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Barry
23-11-2010, 01:16
This posting will only be of interest to a tiny minority of members. However having gone through this exercise on a couple of occasions and most recently in order to prepare an EMT cartridge for audition by someone whose arm uses the widespread and conventional SME/EIA bayonet fixing [1], I thought I would pass on my experience here.

First of all it has to be understood that EMT cartridges were specifically designed to be used in a professional environment, especially that of broadcast studios. A prime consideration (apart from sound quality) was one of consistency and uniformity. EMT developed their own pick-up arm: first the curved 12” 997 (known as ‘the banana’), then later the cranked 9” 929. Whilst these are made to a high standard, there is nothing about them that later arms such as the SME, Ortofon, Fidelity Research or Jelco, couldn’t match. Rather it was the fitting of the arm to the deck that was important, simplifying the installation of the cartridge: once fitted, with the cartridge/headshell mass balanced out and the recommended tracking force and bias set up, the VTA and overhang were automatically correct for the cartridge. Such was the unit-to-unit consistency of the EMT cartridges that in the unlikely event of a cartridge failure, a replacement could be fitted in seconds without having to re-adjust VTA, overhang, azimuth or bias – an important requirement in the broadcast situations where ‘down time’ is to be avoided.

To achieve these ends EMT ended up with a cartridge/headshell design unlike most of its contemporaries. Not only was the headshell quite short (i.e. the distance between the stylus and bayonet fitting connector flange), the contact arrangement was unique and could only be mated with EMT's own arms, that were also designed so as to provide correct overhang: there being no adjustment for overhang within the headshell. The contact arrangement was similar to the now standard SME/EIA arrangement of four spring-loaded plungers that mated with four corresponding contact ‘pips’ on the connector stub, save for one very important difference: the disposition of the contacts were rotated through 45° compared to current use. That is, the contacts have a ‘diamond’ rather than the usual ‘square’ arrangement. This is often referred to as the 'Neumann' configuration, since Neumann supplied EMT with their DST61 and DST62 cartridges after Ortofon ceased supply. It has been said that EMT deliberately retained this contact scheme so as to prevent, in the words of EMT, “sublimation” of the cartridge from the original deck and arm to the arm of an enthusiastic employee!

http://i780.photobucket.com/albums/yy88/barrydhunt/B8T9SrgBGkKGrHqMOKj8EzpUcEsGBM2syIZ51g_121.jpg?t=1 290524991 http://i780.photobucket.com/albums/yy88/barrydhunt/B8T9Qvw2kKGrHqIOKpwEyjC0CBM2syEbkLw_121.jpg
Left: EMT TSD cartridge. Right: Photo showing the unique contact arrangement EMT used for their cartridges.
Photo: eBay

There is one other minor difference between the coupling arrangements of EMT cartridges and those of other headshells: the alignment spigot points downwards, rather than upwards. This is largely unimportant, as most, if not all, arms with bayonet fitting have two diametrically opposed alignment slots.

So to the actual use of EMT cartridges in non-EMT arms:


Mechanical

There are three ways in which one can use an EMT cartridge design on a different arm. These are:

1 Use the EMT XSD design. This uses a modified design of headshell having an extended length bayonet stub (hence the ‘X’ in the designation), solving two problems at once: when fitted to say an SME arm, the overhang is close to optimum and the contact arrangements are as standard. Even the alignment spigot follows the usual convention of pointing upward. Clearly this is the best and most obvious path to follow, however EMT are no longer in business and such modified cartridges are now hard to find.

2 Strip the generator out of the EMT headshell and fit it to one of your choice. Recommended for those who have doubts about the resonant properties of EMT’s headshell and who also have the necessary skill, dexterity and patience to perform such a piece of surgery. The naked moving-coil generator is particularly vulnerable to damage, especially the very fine lead out wires from the coils. I have done such, fitting the generator into an ADC magnesium alloy headshell; but such an operation is not for the faint-hearted! If one is suitably adventurous enough, the generator could be installed in a ‘headshell-less’ arm design or fixed headshell design such as the Hadcock, Infinity ‘Black Widow’ or Graham designs. However the compliance of the EMT design is a moderate 12 cu, so lightweight arms are not necessarily desirable.

