internals 47 labs 4717 integrated

[carlosfm]

I started with the LM3875.
But happens that I have difficult speakers (Epos 11) and the LM3886 works much better for me.
Soundwise, it's the same, believe it or not.
High-end.

[ThorstenL]

Konnichiwa,

Originally posted by moamps
Fedde's pcb is IMO standard quality FR4 material (post 112). "Original" pcb (post 113) looks like "hygroscopic" pertinax.

I am familiar with both materials and their behaviour. Unless you spring for the PTFE board you will find pertinax the superior material in practice. Try it, make a circuit once on FR4, once on Pertinax and once hardwired, then listen.

Sayonara

[KT]

Hi,

Is pertinax a generic name for that brownish board material, or is it made to a certain spec by a certain company?

Thanks,
KT

[ThorstenL]

Konnichiwa,

Originally posted by KT
Is pertinax a generic name for that brownish board material, or is it made to a certain spec by a certain company?

I suspect that it used to be a specific brand but tends to be used generically these days (like the term "velcro" - I once had a request to replace the term "velcro" by "generic hook & loop fastener" on web-pages as velcro is trademark and I was infringing!!!!).

Not all of the pressed wood and resin PCB materials are equally good BTW.

Sayonara

[Jamh]

Originally posted by Steve Eddy


Looks to me like they already are using a small circuit board. What am I overlooking?



Why? They apparently already have a circuit board with the traces and holes right where they want them.



Why? I don't see any problem unless you planned to use it in a marine environment or something.

se

steve,

We are fortunate in Sacramento with very low humidity. Bit closer to the coast this could become a problem. As for circuit board, I meant something like Brian's so that you can speed up the manufacture. But like I said earlier, I dig their sense of esthetics.

[Steve Eddy]

Originally posted by Jamh
We are fortunate in Sacramento with very low humidity. Bit closer to the coast this could become a problem. As for circuit board, I meant something like Brian's so that you can speed up the manufacture. But like I said earlier, I dig their sense of esthetics.

Yeah, we're not as bad as places like the deep south, but by the same token not as dry as places like the southwest. The humidity here can get sufficiently high though that our evaporative cooler is little more effective than a fan, at which point I don't feel too fortunate.

Not sure a more formal circuit board would speed up production. Since the innards of the 47 Labs stuff just screams "cheap" I'd guess they decided it would be less epxensive to just cobble the boards themselves rather than pay to have more formal boards made.

se

[Frank Berry]

"Since the innards of the 47 Labs stuff just screams "cheap"

Amen!
There is "fair profit" and there is "gouging".
47 Labs is gouging.

[powerflux]

Took one apart.

The inputcapacitor is a bipolar, probably around 2.2uF
the feedback-decoupling capacitor is polar, 22uF - 47uF ( i suspect the latter)
The powersupply caps are no more then 3300uF, i suspect 2200uF @ around 35v judging by their size.



gain is set by 22K+680R (pretty high, i always read that you'd want a gain as low as stable with the 1875 to unleash it's magic)

outputfilter is a red 0.01uF WIMA (i suspect a clone) in series with 10 ohms

[Art M]

Looks like a poorly executed Hieronymus Machine. Just get some card board and a Sharpie to draw the Components. Why waste time with parts ?

[powerflux]

Originally Posted by Art M

Looks like a poorly executed Hieronymus Machine. Just get some card board and a Sharpie to draw the Components. Why waste time with parts ?

well, it's almost exactly the same as the typical application note in the datasheet. it does work.