Subwoofer story

Archived from groups: rec.audio.tech (More info?)

Here's a story that may interest some of you (in point form for space
reasons - took about 3 months to evolve.)

-- Bought an Infinity BU-120 sub on eBay from a seller who had not
used it for many months. Paid cash.
-- Sub worked fine for an hour (sounded good)
-- Sub started going "blp... blp.." at random. Very odd!
-- Into the workshop, took out amplifier module, powered it up with
test gear.
-- It reproduced down to 30 Hz or so but every so often went "blp..
blp..."
-- It also showed microphony - if you tapped the silver Class D
module you could mostly make it go "blp" and "clack" (How do you
spell "blp"?
<g> )
-- Could not find intermittent connection so now quite p****d off with
it!
-- Hit the Internet and googled "Infinity BU-120" - may hits, many
negative about the amplifier.
-- Found a discussion group where "hundreds of people" had this amp.
go "blp" or even "machine gun", one in the middle of the night! (he
had left it on auto.)
-- Scrapped the amp. and salvaged a few parts (very few, what junk!)
-- Meanwhile, contacted seller. He offered all money back and told me
to take it to the dump to save him the trip. Since the box and
speaker unit had some value to me we negotiated only partial
repayment. Now I had a passive sub with a large whole in the back!
-- I covered the hole with 5/8 inch ply painted black and installed a
pair of speaker terminals in a round cut-out - looks very nice.
-- Set it up on one channel of my Yamaha M4 (with electronic X/O and
pre-amp.) Voila! A 12 inch sub with lots of punch ( the other channel
ran one of my Energy Esub2's).
-- Looked for sub. amps. Found http://www.partsexpress.com/ Great
products! (I've no commercial connection to this company.)
-- Bought a 200 watt sub amp, part number 300-804.
-- Bad news! Free shipping in the US but NOT to Canada, i.e. shipping
is in the price but they won't take it out for Canadians.
-- Had it shipped to a US resident relative, picked it up on a trip
and
imported it legally tax free under my duty free allowance.
-- Connected it to the Infinity "passive" box - fantastic! IIRC, this
is a linear MOSFET amp, class AB, weighs over 12 lbs with massive heat
sink - none of your picky, unreliable Class D stuff that fails!
-- I did not build in into the box (yet) since I wanted flexibility,
not did I want to take up the internal space (it sits just behind the
sub box.)
-- End of story.

P.S. the 300-804 is now on special at Parts Express - US$100 delivery
included to a US address (only!).

Moral: it's a very good thing to adapt, rebuild, recycle and reuse
stuff - sometimes the results are better than the original! Also,
"Free Trade" is an illusion!

Cheers,

Roger

Archived from groups: rec.audio.tech (More info?)

Engineer wrote:

> Here's a story that may interest some of you

Thanks for posting, a creative way out of a problem - negotiation as
well as tech solution - and a good reminder to google and msnsearch
first and buy later.

> Roger


Kind regards

Peter Larsen

--
*******************************************
* My site is at: http://www.muyiovatki.dk *
*******************************************

Archived from groups: rec.audio.tech (More info?)

I missed the original thread but I have a PEx subwoofer amp that I got from
Ebay for $105 and is performing according to its specs.. I paired it with an
Adire Shiva driver in a 112 liter box.

"Peter Larsen" <SPAMSHIELD_plarsen@mail.tele.dk> wrote in message
news:41471EC6.E5D6B60E@mail.tele.dk...
> Engineer wrote:
>
> > Here's a story that may interest some of you
>
> Thanks for posting, a creative way out of a problem - negotiation as
> well as tech solution - and a good reminder to google and msnsearch
> first and buy later.
>
> > Roger
>
>
> Kind regards
>
> Peter Larsen
>
> --
> *******************************************
> * My site is at: http://www.muyiovatki.dk *
> *******************************************