Audial S4 D/A Converter – King of the TDA1541

The audio world is an interesting hobby to be in. In no other industry could subjective opinions weigh as much or more than objective. And yet, that’s where I often find myself. Sometimes, it’s almost infuriating.

D/A Converters are one of those hotly contested topics within audio. As I’ve pointed out in previous posts, I’m a firm believer in measurements when it comes to DAC’s. But at the same time, I’m also a firm believer in what my ears hear.

Does that mean my reviews could be considered scientifically flawed? Yes. I guess it’s fair to say that any review that brings personal opinion into the matter is flawed. But that’s okay.

Okay. Let’s get to the main course.

Introducing the TDA1541

The Philips TDA1541 can be considered by some to be the precursor to all modern D/A Converters. Introduced in the mid-late 80’s (with production ceasing around 1995), it was revolutionary to the market.

I won’t go into too much detail about the inner workings, because the fine fellows over at DutchAudioClassics already have a great article explaining things.

The major point to make though is that this is not a delta-sigma chip, like everything modern. Nope, it’s tried and true multi-bit. Like all chips back then, it was expensive to produce (at the time) and they ran hot. As such, it’s never been a recommendation to leave them powered 24/7 but instead save that for when you’re doing the actual listening

Old vs New

A question I often asked myself before I heard the Audial S4 for the first time was, “Why do I have any reason to believe that this will sound good if, at its core, is a chip that’s almost 25 years old? This question becomes paramount when we consider that you can buy a top performing dac these days for pennies on the dollar. So, why should I care about this old monolithic dac?

Well, that’s because it still measures great! While I would never consider myself an aficionado, I do know that 16-bit depth music is, for all intents and purposes, audibly indistinguishable from its 24-bit brethren. Even before I read about the science behind this, I already knew it to be true based on self conducted ABX listening. Even with a highly resolving system, I was unable to tell the difference between the same song at these two bit depths. Most of the time at least.

This, strangely enough, works out perfectly for the TDA1541A (and S4 by extension), since its maximum supported bit depth is… drum roll please…. 16 bits. And this is extra nice since the most common form of lossless music is “CD quality”, or 16 bits.

Most of the space is taken up by a quad of toroid transformers. Two used for power supply isolation and deliver, two for signal output isolation.

A word about specifications

I had some time to exchange emails with the mastermind behind the S4, Pedja, and I came away very impressed with his deep knowledge of the old chip and all of its quirks. If you read his blog posts here <insert link>, you’d see that he’s taken the chip to its very limits. Not only that, but he did the research to find which “batches” of chips were the best of the best. Yes, the dedication to his craft is most impressive.

Pedja takes pride in his measurements, but also takes care in bringing out the true “nature” of the 1541 sound signature. The quoted distortion numbers are 0.003% @ -6dBFS, reaching a still impressive .9% @ -60dBFS. If my math is correct, that gets you roughly 90.5 dB of SINAD. That is spot-on with the TDA1541 specifications, so clearly this is wringing out every drop of performance possible.

If we take a look at the output impedance, we see that it’s a wonderfully low 3.5 ohms. Optionally, you can opt for additional transformer coupled outputs that have a 30 ohm output impedance.

Now, this is my favorite part. At the time of ordering, you can specify if you want support for the 384 kHz sample rate. This is especially nice, because it allows the user to decide what’s more important. Better measurements (like jitter and such), or support for a higher bit-rate. Personally, I chose measurements and so stuck with 192 kHz being the max sample rate.

Simple back-end hides the sophisticated inner-workings

Delivery and Setup

Communication from Pedja as wonderful as he made sure to keep me notified of progress on my DAC. Shipping was roughly 4-5 days to the USA, and another day or two my doorstep. As you’d expect from any top-end product, it was packed extremely well – there was no chance of damage during shipping.

I set it up in my reference system, consisting of a Rega Osiris driving Rega RS10 loudspeakers. This system is truly capable of resolving different components before it, so it seemed the perfect companion to this top-tier DAC.

On the streaming side, I use Roon connected directly to the DAC via USB.

Sound

Before talking about the sound of a DAC, I feel the need to explain (more here) my internal conflict about DAC transparency versus my feelings on how it sounds. As an engineer, I fully acknowledge and believe in measurements. In fact, I regularly seek out measurements to enhance gear that I review. My main conflict, though, also comes from said measurements. They tell me that this S4 should be sufficiently “transparent”, or rather it shouldn’t make a single difference to the sound of the speakers. My experiences though tend to tell a different story. What do I believe? The measurements or my ears? While I believe this to be one of the best parts of being in the audio hobby, it’s definitely a point of contention for some.

The S4 has ten separate power supplies, resulting in the purest TDA1541 performance available on the planet

Now back to the review.

My defacto album for starting on a new DAC is almost always “The Courage of Others” by Midlake. Their hometown is just down the street from me, so it’s fair to say I’ve known their sound for a long time. Their sophomore album not only has a little bit of everything, but it’s well recorded and mastered.

The S4 here did a splendid job from beginning to end. The magic of the TDA1541 was not lost, but instead brought out in its purest form. In particular, I found myself lost in the vocals, much more-so than any other DAC I’ve ever had in my system. Instrument separation was good, I had no problems closing my eyes and “pointing” to where the sounds were coming from. As sounds bounced between the two speakers, I was easily able to follow. As the going got tough with more dynamic and complex music, the S4 kept on going without showing a hint of having trouble.

Coming back to the vocals, I consistently see this as a strong point of the TDA1541. I’m not entirely sure what it is, but it imparts a wonderful bit of magic on the vocals. Its performance there is completely bewildering considering the measurements that would say otherwise.

If I had to be nit-picky about the performance, it would be entirely based on the bit-depth limitation. While I myself have a hard time consistently telling the difference between 16 and 24 bit, I know some people will be less than enthusiastic. I didn’t find it a shortcoming in my listening sessions, but instead found it re-assuring in regards to the long-term stability of 16-bit content.

In Conclusion

In short, the Audial S4 is TDA1541 perfection in a box. I have listened to my fair share of DAC’s using this chip, but this is by far the best. Pedja flexes his engineering muscles by delivering one of the best experiences I’ve ever had the pleasure of listening to.

For anyone that is hesitant about a DAC that’s a blast-from-the-past, especially when modern offerings with excellent measurements can be had for far less, fret not! This S4 is the real deal. It proves that a two decade old design can stand up to modern times and proves, yet again, that it’s not the chip, but the implementation that matters.

If you don’t mind parting ways with your wallet, you can find the absolutely splendid S4 here.

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