Jacken’s Blog

Many months ago I bought a DAC to use with my computer in the bedroom. Just to connect to my Musical Fidelity X-Can V2 for some serious headphone listening. I have used it, but not been impressed by it at all. But when surfing around, I got in to this amazing/crazy page about installing a tube amp output on CD players and DACs. And he listed the cheap one I have as one of the best DACs he ever heard. The guy bypasses the output stage and replaces it with a simple tube buffer/amp. This got me interested.

Due to the fact that I was in the middle of modding my Tianyun Zero DAC, and wished that I had done some measurement on it before starting the mod, to be able to compare and see if it’s really is an improvement. But I forgot.

So I took out the CS4397 DAC and measured it.

Here’s the frequency response. As you can see it’s horrible! -3db down at around 12.000 hz. No good.

I knew that oversampling Digital to Analog converters usually have a lot of noice in the higher frequencies but the applied low pass filter is obviously wrong. So I started to search the net, and found this forum. So I tried all the classical mods first, like beefing up the power supply. Changed the surface mounted capactors to low ESR (Panasonic FM). Removed the output caps etc.

All this changes made for a better sound quality, but did not fix the big dip in the upper frequency. So out with the soldering iron again and changed the C32, C33, C34, C35 to 150pF surface mounted caps. And as always when dealing with surface mount parts you realize that your getting old. Shaky and with bad vision. But I managed to get them mounted. The DC output offset on it used to be 0.300V but is now 0.006V on both the RCA connectors.

Did it make an inprovement? Well, let the measurement do the talking…

I say! That obviously worked!

And here’s the really annoying part. My wife thinks that this cheap DAC sounds better and more open than my extensivly modified Zero DAC. That I’ve been working on for weeks. And she’s right.

So now, I have to rebuild and improve the power supply to try to lower the noise level to the same I have on my ZERO DAC.

After that, I’m going to rebuild the SPDIF input with a transformer. And then modify it so that it will work with 24/192khz input.

since using my new mail system Zimbra, I Must say I’m very impressed. The web client is actually so good that I now use it more than Apples built in mail that I’ve used forever. But until it’s time to migrate this setup to work I need to run it a bit more and also try to restore a backup. I can’t use the standard backup because thats not included in the open source addition. I also need to read up on the performance of it. Using it at home with 5 users really does not give a good indication on how much processing power needed for 45 users. Theres also two ways of doing the install, one is to install everything on one machine, another to split up the work to several servers. It does seem to be a problem to upgrade a single server to multi-server so I need to get it right from the beginning.

After getting a 3G connection on my new toy, I noticed that connecting to a site when browsing the web could take a long time, but as soon as it gets to the page it’s fast. Typical behavior of a slow DNS server. So after changing my /etc/resolv.conf file to use the OpenDNS servers instead, the increase in speed is incredible!

The eee PC use resolvconfig, so to make the changes permanent you need to go to the directory

sudo pico /etc/resolvconf/resolv.conf.d/base

Add these two lines:

nameserver 208.67.222.222
nameserver 208.67.220.220

to the file and save.

My guess is that Tre has a lot of customers that gets annoyed of the slow speed, and all the provider needs to do is to upgrade their dns servers. Or maybe tip their customer of a better alternative. Go figure…

I just got my Asus eee pc 900 from Taiwan. Here’s a quick tip for other users of tre.se 3G wireless broadband. When connecting the Huwei USB modem, the Asus Mobile Phone tool automatically starts. But the supplied carriers are only for Taiwan. Select Chungwa and select “Others”. Enter bredband.tre.se in the field. Save the settings and your up and running!

Update: There’s actually an option to select tre.se when creating a new connection.

After trying to start VPN Tracker 4 and failing after upgrading to Mac OS X Leopard 10.5 I could no longer contact any servers at the same domain as the network I tried to connect to. To fix this, look inside the /etc/resolver directory, if there is a couple of files called vpn-resolver-#### you have to remove these files to get everything to work again.

There’s a new version 5 of VPN Tracker that supposedly fixes problems with Leopard, but you have to buy an upgrade. I just wish that Apple could make a front end to Racoon. It’s very irritating to have to pay Equinux $80 to get functionality that’s essentially built in the operating system. And I have always hated their way of locking the program to one specific machine serial number.

