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PH-77
Frequently asked questions about the PH-77 Reference Class Phono Equaliser
Equalisation (EQ)
Gain
Load
Design
Analogue-to-Digital Converter
Others
The simple answer is that as not all LP’s have been equalised using the same RIAA equalisation, additional equalisation curves are needed.

At the introduction of the Long Play record (LP) in 1948, most record companies implemented their own particular equalisation curve and continued to experiment with equalisation in order to extract the best performance from the new medium. This led to a baffling array of different and incompatible equalisation curves being applied worldwide.

In the mid-1950’s, most of the record companies agreed to adopt the RCA Orthophonic equalisation curve, the Recording Industry Association of America (RIAA) promulgated this curve as a common standard which became known as the “RIAA equalisation”.

However, as this was essentially an American standard, it had little impact outside of the USA. The RIAA equalisation only became a truly international standard by the mid-to-late 1970’s when European recording labels slowly and finally began to adopt the RIAA equalisation. It was even later when some Asian recording labels joined the bandwagon and adopted the RIAA standard. Right up to the fall of the Berlin Wall in 1989, many Eastern European recording labels (including Russian recording labels) were still, using their own CCIR equalisation.

To further complicate matters, even after officially agreeing to implement the RIAA equalisation curve, many recording labels still continued to use their own, proprietary equalisation, even well into the 1970’s. Columbia is one such prominent example in the USA, Decca/Telefunken/Teldec in Europe is another.

According to Peter Copeland in his excellent “Manual of Analogue Sound Restoration Techniques”:

“I consider the whole subject should be a warning to today’s audio industry; practically everything which could go wrong did go wrong, and it isn’t anybody’s fault. But much worse is everyone’s apparent attempts to hide what happened.”

Of course, no damage will result. However, the true quality of the LP recording will not be fully realised.

For example, when played back using RIAA equalisation:

A Decca Stereo LP (UK mastered or pressed – correct equalisation: Decca EQ) or Deutsche Gramophon LP (Germany mastered or pressed – correct equalisation: Decca EQ), will typically sound bright and edgy with a recessed midrange.

A Columbia Stereo LP (correct equalisation: Columbia EQ) will typically sound boomy in the bass, lacking in warmth and body and overly bright at higher frequencies.

A European LP (correct equalisation: CCIR EQ) will sound dull, lifeless and lacking in detail.

Armed with this understanding of how equalisation affects playback, given the considerable investment in an LP collection and an audio system, AMR believes that at the outset, the correct equalisation for each and every LP should not be overlooked as it is just as important as the rest of the playback chain.

While the notes in the PH-77 User Manual provide informative guidelines, the application of equalisation curves by various different recording labels was in fact, quite inconsistent. Therefore, the final choice really often comes down to listening.

For example:
• A 1960’s Decca USA LP, cut and pressed in the USA from master tapes shipped from the UK, would likely have been equalised to the RIAA standard.
• A 1960’s Decca USA LP, cut in the UK but pressed in the USA, even after the introduction of the RIAA standard, is likely to have been equalised to the the Decca UK in-house standard at that time, which is likely to have been Decca FFSS.

In order to attain the absolute best possible sound quality, all the equalisation curves in the PH-77 are purely passive.
No, all equalisation curves in the PH-77 are implemented purely in the analogue domain.
The common RIAA equalisation requires low frequencies to be boosted around 20dB and high frequencies to be attenuated by around 20dB. To implement the equalisation in the digital domain, at high frequencies, one would have to remove some 40dB of dynamic range available from the Analogue-to-Digital Converter.

A state-of-the-art 24-Bit Analogue-to-Digital converter will have ~114dB of dynamic range. This means only 74dB of dynamic range is available at high frequencies. That is equivalent to less than 13-Bit actual resolution and correspondingly will result in a much lower level of resolution than the red book CD standard and is in fact, more in-line with the MP3 format.

Very comprehensive, if not totally exhaustive. AMR’s awareness and research into this topic has equipped the PH-77 with a full and comprehensive catalogue of just about every equalisation curve that has ever existed. For a particular LP, information from the PH-77 User Manual and from many available vinyl resources should resolve which EQ curve should be used.

Further, a little known fact is that in many cases, identical equalisation curves existed but were named differently by different recording labels. For example, some small recording labels advertised certain “special” curves such as “New FFRR” and “New NAB” which were in fact, RCA Orthophonic curves.

