Jkx@home » audio http://www.larsen-b.com Titanium Exposé Wed, 20 May 2026 16:33:52 +0000 en-US hourly 1 http://wordpress.org/?v=3.5 MP3 Bitrates compared http://www.larsen-b.com/Article/273.html http://www.larsen-b.com/Article/273.html#comments Sat, 03 Nov 2007 13:11:25 +0000 admin Continue reading →]]> A lot of people use some mp3 files right now. I decided to take a look at a spectrum analysis of a sound file at different bitrates. The result is really something, I doesn’t expected..

The original wave file is a radio (FM) recorded… I chose this one, cause this radio have a big noise on the upper part of the spectrum.

Original:

http://jkx.larsen-b.com/photos/blog/spectrum_original.png

b = 128

http://jkx.larsen-b.com/photos/blog/spectrum_128.png

b = 192

http://jkx.larsen-b.com/photos/blog/spectrum_192.png

b = 224

http://jkx.larsen-b.com/photos/blog/spectrum_224.png

Variable bitrate

http://jkx.larsen-b.com/photos/blog/spectrum_variable.png

What we clearly see, it that mp3 encoder (lame here) use a expander, and this is quite a good stuff. I think I should have normalized the input.. but..

After that point, we clearly see it cuts the around 16Khz, I know that my computer system isn’t able to achieve this level, but my stereo system can.

First results show that Ogg give a better results but this is for a future post.

Enjoy sound

]]> http://www.larsen-b.com/Article/273.html/feed 4 Eltax Symphony 6.4 review (Avis ?) http://www.larsen-b.com/Article/267.html http://www.larsen-b.com/Article/267.html#comments Sun, 29 Jul 2007 01:23:41 +0000 admin Continue reading →]]> Eltax Symphony loudspeakers are some really cheap one. It cost around 120 Euros here in France. I was looking for a review for this speakers for a long time. How can Eltax sell speakers for this low price.

http://jkx.larsen-b.com/photos/blog/10228_sys1.jpg

A month ago, I discover that my old Elipson speakers are quite dead.. too old to rock !! ;) So beside I decided to repair them, I need to buy something else during this period (period that could be long, cause I need to find somebody to fix them)

After long googling, I decided to give the Eltax a try. So brought a pair on the web. In fact, I haven’t found anything really interesting on the net about Eltax products, so this is the first real review of Symphonie 6.4 loudspeaker. (Please if you find this one useful, links to this article, in the hope someone else find it)

Aspect:

This is quite important no ? Ok this stuffs are pretty nice floorstanding 2 ways speakers. Eltax has done some serious work here. They seems to be robust, and good quality. This is the first thing that I wasn’t looking for. Cheap speakers != bad products..

The low-middle boomer look a bit too small for me, but ..

Sound:

First, don’t forget I usually use some Elipson, or high end Denon speakers, not this kind of cheap stuffs :) But let’s start. I wired the Eltax on a 2* 80w (big boy) Denon amp, and press the play button. The first impression is really strange. The middle and high are crystal clear. Astomishing !

The highs are a bit to bright for my ears, but this is not a really big issue, because I can fix that with the treble setting. But the middle are really clear, you can listen every small sound and believe me I haven’t heard this kind of middle on a lot of sets.

While playing, I tested several style of music, and discover that’s despite this speakers are really a good discovery, I ‘m missing something. I searched over several CDs, and yes, I found it. Despite the bass are quite fine on this speakers, something is missing: low-mids. I mean, the middle and the bass are really effective, but the low-middle aren’t there. Of course, the problem seems to come from the small boomer, but as the bass-reflex do a good job bass are deep so not really easy to discover at the first listening.

This loudspeakers can play with you, because you when you power them, they give you what you’re looking for: good mids, good highs and deep bass. But after long a listening you will find them a bit strange ..

Even worst, when you try to listen some songs with a lot of different harmonics (Muse is the worst stuff I has on my hand for this time, but it’s a good challenger. Vocals are high, noisy guitars, and lot of bass), the speakers is really in a bad condition. I mean, the speaker doesn’t achieve to play it. Instead of music, you get some noisy background, a mixed bass, and bright vocals, and it sound really bad.

