Jacken's Blog

Last time I ordered some speaker elements from Germany I ordered some extra Tang Band W8-740C subwoofer elements for a later build. I’ve been oogling this design to go with my home-built ProAc 2.5 clones. Micke, a friend will make the boxes for me, provided I sent him the drawings. What an exellent excuse to try to learn Solidworks. Amazing program. I have designed my own version of the venerable GainClone amplifier with a beefed up power supply and will use two subwoofers in stereo. Nice to not have to build the boxes. Last time when I built the clones the apartment was filled with MDF dust for months.

Part two of this series is now up. Read on how to install a better clock.

So I bought this Pioneer PD S-505 for $40 to test how good audio quality I’m able to squeeze out by modifying it. But I’t wil not be just the standard subjective judgement of improvement but also measurements. Back in 2000 you had to pay about $400 for it. It uses the stable platter which means you have to put the CD in upside down. So let’s get going.

The steps I planned is the following:

• Remove the mute transistors.
• Replace the output opamp
• Remove headphone output
• Replace the clock with a GD-Audio clock
• Improve the regulated voltage feeds to the DAC and opamp
• Improve the power supply
• Add a separate regulated power supply for the clock and opamp

But first we need the schematic of the player, so download the Pioneer PD-S505 schematic here.

Ok, lets look at some stuff we need to do. First we have to remove the mute transistors. Less stuff in the audio path equals better sound. The transistors is just there to make the measurements look better for reviews. So they have to go.

Click for larger image

So transistors Q403, Q404, Q453 and Q454 is removed. Desolder och just clip the pins (carefully) with a wire cutter.

Next step, time to desolder the opamp which is a rather old opamp (NE5532). Desolder the opamp IC405 and solder in a socket for easy testing with different opamps. I settled on LM4562 at first.

Remove the heaphone opamp if you don’t going to use it. It’s better to buy an external headphone amplifier like V-CAN Tube Headphone Amplifier or better.

That’s about it for today. Next installment, upgrade the clock to improve jitter numbers…

On to part two on how to add a better clock to your PIONEER PD S-505

There’s a lot of articles on the net about modding and enhancing the sound quality of your audio equipment by replacing components etc. But you never see measurements to backup their claims. Well, I’ve been busy the last two days taking a ten year old middle range CD player and trying to make it to sound really good. But I also have done measurements before and after doing the mod (within reason) and so far it actually confirms that modding really works (if done right). Now, let’s face it, the best measured equipment isn’t necessarily the one that sounds the best, but still, it’s interesting to see what kind of effects different modifications have.My best sounding DAC does not measure as well as some other ones I have. And I have started to get quite the collection.

Will be back with a writeup and test diagrams when I’m finished…

I don’t think they used used ReplayGain.

The people who adds music type tagging at Spotify must be on crack. You select “Alternative, Punk, Hard Rock” and sometimes you get like pop songs for 14 year olds. Very irritating. I know that people really mark up some tags weird, but this is ridiculous.

I’m more and more impressed with EMU0404. They released the EMU 0404 USB driver code for Macintosh. This is a smart move. I once called them about a problem I had with the input pots being to sensitive. The tech support guy told me they actually had to use cheaper parts to be able to use better sounding parts. My god! Honesty! You don’t get that too often when calling a company about their products.

After using Spotify for a couple of days, I must say that they almost nailed it. And I have never seen as much entusiasm about a new service among people of so different age groups. The Mac client is really nice (and fast!) This is something the music business should have come up with a long time ago. I think I bought about five songs on iTunes total. I like the idea of “owning” my music, or at least own the piece of plastic it comes on. But the chear joy of being able to just search and ad a shitload of music and start listening is exhilarating. But I have a couple of gripes…

Hopefully they will increase the bitrate. There is a market for people that want the highest possible quality and are prepared to pay for it. Here’s a possibility to actually get better quality than CD without having to resort to half-assed attempts like SACD. Yeah, I know you need a lot of bandwidth, but I live in Sweden and have had 100mbit connection for years.

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.