Current chip favorite ? - Page 6

mrskinny · 26th August 2004, 04:10 AM

I am comparing these two chips because- 1) The only chip that any of the electronic stores near me stock is the LM1875,and won't order just a couple of chips for me to try.OPA549's were from TI's sample program.Tried National's sample program,but no luck. 2) They both use the same supply voltage. Unfortunately,few surplus transformers around here,and are quite expensive new- the two toroids that I am using now cost $160! 3) As I have efficient speakers,the power output from the chips doesn't really mean much either way. My 8w/ch SE amp will play these speakers more than loud enough.

pinkmouse · 28th August 2004, 02:44 PM

Quote:

Originally posted by aHobbit
My sample OPA549 arrived and I am interested in testing it in inverted mode. Would you be kind enough to point me to your implemented schematic diagram?

Can't post pics at the moment due to only getting internet access from work, but it is basically the original Thorsten circuit, just swap out the 3875 for a 549, (noting pin-out differences, of course), and put a trimmer pot in the place of the 18k to ground.

I'm sure there is a copy of my circuit somewhere on the board, but I couldn't find it searching just now, maybe you will have a little more luck!

tmblack · 19th July 2005, 08:00 PM

What's the current favorite Burr-Brown power amp chip?
And how do the TDA729x compare?

I have the LM3886 and it sounds a little too bright and thin.
And analytical/forward for my tastes.

Tom

soundNERD · 20th July 2005, 12:10 AM

opa549

tmblack · 21st July 2005, 05:50 PM

How does the OPA549 sound?
Anything like the warmth and ease of the OPA627(as preamp)?

Tom

soundNERD · 22nd July 2005, 12:22 AM

You know, I really haven't listened to it as a full range amplifier. As a subwoofer amplifier (mine is bridged), it's pretty good. It's got a lot of power, but I still think the 38xx chips sound better, but they lack the power the 549 has.

The other problem could be the very high gain I have the chip at - this chip doesn't get along with high gain too well.

Maybe if a 3886 or 3875 were in a B/P config, they would have the advantage over the 549.

Oh, the other benefit of the 549 is it can handle lower impedences better than national's chips - I hooked up a 4-ohm speaker to my bridged 549 amp, and although it ran quite hot, the chip didn't complain at all - a 3886 would start making this horrible popping sound when it was given a 2-ohm load.

edit: You mention the 3886 is too bright sounding. How much capacitance do you have on it? I have a hi-fi LM3875 amp I built and it sounds very warm, actually, it sounds better than my very good yamaha 5.1 amp - all except for less power. Maybe add some more capacitance and your issue will get better.

tmblack · 24th July 2005, 03:47 PM

On the LM3886 I used 33pF on the feedback loop but that did not fix the sound.

I will try the OPA549, I only wish it could take a higher voltage.
Is this stable at unity gain?

Tom

soundNERD · 25th July 2005, 12:44 AM

Sorry, I mean power supply capacitance. For me, 4400uf per rail sounds great. The lower, the brighter it will sound, and the higher, the more bass and warmth it will have.

tmblack · 26th July 2005, 04:04 PM

I have 4700uF on the PS but it shouldn't affect the warm if your transformer is large enough.

Maybe LM3875 is warmer, I know TDA2030 sounds very good.

Tom

soundNERD · 26th July 2005, 04:49 PM

No, it most definitely does, because the caps smooth out the AC, and the higher the caps the smoother the sound.

It has nothing to do with transformer size.

Maybe try adding some more capacitance to each rail.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Favorite Threads and Posts in "Chip Amps"	Variac	Chip Amps	7	28th January 2011 10:13 PM
Favorite low power chip amps	johnr66	Chip Amps	12	17th December 2010 10:29 AM
Favorite transformers for chip amp and gainclone?	danielwritesbac	Chip Amps	19	18th October 2008 07:09 AM
What's the current state of the art chip amp?	Bricolo	Chip Amps	5	27th April 2005 11:44 PM
chip amp idle current	maylar	Chip Amps	2	29th December 2004 03:25 PM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

26th August 2004, 04:10 AM	#51
mrskinny diyAudio Member Join Date: Feb 2004 Location: GTA	I am comparing these two chips because- 1) The only chip that any of the electronic stores near me stock is the LM1875,and won't order just a couple of chips for me to try.OPA549's were from TI's sample program.Tried National's sample program,but no luck. 2) They both use the same supply voltage. Unfortunately,few surplus transformers around here,and are quite expensive new- the two toroids that I am using now cost $160! 3) As I have efficient speakers,the power output from the chips doesn't really mean much either way. My 8w/ch SE amp will play these speakers more than loud enough.

19th July 2005, 08:00 PM	#53
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	What's the current favorite Burr-Brown power amp chip? And how do the TDA729x compare? I have the LM3886 and it sounds a little too bright and thin. And analytical/forward for my tastes. Tom

20th July 2005, 12:10 AM	#54
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	opa549

21st July 2005, 05:50 PM	#55
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	How does the OPA549 sound? Anything like the warmth and ease of the OPA627(as preamp)? Tom

22nd July 2005, 12:22 AM	#56
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	You know, I really haven't listened to it as a full range amplifier. As a subwoofer amplifier (mine is bridged), it's pretty good. It's got a lot of power, but I still think the 38xx chips sound better, but they lack the power the 549 has. The other problem could be the very high gain I have the chip at - this chip doesn't get along with high gain too well. Maybe if a 3886 or 3875 were in a B/P config, they would have the advantage over the 549. Oh, the other benefit of the 549 is it can handle lower impedences better than national's chips - I hooked up a 4-ohm speaker to my bridged 549 amp, and although it ran quite hot, the chip didn't complain at all - a 3886 would start making this horrible popping sound when it was given a 2-ohm load. edit: You mention the 3886 is too bright sounding. How much capacitance do you have on it? I have a hi-fi LM3875 amp I built and it sounds very warm, actually, it sounds better than my very good yamaha 5.1 amp - all except for less power. Maybe add some more capacitance and your issue will get better.

24th July 2005, 03:47 PM	#57
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	On the LM3886 I used 33pF on the feedback loop but that did not fix the sound. I will try the OPA549, I only wish it could take a higher voltage. Is this stable at unity gain? Tom

25th July 2005, 12:44 AM	#58
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	Sorry, I mean power supply capacitance. For me, 4400uf per rail sounds great. The lower, the brighter it will sound, and the higher, the more bass and warmth it will have.

26th July 2005, 04:04 PM	#59
tmblack diyAudio Member Join Date: Jan 2005 Location: UK	I have 4700uF on the PS but it shouldn't affect the warm if your transformer is large enough. Maybe LM3875 is warmer, I know TDA2030 sounds very good. Tom

26th July 2005, 04:49 PM	#60
soundNERD diyAudio Member Join Date: Sep 2003 Location: Illinois	No, it most definitely does, because the caps smooth out the AC, and the higher the caps the smoother the sound. It has nothing to do with transformer size. Maybe try adding some more capacitance to each rail.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)