Lm3886t

Nobodysfool · 20th May 2006, 11:46 PM

Hi there! I got two LM3886 and was wondering were can i find a schemtaic for a good audio amp. Since im a beginner and pretty much dont have a clue , any advice is highly appreciated!! Thank you !

Mike

! · 20th May 2006, 11:56 PM

Try the Chipamp forum @ diyaudio.com

You could start with the reference design in the spec sheet to get your feet wet. Decibel Dungeon also has a lot of info together.

davidlzimmer · 21st May 2006, 05:49 PM

Just biult a pair of these lasr Saturday. Point to point took about 3 hours. Works great!!! The schematic is right out of BrianGT's manual.

Note: I did not use the Zobel network or

davidlzimmer · 21st May 2006, 06:00 PM

PS. I also did not use Cm or switch. Just wired Rm striaght to V-.

Bazukaz · 21st May 2006, 06:10 PM

Quote:

Originally posted by davidlzimmer
PS. I also did not use Cm or switch. Just wired Rm striaght to V-.

Hi,
I would like to ask , what is purpose of R1, R2 in the circuit ? Seems of no use to me.

Regards,
Lukas.

davidlzimmer · 21st May 2006, 10:44 PM

Disclaimer: I don't know. Hopefully the more knowledgeable will jump in.

As far as R1, I was curious myself. While bench testing, I temporally bypassed R1 and noticed no difference.

R2 is in every chimpamp circuit. I've always assumed it set up a reference voltage like bias.

Bazukaz · 21st May 2006, 11:00 PM

Hi,
I think that something is missing here (probably DC blocking cap).In that case , R2 would make a sense. Now it is just a paralell resistor to volume control potentiometer. However , this should change anything at all...

Regards,
Lukas.

dfdye · 22nd May 2006, 02:17 AM

Coupling/input caps aren't necessiary for these circuits in my experience. If you want to add one in, be sure to make it pretty high quality since it can make a substantial impact on the sound of the amp.

It makes sense to me that R1 and R2 are there to set up an input voltage divider. R1+Rin makes the first stage, but on looking at it again, it is a little wierd. . .

dfdye · 22nd May 2006, 02:29 AM

Oh yea, back on topic, in addition to the gainclone-esque circuits, I like the Linkwitz LM3886 implementation(attached). I am powering mine with +/-30V rails with 4,400uf per rail using a dual mono unregulated PSU. This is probably a little overkill, and the amps definitely work with 2,200uf/rail/chip, but I had a surplus of 2,200uf caps laying around, and one thing led to another. . .

! · 22nd May 2006, 02:37 AM

Determination of whether the input coupling (DC blocking) cap is needed depends on the DC offset (or lack thereof) from the prior stage.

Prior stage is commonly the source, or a buffer/pre/etc. Many have coupling caps on their outputs already, in which case another coupling cap on the power amp stage input is redundant. Some (especially DIY), "might" not have that output coupler cap, so before one goes amplifying the signal to power amp levels it is important to measure for the DC offset (L to Gnd, and R to Gnd) if there is any uncertainty.

20th May 2006, 11:46 PM	#1
Nobodysfool diyAudio Member Join Date: May 2006	Lm3886t Hi there! I got two LM3886 and was wondering were can i find a schemtaic for a good audio amp. Since im a beginner and pretty much dont have a clue , any advice is highly appreciated!! Thank you ! Mike

21st May 2006, 06:00 PM	#4
davidlzimmer diyAudio Member Join Date: Jan 2006 Location: Fairmount, GA	PS. I also did not use Cm or switch. Just wired Rm striaght to V-. __________________ Poor stereo mix? Switch to mono! Perfect.

21st May 2006, 10:44 PM	#6
davidlzimmer diyAudio Member Join Date: Jan 2006 Location: Fairmount, GA	Disclaimer: I don't know. Hopefully the more knowledgeable will jump in. As far as R1, I was curious myself. While bench testing, I temporally bypassed R1 and noticed no difference. R2 is in every chimpamp circuit. I've always assumed it set up a reference voltage like bias. __________________ Poor stereo mix? Switch to mono! Perfect.

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
10 pcs LM3886T	daedalus	Swap Meet	3	28th March 2009 04:39 AM
Wtb :- LM3886T PCB	poynton	Swap Meet	7	6th September 2007 05:18 AM
Different between LM3886T & LM3886TF	ttan98	Chip Amps	13	5th August 2007 03:53 PM
Lm3886t / Lm3886tf ?	matt09	Chip Amps	8	9th August 2006 02:38 AM
LM3886T/TF for sale	elementx	Swap Meet	1	3rd June 2006 11:13 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

20th May 2006, 11:56 PM	#2
! diyAudio Member Join Date: Jun 2005 Location: Midwest	Try the Chipamp forum @ diyaudio.com You could start with the reference design in the spec sheet to get your feet wet. Decibel Dungeon also has a lot of info together.

21st May 2006, 11:00 PM	#7
Bazukaz diyAudio Member Join Date: Nov 2005	Hi, I think that something is missing here (probably DC blocking cap).In that case , R2 would make a sense. Now it is just a paralell resistor to volume control potentiometer. However , this should change anything at all... Regards, Lukas.

22nd May 2006, 02:17 AM	#8
dfdye diyAudio Member Join Date: Dec 2005 Location: USA	Coupling/input caps aren't necessiary for these circuits in my experience. If you want to add one in, be sure to make it pretty high quality since it can make a substantial impact on the sound of the amp. It makes sense to me that R1 and R2 are there to set up an input voltage divider. R1+Rin makes the first stage, but on looking at it again, it is a little wierd. . .

22nd May 2006, 02:37 AM	#10
! diyAudio Member Join Date: Jun 2005 Location: Midwest	Determination of whether the input coupling (DC blocking) cap is needed depends on the DC offset (or lack thereof) from the prior stage. Prior stage is commonly the source, or a buffer/pre/etc. Many have coupling caps on their outputs already, in which case another coupling cap on the power amp stage input is redundant. Some (especially DIY), "might" not have that output coupler cap, so before one goes amplifying the signal to power amp levels it is important to measure for the DC offset (L to Gnd, and R to Gnd) if there is any uncertainty.

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