The PH-77 has 8 different levels of gain: MC Low: 72, 66, 60, 54dB; MM/MC High: 48, 42, 36, 30dB + Mute
No, one gain setting for MC and one gain setting for MM is often not sufficient.

Taking MC cartridges as an example, the output levels of MC cartridges vary widely from ~0.1mV to ~2.5mV. This is a range of 28dB difference within MC cartridges only. The situation is similar with MM cartridges.

So, having one level of gain for each type would means a compromise of either:

a. If the cartridge output is too low - having too much noise and the sound is too soft even with the volume turned up all the way;

or

b. If the cartridge output is too high, overload the phono equaliser or the preamplifier/amplifier and clipping the sound output. More significantly, the clipping may damage downstream equipment including the speakers.

In order to optimise both the signal to-noise ratio and to avoid overloading the system, it is very important to properly match the gain of the phono equaliser to the output of the cartridge used. Hence, having varying levels of gain selections on a phono equaliser is considered essential.

Yes. However, a 10 second mute is applied in order to allow the valve circuitry to stabilise.

A gain level of 72dB is more than sufficient for just about every cartridge. On most LP’s, cartridges with a very low output (e.g. 0.1mV@ 5cm/s) at a gain setting of 72dB, will produce an output level sufficient to match that of a well recorded CD.

Cartridges with an ultra low output (much lower than 0.1mV@ 5cm/s) are usually accompanied by their own dedicated matching/step-up device. As such, this type of cartridge may still be used in conjunction with the PH-77.

No, the PH-77 does not use step-up transformers of any kind.

The quality of MC step-up transformers is often the bottleneck in phono equaliser designs. Together with an inability to match more than one/two cartridges to the transformer used, this “jack of all trades but master of one” approach means the use of an MC step-up transformer in practice, is often more detrimental than beneficial.

The PH-77 has 64 different levels of load:

MC(ohm): 47, 48, 50, 52, 54, 56, 58, 60, 63, 66, 69, 72, 75, 80, 85, 90, 95, 100, 110, 120, 130, 140, 160, 180, 200, 250, 300, 350, 500, 750, 1.5K, 47K

MM(pF): 70, 90, 110, 130, 145, 165, 185, 200, 220, 240, 260, 280, 300, 315, 330, 350, 370, 390, 410, 430, 445, 460, 485, 500, 520, 540, 560, 580, 600, 620, 640, 680

Dependent upon cartridge design and parameters, the effect of changing the load can vary from the very subtle to the very dramatic.

The PH-77 has a total of 23 equalisation curves.

Equalisation Curves (Stereo):
• RIAA (Modern stereo LP playback curve)
• Enhanced RIAA (with Vinyl Cutting Lathe HF Roll-Off and Phase-Shift Compensation)
• RIAA DMM - (The RIAA ‘Direct Metal Mastering Curve' by AMR)
• Columbia (Columbia LP Stereo)
• Decca FFSS (Decca & London, Deutsche Grammophon, Archiv, Polygram, NAB, Philips, and Argo)
• CCIR (Europe pre ~1962, Eastern Europe & Asia pre ~1975 eg. Amiga, Eterna, Deutsche Grammophon and Melodiya)

Equalisation Curves (Mono):
• RIAA (Mono, also RCA Orthophonic)
• Enhanced RIAA (Mono, with Neumann Cutter HF Roll- Off Compensation)
• Columbia 52 (later Columbia LP Mono)
• Columbia 48 (early Columbia LP Mono)
• Columbia 38 (78rpm, Columbia Electrical post-1938)
• Decca FFRR 53 (also London Records post-1953)
• Decca FFRR 52 (also London Records 1952)
• Decca FFRR 51 (also London Records 1951)
• Decca FFRR 49 (also London Records 1949 -1951)
• RCA 50 (RCA, Urania, Lyrichord)
• RCA 38 (78rpm, RCA Electrical post post-1938)
• AES 51 (1951 AES Standard)
• Bartok LP
• NAB (1942 also NARTB)
• EMI (early EMI Mono LP)
• CCIR 56 (Mono, Europe pre ~1962, Eastern Europe & Asia pre ~1975)
• CCIR 53 (Europe pre~ 1956)

The frequency response of any record cutting lathe will fall at a higher frequency and become less efficient, hence a lower level of high frequency detail was cut into the LP at the time of manufacture.