Conclusion:

I read a lot of good comments on the Eltax Monitor III, and right now I know why. I’m quite sure they deliver the same clear middle, and great vocals. This is perfect for a home-cinema setup, but not for Hifi. I’m quite sure, I will buy a Eltax center channel for my next setup, because this is exactly what everybody is looking for.

My first goal with this speakers was to use them for the back channel in home theater setup, and they are really good enough for that. If you want to buy this speakers for a HT setup, let’s do it, it will give some really good results.

I discover that one of my speakers has an issue on low bass (50Hz/60Hz) and low volume, I can ear some scracth. This doesn’t affect sound-stage at normal level (very weird) so I decided to send them back.

So guess what, you should read another Cheap Hifi speaker review soon ;)

]]> http://www.larsen-b.com/Article/267.html/feed 2 Lot of DIY stuffs to do, so litte time, and waiting for holidays http://www.larsen-b.com/Article/265.html http://www.larsen-b.com/Article/265.html#comments Wed, 11 Jul 2007 21:30:03 +0000 admin Continue reading →]]> Ok, my english exam is over .. waiting for the final result

I had a lot of stuffs on the way right now, so I hope to have the time to finish them before going on holidays here a little list:

  • A subwoofer (with a big 12″ woofer that goes damn low !
  • A subwoofer amp, this is the most hardest part, cause I need to build a mixer, a bandwith filter, and something like a 100W amp.
  • Finish a little test with my AVR32 (more to come on this way soon)
  • Repair my current HIFI system (restore some HP, even if I bought a low cost one to wait)
  • Start my new tube amp (sitll waiting for some big inductors ..)

So, I think i will be busy on my holidays :)

Perhaps, I will re-do this website design too, cause I want re-order some stuff, change the color scheme (cause borring right now) …

]]> http://www.larsen-b.com/Article/265.html/feed 0 Howto hack USB port on a LG LAC-M6500R MP3 Player (CD/Radio/MP3 Player) http://www.larsen-b.com/Article/257.html http://www.larsen-b.com/Article/257.html#comments Sun, 04 Mar 2007 13:06:59 +0000 admin Continue reading →]]> Some friends buy me a nice MP3 player for my car last year (birthday): LAC-M6500R

This stuff looks great and you can even plug a hard-drive. The main issue is that the firmware only support 999 files on a single USB device, so that’s enougth for ~4Go of MP3 but not more. So I decided to buy some USB sticks, it’s far more simple .. no external power supply, and just the room to place a quite large MP3 collection (simply buy 2/3 sticks and that rules)

http://jkx.larsen-b.com/photos/Electronic/DSC02235.sized.jpg

That’s ok, but hum, as you can see on this picture the USB plug is on the front panel. And that’s a mess, cause you have to unplugged it when you want to remove the front panel (some infamous guys already try to open my car 4 times..), or to put a CD in. Beside this is a gift, I decided to open it, and try add a external USB in the back. I think my friends will understand this: “If you can’t open it, you don’t own it” ..

First, I decided to open the front panel, to look how the USB plug is connected. As you can see on the aboves pictures, the USB power-supply come form the main board.

http://jkx.larsen-b.com/photos/Electronic/DSC02242.sized.jpg
http://jkx.larsen-b.com/photos/Electronic/DSC02541.sized.jpg

That’s fine.. We simply have to add take the power from the source ..

http://jkx.larsen-b.com/photos/Electronic/DSC02542.sized.jpg

When I look closely, I discover that the PSU provide 5.5v instead of 5.0v. The main reason, is that the front panel contain a small chips do the final regulation.. Ok, we can do the same ? :) I used a low drop 5.0v regulator: LP38691 with 2 small caps..

http://www.national.com/images/pf/LP38691/20126501.jpg

The final step, is to connect the data bus (DATA- / DATA+), this was really hard, because the front panel USB bus is connected to the main decoder board throught a small wire. As I’m not able to find the right plug, I decided to solder it on the board ..

http://jkx.larsen-b.com/photos/Electronic/DSC02553.sized.jpg

So we have something like this:

http://jkx.larsen-b.com/photos/Electronic/LG_gschm.png

The small PCB:

As you can see on this picture, on the left, there is the wires from the main board, and the 5.0v regulator. On the right the wire that goes to the decoder board, and the external new USB connector.

