Multi-chip amplifier - Concentra, GC, PBA200, multichannel (all in one) - diyAudio
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Chip Amps Amplifiers based on integrated circuits

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Old 29th October 2006, 09:28 AM   #1
veteran is offline veteran  Poland
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Cool Multi-chip amplifier - Concentra, GC, PBA200, multichannel (all in one)

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
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Old 29th October 2006, 12:48 PM   #2
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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.
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Old 29th October 2006, 01:08 PM   #3
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Yes, to make easy to build but powerful amplifier in parallel/bridge mode.

Layout:
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Old 29th October 2006, 01:55 PM   #4
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Very Nice! I like the supply routing, much easier than with the LM3886 and LM4780!

G.
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Old 29th October 2006, 06:22 PM   #5
PierreG is offline PierreG  Canada
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Very interesting.

Would it drive 4 Ohm Loads?
How many watts?
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Old 29th October 2006, 07:13 PM   #6
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I never work with the lm3875, so I donít know much about it dc offset. If it's in the range of the lm3886, how will you deal with it?
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Old 29th October 2006, 07:37 PM   #7
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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.
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Old 29th October 2006, 09:47 PM   #8
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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?
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Old 30th October 2006, 05:09 AM   #9
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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
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Old 30th October 2006, 09:33 AM   #10
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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

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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
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