Go Back   Home > Forums > >

Class D Switching Power Amplifiers and Power D/A conversion

About TA2022 design designers LJM
About TA2022 design designers LJM
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
Old 17th February 2012, 11:12 AM   #21
ljm_ljm is offline ljm_ljm  China
diyAudio Member
 
Join Date: Sep 2006
Quote:
Originally Posted by activexp View Post
I'm running mine at 24V dual rail. I haven't checked the inductors but other than the temperature of the voltage regulators as already mentioned in this thread, I've noticed that the 4700uF/35V smoothing caps get quite hot too. In fact one of them is showing signs of bulging

Apparently this is caused by 'Bus Pumping'.

Expanation: "A switching amplifier that is single ended (IE not a bridge) will cause what is known as "bus pumping". Energy that is stored in the output inductor has to go somewhere when the output stage switches & as it can't run in a continual loop like the current could in a bridge amp it over charges the main reservoir capacitors."

I'm going to replace them with 6800uF/50V ones.

Despite all this, the amp itself is working fine and sounds OK.

Now, TA2022 Selection 50V 4700UF electrolytic capacitor.Meet the voltage requirements.
  Reply With Quote
Old 17th February 2012, 03:32 PM   #22
jonfrason is offline jonfrason
diyAudio Member
 
Join Date: Nov 2011
Quote:
Originally Posted by activexp View Post
I'm running mine at 24V dual rail. I haven't checked the inductors but other than the temperature of the voltage regulators as already mentioned in this thread, I've noticed that the 4700uF/35V smoothing caps get quite hot too. In fact one of them is showing signs of bulging

Apparently this is caused by 'Bus Pumping'.

Expanation: "A switching amplifier that is single ended (IE not a bridge) will cause what is known as "bus pumping". Energy that is stored in the output inductor has to go somewhere when the output stage switches & as it can't run in a continual loop like the current could in a bridge amp it over charges the main reservoir capacitors."

I'm going to replace them with 6800uF/50V ones.

Despite all this, the amp itself is working fine and sounds OK.

Can you check the temperature on your inductors?
As i wrote in the prior post, i changed the inductors for 10uH and changed the LC caps to .22uF, as recomended by tripath.
In fact, the heat has come down a bit. It also takes longer for the inductors sot heat up.

I will do some testing myself. Including short the input (i have quite high hiss/buzz), changing the 4700uF tank caps and add some more smoothing on the output of the transformer (i have connected the transformer directly on the terminals). My caps is quite cool. Do you think changing the caps will have an effect on the inductors?

The relay does not switch off in mute mode anymore!
It did when I first ran the amp on a lower rail voltage, don't remember exactly but i think it was approx 18V dual.
Seems like the amp don't like the voltage range printed on the PCB.

I hope we can find a solution on this heat problem, because i'm about to throw this thing in the bin soon!
(I also have an TK2050 and a TA2020 based amp. No problem with those...)

jon
  Reply With Quote
Old 17th February 2012, 04:26 PM   #23
activexp is offline activexp  United Kingdom
diyAudio Member
 
activexp's Avatar
 
Join Date: Jul 2009
Send a message via ICQ to activexp Send a message via AIM to activexp Send a message via MSN to activexp Send a message via Yahoo to activexp
Yes, my inductors get quite hot too

I also have the hiss/buzz. Oddly the buzz disappears when I short the inputs but returns as soon as I re-connect my pre-amp. It looks like the buzz is caused by the pre-amp but if I connect it to a TA2024 amp there is no buzz (or hiss for that matter).

Unfortunately I've been unable to replace the smoothing caps for the simple reason I can't get them out of the board! Even using a desoldering pump they refuse to shift so I've given up with that idea If anyone can suggest a method of removal I like to hear it !

Can't comment on your mute/relay problem. Mine appears to work normally.

I feel the same way as you regarding the heat and noise issues and that it is destined for the bin. Something is going to fail in the not too distant future, that's for sure.

Steve
  Reply With Quote
Old 1st March 2012, 03:31 PM   #24
activexp is offline activexp  United Kingdom
diyAudio Member
 
activexp's Avatar
 
Join Date: Jul 2009
Send a message via ICQ to activexp Send a message via AIM to activexp Send a message via MSN to activexp Send a message via Yahoo to activexp
Default Update

Tried a different pre-amp and the buzz has gone. Still left with some hiss but it's very low level and doesn't intrude.

As I gave up trying to remove the 4700uF caps from the board I've wired the 6800 ones in parallel which hopefully will reduce 'bus pumping' effects.

There's still a heat issue of course but the amp seems quite stable and unaffected.