http://jkx.larsen-b.com/photos/Electronic/DSC02551.sized.jpg

Here the finished product:

http://jkx.larsen-b.com/photos/Electronic/DSC02558.sized.jpg

Ok, that’s fine, now, you can place this small board in system (there is a lot of room), and enjoy the external USB cable ;)

]]> http://www.larsen-b.com/Article/257.html/feed 8 DIY KT88 + 6SN7 push-pull Amp / Part 1 http://www.larsen-b.com/Article/255.html http://www.larsen-b.com/Article/255.html#comments Fri, 09 Feb 2007 11:04:57 +0000 admin Continue reading →]]> In a previous post, I talk about a new amp project. Since this post, I bought several stuffs to build it. But while looking for parts, I talk with several people. And they convince me to build a push-pull instead of a single-end.

So, I got 4 outputs transformers (2 SE and 2 PP), I gonna try the PP first, and if this work great perhaps, I will sell the single transformers or build a second amp.

The main difference between single-end and push-pull, is distortion. In fact, SE produce a lot of harmonics, so a lot of distortion. Beside this is a bad idea for a power amp, this is really what a lot of people call a “real tube sound”. Anyways let’s start with a full featured push-pull, and perhaps came back to a simple SE just for the fun.

The main issue right now, is that push-pull are a lot of more complicated. I mean you can build a simple SE with only a spare components.. this is not the case of a push-pull. For a single channel, I need 2 tubes, 1 bias power-supply, a highly regulated power supply and a phase shifter ..

For the tubes, I decided to use some KT88. In fact, a friend give me a spare matched quad of NOS (plain old) Gold Lion tubes + the needed output transformers so .. This tube are really great for the HIFI. And they look really great !!!

http://jkx.larsen-b.com/photos/TubesAmps/KT88.sized.jpg

For the input stage, I decided to do something not really common. In fact most tube amps use some ECC82 / ECC83 for the input stage. My choice is something little different cause, I want to use some bigger tube. A lot of people say the 6SN7 (or 12SN7) are great for this stuff too. And some high quality power amps tube this, so why not. After looking for a while for a good schematic, and tested severalls stuff, here the one I gonna build:

http://jkx.larsen-b.com/photos/TubesAmps/canal.sized.gif

In the comming (soon I hope), I will describe the schem and the modification I made. Right now, I’m waiting for the power transformer (comming from US take a long time). In a next post, I will post some photos of my input test bench …

Enjoy light ?

]]> http://www.larsen-b.com/Article/255.html/feed 11 Howto listen mp3 in the bathroom ? http://www.larsen-b.com/Article/245.html http://www.larsen-b.com/Article/245.html#comments Sat, 18 Nov 2006 23:39:23 +0000 admin Continue reading →]]> I was looking for a simple way to listen some good music while I’m not in my living room (hum, I’m mean in the bathroom). There is a lot of small MP3 players right now, the only issue is that most of them cost a lot of money if you want to put a great amount of mp3 on..

Another way, perhaps look at wifi powered mp3 player like the one made by Roku. But you know, this cost a little money (around 200$), just a bit too much for the bathroom ;)

So, I decided to look at FM transmitters, but I read on most websites that they don’t perform really well. Ok, let’s go for a DIY way, after a little search on eBay, I found a small (really small) FM transmitter pair for 15$ from Sure Electronics.

http://jkx.larsen-b.com/photos/Electronic/DSC02440.sized.jpg

Hum, let’s give it a try:

  • plug a 12v PSU
  • solder a long (70cm) wire antenna
  • solder a stereo jack (and plug it to the soundcard output)
http://jkx.larsen-b.com/photos/Electronic/DSC02444.sized.jpg

And this little stuff, is really working great !! I haven’t test the range right now, I have a clear listen all around my home.

/Enjoy Neighborhood

]]> http://www.larsen-b.com/Article/245.html/feed 4 Build a DIY vacuum tube amp ( EL34 / KT88) http://www.larsen-b.com/Article/233.html http://www.larsen-b.com/Article/233.html#comments Mon, 17 Jul 2006 14:24:44 +0000 admin Continue reading →]]> I decided to build a tube amp for the fun. In fact I think of that stuff since a really long time now (since the first amp, I ‘ve built ten years ago).

