The importance of signal-to-noise ratio (SNR) to audio quality

[GyroTuner]

It seems if a recording of the the same source material was played through several mediums (with the same amp and speakers), it would sound best on the medium where the signal-to-noise ratio (SNR) is the highest. After all, the signal would be the music, and the noise would be everything else. If that simple analogy is true, it follows that a high SNR would correlate with high quality sound reproduction.

By looking at specs of gear that I've had, have, or heard, I came up with these approximate SNR figures for turntables, cassette decks, tuners, and CD players. I didn't look at DACs or other devices used for streaming, just the old school stuff. Nor did I look at R-2-R decks.

Cassette Decks

It seems 75 dB SNR is pretty good with noise reduction (Denon DN-790R, some JVCs, maybe some Naks but the Dragon is only 72 dB) so let's use 75 dB for cassette top end.

Turntables

I've heard TTs that get to 80 dB, but I don't think any of the highly lauded Technics tables did. Best I've owned was 78 dB. Let's use 80 dB for TT top end.

Tuners

A lot of tuners are in the 60 to 80 db range, but many go 90 db or higher, including several Yamahas (T-2, T-85, TX-950, etc.). Obviously you need a strong signal and/or a good antenna. But use 90 dB SNR as tuner top end.

CD Players

Everything but the early players go over 100 dB SNR. I've had several spec'ed at 115 dB or higher (Sony CDP-X229ES, and some Denon DVD/SACD players). So lets use 115 dB SNR for CD players.

The ranking then for sound quality of good gear is CD #1 (115 dB), FM Stereo Tuner #2 (90 dB), Turntable #3 (80 dB), Cassette #4 (75 dB). That order sounds right to me in terms of sound quality, although I like the sound of a tape recorded on a good deck, so I might flip #3 and #4.

What do you think?

 

[rothwellaudio]

What do you think?

Having low noise is a good thing, but it doesn't really have much correlation with good sound.

 

[Hyperion]

Having low noise is a good thing, but it doesn't really have much correlation with good sound.

I think it is more to do with the ability of the transducers involved to first extract, and then reproduce, the sound involved.

 

[nj pheonix]

yes
Its sort of been covered.
Specs (whether they are distortion, THD, IMD, frequency response, S/N ratio ) are useful tools to a degree, but don't tell the whole story.
I wouldn't get too caught up in it.
You're better off finding what sounds best to you.

One other associated thought.
On any given recording, the quality of the production can vary. That is, you may find a better sounding cd than record or tape. Or the opposite.
Even 2 different pressings of the same lp may not be equal.
Therefore its difficult to do an apples to apples comparison of any.
Clear as mud, right?

 

[62caddy]

Keep in mind S/N spec for turntables is for mechanical vibration only and does not account for the noise generated by the friction of the stylus against the record which is many times higher.

Of course, equipment specs have nothing to do with the noise present in the recorded material itself which I have found to be higher far more often than not.

As far as I'm concerned, S/N specs much higher than 80 dB don't contribute significantly to performance and only on the quietest of passages at that. Point in fact, I've recently put a unit back in rotation that had been in semi-retirement which has the lowest S/N specs of everything in my arsenal that outperforms the multiple combinations of far better equipment "on paper" and far more expensive. As always, YMMV.

 

[PPstereo]

When I read the thread title and then saw break downs of tuners, turntables, tape decks it caught me by surprise.

Only because those seem to have reached their peaks in performance for a while now. Also they seem to be limited to their medium in terms of performance. But thats not to say they cant sound good.

Ive been looking at S/N specs in AD DA boxes, Pre amps, Power amps, Active Xovers, EQs. All depends on what one is playing with.

Being completely honest Ive wondered how much a difference these devices impart on the quality of sound in a home stereo. I suspect a big determining factor is how efficient and or revealing ones speakers are???

If its a simple pre amp / power amp setup, I suspect the S/N of the preamp COULD be revealing in terms of sound quality. The power amp to a lesser extent. Take all I say with some salt...

Look at the importance of S/N in mic preamps, mixers, compressor limiters, DA AD so on. These days loads of folks are into podcasts and low budget film production so on. Nowadays you can find forum posts of folks involved in these scenes and talking about consumer / pro sumer gear and describing their experiences and bringing up these specs ALLOT. Far more than ever seen on a wide scale prior. I find these posts interesting.

In a nut shell I think S/N Distortion specs are important. But in the home audio scene I dont think its simple to draw comparisons and assumptions. Theres allot that goes into the chain and what a person hears after the fact. I too am interested to hear what other folks have experienced and think about these matters.

 

[GyroTuner]

Having low noise is a good thing, but it doesn't really have much correlation with good sound.

Your opinion is held by many, so the obvious next question is, why doesn't it correlate?

If you believe that SNR doesn't correlate to good sound, it suggests that you feel that the presence of noise makes music sound better.

An analogy would be the taste of meat. I would readily admit, for example, that a fatty piece of meat has more flavor than a lean piece of meat. That suggests I like the taste of the fat, and not just the taste of the meat.

