Bang & Olufsen Cartridges for Record Decks - Which ones fit ?
MMC pickup cartridges
The cartridge is all important. Even a superb turntable in a high specification record-based music system is totally dependant on the cartridge. The cartridge is the only component which comes into direct contact with the record and the one which transmits the complete sound picture. The quality - and the price - of a cartridge is partly determined by what is technically known as the 'Effective Tip Mass' (ETM). This is the weight of the diamond plus the weight of the cantilever - and the lower the ETM the better.
So how can something so incredibly light be so finely engineered? The MMC cartridge was a stunning example of Bang & Olufsen's continual insistence on quality. 'MMC' stands for Moving Micro-Cross, a design principle which resulted in the complete integration of all components - stylus, cantilever, coils and magnet became the patented moving-iron principle upon which all B&O cartridges were based. The MMC principle gave the finest groove separation and produced extremely accurate sound reproduction of records. The unique MMC system employed a cross-shaped armature which, among other advantages, guaranteed exceptional stereo separation since each channel moves on a separate axis.
The job of any pickup cartridge is to transform the record's physical profile (groove modulation) into corresponding electrical signals (which are then amplified or enlarged by the amplifier and turned into audible sound waves by the loudspeaker).
In 1958, Bang & Olufsen introduced the first stereo pickup cartridge ever made in Europe. This was the SP1 range of combined cartridges and styli. Since then, many design innovations and the creative use of new materials kept B&O's cartridges at the forefront of audio technology. Looking at the B&O stereo cartridges, there were 4 distinct families. The SP1/2 was the first of the stereo cartridges and had a 25 degree tracking angle and is hence not compatible with the later arms. These also had separate styli which could be replaced. This family was replaced by the later SP range which comprised the SP6/7 and SP8/9. These were now using the internationally standard tracking angle of 15 degrees. The nomenclature at this time was confusing with odd number Cartridges fitting Beograms and even numbers designed with a 1/2" bracket already attached. The SP6/7 had a spherical diamond and the SP8/9 , an elliptical one.
These were replaced by the later SP10 and SP12, the designation for cartridges to fit Beograms now being signified by an A. The SP12 was the best of the SP cartridges with an elliptical diamond, and a frequency response up to 25kHz. A later lower compliance model was also made, the SP14 which had a similar spherical diamond to the SP10.
In the early 70s, B&O introduced the groundbreaking Beogram 4000 and in conjunction with this a new smaller and incompatible cartridge range was introduced. The first of the range was the confusingly named SP15, the work of the engineer Subir Pramanik. This was a tiny integrated cartridge with a non replaceable stylus assembly. This fact allowed very close tolerances to be achieved during manufacture.
It was quickly realised that SP15 left no room in nomenclature terms for a lower grade cartridge, so it was slightly modified and became the MMC4000. This had the same elliptical stylus as the SP15 and was fitted as standard to the Beogram 4000. Three other members of this family MMC 3000 - 6000 were also introduced.
The MMC 3000 was the base model with a spherical stylus fitted and was fitted to the radial decks of the time and also the music centres.
Of more interest were the two cartridges introduced for the new Quadraphonic record players designed for CD4 as well as SQ record replay. The cheaper of these was the MMC5000 which was fitted with a Shibata type stylus, a fairly standard modified elliptical stylus used by many cartridge makers at this time, mounted on a titanium cantilever. It was designed for use in the radial Beogram 3400.
However the pinnacle at this time was occupied by the MMC6000 which was fitted with a Beryllium cantilever onto which was bonded a special multi radial stylus designed by Subir Pramanik and which bore his name. This was designed for the tangential Beogram 6000 as the design of these decks lent themselves to the accurate tracking required by the new CD4 records.
As was seen, CD4 records were only a passing phase and B&O refreshed the range by introducing the the MMC 20 range and dropping any reference to CD4 ability. Instead excellence in stereo reproduction was promised and a new cartridge, the MMC20CL was introduced with a single crystal sapphire cantilever and line contact stylus, a development of the Pramanik stylus though simplified.
The MMC4000 was renamed the MMC20EN but was in most ways unchanged.
At the lower end of the range , a new elliptical model was introduced, the MMC20E, and the range was completed with the replacement for the MMC3000, the MMC20S. Both the S and E models could be easily differentiated from the other MMC cartridges as the bodies were black which suited the arms of the radial decks in which they were intended to serve as these too were black. The tangential decks continued to have silver tone arms and were matched by the MMC20EN and CL.
The MMC3000-6000 range and the MMC20S-MMC20CL can be seen to be part of the same family of cartridges as they share a common mount and are interchangeable. They were to be replaced by a new and once again incompatible type, the MMC 1 - 5 range.
