Joplin mkIII A/D Omvandlare & MC/MM RIAA förförstärkare
Detta är en helt unik hifiprodukt: En A/D omvandlare. Den kan användas för att digitalisera vilken analog hifisignal som helst, till och med direkt från en skivspelare. I och med att det finns ett highend, digitalt RIIA steg inbyggt som har långt mer funktioner än vad som finns på traditionella RIAA-steg.
Vad som mer är unikt är att man kan välja vilken typ och format på digital utsignal man önskar. PCM upp till 786 kHz sampling ,16-32Bitar och DSD 256x !
Det finns utgångar för Optisk, Coax, AES/EBU, I2S och USB, samt ingångar för obalanserad analog och SP-Dif Coax.
Joplin mkIII är även en dedikerad förförstärkare och phono-equalizer för både MM/MCmodell. Den har två phono-ingångar, en för lågnivå MC-pickup och en för MM-pickup (och även högnivå MC).
För många kan möjligheten med en A/D-omvandlare för hifibruk , även utrustad med funktionaliteten hos en phonoförförstärkare av mycket hög kvalitet, åtminstone verka som ett långskott.
Men framgången med Joplin-projektet, är sedan 2011, i dess olika versioner, oöverträffat på alla punkter. I den senaste MkIII-utgåvan erbjuder Joplin prestanda och flexibilitet på toppnivå som möter alla behov.
Tillverkningen av Joplin har legat nere ett par år på grund av komponentbrist, detta har gjort att Joplin, i sina olika versioner sålts begagnade för i stort sett nypris.
Joplin mkIII har ett par analoga ingångar med variabel förstärkning från 0dB till 65dB, driven av Burr-Brown PGA2500 mikrofonförförstärkare. Ingångsimpedansen kan justeras sömlöst mellan 10 Ohm och 50 kOhm, för att optimera gränssnittet med alla typer av kassetter, men också med linjenivåkällor som rullbandspelare och kassettbandspelare, mixer, tuners mm.
En S/PDIF-ingång gör att du kan skicka en signal redan i digitalt format till Joplin. Denna signal görs tillgänglig på alla utgångar och skickas även till USB-gränssnittet. Digitalingången låter dig även att sampla om PCM-signaler upp till 384 kHz samplingsfrekvens och 32 bitar. Man kan också använda denna funktionen för att sampla ner till lägre upplösning , ner till 16 bitar och/eller tillämpa dithering.
Joplin MkIII har digitala utgångar i S/PDIF, AES/EBU, Toslink, USB & I2S (i PS Audio-format) . Den senare betjänas av en SRC (sampling frequency converter) som gör att du kan ha en PCM-signal upp till 768kHz eller en DSD-signal upp till 256x. USB fungerar i asynkront läge enligt UAC 2.0-standarden (USB Audio Class) och används för att skicka signalen som hämtas från A/D-sektionen eller den som kommer från S/PDIF-ingången till en dator.
Joplin MkIII är utrustad med en digital signalbehandling (DSP) sektion som används för olika ändamål:
- Implementera en av de 27 tillgängliga phono- och frekvensutjämningskurvorna (Mer info längre ner på sidan)
- Funktion för högpass- och/eller lågpassfilter på signalen, om nödvändigt
- Funktion för MPX-filtret när du tar in ljud från en FM-mottagare.
Den justerbara förstärkningen, den justerbara ingångsimpedansen och tillgången på olika utjämningskurvor gör det möjligt att direkt ansluta en skivspelare till Joplin MkIII, utan att en phono-förförstärkare behöver användas. Den inhämtade signalen kan skickas till en dator via USB för inspelning eller till ingången på en DAC för lyssning i realtid. Denna senaste konfiguration (Joplin MkIII + DAC) skapar en ovanlig phono-förförstärkare som kan få analoga entusiaster att se rött, men som innehåller många trevliga överraskningar för den mest upplysta och figjorda audiofilen. ;-D
Joplin MkIII är försedd med en infraröd fjärrkontroll som tillåter total kontroll.