3 Use an adapter with a conventional EMT TSD design. This is what I have done recently and a method that requires further expansion.

The adapter I used is made by Ortofon and is designated APJ-1. Ortofon make this adapter, not for use with EMT cartridges but with their own C-type cartridges. These cartridges, made by Ortofon in the days before they introduced the longer ‘whale’- shaped headshell familiar to SPU users, use a short headshell designed to mate with the Ortofon RMA 229 and RF229 arms (supplied to EMT and fitted to the 927 and 930 turntables, before EMT came up with their own designs in 1951). The Ortofon C-type cartridges are (for whatever reason) now in production again and so Ortofon have made an adaptor so as to allow their use with conventional current pick-up arms. What this adaptor does is to extend the length of the bayonet stub by 21.5mm, so that the stylus to bayonet flange distance is the same as that of the SPU series. The adaptor thus consists of a short stub with a four-pole female bayonet connector at one end (to mate with the cartridge) and a four-pole male bayonet connector at the other (to mate with that of the arm).

The contact arrangements on the new Ortofon C-type cartridges follows the modern convention, however if the adapter is opened up by loosening a socket-headed grub screw, a second grub screw is revealed that allows the contacts of the female end of the adaptor to be rotated 45° with respect the keyway, as appropriate for EMT designs.

Now this might appear to solve matters, but it’s not quite so straightforward as that. First of all the Ortofon adapter increases the length of the headshell stub by 21.5mm. However the EMT XSD headshell stub is 19.0mm longer than that of the EMT TSD. 2.5mm difference in length implies a 2.5mm error in stylus overhang.

http://i780.photobucket.com/albums/yy88/barrydhunt/013-1.jpg?t=1290473682
Top: EMT TSD cartridge with Ortofon AJP-1 adapter, overall stub length 21.5mm. Bottom: EMT XSD cartridge, overall stub length 19.0mm.
Photo: BDH

In many arms the adjustment for overhang is made in the headshell. This cannot be done for the EMT/adapter arrangement. Even for arms using a slotted keyway-style arm base, such a large discrepancy might be outside the compass of adjustment if the arm is not positioned optimally relative to the turntable centre. I had to change the arm board on my Thorens 124 deck for one where the SME arm base slot was cut on a near radius, further away from the centre, and even then the arm base had to be positioned as far back as possible, achieving correct overhang but preventing the shielding can to be fitted. Fortunately no hum problems occurred.

The EMT TSD/Ortofon adapter combination weighs 24.2g, compared with 21.0g for the EMT XSD. When mounted in SME arms the arm cartridge resonant frequencies are 8.3Hz for the 3009/II arm, 8.7Hz for the 3009 Improved (this combination needs the 1902/HWR counterweight) and 8.1Hz when used in the 3012 pick-up arm. These figures become 8.8Hz, 9.3Hz and 8.5Hz respectively for the EMT XSD. All of these figures are slightly on the low side, however I have experienced no problems here.

The second consideration when using the Ortofon adapter concerns the precise electrical connection of the cartridge coils to the arm leads.


Electrical

As has been mentioned the contact arrangement on the EMT cartridges differ from convention. The contacts are arranged in a diamond shape: the two vertical contacts connect to the left-hand channel, with the lower contact connecting to the screen, and the two horizontal contacts connect to the right-hand channel, with the right hand contact connected to the corresponding screen. On conventional headshells, when looking into the bayonet connector, the two contacts on the left connect to the left-hand channel and those on the right to the right-hand channel. In both, the lower contacts connect to the screen of the arm lead out cables.

Now when the Ortofon adapter is fitted, with the female bayonet connector rotated by 45°, the two return connections (i.e. the screens) are transposed. What this means is that the return path for the left-hand channel is provided by the screen of the cable corresponding to the right-hand channel and vice versa. Under most situations this will not cause any problems as the screens of the two cables are connected together at the pre-amp. If however, the arm is wired in a balanced configuration, no end of problems will arise since the two coils are now effectively connected in series and in phase, giving a monophonic signal only!

[1] The current standard bayonet and contact arrangement was invented by Ortofon and was first adopted by SME. Owing to the widespread popularity of the SME design, the bayonet fitting is now generally known as the SME or SME/EIA bayonet. SME have always denied any claim to its design, correctly pointing out that credit for the design is due to Ortofon.