Bearing in mind the cost of the board I'm generally satisfied with it and the sound quality is excellent to my ears.
  Reply With Quote
Old 1st March 2012, 03:50 PM   #25
Brusque is offline Brusque  Brazil
diyAudio Member
 
Brusque's Avatar
 
Join Date: Nov 2010
Location: Blumenau, SC, Brazil
Hello Activexp;

> As I gave up trying to remove the 4700uF caps from the board

You can touch the tip of the soldering iron on one of the capacitor terminal, from the bottom of the board. Then, while the solder is melted, you tilt the capacitor to the other terminal side and remove the soldering iron, holding the capacitor tilted untill the solder solidifies again. Now do this to the other pin.

Each time you'll have the capacitor a little raised to the board untill it only have one pin soldered and should be removed very easily. Now clean the board holes with a solder pump and voilą. You're ready to solder the other one in place.

Just be carefull not to get the board very hot. Remember, there's no problem destroying the capacitor but it would be very bad to have the board damaged.

Best regards;

Edson brusque
  Reply With Quote
Old 2nd March 2012, 02:34 PM   #26
activexp is offline activexp  United Kingdom
diyAudio Member
 
activexp's Avatar
 
Join Date: Jul 2009
Send a message via ICQ to activexp Send a message via AIM to activexp Send a message via MSN to activexp Send a message via Yahoo to activexp
Hi Brusque,

Thanks for the advice. I tried everything you describe but to no avail. One problem is that they're 'snap-in' and very reluctant to tilt from side to side. If they were ordinary radial leads I reckon they'd come out easily.

Cheers,
Steve
  Reply With Quote
Old 2nd March 2012, 05:24 PM   #27
Brusque is offline Brusque  Brazil
diyAudio Member
 
Brusque's Avatar
 
Join Date: Nov 2010
Location: Blumenau, SC, Brazil
Hello ActiveXP!

You can always destroy the component, top to bottom, until you have only the pins on the board.

Use a mid-to-heavy cutting pliers and start cutting it carefully. Destroy the capacitor, not the board.

Best regards;

Edson Brusque
  Reply With Quote
Old 5th March 2012, 07:50 AM   #28
activexp is offline activexp  United Kingdom
diyAudio Member
 
activexp's Avatar
 
Join Date: Jul 2009
Send a message via ICQ to activexp Send a message via AIM to activexp Send a message via MSN to activexp Send a message via Yahoo to activexp
Sounds a bit drastic but it's the only way!
  Reply With Quote
Old 9th March 2012, 03:08 PM   #29
ljm_ljm is offline ljm_ljm  China
diyAudio Member
 
Join Date: Sep 2006
Quote:
Originally Posted by jonfrason View Post
Can you check the temperature on your inductors?
As i wrote in the prior post, i changed the inductors for 10uH and changed the LC caps to .22uF, as recomended by tripath.
In fact, the heat has come down a bit. It also takes longer for the inductors sot heat up.

I will do some testing myself. Including short the input (i have quite high hiss/buzz), changing the 4700uF tank caps and add some more smoothing on the output of the transformer (i have connected the transformer directly on the terminals). My caps is quite cool. Do you think changing the caps will have an effect on the inductors?

The relay does not switch off in mute mode anymore!
It did when I first ran the amp on a lower rail voltage, don't remember exactly but i think it was approx 18V dual.
Seems like the amp don't like the voltage range printed on the PCB.

I hope we can find a solution on this heat problem, because i'm about to throw this thing in the bin soon!
(I also have an TK2050 and a TA2020 based amp. No problem with those...)

jon
Please note.Inductance can not be used 10,11 the UH. Must use 22UH.

Otherwise it's very large current
  Reply With Quote
Old 11th March 2012, 05:54 AM   #30
disc is offline disc  United States
diyAudio Member
 
disc's Avatar
 
Join Date: Mar 2010
Location: Champaign, Illinois, USA
Dear ljm_ljm,
I bought your TA2022 board ver. 1.2, blue, on ebay. The board I got is somewhat different from the picture on ebay. For instance, mine has a 7810 regulator instead of 100uH inductor! Could you send me a schematic? My email is tumanov@uiuc.edu
Thank you, Alex
  Reply With Quote

Reply


About TA2022 design designers LJMHide this!Advertise here!
Thread Tools

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
Model designers dbaudio Swap Meet 0 15th October 2008 01:09 PM
Radiotron Designers Handbook Frazzled Tubes / Valves 15 26th March 2007 01:07 PM
Help with design/geometry for DIY table...designers wanted :) Glowbug Analogue Source 11 13th December 2006 09:58 AM
Any horn designers here jerluwoo Multi-Way 10 19th June 2006 06:58 AM


New To Site? Need Help?

All times are GMT. The time now is 01:03 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2021 DragonByte Technologies Ltd.
Copyright ©1999-2021 diyAudio
Wiki