Hello Everyone,
This is a review and detailed measurements of the Teac VRDS-20 stereo CD player.
View attachment 393567
I already mentioned multiple times that I’m into older CD players (like the
Marantz CD-73), this is one more proof.
Teac VRDS-20 - Presentation
This CD player made me dream when I was much younger. It was way out of my league at the time.
It was released in 1993 at a very high price, featuring a unique look in the Teac range, with the 4 adjustable pillars at each corner. It was available in black and gold.
It plays only the initial silver disc, no SACD, no USB input, no, no Bluetooth either, sorry
No digital inputs, too bad, Teac could have made an effort here.
The elements of interest are:
- The VRDS (Vibration-free Rigid Disc-clamping System) mechanism of course! This is the version CMK-3.2 with resin (or polymer, I’m not sure) molded “bridge” over the (aluminum) clamper that is supposed to reduce vibrations of the disc when rotating. Below that is the Sony KSS-151A magnetic head, one of the most reliable, fastest head. And 30 years later, it runs flawlessly.
- D/A architecture (thanks to @AnalogSteph for the deep dive): A double mono conversion via two stereo Philips TDA1547 converter which was the first and high-end 1bit conversion of Philips, at the time. It is seconded by the Philips noise shaping (SAA7350) which is necessary for rejection of the noise generated by the decimation to 1bit. Preceding the SAA7350 is the oversampling and filtering function provided by an NPC SM5840 that runs at 8 times. If the SAA7350 could be used to convert directly, as it includes a 1bit DAC too, the couple SAA7350 + TDA1547 was the high-end conversion offer of Philips, and it was called DAC7.
- Incredible mechanical construction: it does not stop at the VRDS as the entire device is built like crazy, with attention to every detail (I’ll come back to that later). As such it looks like an “Esoteric” before the time, and before it became a brand as such, outside of Japan.
Back panel has RCA and XLR analog outputs. We also find standard digital coax and Toslink, with a less standard St optical out:
View attachment 393568
There’s a window on the top of the player, the VRDS mech had to be seen.
View attachment 393569
As with many of these old players, and despite the complex and heavy VRDS, it is super-fast to skip one or multiple tracks back and forth (thanks to the Sony KSS-151A). With the big buttons on the front, very easy to read, it’s only a pleasure to use.
Before we go to measurements, let me guide you to the inside, because it’s worth a detour.
Below the aluminum top, we find … a second steel cover, and after removal of side panels with the 4 pillars, we find … a third copper cover. Really?
View attachment 393570
When finally inside, we are faced with something NASA-class built, except that it’s too heavy to go into a satellite
View attachment 393571
The player is divided into 4 sections:
- VRDS mech in the middle
- Power supply behind the drive
- Servo card and digital out on the right
- D/A conversion (with oversampling and noise shaping ICs) and analog out on the left
This is very neat, and attention to details goes as far as adding a copper pad on critical components as you can see above on the two TDA1547. I guess this is again NASA-habit to protect 0s and 1s from spatial radiations which could change their status?
I will spare you more details as I guess you want to know how this nuclear plant measures. But note that below the beautiful VRDS bridge (not decorum in this player, as it was with the T1 transport for instance), the aluminum clamp is so heavy that it requires a small disc brake with a caliper and respective pad. Why make it simple?
Teac VRDS-20 - Measurements (Analog out)
From now on, I will be consistent with my measurements as I described them on the
Onkyo C-733 review. So over time, this will help comparing the devices I reviewed.
The Teac VRDS-20 outputs 1.9Vrsm from its RCA outputs and 3dB more from XLR (2.62Vrms). RCA and XLR showed the same performances, only a little more power supply noise from RCA.
Here you go with the standard 1kHz sine @0dBFS (dithered) from my test CD (XLR out):
View attachment 393573
Both channels are represented but only one gets evaluated in that window. Left channel is a little less performing (THD loses 4dB). That kind of difference happens especially when two different DACs running in mono mode are used.
THD sits at -104dB and so will clear CD Audio content. SINAD and ENOB are limited by the dithered noise of the test CD (roughly -93dB).
XLR and RCA are very close in performance, except that RCA has more power supply related noise.
It is to note that distortion stays very low even when digital signal goes down, which was not always the case with old DACs. As seen below, THD is still at -105dB at -6dBFS:
View attachment 393574
This is an overlay of left and right channels, from RCA and XLR out, so you get the best (XLR right) and the worse (RCA Left) at once. THD is well below -100dB which is very good for the time. Overall, the trace shows some “grass” of harmonic and non-harmonic low level distortions, but that’s not a surprise for a 1bit DAC and is well contained considering this was the first iteration of Philips (more than 30 years ago).
The datasheet of the TDA1547 specifies a best case THD of -88dB at -20dBFS (worst case is -84dB). And -88dB THD is very precisely what I get from the Teac. In other words, best possible implementation of that DAC here, thanks to mono mode too.
You probably already noticed, there is a little power supply leakage (50Hz and harmonics) which, even if without negative consequences at this very low level, I would have preferred not to see (1kHz @0dBFS, XLR out, left and right channels):
View attachment 393575
That said, the player being 30 years old could explain this.
Now, let's have a look at the bandwidth:
View attachment 393576
There’s a 0.1dB channel mismatch, and the service guide says it’s a pass up to 0.5dB, so I shall be very happy
We can see the oversampling filter ringing at the end of the frequency range. This is typical of oversampling filters lacking some power. And so, staying with the oversampling filter effect, let's have a look at wide band (up to 48kHz):
View attachment 393578
This an overlay of periodic white noise (red trace) and dual tones (18kHz and 20kHz). It shows the ringing of the filter. Out of band attenuation is only 60db (see the blue spikes of images from the test tones at 26.1kHz and 24.1kHz respectively). To be honest, I was disappointed to see that, even if better performing, it is similar to previous 4x oversampling filters of the era, especially the one of Philips. But I’ve seen better 8x filters of the same time both on ripple and attenuation.