The MMC 3000 - 6000 range was the forerunner to the MM1 - 5 series of combined cartridges and styli:
This pick-up cartridge was specially designed for use in Bang & Olufsen record-players with tangential arms. It was designed to track SQ 4 channel matrix records and tracked both mono and stereo records extremely well. It was fitted to Beogram 4002. The stylus was an elliptical naked diamond, radii 5x17u. Recommended tracking force was 1g. Each MMC 4000 was designed as an integrated unit. This meant that all critical components were designed and constructed as an entity in order to give optimum performance. The stylus unit was not separately replaceable as it was part of the integrated unit. Frequency range was 20-30,000 Hz ± 3 dB. Effective tip mass was a mere 0.5 mg and compliance was higher than 30x10-6 cm/dyne.
Bang & Olufsen's (then) most accomplished pickup cartridge was fitted to Beogram 6000. The MMC principle was adapted to track 4-channel records: both Quadradiscs and SQ. MMC 6000 would track both mono and stereo records with the utmost fidelity. It was designed for record-players with tangential arms. The stylus was the Pramanik diamond, named after its inventor: engineer S K Pramanik from Bang & Olufsen's Laboratories. The diamond's radii were 7 um/2 x 50 um. It was a refinement of the elliptical shape, rather like the shape of the cutter-head, and enabled greater contact with the undulations of the record groove. The cantilever was made of berylium - a material which is harder yet lighter than popularly-used aluminium. Effective tip mass was 0.22 mg. Compliance was higher than 30x10-6 cm/dyne. Recommended- stylus pressure was 1g. The total frequency range was 20-45.000 Hz. In the audible range: 20-15.000 Hz there is less than 1.5 dB variation and in the inaudible range 20,000-45,000 Hz where the carrier frequencies lie, the pick-up fulfils RCA/JVC's specifications for a Class A discrete 4-channel pick-up cartridge. Each cartridge is an integrated, individually calibrated unit. The stylus unit is not separately replaceable since it is part of the integrated unit. An individual frequency response curve traced on a Bruel & Kjaer level recorder and a complete Calibration Card were enclosed with every MMC 6000 sold.
The MMC 4000 was an integrated pickup cartridge which had an elliptical, naked diamond stylus. Stylus pressure was only 1g with frequency range being 20 - 25000Hz =/- 1,5dB
The turntable pictured here is the Beogram 4002.
Quadraphonic sound
Bang & Olufsen produced two quadraphonic systems in the 1970s. The top model was Beosystem 6000 which comprised Beomaster 6000 and Beogram 6000. Beogram 6000 was a development of Beogram 4000 in that it was a tangential tracking turntable. It had an inbuilt CD4 decoder which was switchable. When 'on' it would detect the presence of the carrier frequencies and a display would illuminate on the record deck's display as '4ch'. The output of the Beogram was at line-level whether in 2- or 4-channel mode. The deck was attached to Beomaster 6000 via a 5-pin DIN lead with all the pins being wired. In Beomaster 6000 there was a replaceable board with a SQ decoder as standard. This was manually switchable. The operator therefore still needed to know the type of quad recording that was to be played. The purpose of the removable board was to allow upgrading should the record industry ever get its act together and find a common standard!
The second system was based on Beomaster 3400 and Beogram 3400 which had a radial deck and a smaller and simpler receiver. This again had similar functions. Beomaster 4000 and a few others had a facility called Ambiophonics which used a system of simulated four track sound from stereo records. Two Bang & Olufsen cartridges were made for playing CD4 records:
MMC 5000 used a fairly standard Shibata profile
the top of the range MMC 6000 used a profile deigned by one of their own engineers - Subir Pramanik - and which bore his name
Pickups
MMC 3000
Spherical diamond
Radius of curvature: 1,5 mm
Frequency range: 20 - 25000 Hz+/- 3dB, 20 - 16000 Hz +/- 2dB
Channel separation 1000Hz: > 20dB
40 - 10000Hz: > 15dB
Channel difference: <2dB
Intermodulation: <1%
Recommended stylus pressure: 1,2g
Compliance: 25 x 10(-6) cm/dyne
Effective tip mass: 0,5mg
Output mV/cm/sec.: 0,6mV/47kOhms
MMC 4000
Elliptical naked diamond
Radius of curvature: 5 x 1,7 mm