The Enhanced RIAA EQ is an amendment of the standard RIAA that approximates closely the actual frequency response of the cutting system and compensates for this particular roll-off; bringing the missing level of high frequency detail back into the recording.


Due to interactions with the tonearm’s mass and resonant behaviour, even cartridges that are the same make/model may only perform at their best at different levels of load.

Notwithstanding, a good starting point is the value recommended by the cartridge manufacturer. Then adjust either side from this point. When the load is the correct one, the sound will “lock-in” to sound “just right”. Feel free to experiment; different load values will sound different. When adjusting the load, there is no risk of damage to either the cartridge or the PH-77.


Yes.
Yes, PH-77 has custom load RCA sockets available for this purpose.

One Direct input (non-switched) or 3 Normal inputs (switched).
Different types of records work best with different types of cartridges. For example, one input for elliptical/line stereo stylus; one input for spherical stereo stylus and one input for mono playback.

Further, this option also allows for a comparison/evaluation of different vinyl setups “on the fly”.

The PH-77 uses computer matched New Old Stock Mullard ECC81/12AT7 and New Old Stock Philips ECG 5687WB for amplification and New Old Stock EZ80 for valve rectification duties.
Active power regulation circuitry in the traditional design sense often degrades the sound and imparts a mechanical, artificial characteristic to the music which is clearly undesirable.

By using AMR’s patent pending OptiMains® technology, the PH-77 optimises the supply voltage without any sonically degrading active power regulation.

Further, the use of a 28-stage passive power filter allows the PH-77 to achieve noise levels that are unmatched by active power regulation.

With an equivalent input noise performance of <-145dBV (< 0.056uV), the PH-77 is one of the quietest phono equalisers ever made.

No. For the Direct input and RIAA equalisation, the PH-77 contains no switching in the signal path whatsoever.

When using the Normal inputs and the other equalisation curves, additional passive components are connected in shunt mode via hermetically sealed, gold over silver contact relays. This uncompromising approach is second only to the ideal of no switching.

No. The input stage of the PH-77 is a unique circuit devised from quantum particle research using discrete components; no operational amplifiers whatsoever are used. The rest of the PH-77 is purely valve-based.

In our opinion, a well-designed valve-based circuit should be just as quiet as a solid-state circuit. AMR has achieved this with the PH-77, as it is one of the quietest phono equalisers (solid-state or valve-based) on the market today.

With AMR’s unique approach and thorough implementation, the PH-77 boasts the same excellent performance as any dedicated RIAA phono equaliser. In fact, the PH-77 is one of the most organic and finest sounding phono equalisers ever produced, while at the same time, offering a comprehensive range of dedicated equalisation curves, including RIAA.

The Analogue-to-Digital Converter enables one with ease, to digitally archive an LP by recording music (i.e. transferring) directly to a computer via the USB connection for the highest quality. When the PH-77 is used for dedicated listening to vinyl, as the Analogue-to-Digital Converter section is not required, it is powered off and completely disengaged from the audio signal path. Hence, it has no sonic impact during playback.

No. The Analogue-to-Digital converter supports sample rates and resolution up to 96KHz and 24-Bit. The actual sample rate is user-selectable through the particular recording software on the computer, e.g. 16-bit or 24-bit, 44.1, 48, 88.2 or 96KHz etc.

As there is virtually no limit to the number of recording software titles available and it is ever changing, no official recommendation can be made. However, we have noted that Cool Edit/Adobe Audition and Audacity are relatively easy to use programs. Another program which is more complex, but is liked by many professionals, is Cedar.

Approximately 90 seconds. We recommend serious listening after the valves have warmed up for one hour.
The built-in Analogue- to-Digital Converter is able to operate up to 24-Bit/96KHz and will directly stream the equalised music from the LP into a computer via a USB connection. This user-friendly approach fully preserves the unique sonic qualities of the PH-77 and the rest of the settings applied (e.g. EQ, gain and load) to maximise the sound quality.

Yes, the valves in the PH-77 are constantly operated in a very conservative manner. However, when not in use, placing the PH-77 in Standby mode (or Power OFF) is highly recommended, purely to maximise valve-life.

The New Old Stock valves used in AMR products are qualified by the valve manufacturer for operation at maximum rating (maximum allowed power) up to a maximum of 10,000 hours without degrading performance.

Mindful that valves operated at near maximum ratings (maximum allowed power) have a drastically reduced valve life, the PH-77 operates its valves in a very conservative manner and implements soft-start procedure to prevent any additional stressing of the valves during switch-on.