It seems that those who feel a high SNR doesn't correlate to good sound should be able to readily admit that adding noise to music makes it sound better, and perfect sound reproduction is not what they are looking for.

 

[GyroTuner]

I think it is more to do with the ability of the transducers involved to first extract, and then reproduce, the sound involved.

I agree, but that statement is pretty broad. One of the most important specs of a transducer is SNR, and it's already factored into the specs for the source devices mentioned above (CD players, tape decks, turntables).

For example, the sensor in a CD player, the playback head in a tape deck, and the phono cartridge on a turntable are all transducers. The specs already indicate that a phono cartridge is a noisier transducer than a CD sensor.

Of course, the microphones that made the original recording are the most important transducers of all. For this simple analogy, assume that the sound picked up by the microphones is broadcast live over the air for FM radio, and is simultaneously used to make the master recording for the CD, cassette, and vinyl. Does the SNR of the playback device matter then, when it comes to sound quality?

 

[rothwellaudio]

Your opinion is held by many, so the obvious next question is, why doesn't it correlate?

Noise can be transparent enough to listen through. Yes, it has a masking effect which can obscure low level details, but a good recording with some added noise is still a good recording. A bad recording with no noise is still a bad recording. The presence or absence of noise isn't really what distinguishes a good recording from a bad one.
I'd rather have low distortion with some noise rather than high distortion with no noise.

If you believe that SNR doesn't correlate to good sound, it suggests that you feel that the presence of noise makes music sound better.

That's quite a leap. No, I don't feel that.

 

[62caddy]

In some ways, it could be argued that ultra quiet reproduction is antithetical to a live performance where some level of background noise is always present.

I suspect this is a major reason why vinyl continues to enjoy the popularity (and resurgance) it has. Paul Klipsch once even remarked about this, not caring for modern digital formats, saying (to paraphrase) "It's too dry, so 'sterile' it doesn't sound natural." - with which I'm in substantial agreement. Of course, CDs/digital do offer significant other advantages over vinyl in other areas.

In any case, as far phono stages are concerned, S/N spec is the least of one's worries.

 

[PPstereo]

In some ways, it could be argued that ultra quiet reproduction is antithetical to a live performance where some level of background noise is always present.

I suspect this is a major reason why vinyl continues to enjoy the popularity (and resurgance) it has. Paul Klipsch once even remarked about this, not caring for modern digital formats, saying (to paraphrase) "It's too dry, so 'sterile' it doesn't sound natural." - with which I'm in substantial agreement. Of course, CDs/digital do offer significant other advantages over vinyl in other areas.

In any case, as far phono stages are concerned, S/N spec is the least of one's worries.

Im curious what you think of this theory.

I cant help but think much of the anti digital sentiment of the 80s and mid to early 90s was born out of it being a transitional era. Mixes and masters werent always done with the end product being an LP / Tape vs CD. Also folks were doing allot of learning in terms of how to handle and tackle this new technology. It presented allot of new challenges and ways of things getting done. This isnt to say everything was bad that was put out on digital. There has always been hits and misses in the end product put on either medium back then and today. I simply feel competent production companies likely have a better hold of dealing with digital now than before.

Great recordings and issues have been made both with digital and analog means then and now. And can still be done. I dont see one or the other as better or lesser at this point in time.

 

[ic-racer]

I think you are looking at the wrong end of the chain. You need to look at recording venues, noise gates, recording preamps, mics, crosstalk, instrument isolation, 'snake' length, etc.

 

[62caddy]

Great recordings and issues have been made both with digital and analog means then and now. And can still be done. I dont see one or the other as better or lesser at this point in time.

I couldn't agree more!

Some of the finest recordings I've ever heard have some of the highest levels of audible noise and produced decades before the digital era. But the recording setup, mixing, mastering techniques (or whatever else) was done so incredibly well that it completely overshadows whatever noise level deficiencies present in the material, raising the net level of enjoyment far higher when taken as a whole.

Unfortunately there are no "specifications" for the recording quality itself, aside of basic technical specs used for equipment itself. This is why I am constantly amused by the endless pursuit of ever infinitesimal "improvements on paper" which in my experience contribute very little to the overall listening enjoyment and satisfaction, if it all.

 

[PPstereo]

I couldn't agree more!

Some of the finest recordings I've ever heard have some of the highest levels of audible noise and produced decades before the digital era. But the recording setup, mixing, mastering techniques (or whatever else) was done so incredibly well that it completely overshadows whatever noise level deficiencies present in the material, raising the net level of enjoyment far higher when taken as a whole.

Unfortunately there are no "specifications" for the recording quality itself, aside of basic technical specs used for equipment itself. This is why I am constantly amused by the endless pursuit of ever infinitesimal "improvements on paper" which in my experience contribute very little to the overall listening enjoyment and satisfaction, if it all.

Yep I hear ya on all this.

Spit balling another idea. And this assumes one has a VERY revealing stereo setup. Headphones is another real contender in this which I think largely gets overlooked here at AK. Ive heard and owned ALLOT of super revealing headphone rigs.

