Paralleling LM4780 chips?

Dominick22 · 24th February 2006, 11:59 PM

I am paralleling 2 LM4780 chips per channel fo my amp.

I have the power wired, but I am unsure of how to wire the signal paths. Both IN AND OUT.

I have ideas but thought I better ask before I see that magic black smoke!!LOL
Do I just run the + signal to one chip and the - to the other and then the corresponding polarity to the output jack?
*A diagram would be nice*

I am using the kits from audiosector.com.

Thanks a ton,

Dominick

amt · 25th February 2006, 01:09 AM

How about the schematic thats on the website, showing the connections?

amt

Bazukaz · 25th February 2006, 01:10 AM

Read LM4780's datasheet.There is a schematic of paralell config.
If the power supply is wired correctly,you shouldn't smoke LMs that easy.
A common problem is when there is no insulation washer between chip and heat sink(chip has -Vs connected to its case). If the sink is grounded , the power supply is usually powerful enough to blow IC in chunks.I have done it by myself once

.

Regards ,
Lukas.

Dominick22 · 25th February 2006, 01:33 AM

I dont think that my question was understood.

I have 2 chips already wired in parallel. Now I need to know how to parallel the paralelled chips!!

Dominick

joecool85 · 25th February 2006, 01:38 AM

If I'm correct, that would give you support of down to 1ohm...any reason to need it that low?

Dominick22 · 25th February 2006, 02:35 AM

Good observation.

That is exactly why I am doing it.

I intend on using this amp on my Martin Logan Ascent i speakers.
I called the company direct and they said that the speakers run at 2.5 ohms @ 20k.

Dominick

joecool85 · 25th February 2006, 03:03 AM

2.5 ohms...that would run fine just with a parallel lm4780. 1 x 4780 parallel should give you about 120w @ 2 ohms I'm pretty sure.

Dominick22 · 25th February 2006, 05:33 AM

I already tried it and blew one of the chips in less than a minute!

Dominick

joecool85 · 25th February 2006, 11:20 AM

Did you have a heatsink on it? It shouldn't be a problem at all. People use the paralleled lm4780 setup from brian at chipamp.com for 2 ohms.

**edit**
Here is the schematic they use:
http://chipamp.com/lm4780.pdf

Bazukaz · 25th February 2006, 12:31 PM

LM3886s can stand continous short circuit and has lots of protection.
Adding more in parallel may even worsen results , if ICs have DC offsets greater than a few mV.

24th February 2006, 11:59 PM	#1
Dominick22 diyAudio Member Join Date: Aug 2005	Paralleling LM4780 chips? I am paralleling 2 LM4780 chips per channel fo my amp. I have the power wired, but I am unsure of how to wire the signal paths. Both IN AND OUT. I have ideas but thought I better ask before I see that magic black smoke!!LOL Do I just run the + signal to one chip and the - to the other and then the corresponding polarity to the output jack? A diagram would be nice I am using the kits from audiosector.com. Thanks a ton, Dominick __________________ A real amateur enthusiast!

25th February 2006, 01:33 AM	#4
Dominick22 diyAudio Member Join Date: Aug 2005	I dont think that my question was understood. I have 2 chips already wired in parallel. Now I need to know how to parallel the paralelled chips!! Dominick __________________ A real amateur enthusiast!

25th February 2006, 01:38 AM	#5
joecool85 diyAudio Member Join Date: Jan 2006 Location: Maine	If I'm correct, that would give you support of down to 1ohm...any reason to need it that low? __________________ Life is what you make it. http://www.ssguitar.com

25th February 2006, 02:35 AM	#6
Dominick22 diyAudio Member Join Date: Aug 2005	Good observation. That is exactly why I am doing it. I intend on using this amp on my Martin Logan Ascent i speakers. I called the company direct and they said that the speakers run at 2.5 ohms @ 20k. Dominick __________________ A real amateur enthusiast!

25th February 2006, 03:03 AM	#7
joecool85 diyAudio Member Join Date: Jan 2006 Location: Maine	2.5 ohms...that would run fine just with a parallel lm4780. 1 x 4780 parallel should give you about 120w @ 2 ohms I'm pretty sure. __________________ Life is what you make it. http://www.ssguitar.com


	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

25th February 2006, 01:09 AM	#2
amt diyAudio Member Join Date: Feb 2003 Location: oregon	How about the schematic thats on the website, showing the connections? amt

25th February 2006, 01:10 AM	#3
Bazukaz diyAudio Member Join Date: Nov 2005 Location: Vilnius	Read LM4780's datasheet.There is a schematic of paralell config. If the power supply is wired correctly,you shouldn't smoke LMs that easy. A common problem is when there is no insulation washer between chip and heat sink(chip has -Vs connected to its case). If the sink is grounded , the power supply is usually powerful enough to blow IC in chunks.I have done it by myself once . Regards , Lukas.

25th February 2006, 05:33 AM	#8
Dominick22 diyAudio Member Join Date: Aug 2005	I already tried it and blew one of the chips in less than a minute! Dominick __________________ A real amateur enthusiast!

25th February 2006, 11:20 AM	#9
joecool85 diyAudio Member Join Date: Jan 2006 Location: Maine	Did you have a heatsink on it? It shouldn't be a problem at all. People use the paralleled lm4780 setup from brian at chipamp.com for 2 ohms. edit Here is the schematic they use: http://chipamp.com/lm4780.pdf __________________ Life is what you make it. http://www.ssguitar.com

25th February 2006, 12:31 PM	#10
Bazukaz diyAudio Member Join Date: Nov 2005 Location: Vilnius	LM3886s can stand continous short circuit and has lots of protection. Adding more in parallel may even worsen results , if ICs have DC offsets greater than a few mV.

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
Paralleling up DAC chips	5th element	Digital Source	103	2nd January 2013 07:12 PM
Paralleling LM4780/3886: any impact on sound quality?	Arnop	Chip Amps	51	4th May 2011 01:37 AM
paralleling chips	odysseybmx414	Chip Amps	15	14th December 2005 06:57 PM
paralleling 2 BrianGT lm4780 kits	jimbo1968	Chip Amps	0	30th November 2005 04:34 PM
Any warnings about paralleling chips?	Morse	Chip Amps	13	29th March 2004 09:28 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