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Noulakaz

Noulakaz

The blog of Avinash, Christina, Anya and Kyan Meetoo.

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Avinash Meetoo

Dilemma: better speakers or a subwoofer?

19 December 2007 By Avinash Meetoo 23 Comments

Today I went to J. Kalachand to listen to a subwoofer that I was planning to buy. But I couldn’t help myself asking some questions to the salesman there and now I have a dilemma.

What I have now

I currently use a pair of Pioneer S-H210V speakers as the front speakers of my home cinema setup as well as the main speakers when I am listening to music or watching satellite. Here are their technical characteristics:

  • Bass-reflex configuration
  • 2 x 13 cm medium/bass speakers
  • 1 x 5 cm tweeter
  • Sensitivity 90 dB/2.83 V/1 m
  • Frequency response 50-20,000 Hz
  • Impedance 8 ohms
  • Input Power 80 W
  • Weight 4,2 kg

As I wrote in my previous post, there is a definite problem with the bass (and this is easy to understand given the frequency response of the speakers) and even though I like the sound when watching a DVD, I have some issues when listening to music: the high frequencies are strange.

1st possibility – the Yamaha YST-SW215 subwoofer

This subwoofer is available at J. Kalachand and costs Rs. 9,155. The YST-SW215 is a current product and this is somewhat rare in Mauritius where shops routinely sell outdated equipment for lots of money.

I spent about 30 minutes listening to some music (a UB40 CD and some tracks from my iPod Nano) and the effect was subtle. The very helpful salesman, Pierre Alain (by the way, thanks David), told me that Yamaha has adopted a new strategy concerning its subwoofers: less boom-boom but more quality and fidelity. And I’m 100% happy with that. Except that the effect was so subtle. I’ll definitely bring some DVDs there. The technical characteristics are:

  • 150W dynamic power
  • 20cm (8″) multi-range driver with magnetic shielding
  • 30–200Hz low frequency reproduction

So it seems that this subwoofer has the potential to supplement my S-H210V well (at least in the 30-50 Hz region) and solve my bass problems. But what about the high-frequencies?

2nd possibility – a pair of Yamaha NS-50F speakers

While having a look in the showroom, I noticed the NS-50F. J. Kalachand sells a pair of those at Rs. 9,720 i.e. a pair is comparable in price with one YST-SW215. Here are the technical characteristics:

  • Bass-reflex configuration
  • 2 x 16 cm medium/bass speakers
  • 1 x 3 cm tweeter
  • Sensitivity 90 dB/2.83 V/1 m
  • Frequency Response 35–35,000 Hz
  • Input Power 80 W
  • Impedance 6 ohms
  • Weight 12.5 kg

There are two major differences with my current S-H210V: (i) the frequency response and (ii) the weight.

The NS-50F can go down to 35Hz compared to the 50Hz of the S-H210V. Maybe 15Hz does not seem much but I can assure you that this is where the .1 data in a 5.1 encoding is.

I didn’t have time to test the NS-50F but I’m pretty sure it’s treble is bound to be much better than what I have currently.

The weight difference (12.5 kg v.s. 4.2 kg) is a clear indication of how “professional” the Yamaha is compared to the Pioneer.

Dilemma

Given the price difference which is relatively small, is it better to buy the YST-SW215 (at Rs. 9,155) or a pair of NS-50F (at Rs. 9,720)? What do you think?

Filed Under: Movies, Technology

Linus: Trial-and-error with feedback rocks!

19 December 2007 By Avinash Meetoo 6 Comments

Someone said that Linux was progressing only through sheer luck… And this make Linus Torvalds react:

And don’t EVER make the mistake that you can design something better than what you get from ruthless massively parallel trial-and-error with a feedback cycle. That’s giving your intelligence much too much credit.

Linus was referring to the open source development model (have you read The Cathedral and the Bazaar? You really really should!) compared to the classical corporate model of software development.

And, of course, he is right.

Filed Under: Linux, Programming, Technology

Emtel’s Huawei E220 with Linux in Mauritius

16 December 2007 By Avinash Meetoo 41 Comments

Emtel has recently started selling a USB modem (a Huawei E220) which uses its 3G cellular network (specifically HSDPA) to provide an Internet connection of up to 1.8Mbits/s.

A good friend of mine has bought one for his company but has not been able to make it work with Linux. Always looking for a new technical challenge (yes, I am a geek), I told him that I was willing to give it a try during the week-end. And this post is about what I did to make it work.

