First Gainclone finished - Page 2 - 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 1st May 2004, 02:05 AM   #11
diyAudio Member
 
Join Date: Sep 2002
Location: Oregon, USA
I checked DC offsets today with cables connected, I'll run the scope on them too. I have a ~100R series resistance on the output of every opamp that'll be driving an interconnect cable. Used to be a time when I'd buy Vishay/Dales for these since they're "in the signal path"... now I'm just dipping into my stash of metal films.

Quote:
very high fidelity high frequency sine wave generators
I've done that, and I've made mine generate perfect looking square waves too. It was pretty cool to look at on the scope, and I'd have played with it longer if the opamp wasn't heating up so quickly. The AD826 had something in its datasheet about handling 'unlimited capacitance' though - the gain-bandwidth comes down as the capacitance increases, or something like that. I didn't pay too much attention to it since I didn't understand it, but I did notice it said that. FWIW *shrug*
  Reply With Quote
Old 1st May 2004, 06:48 PM   #12
diyAudio Member
 
Cro maniac's Avatar
 
Join Date: Feb 2004
Location: Zagreb, Croatia
Blog Entries: 2
Send a message via Skype™ to Cro maniac
Quote:
I have noticed with several of my Gainclones that when new the chips and heatsink get very hot. Then for some reason they start operating at a lower temperature.
A have finished my TDA7293 amp few days ago, and when it was playing loud it was hot like hell. Now, after about 5 days it doesn't get hot at all.
  Reply With Quote
Old 1st May 2004, 07:45 PM   #13
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Quote:
A have finished my TDA7293 amp few days ago, and when it was playing loud it was hot like hell. Now, after about 5 days it doesn't get hot at all.
Well, I knew that I wasn't imagining it but it's good to have somebody else experience the same thing.
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 5th May 2004, 09:03 AM   #14
jarkaa is offline jarkaa  Finland
diyAudio Member
 
Join Date: Feb 2004
Location: Tampere
Nuuk, you were absolutely right. The chips are not getting hot anymore. It took about a week or so to settle the heating down.
Even the sound has improved a lot too.

It would be interesting to know what is the physical explanation of the heating problem and the sound improvement.


I just bought few Opa549 and 541 chips and I am interested to see what how they sound like.

It looks like that I am becoming an electronics addict
  Reply With Quote
Old 5th May 2004, 09:54 AM   #15
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
Quote:
It would be interesting to know what is the physical explanation of the heating problem and the sound improvement.
Yes it would! I am always most careful with the (few) connections required in a Gainclone so I don't think that it is a case of a joint becoming 'better' as it burns in.

As nothing else changes physically, this is a most interesting phenomenon and I join the queue waiting for a logical explanation!
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 30th May 2004, 02:30 PM   #16
cpemma is offline cpemma  United Kingdom
diyAudio Member
 
Join Date: Jul 2003
Location: S Yorkshire OK
Quote:
Originally posted by jarkaa
...The chips are not getting hot anymore. It took about a week or so to settle the heating down.
Even the sound has improved a lot too.

It would be interesting to know what is the physical explanation of the heating problem and the sound improvement.
In the computer overclocking world, it's quite common for cpu chips to benefit from a bedding down period at normal speeds before being gradually ramped up. Again the danger is over-heating.

Could it be the thermal compound layer thinning down a bit by sideways creep under the bolt stress, and greatly improving heat transfer to the sink?

It may be better than air, but as a heat conductor it's lousy, and I've noticed a few people here believe more is better.
  Reply With Quote
Old 31st May 2004, 05:29 PM   #17
jarkaa is offline jarkaa  Finland
diyAudio Member
 
Join Date: Feb 2004
Location: Tampere
Sounds like good explanation

I am not familiar with constructing tecnology though

Right now Iīve been playing around with opa549 and it does not practically heat at all.

Weirdest part is that I am runnig them with 24v regulated supply and the sinks are currently small pieces of aluminium plate. When I stress the amp with high volumes the sinks are only a bit warm.

Does anyone have similar experiences with Burr-Brown chips?

By the way opa549 sounds great after a little tweaking, much better than lm3886.
  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
Finished my first Gainclone. Need some help. samsagaz Chip Amps 1 1st May 2008 05:04 AM
I finished my first Gainclone!!! lanchile07 Chip Amps 18 30th October 2007 01:47 AM
Semi finished gainclone LM3875 enzedone Chip Amps 7 4th October 2005 03:11 AM
Another finished Gainclone Treefingers Chip Amps 6 21st September 2005 09:32 PM
Finished my GainClone dezzz Chip Amps 4 23rd October 2004 04:15 PM


New To Site? Need Help?

All times are GMT. The time now is 12:23 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