1. Spotify for my Hi-Fi / 2. SMPS vs Battery

1. Spotify for my Hi-Fi

My family has subscribed to Spotify Premium for a while. The kids love it for its convenience, huge selection, and user friendliness. For me, as Spotify does not offer CD-quality or hi-res music, I have been using it to check out new music or for casual listening on my handphone. 

But, I have this nagging feeling, I was itching to know how Spotify's lossy music files would sound on my Hi-Fi rig (Spotify uses the Ogg Vorbis codec, which is similar to MP3). I know they won't sound close to CD/SACD quality, but if they sounded just ok I'd have even more music to play. 

I decided to experiment. Not sure of the outcome, I resolved to keep things simple, keep the cost down and make use of what I already have. 

I already have a DAC. My TAD-D600 CD//SACD player comes with digital inputs, and I know the quality of its DAC section is formidable. The digital inputs are AES/EBU (XLR) and S/PDIF (coaxial only, no optical). They accept up to 24bit/196kHz. Spotify's bitrate is not even close, so no problem there (gentle reminder to Spotify Premium subscribers - set "music quality" in your Settings to "Very high", that will give you the highest bitrate of 320kb/s). 

Next was how to get the bits into the TAD-D600. I wanted a simple and low cost option. I thought the most straightforward solution was to go through the Bluetooth route, where I could stream the signal wirelessly from my handphone or my notebook PC. Bluetooth's transmission protocol can handle Spotify's 320kb/s bitrate without loss (sure, there are many other higher quality solution than Bluetooth that I could explore of course, that will be for another time).

So, my requirement was to get a Bluetooth receiver sans DAC that would output at least a S/PDIF signal via a RCA jack. The obvious thing was to search online for it. It turned out that there are many choices for Bluetooth with S/PDIF optical output, but one with RCA was not so common. I found one eventually for slightly over RM100 (~USD25) from where else but China. 

The no-name Bluetooth receiver with digital out

The Bluetooth receiver takes a 5v DC power input via a mini USB jack, so any phone charger would suffice. I used one from my iPad. 

For the digital cable I dug up my old van den Hul The First interconnect cable that also doubled up quite well as a digital cable. 

I didn't have a high expectation of the sound quality. I just wanted to be able to listen to music, to explore, via my Hi-Fi rig. With the bar set low, the results surprised me actually. I could not only listen to music but actually enjoy it a lot too. 

The Bluetooth feed going into the coaxial digital input of the TAD-D600 player

From the audiophile's point of view, I can say these from my listening experience with Spotify played via a HiFi rig:

- The sound is relatively warm - so most of the time it is a nice and comfortable listen. Just put on one's music-enjoyment mode and put the sound-analysis mode behind. That is to put it positively. To be more critical, the sound is rolled off at the top though not to the point of making the music sound dark, the lower mid and the bass region is also somewhat blurry and lacking resolution (thus the perception of  warmness in the music). 

- Playing simpler and quieter music is very acceptable and quite enjoyable (folk, vocal accompanied with a few instruments, small ensembles). Not quite so with complex music (such as big symphonies, dynamic sound tracks, or hard rock), and not when one wishes to push the volume higher. The sound would fall apart, getting somewhat disorganized, and rough around the edges when faced with these challenges. It is like there aren't enough "bits" to go around to construct the music.

- Dynamic range and transient attack is somewhat compressed compared to what I am used to from CDs. This is not an entirely bad thing, simpler music would do more than fine, sounding sweet and relaxed.

- There is soundstage and imaging, though on a smaller scale and less sharply done than with CDs, but it is there. Separation and layering are quite acceptable too.  

Here are a few clips of my system playing streams from Spotify. The video recordings were done on an iPhone SE 2020, handheld (so pardon the not-so-stable video), no other equipment was used.

1. Anne-Sophie Mutter and John Williams - "Rey's Theme - From "Star Wars: The Force Awakens" - from the album "Across The Stars". Track 1

2. Mendeleyev, a "The Voice" contestant, doing a cover version of Bob Dylan's "Girl from The North Country"

3. Regina Spektor - "The Call". 

If not for my daughter's Spotify playlist, I would not have discovered this song - this thing is really letting me discover new music already. 

Streaming Spotify is not going to replace my main CD music diet, that is for sure. Some say 320kbit/s is close enough or even similar to CD's sound quality, I respectfully disagree, it is just not so with my own experience, especially when listening at more realistic level. However Spotify has open up a great new dimension for music exploration. I have gone on to buy the CD version of albums that I heard and liked on Spotify. 

After a few days, just like any audiophile, I started to think what tweaks I could try, to see whether the sound quality could be improved upon. 

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2. SMPS vs Battery

I mentioned that I used an iPad charger to supply 5V DC to the Bluetooth receiver right? Just like any other phone charger it is of the SMPS (switch-mode power supply) type. We read a lot in the Hi-Fi press that an SMPS is noisy and an LPS (linear power supply) is better for sound quality anytime. 

But an LPS can be expensive, some go into the 4-figure region, which kinda violates the rule I set for myself - simple and cheap. So my mind turned to battery - don't we also read that battery power supply is quiet and good, even better than LPS in some applications? 

Initially I thought of using a handphone powerbank for this purpose. It worked, but the powerbank shut itself down automatically after a few minutes of use. I think its internal circuit sensed that it was not connected to a handphone that is being charged, though the Bluetooth receiver is actually drawing power from it. 

So I turned to online shopping again. I found a power supply originally meant for bicycle LED light. It takes 4 AA batteries and has a USB output, just the thing for the Bluetooth receiver. Cost? Less than RM20 (~USD5) shipped from China. 

I was a little surprised when I plugged the Bluetooth receiver into the battery power supply. The sound quality did improve, but it was not about the background noise or the sound becoming quieter, which was the effect I expected from battery vs SMPS. 

Rather, the rolled off highs took on a bit more extension and clarity, the lower mid and bass region gained a bit more definition. Dynamic and attack were better, and this opened up the sound further. The roughness and feeling of disorganization with complex music or when played loud was reduced. 

Not night and day differences, but not bad for such a low cost and simple option. 

Not sure how well you can hear these differences from a phone recording. Anyway, here goes, the same music as previously, with the preamp volume set at the same level as before.

4. Anne-Sophie Mutter and John Williams - "Rey's Theme - From "Star Wars: The Force Awakens" - from the album "Across The Stars". Track 1 - Recording 2 with battery power supply on the Bluetooth receiver

With the battery supply on the Bluetooth receiver, there is a bit more shimmering in the violin tone, and greater extension in the higher registers. The sound is a little more dynamic, it holds the listener's attention better. It is more exciting to listen to overall, pay attention to the points where the music shifts gear around 0:31, 1:38 and 2:05.

 

5. Mendeleyev, doing a cover version of Bob Dylan's "Girl from The North Country" - Recording 2 with battery power supply on the Bluetooth receiver 

The strumming on the guitar is more emphatic and has better attack. The guitar is also brought more in line with the vocal, whereas previously the guitar tone is relatively more subdued. Mendeleyev's vocal also shows more nuances. 

 

I am happy with these results and has been exploring new music, though the MP3 level sound quality is nowhere close to CD (but of course). We audiophiles do not know when to leave well enough alone, I started thinking again about what else to do to improve the sound quality from Spotify further. Well, that's for the next write-up.