U.S. military data suggests an average lifespan of 100,000 operational hours under such conditions. If the average listening time is 10 hours per day, this equates to around 27 years. Individual valves may fail earlier or last longer than the average predicted lifespan.

A high-quality tonearm cable with as few breaks in the connection path as possible is recommended. Use high-quality, neutral sounding line-level interconnects for the output connections, such as AMR’s IC-77-RCA or IC-77-XLR. This will allow for the purity of the music to flow unhindered.
The extant literature commonly available features many inaccuracies, errors and omissions. This is made worse by the fact that many authors have simply relayed data from earlier articles containing erroneous data, so the mistakes have been repeated so many times, that they have become the authoritative take on the subject.

For example, our research highlighted the prevalence of inaccurate information pertaining to the actual frequency response of several equalisation curves. For example the Decca Stereo EQ (FFSS) has actually a lower turnover frequency of 70Hz, and not 125Hz as erroneously quoted in some cases. In several other cases, ostensibly different equalization characteristics turned out to be different names for the same principle equalisation.

As a result, AMR consulted with a wide range of professionals in the (LP) archiving and transcription fields and used as complete as possible sources in our research, that is best described as audio archaeology. Much of the Knowledge that is still extant exists only in the minds of these professionals, many of which are of advanced age.

The best written compendium on the subject is the late Peter Copeland’s “Manual of Analogue Sound Restoration Techniques”, which contains some 60 pages devoted to the subject of equalisation curves.

While label, logo shape, country of origin (of the LP, not the sleeve) and year of issue give some indication, they are NOT 100% reliable indicators. However they usually assist one to narrow down to a short list of equalisation curves that may apply.

To determine which equalisation curve is the correct one, the easiest way is to listen and select the equalisation curve (from a short list of likely ones) that produces the most realistic and natural sound.

EMI as large international conglomerate even in the 1950’s included many record companies and labels. The equalisation curves used often reflected the practices of the global region (e.g. US, UK/British Empire/Commonwealth, Western Europe).

For example, British (and Empire/Commonwealth) EMI records have in practice matched Decca equalisation in most cases.

In 1957 an attempt was made to introduce a German Industrial Standard (DIN) that included record equalisation which matched the CCIR (1956) Standard. This attempted standard has on occasion, been erroneously referred to as the Teldec equalisation. It in fact, should correctly be referred to as either DIN 45533 or CCIR.
In 1957 an attempt was made to introduce a German Industrial Standard (DIN) that included record equalisation which matched the CCIR (1956) Standard.

In Germany and Western Europe the CCIR equalisation curve had mostly been discontinued from use by the mid- 1960’s. However, right up to the fall of the Berlin Wall in 1989, many Eastern European recording labels (including Russian recording labels) were still using the CCIR equalisation.

Some West German records from later years may also be erroneously equalised using RIAA or Decca EQ as the cutting and pressing was often contracted out to East Germany (just like the manufacturing of Siemens, Telefunken and Valvo Electron Valves), where on occasion, the cutting was actually done with CCIR equalisation in place, instead of re-adjusting for the specified RIAA or Decca EQ.

In the mid-1970’s Neumann and Teldec developed a new cutting system called Direct Metal mastering (DMM) where the grove was cut directly into a metal foil, not into a lacquer layer.

This eliminated several plating steps in the manufacturing process, allowed for tighter groove spacing and more high frequency level. These differences in the manufacturing process and the different mechanical resonance behaviour of media the groove is cut into (hard metal vs. soft plastic laquer) give DMM records a very different tonality to traditionally manufactured records.

Sonic differences exist even though almost all DMM records have been, to the best of our knowledge, equalised to RIAA standards (excluding East German Amiga/Eterna DMM records and occasional accidents in the East German cutting rooms when undertaking contract work for the West).

The sound from DMM records is often perceived as overly bright and forward. While this is not directly a result of the equalisation employed, the tonality of overly bright DMM records can made more well-balanced or even handed by gently attenuating the upper midrange and lower treble. The RIAA (DMM) curve implemented in the PH-77 is such an implementation.

It is strictly speaking not an international standard (such as RIAA & CCIR) nor a de-facto standard (the Enhanced RIAA curve is an example of a de-facto standard due to the equalisation built into the Neumann Cutting lathes), but rather, a replay adjustment to ameliorate this common sonic shortcoming of DMM records.

 
   
   
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