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Working on LM3886 based amp.

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suds

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Hi,

I am done with First Watt.. now working on LM3886 Based amps.

Inspiration from Chip-Amp, carlosfm (will be based on clarlosfm, chipamp, gainclones, etc). I will be referring to these circuits, can use part of circuit from various designs.

Also will make carlosfm DIY for myself, so guys if you are interested let me know..

Regards
suds
 

suds

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Thanks for your feedback..

I was like looking at various lm3886 circuits, I have Mauro Penasa's schematics, but not sure if there will be IP copyright issues, if I make one from his work.(there will be credit, copyright for him) . also some asked for circuit based on carlosfm work. I can make PCB based on both , but depends on response, of there are enough count,will make both or drop one which has least requirement. :)
Would like to hear from others also on their experiences, about lm3886.

Plan to finish with LM3886 bases circuits by Monday / Tuesday.. :)
 

anm

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Curious - what all you guys do when you say "working on an amp". You design circuit/ pcb and then what?
What else remains in an amplifier? Power supply, caps etc? So where do you fit these PCB/ circuits in?

Can I open up any stereo amp, and just replace this circuit and have a new design amp just like that?

Sorry for the noob questions, but I am curious!
 

suds

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Can I open up any stereo amp, and just replace this circuit and have a new design amp just like that?

yeh, if there is enough space for PSU and Amp boards, you can do so..
or else include a cabinet to your shopping list.. !
 

anm

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so can it not be used with existing cabinet and PSU?
Where to source a good PSU from - as most of the amp reviews focus mainly on the PSU and if PSU is good, and amp is passed off as weighty and good.
How is dynamic headroom created? Are those large capacitors used for the same?

regards

yeh, if there is enough space for PSU and Amp boards, you can do so..
or else include a cabinet to your shopping list.. !
 

suds

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so can it not be used with existing cabinet and PSU?
Where to source a good PSU from - as most of the amp reviews focus mainly on the PSU and if PSU is good, and amp is passed off as weighty and good.

PSU and Amp you can make one yourself.. PSU requirements are different for each amp design ..
 

suds

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Re: Working on LM3886 based amp.(Thread Paused)

Notice from Admin

Dear suds,
Please review the updated Forum Rules.
Thank You.

Would like to know, what rules were broken!

This thread will be paused till Admins believe that "No rules are jumped here!"

:)
 

anm

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Can some DIY expert take a session for lesser mortals? Unfortunately, I am in Delhi.

regards
 

suds

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Well ! I am in Bangalore.

for DIYers in India we can keep in touch on mails, and help each other.
I will try to help with PCB and Ciruits. other will put in their skills, and we can have complete DIY circuits one can assemble with minimum effort.

At last I am done with First Watt clones and Pre-amp. will receive boards in 5 to 6 days. soon will finish LM3886 also.


Can some DIY expert take a session for lesser mortals? Unfortunately, I am in Delhi.

If we are experts, then we are not DIY'ers. And DIY'ers are not experts !
Yeh but a expericed DIY'er can help ! :)
 
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suds

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Continuing effort on LM3886, I am done with AD815-cfm Line Preamp PCB
This PCB is based on Original work by carlosfm AD815 Line preamplifier.

Attached is image for the PCB Layout.. :)
 
Last edited:

suds

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Hi

I completed LM3886 Amps.
Amps schematics are from shine7.com (with permission from author)
PSU is based on Carlos FM (cfm) psu design, similar to chipamp PSU.

There are two amp Boards :
PA100 : 100W rms Peak output on 4 ohms load.
PA150 : 150W peak output on 4 ohms load

PSU PCB is same for both, only transformer rating is different.
Please refer to LM3886 datasheet and Application notes for more info.
Amplifier PCB are based on schematic from shine7.com , there are not modifications in amplifier schematic only added filter caps to power line.

Will make prototype next week , and will keep you posted .


-suds
 

Attachments

  • PA100-S7-LM3886-REVA.jpg
    PA100-S7-LM3886-REVA.jpg
    46.8 KB · Views: 231
  • CFM-PSU-LM3886.jpg
    CFM-PSU-LM3886.jpg
    28.3 KB · Views: 225
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quad

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Is it possible to offer a regulated PSU option too?
Also, for the snubbed CarlosFM style PSU, there was
a buggy schematic going around. As far as I can see, your
implementation seems to be fine.
 

suds

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Is it possible to offer a regulated PSU option too?
Also, for the snubbed CarlosFM style PSU

Yeh will work on that later..


there was
a buggy schematic going around. As far as I can see, your
implementation seems to be fine.

I came across that, it was in chipamp pdf, rectifier diode connections were not correct ..

Thanks cranky for suggestions.. I was working on ground planes only... I have not finalized the design yet, to learn more about grounding issues will make prototype to check if there is distortion.
 
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suds

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Unfortunately while replying to your post I cannot see the posted pictures anymore,

Open two Browser window , open same post in both, then reply to post in one..
you can tile , cascade browser window to see both .. :)
 

suds

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I have changed the Layout for PA100 and PA150.
below is the image of PA100
 

Attachments

  • PA100-S7-LM3886-REVA-1.jpg
    PA100-S7-LM3886-REVA-1.jpg
    37.7 KB · Views: 194

suds

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ok.. will slightly increase the trace.. will use 70micron copper for PCB

Production PCB spec: 2mm PCB , 70micron copper.

Any more suggestions for PSU ?
 

suds

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PA150 Layout Image..

will make prototype (PA100 and PA150) next week :)

There is no change in schematic / component values.
only layout is modified.
some more power filter capacitors (C27, C13) are added across but these are optional.
 

Attachments

  • PA150-S7-LM3886-REVA.jpg
    PA150-S7-LM3886-REVA.jpg
    30.6 KB · Views: 200

1000w

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I used 3886 to build an amp for my subwoofer a few years back and still going strong. Its been two years and still not complete ;(, yet to add a sub filter. Driving it directly from LFE output of Yamaha 640.
Need to get around finishing it soon.
-Manish
 
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