So, was it intentional from Teac?
If one was to attribute a sound characteristic to such oversampling filters, and if it was believed to be the reason why the previous Philips converter TDA1541 and its associated filter SAA7220 were praised, then it could have been intentional. It is important to remember that the DAC is only the final part of the digital journey before reaching our amplifiers and speakers. DAC filters work well with matching ADC filters, and are ideal in that case.
At the time, the CD catalogue was already significant, most of it being built from Analog maters. The ADC digital filtering in use, to reject out of audio band frequencies, lacked power too and were likely to match what you see above (my guess). That’s the reason why I (like to) think this was intentional from Teac. Let me dream
It could very well be a (less poetic) technical partnership to satisfy too, and so many other reasons.
Let's continue with the multitone test (1/20 decade):
View attachment 393579
I am sorry I forgot to adjust the FFT length which explains the increased noise floor of the trace at low frequencies. I’ll redo it when time allows. This is the “worst” left channel shown here (XLR and RCA), and we see that resolution is enough for CDA (minimum 16bits), except that spike at 150Hz from RCA. So nothing to worry about.
The Teac VRDS-20 showed reasonable amount of Jitter:
View attachment 393581
The red trace is what is recorded on the test CD (From the digital outputs), it can't be better. The blue trace is from the XLR ouput. We have again low level noise not of real concern (power supply related though).
Let’s have a look at an undithered 1kHz sine at -90.31dBFS. With 16bits, the signal should appear (on a scope) as the 3DC levels of the sign magnitude smallest digital signal:
View attachment 393583
This is a relatively good trace, and it’s disturbed by the low-level noise that I mentioned before.
Starting with this review, and on your request + support (more information
here), I am adding an "intersample-overs" test. It intends to identify if the oversampling filter has sufficient headroom to process near clipping signals. Indeed, and because of the oversampling, there might be interpolated data that go above 0dBFS and would saturate (clip) the DAC and therefore the output. This this effect is highlighted with the measurements below, and revealed through THD+N measurements up to 96kHz:
Intersample-overs tests
Bandwidth of the THD+N measurements is 20Hz - 96kHz | 5512.5 Hz sine,
Peak = +0.69dBFS | 7350 Hz sine,
Peak = +1.25dBFS | 11025 Hz sine,
Peak = +3.0dBFS |
| Teac VRDS-20 | -30.7dB | -26.6dB | -17.6dB |
| Yamaha CD-1 (Non-Oversampling CD Player) | -79.6dB | -35.3dB | -78.1dB |
| Onkyo C-733 | -79.8dB | -29.4dB | -21.2dB |
| Denon DCD-900NE | -34.2dB | -30.4dB | -19.1dB |
I kept some references in the table and will keep the same for other reviews, so you can quickly compare. The results of the Teac VRDS-20 mean the oversampling filter generates clipped signal when presented with specific sine at 0dBFS, so it has no headroom to process them. The Yamaha CD-1 shines here because it's old enough not to have an oversampling filter.
And here are some other measurements:
- SNR : 96.4dB (1kHz @-60dBFS without dither)
- Crosstalk : -116dB (@1kHz)
- IMD AES : -94.2dB (18kHz+20kHz 1:1 @-5dBFS)
These are very good results for the time.
What else? Oh yes, of course, one of my favorite measurements, the THD vs Frequency at -12dBFS (THD only, over the first 5 harmonics). I already commented that I use it especially to test older R2R architectures as it shows their difficulty to be linear below full scale. Below are measurements of the right channel, overlaid with the previously tested (and near best-in-class)
Denon DCD-900NE CD Player:
View attachment 393584
Very good! This was the real benefit of going 1bit as it improves linearity (compared to R2R DACs), at the expense of noise created (but that can be pushed beyond 20kHz with noise shaping).
All of these are very good measurements for the time, but I have to mention that JVC, with its proprietary DAC, did better (see the review of the
JVC XL-Z335), even in low cost players.
Teac VRDS-20 - Measurements (Digital out)
Are you surprised if I tell you that I did not find any flaws in its digital output? I’ll keep it simple, with what I believe to be the most representative measurement of the digital output quality, and that is a 1kHz sine at -90.31dBFS which shows the 3DC levels of the smallest digital signal in 16bits sign magnitude representation:
View attachment 393585
Because this signal forces a regular change of all bits (due to 2’s complement representation around 0), any deviation from the binary content would immediately show here, with such a “fragile” signal. But if you think there are better ways to check the digital output, let me know.
Other than that, this is the standard dashboard of the 1kHz sine @0dBFS (no averaging because I did this measurement way before I decided to go for 32 averages, but it does not change anything here since there's no distortion):
View attachment 393589
This is what is recorded on the CD, so that is perfect digital out, as I see it.
Conclusion
This player and a few others made the “VRDS legend”, and today Esoteric and Teac continue to leverage this legacy. I could not find a mechanical advantage to all of this, and no issue as well. This is completely over-engineered, and I guess those who worked on this player had a lot of fun (I would have had).
No doubt this player knows how to respect what's on a CD. It is also a delight to use, a pleasure even before pressing the play button (which I won’t miss even without my glasses, thanks so much Teac!).
With an external modern DAC, it would be a perfect transport, as I hoped to be able to report. And it delivers.
I hope you enjoyed the review as much as I enjoyed writing it. Let me know how to improve and if you have questions. I can run additional measurements, if you want, but since this player joined me in the main listening room, you’ll have to be patient enough for me to extract it from its current location.
Thank you.
--------
Flo