Specifications Audio PCM sampling frequencies: 44.1 kHz to 384 kHz 44.1 kHz to 768 kHz (I2S output only) DSD sampling frequencies: 64x to 256x (I2S output only) PCM resolution: 16 to 32 bits THD+N: 0,0005% @ 0dBFS Signal-to-noise ratio: 122 dBA Output impedance: 75 Ohm (S/PDIF) 110 Ohm (AES/EBU) 100 Ohm (I2S) Input impedance: 10 to 50000 Ohm (analog) 75 Ohms (S/PDIF) Inputs and Outputs Inputs: Single-ended analog (RCA) S/PDIF (RCA) Outputs: S/PDIF (RCA) AES/EBU (XLR) Ottico (Toslink) USB 2.0 high speed I2S (HDMI, standard PS Audio) Size and Weight Size: 200x200x50mm (WxDxH) Weight: net 2.0 kg (including ancillaries) gross 2.5 kg Electrical Input Sensitivity: 2.5 Vrms (gain: 0dB, 0dBFS) 1.4 mVrms (gain: 65dB, 0dBFS) Output voltage: 500 mVpp (S/PDIF) 2,0 Vpp (AES/EBU) 150 mVpp (I2S) Supply voltage: 15 VDC Power requirement: 4.5 VA 0.15 VA (standby)
Frequency Corrections for Record playback
1. RIAA
It’s the standard curve of present days, used from almost all the record labels since 1954.
Its use is generally indicated on the record label and/or on the cover. It is actually the
same curve as the RCA’s “New Orthophonic”, so it can be used to play RCA records
claiming the use of that curve also.
During the years, RIAA made some amendments to the curve. The most relevant, after an
indication from IEC, was the addition of a 16Hz high pass to cope with the rumble
produced by warped records or noisy turntables. Not all cutting plants adopted this
amendment and it’s very difficult to tell whether or not it’s been adopted for a certain
pressing, as the curve is always indicated as RIAA.
The JOPLIN MKIII has not a specific RIAA/IEC curve, but it can be obtained by selecting
RIAA and the high-pass filter at 16Hz (see Section 8.3.8).
2. AES
AES (Audio Engineering Society) proposed a phono equalization curve back in 1951. As
far as we know, no label explicitly adopted it, but the discerning record collector may be
aware of its use, so it’s been included for completeness.
3. Angel (ANG)
Angel was a record label incorporated by EMI who produced great records.
4. Audiophile (AUDP)
Audiophile is known amongst record collectors for her great recordings, on both 78rpm
and microgroove LP. Acoustic Sounds proposed the reissue of some Audiophile
recordings on coloured heavy weight vinyl some 15 years ago. The label was mainly
devoted to jazz and blues.
5. Bartok (BAR)
Bartok Records is an old record label purposely founded to promote the work of the great
composer Béla Bartók. Many titles are available since 1949.
6. Capitol (CAP)
Capitol had a large production of very good mono recordings.
7. Columbia (COL)
Columbia is the inventor of microgroove LP, which got to success after a market war
against RCA, who was sponsoring a 45rpm microgroove standard.
8. HMV
HMV (His Master’s Voice, after the painting with the dog Nipper listening to a
gramophone), formerly The Gramophone Company, is one of the oldest record labels
ever. It later became part of EMI when the latter bought Capitol, and had RCA as
shareholder for a certain time. From 1948 to 1954 recorded a lot of jazz, pop and classical
music, pressing LP’s with her proprietary curve.
9. Decca/London FFRR
The English Decca developed her FFRR LP curve based on the 78rpm eq curve with the
same name. Most of the great recordings of the stereo era (after 1954) were also
produced in mono and used to make the mono LP’s cut using the FFRR curve.
10. MGM
The famous entertainment company also produced LP’s during the mono era using her
proprietary curve.
11. NAB
NAB (National Association of Broadcasters) was founded by commercial radio companies
to address many aspects of their activity. Amongst these, the technical issue related to
broadcasting. NAB proposed a phono curve to be used for the records which were made
at the time especially for broadcasting, with live and rare recordings of famous artists. The
record collector who own these records should use this curve to play them.
12. Oiseau-Lyre (OYLR)
Before being purchased by Decca, Oiseau-Lyre made many great recordings of classical
music.
13. Pacific Jazz (PACJ)
Jazz was a great business in USA after WWII, so some specialized labels chose to
develop their eq curves to press their microgroove LP’s. Pacific Jazz was one of them.
14. Philips
Of course, Philips, one of the greatest European brands related to music, developed its eq
curve.
15. RCA (RCA1, RCA2 and RCAO)
RCA developed many equalization curves, to be used with her 45rpm’s and, later, for the
microgroove LP’s after losing the format war against Columbia, so it’s difficult to say which
curve was used for a certain record. The JOPLIN MKIII offers three choices, based on
record’s year of cutting. RCA1 is the oldest. The newest, RCA Orthophonic, is the one on
which the “New Orthopohonic” was developed, thus leading to RIAA.
16. Brunswick
Brunswick is a very old record company who mainly produced 78rpm’s. The curve offered
with the JOPLIN MKIII is the one used for the 78rpm’s.