I just bought a new Mac Mini Core Duo2 as a media player in my bedroom. I connected it an old 23″ Cinema display that I don’t use. First I was a bit annoyed that I needed to use the keyboard and mouse, but then I found Remote Buddy. What a relief! I can now do almost anything with Apples lovely simple remote. I’m going to use it for playing back my CD collection that’s been ripped to a large hardisk. Watching DiVX, DVD, MPG films on it. And watch TV with my EyeTV kit.

So the next step was getting the audio out of the mini. Well, let’s face it, the output quality from line-out isn’t something you can call great. So I’m about to order an Zhaolu DAC 2.5 and mod the crap out of it! I’m thinking of installing a ZapFilter, better clocking etc. I’m then going to use mini-spdif connector to get the digital data out from the mac to the DAC.

Now I just need to get my home built amp finished.

I’ve now been in my HIFI obsession mode for almost half a year. There’s always a new obsession around the corner. Maybe my next one will be photography again? I have these stints of interest for a specific area that is all consuming. Thankfully I have a very understanding wife.

I’m currently working on moving my homebuilt class-D amplifier to a new rack enclosure. So the kitchen is full of PCBs, connectors and tools. But it seems like I’m never going to get this amp finished. I was really annoyed with the amplifier, because I really need a remote for it. So I ordered a kit for a passive motor controlled Alps control. This time I have put in a lot of effort in getting all the wires as short as possible. So the volume control is sitting at the back of the amp and I’ve made a brass rod as an extension.

I also added a notch filter to my ProAc clones. First I was very happy with the sound, but after a couple of weeks, I realized that I got tired of listening to them after just 20 minutes. Well, turns out I had made one of the tweeter filters the wrong way, so now with the notch filter they finally sounds more to my preference. Success!

So finally my new speakers is playing music. And how they play! I got myself a new Class-A amplifier to have something nice to drive them with. At first they sounded a bit short on the bass side, but now after about 20 hours of listening, the bass starts to improve. I’ve never believed in the “burn-in” of speakers, but I have to say I’ve been mistaken.

I invited some friends over for a music listening party. A lot of records and an even larger amount of beer made for a beautiful evening.

At the same time I ordered my new amplifier, I also ordered a new DVD player with DVD-Audio and SACD playing capability. So I rush out to get my hands on a SACD record, but the only one I could find was the slightly overplayed Dark side of the moon by Pink Floyd. But it was a good test record because I have two different mastering versions on cd, so comparing was easy. And to my surprise the CD (actually Flac played through my Squeezebox) sounded better than the SACD one! So I had to check that the player didn’t play the normal cd layer, but no, it played the SACD layer. The singing voices on the SACD sounded muffled compared to the Japanese pressing of the CD. Also the pinpointing of instrument placements in the stereo image was not as good an coherent from the SACD. The player a Pioneer 696 is a low budget player so it could be it. But I’ll crank up the manual and check so I haven’t done something stupid with the settings.

More testing tomorrow…

So I finally decided to go with the Proac Response 2.5 clone speakers. The original speaker costs $4400, but a very good copy or the original is possible to build for around $1000. It uses high quality Scan Speak speaker elements, and I bought them today. My friend Micke is also building a pair at the same time. So now I have four speakers standing in my livingroom. Everything is covered in MDF dust. Thankfully I have a very understanding wife.

So far we have put together the side and top walls. Today we glued the Bituben dampening material to all the walls (except the front baffle) I still feel faint and feel a stinging sensation in my fingers. Next time, gas masks. Anyway, we are moving along in a good pace. Hopefully we will have a pair of working speakers finished this weekend. The plan is to first finish the speakers, but not glue the back end so we can make adjustments to the stuffing and filtering. I also want to try different lengths of the bass reflex tube. Coming along nicely. But I’m still worried about doing the veneering.

Here’s a quick picture of my finished Cyburg Needles speakers. First time I do any wood crafting, and they sound great! Next up, a pair of Jordan Transmission Line speakers.