The Pursuit of High Fidelity

[Bob Rapoport]

The pursuit of high fidelity audio has been a long and fascinating journey. Since the 1970s, audiophiles have sought to achieve hearing a one-to-one copy of the original master recording at home, with the same bandwidth and dynamic range of the original.

Vinyl records, with their limited bandwidth of 100Hz to 16KHz and 60 dB dynamic range, fell short of this goal. The original magnetic master tapes had a much wider bandwidth and dynamic range, making vinyl a "lossy" format. While equalization curves in phono preamps could restore some of the missing bandwidth, the loss of dynamic range was a significant compromise. The 2" magnetic tape running at 15 IPS could achieve 20Hz to 20KHz bandwidth with 85 dB dynamic range, the vinyl record was compressed by peak limiters to 60 dB.

The advent of CDs in 1984 marked a significant step forward. With a wider bandwidth of 20Hz to 20KHz and dynamic range of 90 dB, CDs offered a superior listening experience. However, they still couldn't store the full digital masters of the day because they could only store 700 Mb of data.

Sony's DVD format, introduced in 1997, offered greater storage capacity of 5 Gb and 105 dB dynamic range. In 2000, they launched SACD, a music-only format that could store the entire original master recording. For audiophiles, SACD became the first format to achieve the holy grail of high fidelity. The original master recording of a standard studio album is a 5 Gb file and so the SACD can store the entire 5 Gb file without compression.

In 2008, Sony's Blu-ray format offered even greater storage capacity of 50 Gb and 120 dB dynamic range, allowing for ultra-high-definition video and the native, uncompressed multichannel soundtrack.. However, concerns about copyright infringement led to the implementation of HDMI with HDCP digital security protocols to prevent copyright infringement.

In 2017, Sony introduced Ultra HD Blu-ray, with even greater storage capacity of 100 Gb with support for 4K video and immersive audio formats like Atmos, an object-based surround format derived from meta-data, adding height channels mounted on the ceiling between the listening position the main left and right front channels.

 

[pickindoug]

I find your statement that records (LPs) don't reproduce below 100 Hz a bit errant. Low E on a regular guitar is 82.41 Hz, and on a bass guitar, half of that. No issue with either of those frequencies on my LPs from the 60s and 70s. And if you claim it's due to RIAA EQ, that's irrelevant. Nearly all recording sources must alter the signal for their process. I won't contest the S/N statement......
On your claim of a 16kHz upper limit, take a look at how CD-4 quad LPs were reproduced, albeit not very well, but bandwidth went up to 40kHz.

 

[Sonnie Parker]

I think it was because vinyl playback was far from perfected back in the day... and much below 100Hz might cause issues with tracking. 100Hz to 10kHz was probably the standard, although there may have been a few to reach down into the 80Hz range. We have albums from the early '60s on up... those old ones lack any resemblance of bass, that is for sure.

No doubt we have come a long way in the last 50-60 years. The progression over the last 10 years has been phenomenal, and even the last 5 years have been incredible. I'm sitting here listening via Roon, and the quality is crazy good—this is streaming.

 

[Bob Rapoport]

I find your statement that records (LPs) don't reproduce below 100 Hz a bit errant. Low E on a regular guitar is 82.41 Hz, and on a bass guitar, half of that. No issue with either of those frequencies on my LPs from the 60s and 70s. And if you claim it's due to RIAA EQ, that's irrelevant. Nearly all recording sources must alter the signal for their process. I won't contest the S/N statement......
On your claim of a 16kHz upper limit, take a look at how CD-4 quad LPs were reproduced, albeit not very well, but bandwidth went up to 40kHz.

Hi Doug, I owned 5000 vinyl albums and was a co-founder of Mobile Fidelity Sound Labs in 1977 so I know we can get decent bass from vinyl LPs. The bandwidth limitation at 100 Hz is meant to allow more play time, using the RIAA equalization is a handy way to solve the problem of recording time. Sorry for being a bit errant in my description.

RIAA equalization is a form of pre-emphasis on recording and de-emphasis on playback. A recording is made with the low frequencies reduced and the high frequencies boosted, and on playback, the opposite occurs. The net result is a flat frequency response, but with attenuation of high-frequency noise such as hiss and clicks that arise from the recording medium. Reducing the low frequencies also limits the excursions the cutter needs to make when cutting a groove. Groove width is thus reduced, allowing more grooves to fit into a given surface area, permitting longer recording times. This also reduces physical stresses on the stylus, which might otherwise cause distortion or groove damage during playback.

A potential drawback of the system is that rumble from the playback turntable's drive mechanism is amplified by the low-frequency boost that occurs on playback. Players must, therefore, be designed to limit rumble, more so than if RIAA equalization did not occur.

The biggest drawback of vinyl LPs is the limited dynamic range of 60 dB. The original 2" magnetic master tape running at 15 IPS can reach 85 dB dynamic range and since our hobby is called "high fidelity", the loss of dynamic range from the original makes vinyl a "lossy" source. There's nothing wrong with that except its not high fidelity, equal to the original.

