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Welcome to my blog, which was once a mailing list of the same name and is still generated by mail. Please reply via the "comment" links.

Always interested in offers/projects/new ideas. Eclectic experience in fields like: numerical computing; Python web; Java enterprise; functional languages; GPGPU; SQL databases; etc. Based in Santiago, Chile; telecommute worldwide. CV; email.

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Roksan K2 Amp + ATC SCM7 Speakers

From: andrew cooke <andrew@...>

Date: Sat, 23 Mar 2013 15:29:05 -0300

[Bear with me; audio stuff starts in a para or two].  Two months yesterday I
was terrified.  It was the day I predicted I would have a third outbreak of
MS, given the timing of the previous two.  That didn't happen; I am now two
months clean and have been celebrating.  First, a t-shirt - 
http://www.acooke.org/images/ndy.png - and second, some new audio gear.

Now let's jump back in time for some context.

The illness means I have been spending more time in bed.  So I moved the Quad
12l speakers, that we had bought for the living room, placing on them our
bedside tables.  And I connected everything up to an old Cyrus amp (so old the
pre-amp is dead; I've wired the input directly to the internal power amp) and
an AudioEngine D2 for DAC/WiFi.

That sounded great, to me.  The Quads have a very laid-back sound, which I
have really come to enjoy (especially when, in the first few weeks after the
outbreaks, any abrupt, harsh sound sent electricity down my spine).

But Paulina was less than happy with the rather large, cherry, lacquered
cabinets.  And we had no music in the living room...

...so I decided to find some smaller speakers and, frustrated with the lack of
volume control (I've been setting the volume in the digital stream from the
computer, which isn't optimal), a new amp.  The obvious candidate (options are
fairly limited in Chile) was a pair of ATC SCM7s, which the nice guy at
Audiolux - http://www.audiolux.cl - was importing

The original date for the import arriving was near the end of January.  That
matched the date I expected to have a new outbreak.  I dared not hope for no
attack; instead I hoped that I would be able to hear the speakers before it
happened - that if I was going to be bed-ridden, I would at least have
something new to enjoy.

But the shipping was delayed, several times.  Each time I shifted my hopes,
and each time the outbreak failed to appear.  So I made it to today.  Yay!


So we spent the morning in the Audiolux listening room.

We started listening to a Quad Elite CD player and integrated amp, with Roksan
K2 speakers.  That didn't sounds so great - thin and lacking in life.  But
when we switched to the Roksan K2 amp the difference was night and day.  Which
was a pity as the Roksan is ugly and the Quad is on sale.  The problems of the
rich...

At that point we switched to the AudioEngine D2.  That sounded a little more
flat than the Quad CD player, but not such a big change compared to the
difference in amps.  But since that was the output we have, we had to stay
with it.

So then we started running through the different speakers available.  Compared
to the K2 speakers, the ATC SCM7 sounded like a smaller box (which was fair
enough and not such a big deal), but also more "shut in".  The treble on the
K2s (which have a ribbon speaker) is very detailed.  On the other hand, we
weren't impressed with the treble on Quads but ended up loving the sound when
we had to live with it...

After that we tried a Vienna Acoustics Haydn Grand.  That extended the treble
back out, compared to the SCM7s, but the bass/midrange was missing.  It really
didn't work that well, with a strange emphasis in the lower highs.

So on sound alone, I preferred the K2s, with the SCM7s sounding pretty good
too.  But unfortunately the K2s are as big as the Quads.  And they have a
rear-firing port, which means no wall mounting.  So that would be no
improvement on the Quads (from an interior decoration POV).  Which meant a
veto from Paulina.

So the final choice - a slight compromise, but one I can live with - was the
SCM7s with the Roksan K2 amp.


Arriving back home, I connected the speakers first.  And my heart sank.  They
didn't sound at all special.

But then I remembered the difference switching amps made, and unpacked the
Roksan amplifier.  When I replaced the old Cyrus everything opened up again.
It was the sound we had listened to and, in our small bedroom, sounded even
better than in the Audiolux listening room (I think!).


And, best of all, the speakers are so small that I think Paulina is OK with
them staying on the bedside tables.  Which means no messing around trying to
find wall mounts - and also means that when I am lying in bed feeling crappy
they are positioned like near field monitors and just rock...

Andrew

Small Problem with Roksan K2 Amp

From: andrew cooke <andrew@...>

Date: Sun, 24 Mar 2013 18:58:16 -0300

I just spent this afternoon (a Sunday!) back at my ever-helpful dealer -
http://audiolux.cl - trying to understand a problem with the amp we bought
yesterday.

Rather than give the whole story, with lots of confusion and tests, I'll just
describe the issue:

First, like many amplifiers, the Roksan K2 has a powered standby (a kind of
half-off state) which kills the output, but leaves the circuit in a "ready"
state to play again.

There's also a "real" power switch (below the left hand side of the front
plate) that controls the power.

So when you turn the amplifier on you first press the lower left power switch,
after which the front "mode" light shows green.  You're now in standby.

From standby, pressing the "mode" switch changes the mode light to red, then
selects the output channel (a click of relays and a red light showing the
channel), and finally connects output (another click and you hear music).

To get back to standby you press and hold "mode" again, the sound cuts, the
relays click, and you end up with a green mode light.  Pressing "mode" again
gets you back to playing, etc etc.

That's how it should work.

In practice if you (1) have not been playing music (ie the system is "cold")
and (2) you already have an input signal on the channel you want to play (but
see below) then pressing the "mode" button does nothing.  Or rather, what is
seems to do is attempt to turn things on, but then trip the overload
protection.  This can either happen "immediately" (mode light flashes red,
single click of relays, and back to green) or at either of the steps described
above (output channel selection or sound turning on).

After a couple of attempts (more if the system is very cold), everything
works.

This happens on my own amplifier, and also on another belonging to Audiolux.
The two were bought from Roksan at different times so are unlikely to be from
a single, broken, batch.

It happens with input from my AudioEngine D1, D2, and a Roksan CD player (not
Kandy - the next model up, I guess).

It seems to depend to some extent on the music being played (bass seems to
make the problem more likely).  And on the volume setting (setting the volume
lower seems to make the problem less likely).

It also happens when the remote control is used.

Most people will probably never see this, because most people control their
music by selecting the source.  But I have music streaming 24/7 from the
computer and simply turn the amp on to hear something.

Anyway, it's not a deal-breaker by any means.  In fact, I prefer this problem
plus output protection, to no protection.  And since it is present on two
instances of the amp it seems to be a "feature" rather than an error that will
get worse with time.

I tried to register at the Roksan site (which has discussion forums), but the
email contact address there (needed to register) bounces (exceeded quota).
Andres (the nice guy at Audiolux) said he'd try talking to Roksan.  If he gets
back to me with more details I'll post here.

And finally, what would a post from me be like without a complaint about MS?
Driving back from Audiolux I was terrified I was having an outbreak, as both
legs felt strange on the car seat.  Turns out I had a USB stick in one back
pocket and my cellphone in the other.  And the pockets on these jeans are
"fashionably" low...

Andrew

PS Input Signal

From: andrew cooke <andrew@...>

Date: Sun, 24 Mar 2013 19:01:05 -0300

I forgot to say that the input signal can be "flat".  It's enough to connect
my D1, powered, with no transmitted signal.

Which makes me think (along with the other details) that it's some kind of
grounding issue.  And Andres suspected the same, with the D1 being ungrounded.
But then we tried the (most certainly grounded) Roksan CD player and saw the
same...

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