I run Kubuntu 7.10 (with kernel 2.6.22 which is > 2.6.19 which means that everything should normally work out of the box). Of course, this was mostly true in my case. Here is the exact version of Linux I’m using:

Linux noulakaz 2.6.22-14-generic #1 SMP Sun Oct 14 23:05:12 GMT 2007 i686 GNU/Linux

Plugging the Huawei E220 and typing dmesg, I get:

[ 112.528000] usb 2-1: new full speed USB device using uhci_hcd and address 2
[ 112.688000] usb 2-1: configuration #1 chosen from 1 choice
[ 112.796000] usbcore: registered new interface driver usbserial
[ 112.800000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/usb-serial.c:
USB Serial support registered for generic
[ 112.800000] usbcore: registered new interface driver usbserial_generic
[ 112.800000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/usb-serial.c:
USB Serial Driver core
[ 112.808000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/usb-serial.c:
USB Serial support registered for GSM modem (1-port)
[ 112.812000] option 2-1:1.0: GSM modem (1-port) converter detected
[ 112.812000] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0
[ 112.812000] usbcore: registered new interface driver option
[ 112.812000] /build/buildd/linux-source-2.6.22-2.6.22/drivers/usb/serial/option.c:
USB Driver for GSM modems: v0.7.1
[ 112.824000] usbcore: registered new interface driver libusual

Of course, the important information here is:

GSM modem (1-port) converter now attached to ttyUSB0

In /dev, the following device is created automatically:

crw-rw—- 1 root dialout 188, 0 2007-12-16 10:24 ttyUSB0

BIG PROBLEM!

/dev/ttyUSB1 and /dev/ttyUSB2 do not exist meaning that the modem won’t respond. After searching, I found the solution online on Mohd Shakir Zakaria‘s weblog. The solution is to remove the uhci_hcd kernel module, reload it and wait for ttyUSB1 and ttyUSB2 to be created (this looks like a bug in uhci_hcd) [Thanks to Shakir who sent me a mail to tell me that uhci_hcd only has to be removed and reloaded once for the appropriate devices to be created…]

sudo modprobe -r uhci_hcd
sudo modprobe uhci_hcd

and the following is logged after some time:

[ 776.960000] option 2-1:1.0: GSM modem (1-port) converter detected
[ 776.960000] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB0
[ 776.964000] option 2-1:1.1: GSM modem (1-port) converter detected
[ 776.964000] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB1
[ 776.968000] option 2-1:1.2: GSM modem (1-port) converter detected
[ 776.968000] usb 2-1: GSM modem (1-port) converter now attached to ttyUSB2

There is a script which automates this process.

Connection to the Emtel network using wvdial is then trivial. This is my wvdial.conf:

[Dialer Emtel]
Phone = *99***1#
Modem = /dev/ttyUSB0
Username = user
Password = pass
ISDN = 0
New PPPD = yes
Baud = 1843200
Init2 = ATZ
Init3 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Modem Type = Analog Modem

Running:

sudo wvdial Emtel

produces:

WvDial<*1>: WvDial: Internet dialer version 1.56
WvModem<*1>: Cannot get information for serial port.
WvDial<*1>: Initializing modem.
WvDial<*1>: Sending: ATZ
WvDial Modem<*1>: ATZ
WvDial Modem<*1>: OK
WvDial<*1>: Sending: ATZ
WvDial Modem<*1>: ATZ
WvDial Modem<*1>: OK
WvDial<*1>: Sending: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
WvDial Modem<*1>: ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
WvDial Modem<*1>: OK
WvDial<*1>: Modem initialized.
WvDial<*1>: Sending: ATDT*99***1#
WvDial<*1>: Waiting for carrier.
WvDial Modem<*1>: ATDT*99***1#
WvDial Modem<*1>: CONNECT
WvDial<*1>: Carrier detected. Waiting for prompt.
WvDial<Notice>: Don’t know what to do! Starting pppd and hoping for the best.
WvDial<Notice>: Starting pppd at Sun Dec 16 10:35:57 2007
WvDial<Notice>: Pid of pppd: 6193
WvDial<*1>: Using interface ppp0
WvDial<*1>: local IP address 10.11.80.28
WvDial<*1>: remote IP address 10.64.64.64
WvDial<*1>: primary DNS address 196.192.4.4
WvDial<*1>: secondary DNS address 213.200.89.89

I tested the Huawei E220 by downloading a couple of my own MP3s:

time wget https://www.noulakaz.net/avinash/music/so-logical/07-play.mp3
Length: 4,879,827 (4.7M)
real 2m5.443s

The download speed is 304 kbits/s

time wget https://www.noulakaz.net/avinash/music/so-logical/04-helium.mp3
Length: 4,276,087 (4.1M)
real 2m5.200s

Download speed is 267 kbits/s

And I also downloaded a 6Mb file from an official Ubuntu server:

time wget http://mu.archive.ubuntu.com/ubuntu/ls-lR.gz
Length: 6,000,019 (5.7M)
real 4m35.690s

Download speed is only 170 kbits/s which is nothing to shout about – but, at least, it works :-)

6 January 2007: an update

I’ve added sudo everywhere because I’ve realized that many Ubuntu (or Kubuntu) users do not know how to log in as root (which is excellent :-) ). I’ve also used dmesg command instead of having a look in the log files directly.

Filed Under: Technology, Web

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Creative Commons License This work is licensed by Avinash Meetoo under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 Unported License.