Multi-chip amplifier - Concentra, GC, PBA200, multichannel (all in one)

veteran · 29th October 2006, 09:28 AM

This is my project of simple, multi-chip amplifier. I'm thinking about something similar to Jeff Rowland Concentra but with LM3875 in output stage so this boards will be a part of it (with external, OPA1632 buffer/driver/inverter).

LM's can be connected in parallel or work in multichannel mode. Available options:
Concentra clone
GC
PBA200
Multichannel

Integrated PS board.

schematic diagram

Gcollier · 29th October 2006, 12:48 PM

Veteran,

That is a nice looking component layout! I particularly like the integrated PSU. So what is the final plan...to bridge two of these units? I am personally a bigger fan of the LM3875 than the LM3886 so I am happy to see that you used it here. I'd be interested in seeing the actual board layout with the traces.

A 3 way active filter in front of one of these boards run as independant channels would make for a great amp for a self powered speaker.

I am interested in seeing more on this design. Keep up the great work!

G.

veteran · 29th October 2006, 01:08 PM

Yes, to make easy to build but powerful amplifier in parallel/bridge mode.

Layout:

Gcollier · 29th October 2006, 01:55 PM

Very Nice! I like the supply routing, much easier than with the LM3886 and LM4780!

G.

PierreG · 29th October 2006, 06:22 PM

Very interesting.

Would it drive 4 Ohm Loads?
How many watts?

jaudio · 29th October 2006, 07:13 PM

I never work with the lm3875, so I don’t know much about it dc offset. If it's in the range of the lm3886, how will you deal with it?

veteran · 29th October 2006, 07:37 PM

It's easy to drive low impedance loads with parallel connected amplifiers.

Quote:

Originally posted by jaudio
I never work with the lm3875, so I don�t know much about it dc offset. If it's in the range of the lm3886, how will you deal with it?

I will have to make selection of LM3875 chips (similar offset voltage). I didn't wanted to use DC Servo circuit here.

jaudio · 29th October 2006, 09:47 PM

I used a similar method. I purchased 2 times the needed chips. I got to within 2.5mv variation. How many chips are you planning on buy per parallel module?

veteran · 30th October 2006, 05:09 AM

They are quite cheap so I will buy about 50 of them. Few of my friends are interested in standard, stereo version of this amplifier so the rest will not waste

jaudio · 30th October 2006, 09:33 AM

Quote:

Originally posted by veteran
They are quite cheap so I will buy about 50 of them.

How many paralllel module are you planning with 50 chips? I gathering OPA549 to make two bridge-parallel amps. So far I have 21 chips,I think I will get 3 more

Quote:

Originally posted by veteran
Few of my friends are interested in standard, stereo version of this amplifier so the rest will not waste

I made a couple of Carlos' non-inverted amp. I still have about 7 chips I need to find a use for

29th October 2006, 12:48 PM	#2
Gcollier diyAudio Member Join Date: Mar 2003 Location: Windsor	Veteran, That is a nice looking component layout! I particularly like the integrated PSU. So what is the final plan...to bridge two of these units? I am personally a bigger fan of the LM3875 than the LM3886 so I am happy to see that you used it here. I'd be interested in seeing the actual board layout with the traces. A 3 way active filter in front of one of these boards run as independant channels would make for a great amp for a self powered speaker. I am interested in seeing more on this design. Keep up the great work! G. __________________ If you take something apart and put it back together again enough times, eventually you will have two of them.

29th October 2006, 01:55 PM	#4
Gcollier diyAudio Member Join Date: Mar 2003 Location: Windsor	Very Nice! I like the supply routing, much easier than with the LM3886 and LM4780! G. __________________ If you take something apart and put it back together again enough times, eventually you will have two of them.

30th October 2006, 05:09 AM	#9
veteran diyAudio Member Join Date: Feb 2004 Location: Poland	They are quite cheap so I will buy about 50 of them. Few of my friends are interested in standard, stereo version of this amplifier so the rest will not waste __________________ Simple audio solutions blog.unisonus.com

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
Jeff Rowland Concentra amplifier	Jaime	Chip Amps	17	15th October 2008 03:06 AM
MULTICHANNEL DSP ...using Cirrus CS497XX chip ..help	JinMTVT	Digital Line Level	30	12th September 2008 03:28 AM
help with layout of multi-kit chip-amp pre-amp	okapi	Chip Amps	8	11th January 2007 11:03 PM
multi channel amplifier	Garnett	Chip Amps	1	5th April 2006 10:18 AM
Multi amplifier connections	The Rocker	Instruments and Amps	4	12th May 2005 08:04 AM


	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

29th October 2006, 06:22 PM	#5
PierreG diyAudio Member Join Date: Oct 2004	Very interesting. Would it drive 4 Ohm Loads? How many watts?

29th October 2006, 07:13 PM	#6
jaudio diyAudio Member Join Date: Oct 2004	I never work with the lm3875, so I don’t know much about it dc offset. If it's in the range of the lm3886, how will you deal with it?

29th October 2006, 09:47 PM	#8
jaudio diyAudio Member Join Date: Oct 2004	I used a similar method. I purchased 2 times the needed chips. I got to within 2.5mv variation. How many chips are you planning on buy per parallel module?

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

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