My "audiophile" LM3886 approach

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orthoefer

Member
Joined 2006
Cases Arrived

My Lansing enclosures arrived today. Measuring 8.5"x 8" x 3.5", they are made of anodized aluminum and are simply beautiful. They remind me of Cello's look with simple lines. I plan on changing the screws from phillips to allen head for less of a DIY look. Overall I am VERY please with the cases--nicely packed too.

Here are a few photos of the cases with the RevC boards and transformers set in place.

Any suggestions for case feet?

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


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


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


Anyone care to guess what this shorter enclosure is for?
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.


Thanks for looking. I know what I will be working on the next few days.
 
Russ White

Russ White

Member
Joined 2005
twistedpearaudio.com
Re: Cases Arrived

orthoefer said:
Here are a few photos of the cases with the RevC boards and transformers set in place.
Click to expand...

Very cool cases, should make a nice set! The short case might just fit a Kookaburra eh.... ;)

For feet I would use rubber or wood simply because neither will scratch things. Otherwise there is no preference. :)

You should have a nice set of amps when all is said and done. Good work! I can't wait to see the project finished. :D:cool:

Cheers!
Russ!
 
wotsascott

wotsascott

Member
Joined 2006
Nice 1, top notch enclosure, I bet they carry a hefty price tag yes?
As to feet, I used 10mm Thick 100mmx100mm clear pespex blox< 3 blox>, quite effective as light gets carried under the amp improving the aesethics further, make those beutifull cases shine??? I did this on an older project.
<sorry about the spelling chaps>
Can anyone recomend any other good and reasonable enclosures? Found some good ones in the US, however, the postage is more than the total enclosure cost, daft no?
Anyway, I'm new at this and have nearly finished one of Brian's chipamp.cpm
Lm3886 sterio kits.
I've only built the base and back plate <see picture>
Can anyone give me some pointers about pcb positioning? How can I shield my amps from the toroid?
Cheers guys,
 

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mark_titano

Member
Joined 2004
1543 said:
Hi Andrea, please have a look if the values of the circiut are OK when using it only as a standalone preamp and not as a gainclone. THX!

Arne
Click to expand...

Hi Arne, you can see in the file I've post the schematic suggested by Mauro. ;)

You can try with different opamps that are unity gain stable.

IMHO opa2132 works good.

You can also use a log potentiometer. I've tried different solutions and the bourns 91A 10K log is the winner for me (alps blue are good too). Due to the sharper gradient in the first half, I've found easier to set the volume to the right level with the log pot in place.

You can find the pcb layout I've drawn here:

http://www.audiofaidate.it/sito.asp?goto=minibax01

Mark
 

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maxlorenz

maxlorenz

Member
Joined 2003
youtube.com/channel/UCIRNCQpvrl-EfalifsmR4KA
Hi wotsascott :)

Can anyone recomend any other good and reasonable enclosures?
Click to expand...

For my first My-ref I painfully made a box adapting part of an obsolete hemodialysis machine I received as a gift. It looks bad but the amp is cool and sturdy.

Now I think I will make monoblocks with a beautifull wood box, internally layered with copper plate :cool: and a thick heatsink.
Will this work?
Any advices welcome.
(the preamp will have the same looks) ;)

Good luck.
M
 
R

riccardo

Member
Joined 2005
maxlorenz said:
Hi wotsascott :)


Now I think I will make monoblocks with a beautifull wood box, internally layered with copper plate :cool: and a thick heatsink.
Will this work?
Any advices welcome.
(the preamp will have the same looks) ;)

Good luck.
M
Click to expand...

You'll must connect copper's plate to ground (as they were a metal cabinet)

In the preamp keep floating signal ground, and connect star ground to copper's plate through a 47 ohm resistor, and then CU plate to AC GND pin
 
M

mark_titano

Member
Joined 2004
1543 said:
Hi Mark,

thanks a lot. Which power Amps do you use with the baxandall pre.
Did you make a comparison with other preamps or a passive atttenuator?

Arne
Click to expand...


When I've build my first “my_ref” rev A, I found it not totally satisfactory. I start to speak with Mauro about my sensation and one of the think he said was that he never listed to the rev A (also rev C) without a good pre.

He shown me this schematic...and when I've listened the changes in sound with this pre (and not only a passive preamp or a simple pot in front of the amp) I was simply astonished.

Honestly, even with the rev C I feel a great step in performance with a good pre.
And the baxandall implementation is really good one, even with standard opamps.
What I love is that, with the pot set for the max attenuation, you can perform a really good S/N ratio. This is due to the fact that also the noise is reduced by the feedback network and this is also the bigger step ahead any passive preamp.

Mauro said that also the cs3310 or the pga series from BB can be a good solution.
With a good buffer before and after (he suggest the opa604), the total performance is adequate to drive his rev C without any loss in transparency.

Mark
 
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