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    SAND amp questions

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    n3ikq

    Posts : 26
    Join date : 2014-10-16

    SAND amp questions

    Post by n3ikq on Sun Jan 18, 2015 2:03 pm

    Now that I'm up and running with my ST-70 system I have at least a working knowledge of the ST-70 circuitry. Lately I've been wondering about the solid state side of life.
    Specifically, what output devices are being used amongst the different "higher end" companies nowadays? It seems that a device (LM3886) has become a favorite with the DIY crowd. I wonder if the same chip is being used by NAD, Rotel, Marantz etc. in their amps. If not are they still using regular BJT's in their designs or other hybrid output devices? It would seem to me that if most companies use the same chips, their sound would become very standardized and bland, essentially eliminating any unique qualities that make their brand special.

    I know this is off topic (and off forum) so:
    Is there a forum that is as friendly and tolerant as this one is but concerning solid state amps?

    If not, is anybody willing to write a thesis covering the history of solid state output devices between the ST-120 and now?!!!

    Tom

    Posts : 166
    Join date : 2011-04-04

    Re: SAND amp questions

    Post by Tom on Mon Jan 19, 2015 9:55 am

    No answer to you questions about what's used by audio companies
    but I did build a sand amp on the 3886, a "chimp amp" > so simple that a...
    ya, you get it.
    I had this great heat sink lying around so I cut it in half
    (figured I might end up with 4 chips instead of 2, haha)
    and voila, the chimp amp.
    Fun and great for Mrs. Tom who thinks that the "radio" should go
    off every time she leaves the room to save electricity and $.
    Her heart is in the right place.


    Very Happy



    Last edited by Tom on Mon Jan 19, 2015 9:57 am; edited 1 time in total (Reason for editing : add pic)

    n3ikq

    Posts : 26
    Join date : 2014-10-16

    Re: SAND amp questions

    Post by n3ikq on Mon Jan 19, 2015 3:48 pm

    Nice, clean build. How does it sound? The LM3886 seems to have a lot of fans.

    peterh

    Posts : 641
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Re: SAND amp questions

    Post by peterh on Mon Jan 19, 2015 7:06 pm

    Tom wrote:No answer to you questions about what's used by audio companies
    but I did build a sand amp on the 3886, a "chimp amp" > so simple that a...
    ya, you get it.
    I had this great heat sink lying around so I cut it in half
    (figured I might end up with 4 chips instead of 2, haha)
    and voila, the chimp amp.
    Fun and great for Mrs. Tom who thinks that the "radio" should go
    off every time she leaves the room to save electricity and $.
    Her heart is in the right place.


    Very Happy


    As the heatsinks are buried inside a box they will not fulfill their role. But i think this chipset has
    a tempsensor that will save it from destruction....

    ( useful heatsinks are located vertically and with free flow of air - or with forced air with a fan)
    Sorry to spoil the fun


    Tom

    Posts : 166
    Join date : 2011-04-04

    Re: SAND amp questions

    Post by Tom on Mon Jan 19, 2015 8:47 pm

    Hey Pete, it's been working pretty well for about 4 or 5 years now...
    What you can't see is the hole under the fins and, of course, the ventilated top of the "box"
    because it's not on there Razz

    Even after a few hours of run at moderately loud volume, the sink is cool to the touch;
    it's much, much too big for the job at hand but, hey, it needed a home, haha!

    n3 - it sounds OK, on par with the Denon sand amp it replaced, but it's only ~60W
    so it starts to sound a bit harsh about 2/3 of the way around the stepped attenuator Roy sells.
    The Denon was 120W and didn't have that issue so I presume clipping.

    Like I said, fun to build, fun to listen to,
    but not really nice enough to invest in a second set of chips to get 120W.

    Smile



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