Frequency range: 20 - 15000 Hz+/- 2dB
Channel separation 1000Hz: > 20dB
40 - 10000Hz: > 20dB
Channel difference: <1,5dB
Intermodulation: <1%
Recommended stylus pressure: 1g
Compliance: 30 x 10 (-6)cm/dyne
Effective tip mass: 0,4mg
Output mV/cm/sec.: 0,6mV/47kOhms
MMC 5000
Shibata diamond
Radius of curvature: CD-4 quadro
Frequency range: 20 - 25000 Hz+/- 1,5dB, 20 - 45000 Hz (CD4)
Channel separation 1000Hz: > 25dB
40 - 10000Hz: > 20dB
Channel difference: < 1,5dB
Intermodulation: <1%
Recommended stylus pressure: 1,5g
Compliance: 25 x 10(-6)cm/dyne
Effective tip mass: 0,4mg
Output mV/cm/sec.: 0,6mV/47kOhms
MMC 6000
Pramanik diamond
Radius of curvature: CD-4 quadro
Frequency range: 20 - 15000 Hz+/- 1,5dB, 20 - 45000 Hz (CD4)
Channel separation 1000Hz: > 25dB
40 - 10000Hz: >20dB
Channel difference: < 1,5dB
Intermodulation: <1%
Recommended stylus pressure: 1g
Compliance: 30 x 10(-6)cm/dyne
Effective tip mass: 0,22mg
Output mV/cm/sec.: 0,6mV/100kOhms
The MMC 1 - 5 range
Unlike many other manufacturers, Bang & Olufsen insisted on developing pick-up cartridges for its own record-players. When the first stereo records were produced in the USA there were still no stereo cartridges in Europe. Bang & Olufsen took up the challenge and developed the first stereo cartridge based upon the Moving Micro Cross principle. Refined and improved upon, this principle withstood the test of time. Apart from fulfilling certain demands, e.g. a small effective tip mass, high channel separation, wide flat frequency response, low tracking force etc. after a few adaptations the MMC principle proved extremely useful in the reproduction of discrete four channel records (Quadradiscs) in the 1970s.
Through the MMC 1 to 5 range of cartridges, the diamond, cantilever and micro-cross formed a unified entity of super light-weight design. MMC1, MMC2, MMC3, MMC4 and MMC5 - comprised five high-quality cartridges in which the electrical and magnetic components were identical. Only the stylus and cantilever differed from model to model, offering a choice of ETM (Effective Tip Mass), tracking force and compliance - and, consequently, of cost.
All Bang & Olufsen record decks were supplied complete with a plug-in MMC pickup, but it was possible to upgrade the performance of the deck, if desired, by choosing the MMC model further up the specification scale. The obvious time to have done this would be when the existing stylus needed replacing after natural wear.
For use with non-Bang & Olufsen decks, a low-mass universal mounting bracket was supplied with each MMC pickup, allowing effortless installation on virtually all brands of tonearm.
Pickups
Description: Nude multi-radial Contact Line diamond, mounted on a sapphire cantilever
Tracking force - grams: 1
Diamond Stylus: Cont. line nude
Cantilever tube: Sapphire
Effective tip mass mg: 0,25
Compliance mg/mN: 30
Frequency 20-20000 Hz=/-dB: 1
Channel separation 1000>dB: 30
Output mV/cm/s RMS: 0,6
Cartridge weight gram: 1,6
MMC2
Description: Nude multi-radial Contact Line diamond, mounted on a sapphire cantilever
Tracking force - grams: 1
Diamond Stylus: Cont. line nude
Cantilever tube: Sapphire
Effective tip mass mg: 0,3
Compliance mg/mN: 30
Frequency 20-20000 Hz=/-dB: 1,5
Channel separation 1000>dB: 25
Output mV/cm/s RMS: 0,6
Cartridge weight gram: 1,6
MMC3
Description: Nude elliptical diamond mounted on a tapered aluminium cantilever
Tracking force - grams: 1.2
Diamond Stylus: Elliptical nude
Cantilever tube: Tap. alum.
Effective tip mass mg: 0,35
Compliance mg/mN: 25
Frequency 20-20000 Hz=/-dB: 2
Channel separation 1000>dB: 25
Output mV/cm/s RMS: 0,6
Cartridge weight gram: 1,6
MMC4
Description: Titanium-bonded elliptical diamond, mounted on a tapered aluminium cantilever
Tracking force - grams: 1.2
Diamond Stylus: Elliptical
Cantilever tube: Tap. alum.
Effective tip mass mg: 0,4
Compliance mg/mN: 25
Frequency 20-20000 Hz=/-dB: 2,5
Channel separation 1000>dB: 22
Output mV/cm/s RMS: 0,6
Cartridge weight gram: 1,6
MMC5
Description: Titanium-bonded elliptical diamond, mounted on a straight aluminium cantilever
Tracking force - grams: 1.5
Diamond Stylus: Elliptical
Cantilever tube: Straight alum.
Effective tip mass mg: 0,5
Compliance mg/mN: 20
Frequency 20-20000 Hz=/-dB: 3
Channel separation 1000>dB: 20
Output mV/cm/s RMS: 0,6
Cartridge weight gram: 1,6
Created: 11th January 2007
Modified: 3rd April 2007