If left purely in the digital realm I can see a case where SN and distortions becomes more important. If there is a vanishing noise floor, the signal chain is kept top notch star to finish, I can see a case where mixing in yesteryear equipment might pose a threat to the end product. However I can also see the merit to older gear used in the initial instrument recording to impose a certain sound to things. Really just focused on the mixing / mastering areas. When theres an absence of the limitations / characteristic of vintage analog gear it could work to the advantage of modern technologies.

Again not saying this to be dismissive of vintage recordings and gear. Im simply saying I can see the advantage of doing things purely in one realm over another.

 

[MudSlideSlim]

Having low noise is a good thing, but it doesn't really have much correlation with good sound.

In another century (the last one) I resisted trying LOMC cartridges because the S/N stats were so much lower for MC than MM inputs. This was one of my lessons in not always relining on stats. I'm not saying are useless I still use them and want them published. If I'm choosing between two phono preamps
the one with the lower S/N

The sound of any TT system generally has a lower SN ratio then most DAC systems but yet TT have have a very loyal following on AK. Why? Because of the quality of the sound

For me the type of the noise in the ratio is also important, the sound of waterfall white noise rarely bothers me but just the slightest bit of 60 Hz hum can drive me crazy.

Michael

 

[SaSi]

S/N ratio is just part of the specs correlating to high quality sound. Not the only. And not the most important.
But you have your scores wrong.

A good cassette deck (since you are accepting noise reduction) can give you 90-95dB with dBx
A typical turntable with a good LP in pristine condition and a fine stylus can go to 55-60dB in my experience. That's the noise level of the between the tracks silent grooves.
An FM stereo tuner, even with a good antenna, can achieve 60-65dB at most.
And a CD player, playing CDs, recorded at 16bits depth, is in the 95-98dB range.

With these scores, a high end cassette deck will rival a CD and a fine tuner with good antenna and a strong signal will rival a turntable but not much more.

But then you need to add THD, frequency response at least to the scorecards.
With frequency response, an FM broadcast is limited to 15kHz (IIRC) and a cassette deck will better that by a little. A turntable has the chance to beat everything in the list but that will become theoretical beyond 18-19kHz for most of us.
With THD, the tuner and cassette deck are possibly comparable, although some cassette decks perform better. The CD is the clear winner here.

And then, there's personal taste. Some hate clicks and pops that are present in many records and I personally hate interference noise in most FM broadcasts. A cassette can't be better than the medium of the original content recorded on cassette although many like the bass bump effect (a maladie) it usually has. And although the CD is the clear winner by specs, many hate the harsh sound of the DACs (I personally don't understand how the sound can be harsh and not get caught by THD measurements but will agree that I sometimes catch myself feeling tired of listening to some CD players).

So, to summarize, S/N ratio is a score. So is THD. And so is frequency response. They all need to be better than a threshold to not be critically bad. A 40dB S/N ratio will be audible and annoying. A 10% THD is unbearable, especially if it's odd harmonics. A frequency response to 5kHz sounds like a telephone. If a medium / player exceeds these (or any other preferred) thresholds, it becomes acceptable. If all relevant scores get even better, playback becomes even better. But I suspect that from there, personal taste kicks in and makes numbers irrelevant.

 

[toddalin]

I don't care how good a piece of equipment is... If I can hear audible hiss or hum, forget it.

This is the case with several pieces of "professional" gear, eqs, etc.

BTW, I didn't see it mentioned but there can be a big difference between S/N at rated power and S/N at 1 watt, both measures of which are commonly used.

 

[toddalin]

Sound is a funny thing, not least because it is only partly about soundwaves. It's also about biology and psychoclogy. For insance, when I first bought a CD-player in the 80's, I couldn't stand the sibilance. So, I went back to listening to LP:s, but lo, now I could here sibilance there too. I just hadn't noticed it before.

There are differences in CD players. I have a Yamaha S-2300 Universal and an Oppo 95 Universal and the Oppo is much smoother. When I first got it, I thought the highs lacked..., compared to the Yamaha. But the Yamaha now sound boosted in the highs and they are more "brittle/grainy" relative to the Oppo.

Thing is, I don't think that "grain" is considered in the S/N ratio.

 

[spicer]

With most any amplifier having a s/n ratio exceeding that of most media, watts aside, or even same, yet some amps sound considerably better than others... have better sound quality. If that is true, and it's true in my experience, than it suggests questions for or about s/n ratio and what exactly is being left out of the measurement related to sound quality. I mean, it is the topology of the amplifier... heard many amps with very low distortion measurement, high s/n ratio that simply to do not sound good, and I mean characteristically, not with a particular or certain types of speakers. The sound quality is not necessarily represented in the s/n ratio or distortion measurements. It's somewhere in the dynamic performance of the amp... phase relationship between frequencies under rapidly changing conditions, impedance between stages, driver and output stage coupling... things affected by the topology and circuit design not represented by static measurements.

 

[vonclod]

SNR to me, is more about speaker selection, running very efficient speaks, the lowest SNR is desirable..particularly the amps SNR.