17. Columbia 1925, Columbia 1938 and Columbia England (CO25, CO38
and COLE)
Columbia was very active cutting 78rpm’s before introducing the microgroove LP. She
used different curves in different years: one between 1925 and 1938 and one from 1938
on. Not only: her English branch, Columbia England, developed her own curve for 78rpm’s
cut in Great Britain.
18. Decca FFRR 78rpm (DEC)
This is the equalization curve for 78rpm used by Decca, from which the LP FFRR was later
developed.
19. MGM 78rpm (MGM7)
Before cutting LP’s, MGM produced 78rpm’s, which were cut using MGM proprietary curve
for 78rpm.
20. Victor 1938-47 and Victor 1947-52 (VIC3 and VIC4)
Victor is an old company, later purchased by RCA, who produced 78rpm since 1925. The
curve adopted between 1925 and 1938 is same as Columbia type 1925 (See 9.2.17), later
curves are offered with specific choices.
Frequency Corrections For REEL-To-REEL tape
1. CCIR/IEC for 9.5cm/s and 19cm/s (3¾ ips and 7½ ips) and CCIR/IEC for
38cm/s (15 ips) (IEC1 and IEC3)
CCIR (Comité Consultatif International pour la Radio) was an European Committee similar
to NAB. They proposed an equalization for reel-to-reel tape recorders which was adopted
by most European manufacturers. It has been said by many that the CCIR equalization is
better than the NAB one. Anyway, the choice of one or the other standard is only an option
when recording, as some tape recorders have both equalizers. For playback, the choice
depends on the standard used to record the tape. For the record, all commercial prerecorded tapes available on eBay or other auction sites are made using NAB.
2. NAB for 9.5cm/s (3¾ ips) and NAB for 19cm/s (7½ ips)
NAB proposed two equalization curves for tapes, one for 3¾ ips (curve B) and one for 7½
ips (curve A), plus an amendment for 15 ips which, anyway, was suggested to avoid (7½
ips was the preferred speed for tape recorders used in broadcasts). The JOPLIN MKIII offers
both curve A and curve B.
4. Acquiring with equalization
When no equalization curve is used, then the rightmost led of each VU-meter bar turn on
right before clipping (that is, when the input signal reaches the clipping value set by menu).
Should the input signal further increase its amplitude, the ADC saturates and the “CLIP”
warning is displayed on the display. User should avoid getting the “CLIP” warning appear
at any time during acquisition.
When an equalization curve is used, then the VU meter is not consistent with the effective
risk of saturation, as it indicates the signal downstream the equalization. User should then
pay attention to “CLIP” warning appearing even when the bar is not completely lit. As a
general rule, ADC clipping may occur when using equalization at a VU meter level such as
the 2-3 rightmost leds are still off (this indicates a post-equalization level of -2/-3dB). This
rule is affected by the clip level set by menu.
5. Interfacing a cartridge or a tape head
The JOPLIN MKIII allows for setting its analogue input impedance between 10 Ohms and 50
kOhms thanks to a small knob on the rear panel (Fig. 2, 8)
The broad setting range allows for accommodating all different cartridges in the market.
When using an MM cartridge or a line level source (phono preamp, tape recorder…) the
impedance should be set to 50 kOhms.
6. Recording Software
When acquiring on a computer with the JOPLIN MKIII, a suitable program of application
needs to be used. Several different programs of packages are available for Windows, Mac
and Linux, some of them are freeware, others need to be purchased.
M2Tech cannot be aware of all the available programs, nor specifically recommend any of
them, nevertheless some indications are useful for the JOPLIN MKIII owner in order to have
a glance of the available features and the possibilities offered by the various programs.
A free package for Windows is Audacity (http://audacity.sourceforge.net/?lang=en) which
allows for recording up to 192kHz 24bits and generates files in WAV, FLAC and other
compressed formats. Several options dedicated to the vinyl are available, as automatic
tracks cut to divide the acquisition of an LP side into the single tracks, and de-clicking.
A much more professional package, Cubase, is sold by Steinberg
(http://www.steinberg.net/en/products/cubase/start.html) and can operate up to 192kHz
32bits.
Mac users may take advantage from PureVinyl (http://www.channld.com/pure-vinyl.html)
by Channel D, as well as from SoundBlade by Sonic Studio
(http://www.sonicstudio.com/sonic/products/sonic_productoverview.html). For sure, free
apps are available as well.
For a very complete list of ripping programs, please check
http://www.recordcollectorsguild.org/modules.php?op=modload&name=sections&file=inde
x&req=viewarticle&artid=6&page=1.