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

[veteran]

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]

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]

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

Layout:

 

[Gcollier]

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

G.

 

[PierreG]

Very interesting.

Would it drive 4 Ohm Loads?
How many watts?

 

[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?

 

[veteran]

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

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]

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]

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]

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

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

 

[ROVSING]

Very interesting - as always when you come up with new projects.

 

[MikeW]

How many boards are you going to make?

 

[veteran]

Standard order - about 20 boards. Minimal quantity to keep price on reasonable level.

Jaudio, I will make one stereo amplifier . I just need more chips to match them. I can sell the rest.

 

[traw]

20 boards ?... hmm, was hoping to pick up a 4 pack to do 6 chip per channel stereo amp...

 

[MikeW]

Standard order - about 20 boards. Minimal quantity to keep price on reasonable level.

Jaudio, I will make one stereo amplifier . I just need more chips to match them. I can sell the rest.

Can I have 2?

 

[troystg]

.......
Layout:

On the side of C1 and C2 there is a "node" on the power trace (facing up) but the same node and jumper is not there on C3.

May I ask what it is for on C1 and 2 and why it's not there for C3?

EDIT:

Sorry the picture was from post #3. Apparently the image doesn't copy when you quote.

 

[troystg]

Ah ha... I see said the blind man.....

The nodes are to connect C4-9 and the connections for C4 & 5 are allllllllll the way to the left....

Sorry I missed it earlier.

But yes the boards do look good. I'd love to have a win-stamp pre to accompany them...

 

[veteran]

I ordered them (30 boards - probably there will be few more).

An externally hosted image should be here but it was not working when we last tested it.

 

[paulb]

Ah ha... I see said the blind man.....
. I'd love to have a win-stamp pre to accompany them...

Any update on the WM Stamp?

 

[ppcblaster]

What Happened to your Remote control Project?

Alot of forum readers were waiting on you