This is the RIAA equalization curve for playback of vinyl records. The recording curve performs the inverse function, reducing low frequencies and boosting high frequencies.

 

[pickindoug]

I think it was because vinyl playback was far from perfected back in the day... and much below 100Hz might cause issues with tracking. 100Hz to 10kHz was probably the standard, although there may have been a few to reach down into the 80Hz range. We have albums from the early '60s on up... those old ones lack any resemblance of bass, that is for sure.

No doubt we have come a long way in the last 50-60 years. The progression over the last 10 years has been phenomenal, and even the last 5 years have been incredible. I'm sitting here listening via Roon, and the quality is crazy good—this is streaming.

With all due respect to your experience, my 1960s experience with LPs was quite different. I learned to play electric bass by playing the same passages over and over. This would not have been possible if the frequency response was weak below 100 Hz and with decent extension to at least 40 Hz. And my system was nothing fancy, kit built tube amp, homemade speaker, and a cheap LP changer with a low end magnetic cartridge fitted.

According to my Radiotron Designer's Handbook, circa 1953, 33 rpm test records made in the 1950s provided test tones as low as 30 Hz, and some went as high as 14 kHz.

With respect to any progress made with LP quality over the years, none of the newer LP purchases I've made are any better than the well recorded and pressed examples of my 60s and 70s originals. There was definitely more variability in quality then, largely due to high production counts. And then there are the exceptions, the D to D from Sheffield Labs and others.

Today, I'm mostly the lazy listener, with 6000 FLAC files in a drive and a nice little streamer to allow me to select on the fly. LPs for special occasions. Some LPs sound better than the digital files, but due to the hard life many led back in the day, most don't.

 

[pickindoug]

Hi Doug, I owned 5000 vinyl albums and was a co-founder of Mobile Fidelity Sound Labs in 1977 so I know we can get decent bass from vinyl LPs. The bandwidth limitation at 100 Hz is meant to allow more play time, using the RIAA equalization is a handy way to solve the problem of recording time. Sorry for being a bit errant in my description.

RIAA equalization is a form of pre-emphasis on recording and de-emphasis on playback. A recording is made with the low frequencies reduced and the high frequencies boosted, and on playback, the opposite occurs. The net result is a flat frequency response, but with attenuation of high-frequency noise such as hiss and clicks that arise from the recording medium. Reducing the low frequencies also limits the excursions the cutter needs to make when cutting a groove. Groove width is thus reduced, allowing more grooves to fit into a given surface area, permitting longer recording times. This also reduces physical stresses on the stylus, which might otherwise cause distortion or groove damage during playback.

A potential drawback of the system is that rumble from the playback turntable's drive mechanism is amplified by the low-frequency boost that occurs on playback. Players must, therefore, be designed to limit rumble, more so than if RIAA equalization did not occur.

The biggest drawback of vinyl LPs is the limited dynamic range of 60 dB. The original 2" magnetic master tape running at 15 IPS can reach 85 dB dynamic range and since our hobby is called "high fidelity", the loss of dynamic range from the original makes vinyl a "lossy" source. There's nothing wrong with that except its not high fidelity, equal to the original.

This is the RIAA equalization curve for playback of vinyl records. The recording curve performs the inverse function, reducing low frequencies and boosting high frequencies.
View attachment 77917

No recording of an acoustic instrument is 100% equal to the original, regardless of the medium used. The question that many audiophiles wrestle with is how it sounds vs how it measures, with those who listen to music preferring the former concept vs those who listen to their gear preferring the latter. The RIAA curve, along with all of the other LP repro curves that led to the adopted standard, was designed to make the most of an inherently flawed but highly marketable medium. Dolby's manipulation of non-linear recording corrected during playback to reduce tape hiss on cassettes is another fine example of not allowing perfection to be the enemy of good. With your background, I'm sure you enjoy the music!

 

[Bob Rapoport]

No recording of an acoustic instrument is 100% equal to the original, regardless of the medium used. The question that many audiophiles wrestle with is how it sounds vs how it measures, with those who listen to music preferring the former concept vs those who listen to their gear preferring the latter. The RIAA curve, along with all of the other LP repro curves that led to the adopted standard, was designed to make the most of an inherently flawed but highly marketable medium. Dolby's manipulation of non-linear recording corrected during playback to reduce tape hiss on cassettes is another fine example of not allowing perfection to be the enemy of good. With your background, I'm sure you enjoy the music!

Just ask yourself about the meaning of the words "High Fidelity". That's what we call our hobby. The pursuit of high fidelity means hearing a one to one copy of the original master recording, with equal bandwidth and the dynamic range of the original recording. There's a reason the Studios and record labels protect Blu-rays, SACDs, and AV Streaming against copyright infringement but allow us to copy everything else. The storage media of all the earlier generations had limitations that prevented us from hearing that one to one copy but with storage capacity today, we can as long as we faithfully follow the security protocols.