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No worries. It just means that the turns ratio in this transformer is such that when you plug the output of it into an MM stage with 47Kohms input impedance (almost all are), the impedance it then presents to the cartridge is 30 ohms. Which I reckon is exactly what an OC9 needs to see.Quote:
Originally Posted by JonR
Ah right - thanks again for the explanation, much appreciated.Quote:
Originally Posted by pure sound
There might be other problems too when using a transformer (step up) instead of an electronic circuit. If a transformer offers 47 or 50 kOhm at the output one has to take care that the link to the MM-input is very very short otherwise cable capacitance (and/or inductance) may filter out the higher octaves. I assume all of you know that LP records can have a bandwidth of 50 - 80 kHz?
A different thing is the input->output impedance relationship. The ratio is a given thing. So if the impedances relate to each other as 1:500 (most step-up's are) one has to take care when connecting to a 50 Ohm (or lower) cartridge impedance .....
If someone is interested I could design a (relatively) cheap active circuit and offer you the pcb with or without components.
Have fun
John
Series capacitance is a low pass filter and series inductance is a high pass filter and series resistance is volume filter ;) AND transformers have all three in far greater quantity than a good active circuit, capacitance especially if you are using an interconnect of any length. Your dealing with minute voltages (relatively), much easier to mess up than line level voltages.Quote:
Originally Posted by johnrtd
The only need for them is that you cannot design a valve mc stage unless it is unacceptably noisy. So out of a design necessity the marketing men try to create an artificial advantage - "don't sell the meat sell the sizzle".
Richard,
As with anything in hi-fi, there is no 'true path' or one 'best' way of dealing with a problem.
I've got quite a bit of experience of active MC stages and transformers with a variety of cartridges and I've come to the conclusion that unless the transformer has been specifically designed to partner an MC cartridge, preferably if it's made by the same manufacturer, and therefore the electrical specifications are properly matched, then you're better off with a good active design.
However, in instances where the cartridge and transformer have been designed to operate together from the ground up by the same manufacturer, or where a manufacturer has specifically designed a transformer that optimises the performance of a particular cartridge, then this in my experience gives the best results. Manufacturers who come into that category are the likes of Audionote, Ortofon and Denon.
The problem with a lot of MC transformers is that they're not specifically designed to optimise the performance of a particular cartridge sonically and electrically - they're designed for general use in many cases by manufacturers who do not design cartridges, so ultimate performance is not achievable unless you're very lucky and just happen to hit upon a perfect match.
Therefore to conclude, use a good active MC stage if your cartridge manufacturer does not supply an optimised transformer for that cartridge, but if your cartridge manufacturer provides a matching transformer then that will give ultimate performance for that cartridge. I have never heard a better sound from my Denon DL-103 Pro than when used with a good MM stage (preferably valve) and Denon's own step-up transformer or my Auditorium 23, which is the result of someone's years of experimentation to find the ultimate transformer match for the 103, and a unique understanding and experience of how that particular cartridge works. It will be the same with those who have produced devices for Ortofon and Audionote.
Marco.
Well ask any valve amplifier designer and if he is being honest and not following the marketing path, he will tell you that he would much prefer to use valve active stages than a transformer, but he can't!!!Quote:
Originally Posted by Marco
So a deficiency is turned into an asset for marketing purposes. Now the real argument is between solid state and valve phono stages. Losing bandwidth and dynamic contrast in exchange for rose coloured glasses, a trade off all are making decisions for. It is human nature to want change and also to follow the most exciting band wagon (marketing). BUT *NOTHING* is perfect, everything is a compromise, the current move to valve will have a corresponding backlash, when people realise that bits of the baby have gone down the plughole. This is why Gromits audio adventures (good title for a book) is so informative and humerous. He is going through all the stages it normally takes people months or years to go through, and is at a regressive stage having gone through valves, then to information and clarity, now back to drive and presence. Hopefully he will realise nothing is perfect and the state of the art *does not exist* and it is down to an individuals *acceptable compromise* that will makes you happy.
Quite simply there is no *best* anything, there is better, worse and different.
Richard,
I know what you mean by "rose coloured glasses." I'm not yet ready to wear mine.
Hi Richard,
I wouldn't ever choose to use a valve MC stage. Transformer every time, particularly with the cartridge I use at home. 0.04mV out needing to see 2-3 ohms!
The majority of cartridge manufacturers also choose to make and generally recommend transformers too. (Denon, Ortofon, Audio Technica, AudioNote, Shelter etc)
Gromit's adventures have been interesting to follow but the decisions he's making are very much based on the speakers he can get to work in his room. He seems to be enjoying the Naim stuff at the moment. Where next I wonder?
Don't you know the equation relating to head room v load impedance, also load rejecting circuit design. I say again the only thing that makes transformers necessary in this application is the electrical characteristics of valves, those constraints are not there in solid state designs. When you are working on the edge of what is possible then loading influences enormously and transformer into cable into valves is just that at that voltage level.Quote:
Originally Posted by pure sound
You know as well as I do why there is the necessity for output transformers with valves amps and how many people have tried to produce a reliable and sensible OTL to counter this. Are you telling me that given the choice you wouldn't get rid of the most expensive and critical component in valve amp design if you could?
I also know the inherent advantages of valve circuits, I wish I could get transistor circuits that simple, I keep trying :scratch: They are just different methods to catch the same monkey, and he is a slippery bugger.
I've yet to hear an OTL that I liked. The nearest thing I've heard to one that works is the Berning which uses a high frequency impedance converter
http://www.davidberning.com/technology
however, even then I prefer the sound of a good transformer coupled amp!