Another Multibit DAC, TDA1541 Inside Sony CDP-750

The journey to experience the great multibit DAC continue.

Previously I've talked about PCM1702 and PCM1704 which they are great high performance DAC. Then again, the next DAC to be evaluate by myself is no other than the famous TDA1541 DAC. This is the only high performance vintage multibit DAC from Philips. Each IC is dual channel 16 bit stereo DAC, which is make the circuit simple in my opinion. Unlike PCM1702 or PCM1704 which they are single channel DAC per IC, this is means when using this TDA1541 in stereo only require one IC to do both channel digital conversion.

In the TDA1541 datasheet explained that this DAC configuration is using dynamic element matching (DEM) for current dividing. This configuration is a masterpiece in DAC history which is totally different to the resistor ladder (R2R) DAC. This DEM is very complex inside and high cost to built. No wonder it is already obsolete for many years ago.

Obtaining TDA1541 chip alone now days is not an easy task. It is almost impossible to get the brand new IC as well. The easy way is having it from the vintage CD player like I did right now. It is a Sony CD player CDP-750 that I will review in this post. It cost me US$100 and I think it is still a great deal.

Inside this CDP-750 is lying the TDA1541A. The "A" mark is the newer version of TDA1541 which manufactured later after the non "A". This "A" is an upgrade version and better sound quality than the "non-A" version.

The layout of the TDA1541 is naturally having many decoupling capacitors on each side of the IC. This is for the active divider like I said earlier. Sadly, because the Sony CDP-750 here is actually a budget CD player, so no wonder all the capacitor using here is also in economical grade.

The analog output from the vintage DAC like this TDA1541 should go to the current to voltage converter circuit. Then it should going to the low pass filter circuit to reduce the high-frequency noise from the digital conversion. Again, since this Sony CDP-750 is a budget CD player, it is only have 1 op-amps to do all the jobs for both channel. Is simple means sound better? In most cases it is not.

I looking more closely on each components in this CD player and quite happy that this unit using Nichicon Muse for DC filter capacitor. This green color capacitor is very well known for it best performance and easily found in vintage high performance audio unit like this. Next to the op-amp is Elna Duorex for signal coupling capacitor. Good choice for smoother audio response.

I do simple cleaning to this dusty vintage CD player unit.

I lift up the mainboard which is quite large, almost take half of entire chassis. This is because the PCB is only a dual layer board and mostly all of the components are through hole components which require extra space.

The power transformer is so tiny for powering a lot of task inside this CD player. Not enough current in my opinion for the better sound.

I put this Sony CDP-750 in my system and playing few my favorite CD albums. My initial sound review for this Sony CDP-750 is not having spectacular sound. At least not as I expected from what I heard about this famous TDA1541 DAC.

It is just an ordinary sound quality in my opinion . The frequency response overall flat and smooth, but not much detail sound. The mid-range is more forward and warm which I am quite enjoying the sound from this CD player because it is far from ear fatigue for the long listening session.

Again, I still think this CD player is tweakable to get better sound quality, or at least the DAC TDA1541A inside is have lot potential if I upgrading the components around it.

So, I did small upgrade in the analog stage first. 

The op-amp used by Sony is low quality 5218. This op-amp is need to replace with the better performance op-amp.

I put 8 pin socket to for this op-amp swap. This socket give me accessibility for experimenting different op-amps IC and how each op-amp effect to the sound quality.

I testing from the NE5532 and the LT1361, but I end up with the OP275 op-amp. In my opinion this OP275 give a better sound. It is more open on top frequency which lead to better sound-stage and more dynamic sound.

I also replaced the signal capacitor with Elna Silmic II. It makes sound more smooth on overall frequency response.

So this Sony CDP-750 with TDA1541A DAC chip is a budget CD player. No doubt it is not push the DAC to the full potential. Many limitation especially in the noisy power supply, yet the under rating current are not enough to push the juice from this great DAC. The analog stage is too simple and lots can be improve in this unit for sure.

The journey for this TDA1541 DAC still continue and please stay tune for the next post.

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