Alex_UK
23-11-2010, 07:02
Very interesting article, well written and illustrated as usual - thanks Barry. Doubt I will ever need the knowledge for practical purposes but good to know!

Marco
23-11-2010, 10:00
Excellent stuff, Barry! Surely an article to be included in the EMT section in The Library? :)

I've not had a chance to listen to the EMT yet, but will do soon :cool:

Marco.

hifi_dave
23-11-2010, 10:31
EMT cartridges are very good indeed - big, beefy, solid and dynamic.

Many, many years ago when the EMT cartridges cost £60 from F.W.O.Bauch in Borehamwood, I used to buy them, remove from their headshells and wire them onto Nagaoka shells. Of course I added some profit on top of the £60 and they sold very well against the high end cartridges of the day, which were much more expensive. I still have one somewhere in my box of golden oldies.

Now, of course, they are extremely expensive and used by the likes of Brinkmann, selling for thousands of Pounds.

DSJR
23-11-2010, 14:10
Do they cost more to make in material and labour terms, or is it yet another case of profit coming first?

Barry
23-11-2010, 15:39
Do they cost more to make in material and labour terms, or is it yet another case of profit coming first?

I wouldn't have thought the EMT designs are any more diffficult to make than any other MC design. I believe the Brinkman versions (headshell-less nude generators) have been 'fettled' and fitted with miniature tantalum capacitors; presumable to tame the 'untidy' top end of the EMTs. The Brinkmann arm is based on the Breuer and Breuer himself intended his arm to be used with his own, modified and nude, EMT cartridge.

The construction of all MCs seem to be labour intensive - but I'm not sure if the £60 in the '80s translates to the thousands charged today. Just look at how much Koetsu want for their Red Signature!

Regards

hifi_dave
23-11-2010, 16:44
When I used to buy them in for £60, they weren't trendy at all, just intended for 'professional' install. I used to mount them on a Nagaoka shell and solder them in with some fine Audionote wires. I believe we used to sell them for £150 or £200 when the Koetsu Red was £600-700 IIRC.

Barry
23-11-2010, 18:04
When I used to buy them in for £60, they weren't trendy at all, just intended for 'professional' install. I used to mount them on a Nagaoka shell and solder them in with some fine Audionote wires. I believe we used to sell them for £150 or £200 when the Koetsu Red was £600-700 IIRC.

How come you were able to buy them for £60? I first became aware of the EMT XSD15 through a comparative MC cartridge review in 'Practical Hi-Fi & Audio' in November 1976, where the EMT was used as a reference. At that time the XSD15 cost £176 inc. VAT.

Regards

hifi_dave
23-11-2010, 19:58
Trade price.

After all these years I can't remember exactly but it was approx £60.

DSJR
23-11-2010, 20:11
Looking at what I was earning in the mid 80's, I'd be living like a king if that was inflation-translated to today.

For example, in 1986 the Denon DL110 was £60, the Dynavector 10X4 was around £75. Today, with the £ re-devalued, the 110 is £130 or so (amazing how a 33% increase a couple of years ago actually means double once transferred to the punter) and the 10XV is £300 or so... An Ortofon OM20 stylus has tripled in price in this time as well and this means the Dual 505 cheapo special would be £300 if sold today - crazy!

The Grand Wazoo
23-11-2010, 20:44
Looking at what I was earning in the mid 80's, I'd be living like a king if that was inflation-translated to today.

For example, in 1986 the Denon DL110 was £60, the Dynavector 10X4 was around £75. Today, with the £ re-devalued, the 110 is £130 or so (amazing how a 33% increase a couple of years ago actually means double once transferred to the punter) and the 10XV is £300 or so... An Ortofon OM20 stylus has tripled in price in this time as well and this means the Dual 505 cheapo special would be £300 if sold today - crazy!

Well, try converting the value of your 1986 £60. This is what you get by several different methods:

Using the retail price index: £131.00

Using the GDP deflator: £130.00

Using the average earnings: £179.00

Using the per capita GDP: £197.00

Using the share of GDP: £215.00

DSJR
24-11-2010, 08:48
Looking at earnings, Gawd, I was doing well back then...