There is a lot schematics on the internet, but finding a good one is pretty hard. I want to build something like that:

  • Good power: 10 Watts seems to be a good starting point.
  • Something simple. I want to build an amp, I can fix by myself. So I decided to build a Single Ended one. (Not a push-pull) Push Pull provide far more power, but need more components and harder to build.
  • Low cost. The best issue for this kind on amp, is the price. You need to buy some output transformers, big power supply transformer and choke. And of course, when we talk about HIFI this cost a lot of money.
  • Look’s good. Something which is important is the way it looks. So I will have to take really care of that.

For people who have never seen this kind a stuff here a little pic I ripped out.

http://www.osbornloudspeakers.com.au/opera/m100se-Bt.jpg

Tubes

For this design, I decided to use some EL34. Check out DrTube[0] for additionnals data. They offer good output power for a decent price.
The reflected load permits to use a KT88 instead if this doesn’t provide enought power.

For the preamp, I think I gonna use a 6SN7 in SRRP. This provide a good gain, and very good linearity.

Output transformers

EL34 has a reflected load of 2KOhm, so I need to find coresponding transformers. Of course this cost a lot of money, Hammond HIFi (not guitar) output transformer for 20w cost something like 99$ each. And
even worst, I unable to find 2.0K only 2.5 are currents.

I found this one:

  • EuphoniaAudio[1] (205$ the pair)
  • Hammond[2] (99$ each)
  • Electra Sud Ouest (86Euros)
  • Elettronocanovarria[3] (75Euros)

Despite, Elett.. offer good price, I unable to buy them here, cause the vendor speack only italian.. and that sucks. Electra sud has a good price too, so I guess I will buy them here if I don’t find anything else.

Update: I found a matched pair of 2.5K / 20W transformators on eBay.

Power Supply

This part isn’t really clear for me right now. Singled Ended amps doesn’t need regulated PSU because they work in pure class A, so the current is fixed (throught the tube bias) but It need to be really stable to avoid distortion.I don’t want to buy a large transformer because they cost a lot of money and doesn’t feet with my needs. EL34 use a quite low voltage (~250v) but need quite a bit of current ~100ma. I think, a good isolating transformer can do the job. Something like 230*230 at 200Va doesn’t cost a lot of money.

Schematic

This is really a hard part. But I found 2 good example:

  • first[4]
  • and second[5]

To be continue… ;)

Links

]]> http://www.larsen-b.com/Article/233.html/feed 9 Playing music on soundcard without locking http://www.larsen-b.com/Article/194.html http://www.larsen-b.com/Article/194.html#comments Wed, 09 Feb 2005 09:06:24 +0000 admin Continue reading →]]> Why this soundcard allow me to play 2 mp3 at the same time while this doesn’t.. Hum good question. In fact to support this kind of stuff the sound card should support have some sub-device, to be sure .. simply aplay -l

Here on my shuttle .. not working

aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: IXP [ATI IXP], device 0: ATI IXP AC97 [ATI IXP AC97]
Subdevices: 1/1
Subdevice #0: subdevice #0
card 0: IXP [ATI IXP], device 1: ATI IXP IEC958 [ATI IXP IEC958 (AC97)]
Subdevices: 1/1
Subdevice #0: subdevice #0

Here on another box (VIA C3 based)

aplay -l
**** List of PLAYBACK Hardware Devices ****
card 0: V8235 [VIA 8235], device 0: VIA 8235 [VIA 8235]
Subdevices: 4/4
Subdevice #0: subdevice #0
Subdevice #1: subdevice #1
Subdevice #2: subdevice #2
Subdevice #3: subdevice #3
card 0: V8235 [VIA 8235], device 1: VIA 8235 [VIA 8235]
Subdevices: 1/1
Subdevice #0: subdevice #0

So yes the C3 can play 4 stream at the same time, while the AC97 doesn’t.

Another way to do this is to use software mixing

Update:

To use the software mix in Alsa: simply change the pcm.default to pcm.dmix

#pcm.default cards.pcm.default
pcm.default pcm.dmix
]]> http://www.larsen-b.com/Article/194.html/feed 1