Suggestion: You've got a 2 amplifiers there, so modify whichever one you like the least, until it sounds superior. Well, the prospect is to mod one to beat the other, and then next, vice versa, round robin fashion, each better than before. Estimated timeframe when using printed board is from 2 to 6 hours depending on methodology with listening tests.
__________________
Tools, Models & Software for DIYClipNipper boostLM1875 TurboPowerful TDA7293 kitTDA7294 pt2pt ♦ My post has opinion.
  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
OPtimizing the VBE MUltiplier fglabach Solid State 45 17th September 2014 08:22 PM
Optimizing active crossover atledreier Multi-Way 27 19th August 2011 03:53 PM
optimizing the VBE multiplier hienrich Solid State 80 29th November 2010 11:25 PM
Interesting linestage optimizing ideas PixelPlay Tubes / Valves 5 23rd June 2008 11:18 PM
optimizing for efficiency Dwiel Solid State 13 10th May 2005 10:31 PM


New To Site? Need Help?

All times are GMT. The time now is 05:29 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